Changeset - 62d63e1cec92
[Not reviewed]
MH - 3 years ago 2022-03-04 19:18:58
contact@maxhenger.nl
Fix conditional compilation, remove some warnings
9 files changed with 22 insertions and 29 deletions:
0 comments (0 inline, 0 general)
src/protocol/eval/executor.rs
Show inline comments
 

	
 
use std::collections::VecDeque;
 

	
 
use super::value::*;
 
use super::store::*;
 
use super::error::*;
 
use crate::protocol::*;
 
use crate::protocol::ast::*;
 
use crate::protocol::type_table::*;
 

	
 
macro_rules! debug_enabled { () => { false }; }
 
macro_rules! debug_log {
 
    ($format:literal) => {
 
        enabled_debug_print!(false, "exec", $format);
 
    };
 
    ($format:literal, $($args:expr),*) => {
 
        enabled_debug_print!(false, "exec", $format, $($args),*);
 
    };
 
}
 

	
 
#[derive(Debug, Clone)]
 
pub(crate) enum ExprInstruction {
 
    EvalExpr(ExpressionId),
 
    PushValToFront,
 
}
 

	
 
#[derive(Debug, Clone)]
 
pub(crate) struct Frame {
 
    pub(crate) definition: ProcedureDefinitionId,
 
    pub(crate) monomorph_type_id: TypeId,
 
    pub(crate) monomorph_index: usize,
 
    pub(crate) position: StatementId,
 
    pub(crate) expr_stack: VecDeque<ExprInstruction>, // hack for expression evaluation, evaluated by popping from back
 
    pub(crate) expr_values: VecDeque<Value>, // hack for expression results, evaluated by popping from front/back
 
    pub(crate) max_stack_size: u32,
 
}
 

	
 
impl Frame {
 
    /// Creates a new execution frame. Does not modify the stack in any way.
 
    pub fn new(heap: &Heap, definition_id: ProcedureDefinitionId, monomorph_type_id: TypeId, monomorph_index: u32) -> Self {
 
    pub fn new(heap: &Heap, definition_id: ProcedureDefinitionId, _monomorph_type_id: TypeId, monomorph_index: u32) -> Self {
 
        let definition = &heap[definition_id];
 
        let outer_scope_id = definition.scope;
 
        let first_statement_id = definition.body;
 

	
 
        // Another not-so-pretty thing that has to be replaced somewhere in the
 
        // future...
 
        fn determine_max_stack_size(heap: &Heap, scope_id: ScopeId, max_size: &mut u32) {
 
            let scope = &heap[scope_id];
 

	
 
            // Check current block
 
            let cur_size = scope.next_unique_id_in_scope as u32;
 
            if cur_size > *max_size { *max_size = cur_size; }
 

	
 
            // And child blocks
 
            for child_scope in &scope.nested {
 
                determine_max_stack_size(heap, *child_scope, max_size);
 
            }
 
        }
 

	
 
        let mut max_stack_size = 0;
 
        determine_max_stack_size(heap, outer_scope_id, &mut max_stack_size);
 

	
 
        Frame{
 
            definition: definition_id,
 
            monomorph_type_id,
 
            monomorph_index: monomorph_index as usize,
 
            position: first_statement_id.upcast(),
 
            expr_stack: VecDeque::with_capacity(128),
 
            expr_values: VecDeque::with_capacity(128),
 
            max_stack_size,
 
        }
 
    }
 

	
 
    /// Prepares a single expression for execution. This involves walking the
 
    /// expression tree and putting them in the `expr_stack` such that
 
    /// continuously popping from its back will evaluate the expression. The
 
    /// results of each expression will be stored by pushing onto `expr_values`.
 
    pub fn prepare_single_expression(&mut self, heap: &Heap, expr_id: ExpressionId) {
 
        debug_assert!(self.expr_stack.is_empty());
 
        self.expr_values.clear(); // May not be empty if last expression result(s) were discarded
 

	
 
        self.serialize_expression(heap, expr_id);
 
    }
 

	
 
    /// Prepares multiple expressions for execution (i.e. evaluating all
 
    /// function arguments or all elements of an array/union literal). Per
 
    /// expression this works the same as `prepare_single_expression`. However
 
    /// after each expression is evaluated we insert a `PushValToFront`
 
    /// instruction
 
    pub fn prepare_multiple_expressions(&mut self, heap: &Heap, expr_ids: &[ExpressionId]) {
 
        debug_assert!(self.expr_stack.is_empty());
 
        self.expr_values.clear();
 

	
 
        for expr_id in expr_ids {
 
            self.expr_stack.push_back(ExprInstruction::PushValToFront);
 
            self.serialize_expression(heap, *expr_id);
 
        }
 
    }
 

	
 
    /// Performs depth-first serialization of expression tree. Let's not care
 
    /// about performance for a temporary runtime implementation
 
    fn serialize_expression(&mut self, heap: &Heap, id: ExpressionId) {
 
        self.expr_stack.push_back(ExprInstruction::EvalExpr(id));
 

	
 
        match &heap[id] {
 
            Expression::Assignment(expr) => {
 
                self.serialize_expression(heap, expr.left);
 
                self.serialize_expression(heap, expr.right);
 
            },
 
            Expression::Binding(expr) => {
 
                self.serialize_expression(heap, expr.bound_to);
 
                self.serialize_expression(heap, expr.bound_from);
 
            },
 
            Expression::Conditional(expr) => {
 
                self.serialize_expression(heap, expr.test);
 
            },
 
            Expression::Binary(expr) => {
 
                self.serialize_expression(heap, expr.left);
 
                self.serialize_expression(heap, expr.right);
 
            },
 
            Expression::Unary(expr) => {
 
                self.serialize_expression(heap, expr.expression);
 
            },
 
            Expression::Indexing(expr) => {
 
                self.serialize_expression(heap, expr.index);
 
                self.serialize_expression(heap, expr.subject);
 
            },
 
            Expression::Slicing(expr) => {
 
                self.serialize_expression(heap, expr.from_index);
 
                self.serialize_expression(heap, expr.to_index);
 
                self.serialize_expression(heap, expr.subject);
 
            },
 
            Expression::Select(expr) => {
 
                self.serialize_expression(heap, expr.subject);
 
            },
 
            Expression::Literal(expr) => {
 
                // Here we only care about literals that have subexpressions
 
                match &expr.value {
 
                    Literal::Null | Literal::True | Literal::False |
 
                    Literal::Character(_) | Literal::String(_) |
 
                    Literal::Integer(_) | Literal::Enum(_) => {
 
                        // No subexpressions
 
                    },
 
                    Literal::Struct(literal) => {
 
                        // Note: fields expressions are evaluated in programmer-
 
                        // specified order. But struct construction expects them
 
                        // in type-defined order. I might want to come back to
 
                        // this.
 
                        let mut _num_pushed = 0;
 
                        for want_field_idx in 0..literal.fields.len() {
 
                            for field in &literal.fields {
 
                                if field.field_idx == want_field_idx {
 
                                    _num_pushed += 1;
 
                                    self.expr_stack.push_back(ExprInstruction::PushValToFront);
 
                                    self.serialize_expression(heap, field.value);
 
                                }
 
                            }
 
                        }
 
                        debug_assert_eq!(_num_pushed, literal.fields.len())
 
                    },
 
                    Literal::Union(literal) => {
src/protocol/parser/pass_rewriting.rs
Show inline comments
 
@@ -174,193 +174,193 @@ impl Visitor for PassRewriting {
 
                call_id_section.push(call_id);
 
                expr_id_section.push(expr_id);
 
            }
 
        }
 

	
 
        // Transform all of the call expressions by takings its argument (the
 
        // port from which we `get`) and turning it into a temporary variable.
 
        let mut transformed_stmts = Vec::with_capacity(total_num_ports); // TODO: Recompute this preallocated length, put assert at the end
 
        let mut locals = Vec::with_capacity(total_num_ports);
 

	
 
        for port_var_idx in 0..call_id_section.len() {
 
            let get_call_expr_id = call_id_section[port_var_idx];
 
            let port_expr_id = expr_id_section[port_var_idx];
 
            let port_type_index = ctx.heap[port_expr_id].type_index();
 
            let port_type_ref = TypeIdReference::IndirectSameAsExpr(port_type_index);
 

	
 
            // Move the port expression such that it gets assigned to a temporary variable
 
            let variable_id = create_ast_variable(ctx, outer_scope_id);
 
            let variable_decl_stmt_id = create_ast_variable_declaration_stmt(ctx, self.current_procedure_id, variable_id, port_type_ref, port_expr_id);
 

	
 
            // Replace the original port expression in the call with a reference
 
            // to the replacement variable
 
            let variable_expr_id = create_ast_variable_expr(ctx, self.current_procedure_id, variable_id, port_type_ref);
 
            let call_expr = &mut ctx.heap[get_call_expr_id];
 
            call_expr.arguments[0] = variable_expr_id.upcast();
 

	
 
            transformed_stmts.push(variable_decl_stmt_id.upcast().upcast());
 
            locals.push((variable_id, port_type_ref));
 
        }
 

	
 
        // Insert runtime calls that facilitate the semantics of the select
 
        // block.
 

	
 
        // Create the call that indicates the start of the select block
 
        {
 
            let num_cases_expression_id = create_ast_literal_integer_expr(ctx, self.current_procedure_id, total_num_cases as u64, ctx.arch.uint32_type_id);
 
            let num_ports_expression_id = create_ast_literal_integer_expr(ctx, self.current_procedure_id, total_num_ports as u64, ctx.arch.uint32_type_id);
 
            let arguments = vec![
 
                num_cases_expression_id.upcast(),
 
                num_ports_expression_id.upcast()
 
            ];
 

	
 
            let call_expression_id = create_ast_call_expr(ctx, self.current_procedure_id, Method::SelectStart, &mut self.expression_buffer, arguments);
 
            let call_statement_id = create_ast_expression_stmt(ctx, call_expression_id.upcast());
 

	
 
            transformed_stmts.push(call_statement_id.upcast());
 
        }
 

	
 
        // Create calls for each select case that will register the ports that
 
        // we are waiting on at the runtime.
 
        {
 
            let mut total_port_index = 0;
 
            for case_index in 0..total_num_cases {
 
                let case = &ctx.heap[id].cases[case_index];
 
                let case_num_ports = case.involved_ports.len();
 

	
 
                for case_port_index in 0..case_num_ports {
 
                    // Arguments to runtime call
 
                    let (port_variable_id, port_variable_type) = locals[total_port_index]; // so far this variable contains the temporary variables for the port expressions
 
                    let case_index_expr_id = create_ast_literal_integer_expr(ctx, self.current_procedure_id, case_index as u64, ctx.arch.uint32_type_id);
 
                    let port_index_expr_id = create_ast_literal_integer_expr(ctx, self.current_procedure_id, case_port_index as u64, ctx.arch.uint32_type_id);
 
                    let port_variable_expr_id = create_ast_variable_expr(ctx, self.current_procedure_id, port_variable_id, port_variable_type);
 
                    let runtime_call_arguments = vec![
 
                        case_index_expr_id.upcast(),
 
                        port_index_expr_id.upcast(),
 
                        port_variable_expr_id.upcast()
 
                    ];
 

	
 
                    // Create runtime call, then store it
 
                    let runtime_call_expr_id = create_ast_call_expr(ctx, self.current_procedure_id, Method::SelectRegisterCasePort, &mut self.expression_buffer, runtime_call_arguments);
 
                    let runtime_call_stmt_id = create_ast_expression_stmt(ctx, runtime_call_expr_id.upcast());
 

	
 
                    transformed_stmts.push(runtime_call_stmt_id.upcast());
 

	
 
                    total_port_index += 1;
 
                }
 
            }
 
        }
 

	
 
        // Create the variable that will hold the result of a completed select
 
        // block. Then create the runtime call that will produce this result
 
        let select_variable_id = create_ast_variable(ctx, outer_scope_id);
 
        let select_variable_type = TypeIdReference::DirectTypeId(ctx.arch.uint32_type_id);
 
        locals.push((select_variable_id, select_variable_type));
 

	
 
        {
 
            let runtime_call_expr_id = create_ast_call_expr(ctx, self.current_procedure_id, Method::SelectWait, &mut self.expression_buffer, Vec::new());
 
            let variable_stmt_id = create_ast_variable_declaration_stmt(ctx, self.current_procedure_id, select_variable_id, select_variable_type, runtime_call_expr_id.upcast());
 
            transformed_stmts.push(variable_stmt_id.upcast().upcast());
 
        }
 

	
 
        call_id_section.forget();
 
        expr_id_section.forget();
 

	
 
        // Now we transform each of the select block case's guard and code into
 
        // a chained if-else statement.
 
        let mut relative_pos = transformed_stmts.len() as i32;
 
        let relative_pos = transformed_stmts.len() as i32;
 
        if total_num_cases > 0 {
 
            let (if_stmt_id, end_if_stmt_id, scope_id) = transform_select_case_code(ctx, self.current_procedure_id, id, 0, select_variable_id, select_variable_type);
 
            link_existing_child_to_new_parent_scope(ctx, &mut self.scope_buffer, outer_scope_id, scope_id, relative_pos);
 
            let first_end_if_stmt = &mut ctx.heap[end_if_stmt_id];
 
            first_end_if_stmt.next = outer_end_block_id.upcast();
 

	
 
            let mut last_if_stmt_id = if_stmt_id;
 
            let mut last_end_if_stmt_id = end_if_stmt_id;
 
            let mut last_parent_scope_id = outer_scope_id;
 
            let mut last_relative_pos = transformed_stmts.len() as i32 + 1;
 
            transformed_stmts.push(last_if_stmt_id.upcast());
 

	
 
            for case_index in 1..total_num_cases {
 
                let (if_stmt_id, end_if_stmt_id, scope_id) = transform_select_case_code(ctx, self.current_procedure_id, id, case_index, select_variable_id, select_variable_type);
 
                let false_case_scope_id = ctx.heap.alloc_scope(|this| Scope::new(this, ScopeAssociation::If(last_if_stmt_id, false)));
 
                link_existing_child_to_new_parent_scope(ctx, &mut self.scope_buffer, false_case_scope_id, scope_id, 0);
 
                link_new_child_to_existing_parent_scope(ctx, &mut self.scope_buffer, last_parent_scope_id, false_case_scope_id, last_relative_pos);
 
                set_ast_if_statement_false_body(ctx, last_if_stmt_id, last_end_if_stmt_id, IfStatementCase{ body: if_stmt_id.upcast(), scope: false_case_scope_id });
 

	
 
                let end_if_stmt = &mut ctx.heap[end_if_stmt_id];
 
                end_if_stmt.next = last_end_if_stmt_id.upcast();
 

	
 
                last_if_stmt_id = if_stmt_id;
 
                last_end_if_stmt_id = end_if_stmt_id;
 
                last_parent_scope_id = false_case_scope_id;
 
                last_relative_pos = 0;
 
            }
 
        }
 

	
 
        // Final steps: set the statements of the replacement block statement,
 
        // link all of those statements together, and update the scopes.
 
        let first_stmt_id = transformed_stmts[0];
 
        let mut last_stmt_id = transformed_stmts[0];
 
        for stmt_id in transformed_stmts.iter().skip(1).copied() {
 
            set_ast_statement_next(ctx, last_stmt_id, stmt_id);
 
            last_stmt_id = stmt_id;
 
        }
 

	
 
        if total_num_cases == 0 {
 
            // If we don't have any cases, then we didn't connect the statements
 
            // up to the end of the outer block, so do that here
 
            set_ast_statement_next(ctx, last_stmt_id, outer_end_block_id.upcast());
 
        }
 

	
 
        let outer_block_stmt = &mut ctx.heap[outer_block_id];
 
        outer_block_stmt.next = first_stmt_id;
 
        outer_block_stmt.statements = transformed_stmts;
 

	
 
        return Ok(())
 
    }
 
}
 

	
 
// -----------------------------------------------------------------------------
 
// Utilities to create compiler-generated AST nodes
 
// -----------------------------------------------------------------------------
 

	
 
#[derive(Clone, Copy)]
 
enum TypeIdReference {
 
    DirectTypeId(TypeId),
 
    IndirectSameAsExpr(i32), // by type index
 
}
 

	
 
fn create_ast_variable(ctx: &mut Ctx, scope_id: ScopeId) -> VariableId {
 
    let variable_id = ctx.heap.alloc_variable(|this| Variable{
 
        this,
 
        kind: VariableKind::Local,
 
        parser_type: ParserType{
 
            elements: Vec::new(),
 
            full_span: InputSpan::new(),
 
        },
 
        identifier: Identifier::new_empty(InputSpan::new()),
 
        relative_pos_in_parent: -1,
 
        unique_id_in_scope: -1,
 
    });
 
    let scope = &mut ctx.heap[scope_id];
 
    scope.variables.push(variable_id);
 

	
 
    return variable_id;
 
}
 

	
 
fn create_ast_variable_expr(ctx: &mut Ctx, containing_procedure_id: ProcedureDefinitionId, variable_id: VariableId, variable_type_id: TypeIdReference) -> VariableExpressionId {
 
    let variable_type_index = add_new_procedure_expression_type(ctx, containing_procedure_id, variable_type_id);
 
    return ctx.heap.alloc_variable_expression(|this| VariableExpression{
 
        this,
 
        identifier: Identifier::new_empty(InputSpan::new()),
 
        declaration: Some(variable_id),
 
        used_as_binding_target: false,
 
        parent: ExpressionParent::None,
 
        type_index: variable_type_index,
 
    });
 
}
 

	
 
fn create_ast_call_expr(ctx: &mut Ctx, containing_procedure_id: ProcedureDefinitionId, method: Method, buffer: &mut ScopedBuffer<ExpressionId>, arguments: Vec<ExpressionId>) -> CallExpressionId {
 
    let call_type_id = match method {
 
        Method::SelectStart => ctx.arch.void_type_id,
 
        Method::SelectRegisterCasePort => ctx.arch.void_type_id,
src/protocol/parser/pass_validation_linking.rs
Show inline comments
 
@@ -1200,197 +1200,197 @@ impl Visitor for PassValidationLinking {
 
            }
 
        }
 

	
 
        if expecting_wrapping_new_stmt {
 
            if !self.expr_parent.is_new() {
 
                let call_span = call_expr.func_span;
 
                return Err(ParseError::new_error_str_at_span(
 
                    &ctx.module().source, call_span,
 
                    "cannot call a component, it can only be instantiated by using 'new'"
 
                ));
 
            }
 
        } else {
 
            if self.expr_parent.is_new() {
 
                let call_span = call_expr.func_span;
 
                return Err(ParseError::new_error_str_at_span(
 
                    &ctx.module().source, call_span,
 
                    "only components can be instantiated, this is a function"
 
                ));
 
            }
 
        }
 

	
 
        // Check the number of arguments
 
        let call_definition = ctx.types.get_base_definition(&call_expr.procedure.upcast()).unwrap();
 
        let num_expected_args = match &call_definition.definition {
 
            DefinedTypeVariant::Procedure(definition) => definition.arguments.len(),
 
            _ => unreachable!(),
 
        };
 

	
 
        let num_provided_args = call_expr.arguments.len();
 
        if num_provided_args != num_expected_args {
 
            let argument_text = if num_expected_args == 1 { "argument" } else { "arguments" };
 
            let call_span = call_expr.full_span;
 
            return Err(ParseError::new_error_at_span(
 
                &ctx.module().source, call_span, format!(
 
                    "expected {} {}, but {} were provided",
 
                    num_expected_args, argument_text, num_provided_args
 
                )
 
            ));
 
        }
 

	
 
        // Recurse into all of the arguments and set the expression's parent
 
        let upcast_id = id.upcast();
 

	
 
        let section = self.expression_buffer.start_section_initialized(&call_expr.arguments);
 
        let old_expr_parent = self.expr_parent;
 
        call_expr.parent = old_expr_parent;
 

	
 
        for arg_expr_idx in 0..section.len() {
 
            let arg_expr_id = section[arg_expr_idx];
 
            self.expr_parent = ExpressionParent::Expression(upcast_id, arg_expr_idx as u32);
 
            self.visit_expr(ctx, arg_expr_id)?;
 
        }
 

	
 
        section.forget();
 
        self.expr_parent = old_expr_parent;
 

	
 
        Ok(())
 
    }
 

	
 
    fn visit_variable_expr(&mut self, ctx: &mut Ctx, id: VariableExpressionId) -> VisitorResult {
 
        let var_expr = &ctx.heap[id];
 

	
 
        // Check if declaration was already resolved (this occurs for the
 
        // variable expr that is on the LHS of the assignment expr that is
 
        // associated with a variable declaration)
 
        let mut variable_id = var_expr.declaration;
 
        let mut is_binding_target = false;
 

	
 
        // Otherwise try to find it
 
        if variable_id.is_none() {
 
            variable_id = self.find_variable(ctx, self.relative_pos_in_parent, &var_expr.identifier);
 
        }
 

	
 
        // Otherwise try to see if is a variable introduced by a binding expr
 
        let variable_id = if let Some(variable_id) = variable_id {
 
            variable_id
 
        } else {
 
            if self.in_binding_expr.is_invalid() || !self.in_binding_expr_lhs {
 
                return Err(ParseError::new_error_str_at_span(
 
                    &ctx.module().source, var_expr.identifier.span, "unresolved variable"
 
                ));
 
            }
 

	
 
            // This is a binding variable, but it may only appear in very
 
            // specific locations.
 
            let is_valid_binding = match self.expr_parent {
 
                ExpressionParent::Expression(expr_id, idx) => {
 
                    match &ctx.heap[expr_id] {
 
                        Expression::Binding(_binding_expr) => {
 
                            // Nested binding is disallowed, and because of
 
                            // the check above we know we're directly at the
 
                            // LHS of the binding expression
 
                            debug_assert_eq!(_binding_expr.this, self.in_binding_expr);
 
                            debug_assert_eq!(idx, 0);
 
                            true
 
                        }
 
                        Expression::Literal(lit_expr) => {
 
                        Expression::Literal(_lit_expr) => {
 
                            // Only struct, unions, tuples and arrays can
 
                            // have subexpressions, so we're always fine
 
                            dbg_code!({
 
                                match lit_expr.value {
 
                                match _lit_expr.value {
 
                                    Literal::Struct(_) | Literal::Union(_) | Literal::Array(_) | Literal::Tuple(_) => {},
 
                                    _ => unreachable!(),
 
                                }
 
                            });
 

	
 
                            true
 
                        },
 
                        _ => false,
 
                    }
 
                },
 
                _ => {
 
                    false
 
                }
 
            };
 

	
 
            if !is_valid_binding {
 
                let binding_expr = &ctx.heap[self.in_binding_expr];
 
                return Err(ParseError::new_error_str_at_span(
 
                    &ctx.module().source, var_expr.identifier.span,
 
                    "illegal location for binding variable: binding variables may only be nested under a binding expression, or a struct, union or array literal"
 
                ).with_info_at_span(
 
                    &ctx.module().source, binding_expr.operator_span, format!(
 
                        "'{}' was interpreted as a binding variable because the variable is not declared and it is nested under this binding expression",
 
                        var_expr.identifier.value.as_str()
 
                    )
 
                ));
 
            }
 

	
 
            // By now we know that this is a valid binding expression. Given
 
            // that a binding expression must be nested under an if/while
 
            // statement, we now add the variable to the scope associated with
 
            // that statement.
 
            let bound_identifier = var_expr.identifier.clone();
 
            let bound_variable_id = ctx.heap.alloc_variable(|this| Variable {
 
                this,
 
                kind: VariableKind::Binding,
 
                parser_type: ParserType {
 
                    elements: vec![ParserTypeElement {
 
                        element_span: bound_identifier.span,
 
                        variant: ParserTypeVariant::Inferred
 
                    }],
 
                    full_span: bound_identifier.span
 
                },
 
                identifier: bound_identifier,
 
                relative_pos_in_parent: 0,
 
                unique_id_in_scope: -1,
 
            });
 

	
 
            let scope_id = match &ctx.heap[self.in_test_expr] {
 
                Statement::If(stmt) => stmt.true_case.scope,
 
                Statement::While(stmt) => stmt.scope,
 
                _ => unreachable!(),
 
            };
 

	
 
            self.checked_at_single_scope_add_local(ctx, scope_id, -1, bound_variable_id)?; // add at -1 such that first statement can find the variable if needed
 

	
 
            is_binding_target = true;
 
            bound_variable_id
 
        };
 

	
 
        let var_expr = &mut ctx.heap[id];
 
        var_expr.declaration = Some(variable_id);
 
        var_expr.used_as_binding_target = is_binding_target;
 
        var_expr.parent = self.expr_parent;
 

	
 
        Ok(())
 
    }
 
}
 

	
 
impl PassValidationLinking {
 
    //--------------------------------------------------------------------------
 
    // Special traversal
 
    //--------------------------------------------------------------------------
 

	
 
    /// Pushes a new scope associated with a particular statement. If that
 
    /// statement already has an associated scope (i.e. scope associated with
 
    /// sync statement or select statement's arm) then we won't do anything.
 
    /// In all cases the caller must call `pop_statement_scope` with the scope
 
    /// and relative scope position returned by this function.
 
    fn push_scope(&mut self, ctx: &mut Ctx, is_top_level_scope: bool, pushed_scope_id: ScopeId) -> (ScopeId, i32) {
 
        // Set the properties of the pushed scope (it is already created during
 
        // AST construction, but most values are not yet set to their correct
 
        // values)
 
        let old_scope_id = self.cur_scope;
 

	
 
        let scope = &mut ctx.heap[pushed_scope_id];
 
        if !is_top_level_scope {
 
            scope.parent = Some(old_scope_id);
 
        }
 

	
 
        scope.relative_pos_in_parent = self.relative_pos_in_parent;
 
        let old_relative_pos = self.relative_pos_in_parent;
 
        self.relative_pos_in_parent = 0;
 

	
 
        // Link up scopes
 
        if !is_top_level_scope {
src/protocol/parser/type_table.rs
Show inline comments
 
/**
 
 * type_table.rs
 
 *
 
 * The type table is a lookup from AST definition (which contains just what the
 
 * programmer typed) to a type with additional information computed (e.g. the
 
 * byte size and offsets of struct members). The type table should be considered
 
 * the authoritative source of information on types by the compiler (not the
 
 * AST itself!).
 
 *
 
 * The type table operates in two modes: one is where we just look up the type,
 
 * check its fields for correctness and mark whether it is polymorphic or not.
 
 * The second one is where we compute byte sizes, alignment and offsets.
 
 *
 
 * The basic algorithm for type resolving and computing byte sizes is to
 
 * recursively try to lay out each member type of a particular type. This is
 
 * done in a stack-like fashion, where each embedded type pushes a breadcrumb
 
 * unto the stack. We may discover a cycle in embedded types (we call this a
 
 * "type loop"). After which the type table attempts to break the type loop by
 
 * making specific types heap-allocated. Upon doing so we know their size
 
 * because their stack-size is now based on pointers. Hence breaking the type
 
 * loop required for computing the byte size of types.
 
 *
 
 * The reason for these type shenanigans is because PDL is a value-based
 
 * language, but we would still like to be able to express recursively defined
 
 * types like trees or linked lists. Hence we need to insert pointers somewhere
 
 * to break these cycles.
 
 *
 
 * We will insert these pointers into the variants of unions. However note that
 
 * we can only compute the stack size of a union until we've looked at *all*
 
 * variants. Hence we perform an initial pass where we detect type loops, a
 
 * second pass where we compute the stack sizes of everything, and a third pass
 
 * where we actually compute the size of the heap allocations for unions.
 
 *
 
 * As a final bit of global documentation: non-polymorphic types will always
 
 * have one "monomorph" entry. This contains the non-polymorphic type's memory
 
 * layout.
 
 */
 

	
 
// Programmer note: deduplication of types is currently disabled, see the
 
// @Deduplication key. Tests might fail when it is re-enabled.
 
use std::collections::HashMap;
 
use std::hash::{Hash, Hasher};
 

	
 
use crate::protocol::ast::*;
 
use crate::protocol::parser::symbol_table::SymbolScope;
 
use crate::protocol::input_source::ParseError;
 
use crate::protocol::parser::*;
 

	
 
//------------------------------------------------------------------------------
 
// Defined Types
 
//------------------------------------------------------------------------------
 

	
 
/// Struct wrapping around a potentially polymorphic type. If the type does not
 
/// have any polymorphic arguments then it will not have any monomorphs and
 
/// `is_polymorph` will be set to `false`. A type with polymorphic arguments
 
/// only has `is_polymorph` set to `true` if the polymorphic arguments actually
 
/// appear in the types associated types (function return argument, struct
 
/// field, enum variant, etc.). Otherwise the polymorphic argument is just a
 
/// marker and does not influence the bytesize of the type.
 
#[allow(unused)]
 
pub struct DefinedType {
 
    pub(crate) ast_root: RootId,
 
    pub(crate) ast_definition: DefinitionId,
 
    pub(crate) definition: DefinedTypeVariant,
 
    pub(crate) poly_vars: Vec<PolymorphicVariable>,
 
    pub(crate) is_polymorph: bool,
 
}
 

	
 
pub enum DefinedTypeVariant {
 
    Enum(EnumType),
 
    Union(UnionType),
 
    Struct(StructType),
 
    Procedure(ProcedureType),
 
}
 

	
 
impl DefinedTypeVariant {
 
    pub(crate) fn is_data_type(&self) -> bool {
 
        use DefinedTypeVariant as DTV;
 

	
 
        match self {
 
            DTV::Struct(_) | DTV::Enum(_) | DTV::Union(_) => return true,
 
            DTV::Procedure(_) => return false,
 
        }
 
    }
 

	
 
    pub(crate) fn as_struct(&self) -> &StructType {
 
        match self {
 
            DefinedTypeVariant::Struct(v) => v,
 
            _ => unreachable!()
 
        }
 
    }
 

	
 
    pub(crate) fn as_enum(&self) -> &EnumType {
 
        match self {
 
            DefinedTypeVariant::Enum(v) => v,
 
            _ => unreachable!()
 
        }
 
    }
 

	
 
    pub(crate) fn as_union(&self) -> &UnionType {
 
        match self {
 
            DefinedTypeVariant::Union(v) => v,
 
            _ => unreachable!()
 
        }
 
    }
 
}
 

	
 
pub struct PolymorphicVariable {
 
    pub(crate) identifier: Identifier,
 
    pub(crate) is_in_use: bool, // a polymorphic argument may be defined, but not used by the type definition
 
}
 

	
 
/// `EnumType` is the classical C/C++ enum type. It has various variants with
 
/// an assigned integer value. The integer values may be user-defined,
 
/// compiler-defined, or a mix of the two. If a user assigns the same enum
 
/// value multiple times, we assume the user is an expert and we consider both
 
/// variants to be equal to one another.
 
pub struct EnumType {
 
    pub variants: Vec<EnumVariant>,
 
    pub minimum_tag_value: i64,
 
    pub maximum_tag_value: i64,
 
    pub tag_type: ConcreteType,
 
    pub size: usize,
 
    pub alignment: usize,
 
}
 

	
 
// TODO: Also support maximum u64 value
 
pub struct EnumVariant {
 
    pub identifier: Identifier,
 
    pub value: i64,
 
}
 

	
 
/// `UnionType` is the algebraic datatype (or sum type, or discriminated union).
 
/// A value is an element of the union, identified by its tag, and may contain
 
/// a single subtype.
 
/// For potentially infinite types (i.e. a tree, or a linked list) only unions
 
/// can break the infinite cycle. So when we lay out these unions in memory we
 
/// will reserve enough space on the stack for all union variants that do not
 
/// cause "type loops" (i.e. a union `A` with a variant containing a struct
 
/// `B`). And we will reserve enough space on the heap (and store a pointer in
 
/// the union) for all variants which do cause type loops (i.e. a union `A`
 
/// with a variant to a struct `B` that contains the union `A` again).
 
pub struct UnionType {
 
    pub variants: Vec<UnionVariant>,
 
    pub tag_type: ConcreteType,
 
    pub tag_size: usize,
 
}
 

	
 
pub struct UnionVariant {
 
    pub identifier: Identifier,
 
    pub embedded: Vec<ParserType>, // zero-length does not have embedded values
 
    pub tag_value: i64,
 
}
 

	
 
/// `StructType` is a generic C-like struct type (or record type, or product
 
/// type) type.
 
@@ -1362,194 +1363,192 @@ impl TypeTable {
 
            let ast_root_id = ast_definition.defined_in();
 

	
 
            return (
 
                &modules[ast_root_id.index as usize].source,
 
                ast_definition.identifier().span,
 
                message
 
            );
 
        }
 

	
 
        fn construct_type_loop_error(mono_types: &MonoTypeArray, type_loop: &TypeLoop, modules: &[Module], heap: &Heap) -> ParseError {
 
            // Seek first entry to produce parse error. Then continue builder
 
            // pattern. This is the error case so efficiency can go home.
 
            let mut parse_error = None;
 
            let mut next_member_index = 0;
 
            while next_member_index < type_loop.members.len() {
 
                let first_entry = &type_loop.members[next_member_index];
 
                next_member_index += 1;
 

	
 
                // Retrieve definition of first type in loop
 
                let first_mono_type = &mono_types[first_entry.type_id.0 as usize];
 
                let first_definition_id = get_concrete_type_definition(&first_mono_type.concrete_type.parts);
 
                if first_definition_id.is_none() {
 
                    continue;
 
                }
 
                let first_definition_id = first_definition_id.unwrap();
 

	
 
                // Produce error message for first type in loop
 
                let (first_module, first_span, first_message) = type_loop_source_span_and_message(
 
                    modules, heap, mono_types, first_definition_id, first_entry.type_id, 0
 
                );
 
                parse_error = Some(ParseError::new_error_at_span(first_module, first_span, first_message));
 
                break;
 
            }
 

	
 
            let mut parse_error = parse_error.unwrap(); // Loop above cannot have failed, because we must have a type loop, type loops cannot contain only unnamed types
 

	
 
            let mut error_counter = 1;
 
            for member_idx in next_member_index..type_loop.members.len() {
 
                let entry = &type_loop.members[member_idx];
 
                let mono_type = &mono_types[entry.type_id.0 as usize];
 
                let definition_id = get_concrete_type_definition(&mono_type.concrete_type.parts);
 
                if definition_id.is_none() {
 
                    continue;
 
                }
 
                let definition_id = definition_id.unwrap();
 

	
 
                let (module, span, message) = type_loop_source_span_and_message(
 
                    modules, heap, mono_types, definition_id, entry.type_id, error_counter
 
                );
 
                parse_error = parse_error.with_info_at_span(module, span, message);
 
                error_counter += 1;
 
            }
 

	
 
            parse_error
 
        }
 

	
 
        for type_loop in &self.type_loops {
 
            let mut can_be_broken = false;
 
            debug_assert!(!type_loop.members.is_empty());
 

	
 
            for entry in &type_loop.members {
 
                if entry.is_union {
 
                    let mono_type = self.mono_types[entry.type_id.0 as usize].variant.as_union();
 
                    debug_assert!(!mono_type.variants.is_empty()); // otherwise it couldn't be part of the type loop
 
                    let has_stack_variant = mono_type.variants.iter().any(|variant| !variant.lives_on_heap);
 
                    if has_stack_variant {
 
                        can_be_broken = true;
 
                        break;
 
                    }
 
                }
 
            }
 

	
 
            if !can_be_broken {
 
                // Construct a type loop error
 
                return Err(construct_type_loop_error(&self.mono_types, type_loop, modules, heap));
 
            }
 
        }
 

	
 
        // If here, then all type loops have been resolved and we can lay out
 
        // all of the members
 
        self.type_loops.clear();
 

	
 
        return Ok(());
 
    }
 

	
 
    /// Checks if the specified type needs to be resolved (i.e. we need to push
 
    /// a breadcrumb), is already resolved (i.e. we can continue with the next
 
    /// member of the currently considered type) or is in the process of being
 
    /// resolved (i.e. we're in a type loop). Because of borrowing rules we
 
    /// don't do any modifications of internal types here. Hence: if we
 
    /// return `PushBreadcrumb` then call `handle_new_breadcrumb_for_type_loops`
 
    /// to take care of storing the appropriate types.
 
    fn check_member_for_type_loops(
 
        breadcrumbs: &[TypeLoopBreadcrumb], definition_map: &DefinitionMap, mono_type_map: &MonoTypeMap,
 
        mono_key: &mut MonoSearchKey, concrete_type: &ConcreteType
 
    ) -> TypeLoopResult {
 
        use ConcreteTypePart as CTP;
 

	
 
        // Depending on the type, lookup if the type has already been visited
 
        // (i.e. either already has its memory layed out, or is part of a type
 
        // loop because we've already visited the type)
 
        debug_assert!(!concrete_type.parts.is_empty());
 
        let definition_id = if let ConcreteTypePart::Instance(definition_id, _) = concrete_type.parts[0] {
 
            definition_id
 
        } else {
 
            DefinitionId::new_invalid()
 
        };
 

	
 
        Self::set_search_key_to_type(mono_key, definition_map, &concrete_type.parts);
 
        if let Some(type_id) = mono_type_map.get(mono_key).copied() {
 
            for (breadcrumb_idx, breadcrumb) in breadcrumbs.iter().enumerate() {
 
                if breadcrumb.type_id == type_id {
 
                    return TypeLoopResult::TypeLoop(breadcrumb_idx);
 
                }
 
            }
 

	
 
            return TypeLoopResult::TypeExists;
 
        }
 

	
 
        // Type is not yet known, so we need to insert it into the lookup and
 
        // push a new breadcrumb.
 
        return TypeLoopResult::PushBreadcrumb(definition_id, concrete_type.clone());
 
    }
 

	
 
    /// Handles the `PushBreadcrumb` result for a `check_member_for_type_loops`
 
    /// call. Will preallocate entries in the monomorphed type storage (with
 
    /// all memory properties zeroed).
 
    fn handle_new_breadcrumb_for_type_loops(&mut self, arch: &TargetArch, definition_id: DefinitionId, concrete_type: ConcreteType) {
 
        use DefinedTypeVariant as DTV;
 
        use ConcreteTypePart as CTP;
 

	
 
        let mut is_union = false;
 

	
 
        let type_id = match &concrete_type.parts[0] {
 
            // Builtin types
 
            CTP::Void | CTP::Message | CTP::Bool |
 
            CTP::UInt8 | CTP::UInt16 | CTP::UInt32 | CTP::UInt64 |
 
            CTP::SInt8 | CTP::SInt16 | CTP::SInt32 | CTP::SInt64 |
 
            CTP::Character | CTP::String |
 
            CTP::Array | CTP::Slice | CTP::Input | CTP::Output | CTP::Pointer => {
 
                // Insert the entry for the builtin type, we should be able to
 
                // immediately "steal" the size from the preinserted builtins.
 
                let base_type_id = match &concrete_type.parts[0] {
 
                    CTP::Void => arch.void_type_id,
 
                    CTP::Message => arch.message_type_id,
 
                    CTP::Bool => arch.bool_type_id,
 
                    CTP::UInt8 => arch.uint8_type_id,
 
                    CTP::UInt16 => arch.uint16_type_id,
 
                    CTP::UInt32 => arch.uint32_type_id,
 
                    CTP::UInt64 => arch.uint64_type_id,
 
                    CTP::SInt8 => arch.sint8_type_id,
 
                    CTP::SInt16 => arch.sint16_type_id,
 
                    CTP::SInt32 => arch.sint32_type_id,
 
                    CTP::SInt64 => arch.sint64_type_id,
 
                    CTP::Character => arch.char_type_id,
 
                    CTP::String => arch.string_type_id,
 
                    CTP::Array => arch.array_type_id,
 
                    CTP::Slice => arch.slice_type_id,
 
                    CTP::Input => arch.input_type_id,
 
                    CTP::Output => arch.output_type_id,
 
                    CTP::Pointer => arch.pointer_type_id,
 
                    _ => unreachable!(),
 
                };
 
                let base_type = &self.mono_types[base_type_id.0 as usize];
 
                let base_type_size = base_type.size;
 
                let base_type_alignment = base_type.alignment;
 

	
 
                let type_id = TypeId(self.mono_types.len() as i64);
 
                Self::set_search_key_to_type(&mut self.mono_search_key, &self.definition_lookup, &concrete_type.parts);
 
                self.mono_type_lookup.insert(self.mono_search_key.clone(), type_id);
 
                self.mono_types.push(MonoType{
 
                    type_id,
 
                    concrete_type,
 
                    size: base_type_size,
 
                    alignment: base_type_alignment,
 
                    variant: MonoTypeVariant::Builtin
 
                });
 

	
 
                type_id
 
            },
 
            // User-defined types
 
            CTP::Tuple(num_embedded) => {
 
                debug_assert!(definition_id.is_invalid()); // because tuples do not have an associated `DefinitionId`
 
                let mut members = Vec::with_capacity(*num_embedded as usize);
 
                for section in ConcreteTypeIter::new(&concrete_type.parts, 0) {
 
                    members.push(TupleMonomorphMember{
 
                        type_id: TypeId::new_invalid(),
 
                        concrete_type: ConcreteType{ parts: Vec::from(section) },
 
                        size: 0,
 
                        alignment: 0,
 
                        offset: 0
 
                    });
 
                }
 

	
src/runtime/scheduler.rs
Show inline comments
 
@@ -317,197 +317,197 @@ impl Scheduler {
 

	
 
                    // First pass: transfer ports and the associated messages,
 
                    // also count the number of ports that have peers
 
                    let mut num_peers = 0;
 
                    for port_id in initial_ports {
 
                        // Transfer messages associated with the transferred port
 
                        scheduled.ctx.inbox.transfer_messages_for_port(port_id, &mut new_connector.ctx.inbox);
 

	
 
                        // Transfer the port itself
 
                        let port_index = scheduled.ctx.ports.iter()
 
                            .position(|v| v.self_id == port_id)
 
                            .unwrap();
 
                        let port = scheduled.ctx.ports.remove(port_index);
 
                        new_connector.ctx.ports.push(port.clone());
 

	
 
                        if port.state == PortState::Open {
 
                            num_peers += 1;
 
                        }
 
                    }
 

	
 
                    if num_peers == 0 {
 
                        // No peers to notify, so just schedule the component
 
                        self.runtime.push_work(new_component_key);
 
                    } else {
 
                        // Some peers to notify
 
                        let new_component_id = new_component_key.downcast();
 
                        let control_id = scheduled.router.prepare_new_component(new_component_key);
 
                        for port in new_connector.ctx.ports.iter() {
 
                            if port.state == PortState::Closed {
 
                                continue;
 
                            }
 

	
 
                            let control_message = scheduled.router.prepare_changed_port_peer(
 
                                control_id, scheduled.ctx.id,
 
                                port.peer_connector, port.peer_id,
 
                                new_component_id, port.self_id
 
                            );
 
                            self.debug_conn(connector_id, &format!("Sending message to {:?} [newcom]\n --- {:#?}", port.peer_connector, control_message));
 
                            self.runtime.send_message_assumed_alive(port.peer_connector, Message::Control(control_message));
 
                        }
 
                    }
 
                },
 
                ComponentStateChange::CreatedPort(port) => {
 
                    scheduled.ctx.ports.push(port);
 
                },
 
                ComponentStateChange::ChangedPort(port_change) => {
 
                    if port_change.is_acquired {
 
                        scheduled.ctx.ports.push(port_change.port);
 
                    } else {
 
                        let index = scheduled.ctx.ports
 
                            .iter()
 
                            .position(|v| v.self_id == port_change.port.self_id)
 
                            .unwrap();
 
                        scheduled.ctx.ports.remove(index);
 
                    }
 
                }
 
            }
 
        }
 

	
 
        // Finally, check if we just entered or just left a sync region
 
        if scheduled.ctx.changed_in_sync {
 
            if scheduled.ctx.is_in_sync {
 
                // Just entered sync region
 
            } else {
 
                // Just left sync region. So prepare inbox for the next sync
 
                // round
 
                scheduled.ctx.inbox.clear_read_messages();
 
            }
 

	
 
            scheduled.ctx.changed_in_sync = false; // reset flag
 
        }
 
    }
 

	
 
    fn try_go_to_sleep(&self, connector_key: ConnectorKey, connector: &mut ScheduledConnector) {
 
        debug_assert_eq!(connector_key.index, connector.ctx.id.index);
 
        debug_assert_eq!(connector.public.sleeping.load(Ordering::Acquire), false);
 

	
 
        // This is the running connector, and only the running connector may
 
        // decide it wants to sleep again.
 
        connector.public.sleeping.store(true, Ordering::Release);
 

	
 
        // But due to reordering we might have received messages from peers who
 
        // did not consider us sleeping. If so, then we wake ourselves again.
 
        if !connector.public.inbox.is_empty() {
 
            // Try to wake ourselves up (needed because someone might be trying
 
            // the exact same atomic compare-and-swap at this point in time)
 
            let should_wake_up_again = connector.public.sleeping
 
                .compare_exchange(true, false, Ordering::SeqCst, Ordering::Acquire)
 
                .is_ok();
 

	
 
            if should_wake_up_again {
 
                self.runtime.push_work(connector_key)
 
            }
 
        }
 
    }
 

	
 
    fn debug(&self, message: &str) {
 
    fn debug(&self, _message: &str) {
 
        // println!("DEBUG [thrd:{:02} conn:  ]: {}", self.scheduler_id, message);
 
    }
 

	
 
    fn debug_conn(&self, conn: ConnectorId, message: &str) {
 
    fn debug_conn(&self, _conn: ConnectorId, _message: &str) {
 
        // println!("DEBUG [thrd:{:02} conn:{:02}]: {}", self.scheduler_id, conn.index, message);
 
    }
 
}
 

	
 
// -----------------------------------------------------------------------------
 
// ComponentCtx
 
// -----------------------------------------------------------------------------
 

	
 
enum ComponentStateChange {
 
    CreatedComponent(ConnectorPDL, Vec<PortIdLocal>),
 
    CreatedPort(Port),
 
    ChangedPort(ComponentPortChange),
 
}
 

	
 
#[derive(Clone)]
 
pub(crate) struct ComponentPortChange {
 
    pub is_acquired: bool, // otherwise: released
 
    pub port: Port,
 
}
 

	
 
/// The component context (better name may be invented). This was created
 
/// because part of the component's state is managed by the scheduler, and part
 
/// of it by the component itself. When the component starts a sync block or
 
/// exits a sync block the partially managed state by both component and
 
/// scheduler need to be exchanged.
 
pub(crate) struct ComponentCtx {
 
    // Mostly managed by the scheduler
 
    pub(crate) id: ConnectorId,
 
    ports: Vec<Port>,
 
    inbox: Inbox,
 
    // Submitted by the component
 
    is_in_sync: bool,
 
    changed_in_sync: bool,
 
    outbox: VecDeque<Message>,
 
    state_changes: VecDeque<ComponentStateChange>,
 

	
 
    // Workspaces that may be used by components to (generally) prevent
 
    // allocations. Be a good scout and leave it empty after you've used it.
 
    // TODO: Move to scheduler ctx, this is the wrong place
 
    pub workspace_ports: Vec<PortIdLocal>,
 
    pub workspace_branches: Vec<BranchId>,
 
}
 

	
 
impl ComponentCtx {
 
    pub(crate) fn new_empty() -> Self {
 
        return Self{
 
            id: ConnectorId::new_invalid(),
 
            ports: Vec::new(),
 
            inbox: Inbox::new(),
 
            is_in_sync: false,
 
            changed_in_sync: false,
 
            outbox: VecDeque::new(),
 
            state_changes: VecDeque::new(),
 
            workspace_ports: Vec::new(),
 
            workspace_branches: Vec::new(),
 
        };
 
    }
 

	
 
    /// Notify the runtime that the component has created a new component. May
 
    /// only be called outside of a sync block.
 
    pub(crate) fn push_component(&mut self, component: ConnectorPDL, initial_ports: Vec<PortIdLocal>) {
 
        debug_assert!(!self.is_in_sync);
 
        self.state_changes.push_back(ComponentStateChange::CreatedComponent(component, initial_ports));
 
    }
 

	
 
    /// Notify the runtime that the component has created a new port. May only
 
    /// be called outside of a sync block (for ports received during a sync
 
    /// block, pass them when calling `notify_sync_end`).
 
    pub(crate) fn push_port(&mut self, port: Port) {
 
        debug_assert!(!self.is_in_sync);
 
        self.state_changes.push_back(ComponentStateChange::CreatedPort(port))
 
    }
 

	
 
    /// Notify the runtime of an error. Note that this will not perform any
 
    /// special action beyond printing the error. The component is responsible
 
    /// for waiting until it is appropriate to shut down (i.e. being outside
 
    /// of a sync region) and returning the `Exit` scheduling code.
 
    pub(crate) fn push_error(&mut self, error: EvalError) {
 
        println!("ERROR: Component ({}) encountered a critical error:\n{}", self.id.index, error);
 
    }
 

	
 
    #[inline]
 
    pub(crate) fn get_ports(&self) -> &[Port] {
 
        return self.ports.as_slice();
 
    }
 

	
 
    pub(crate) fn get_port_by_id(&self, id: PortIdLocal) -> Option<&Port> {
 
        return self.ports.iter().find(|v| v.self_id == id);
 
    }
 

	
 
    pub(crate) fn get_port_by_channel_id(&self, id: ChannelId) -> Option<&Port> {
 
        return self.ports.iter().find(|v| v.channel_id == id);
 
    }
 

	
 
    fn get_port_mut_by_id(&mut self, id: PortIdLocal) -> Option<&mut Port> {
 
        return self.ports.iter_mut().find(|v| v.self_id == id);
src/runtime2/component/component_context.rs
Show inline comments
 
use crate::runtime2::scheduler::*;
 
use crate::runtime2::runtime::*;
 
use crate::runtime2::communication::*;
 

	
 
#[derive(Debug)]
 
pub struct Port {
 
    pub self_id: PortId,
 
    pub peer_comp_id: CompId, // eventually consistent
 
    pub peer_port_id: PortId, // eventually consistent
 
    pub kind: PortKind,
 
    pub state: PortState,
 
    #[cfg(debug_assertions)] pub(crate) associated_with_peer: bool,
 
}
 

	
 
pub struct Peer {
 
    pub id: CompId,
 
    pub num_associated_ports: u32,
 
    pub(crate) handle: CompHandle,
 
}
 

	
 
/// Port and peer management structure. Will keep a local reference counter to
 
/// the ports associate with peers, additionally manages the atomic reference
 
/// counter associated with the peers' component handles.
 
pub struct CompCtx {
 
    pub id: CompId,
 
    ports: Vec<Port>,
 
    peers: Vec<Peer>,
 
    port_id_counter: u32,
 
}
 

	
 
#[derive(Copy, Clone, PartialEq, Eq)]
 
pub struct LocalPortHandle(PortId);
 

	
 
#[derive(Copy, Clone)]
 
pub struct LocalPeerHandle(CompId);
 

	
 
impl CompCtx {
 
    /// Creates a new component context based on a reserved entry in the
 
    /// component store. This reservation is used such that we already know our
 
    /// assigned ID.
 
    pub(crate) fn new(reservation: &CompReserved) -> Self {
 
        return Self{
 
            id: reservation.id(),
 
            ports: Vec::new(),
 
            peers: Vec::new(),
 
            port_id_counter: 0,
 
        }
 
    }
 

	
 
    /// Creates a new channel that is fully owned by the component associated
 
    /// with this context.
 
    pub(crate) fn create_channel(&mut self) -> Channel {
 
        let putter_id = PortId(self.take_port_id());
 
        let getter_id = PortId(self.take_port_id());
 
        self.ports.push(Port{
 
            self_id: putter_id,
 
            peer_port_id: getter_id,
 
            kind: PortKind::Putter,
 
            state: PortState::Open,
 
            peer_comp_id: self.id,
 
            associated_with_peer: false,
 
            #[cfg(debug_assertions)] associated_with_peer: false,
 
        });
 
        self.ports.push(Port{
 
            self_id: getter_id,
 
            peer_port_id: putter_id,
 
            kind: PortKind::Getter,
 
            state: PortState::Open,
 
            peer_comp_id: self.id,
 
            associated_with_peer: false,
 
            #[cfg(debug_assertions)] associated_with_peer: false,
 
        });
 

	
 
        return Channel{ putter_id, getter_id };
 
    }
 

	
 
    /// Adds a new port. Make sure to call `add_peer` afterwards.
 
    pub(crate) fn add_port(&mut self, peer_comp_id: CompId, peer_port_id: PortId, kind: PortKind, state: PortState) -> LocalPortHandle {
 
        let self_id = PortId(self.take_port_id());
 
        self.ports.push(Port{
 
            self_id, peer_comp_id, peer_port_id, kind, state,
 
            #[cfg(debug_assertions)] associated_with_peer: false,
 
        });
 
        return LocalPortHandle(self_id);
 
    }
 

	
 
    /// Removes a port. Make sure you called `remove_peer` first.
 
    pub(crate) fn remove_port(&mut self, port_handle: LocalPortHandle) -> Port {
 
        let port_index = self.must_get_port_index(port_handle);
 
        let port = self.ports.remove(port_index);
 
        debug_assert!(!port.associated_with_peer);
 
        dbg_code!(assert!(!port.associated_with_peer));
 
        return port;
 
    }
 

	
 
    /// Adds a new peer. This must be called for every port, no matter the
 
    /// component the channel is connected to. If a `CompHandle` is supplied,
 
    /// then it will be used to add the peer. Otherwise it will be retrieved
 
    /// from the runtime using its ID.
 
    pub(crate) fn add_peer(&mut self, port_handle: LocalPortHandle, sched_ctx: &SchedulerCtx, peer_comp_id: CompId, handle: Option<&CompHandle>) {
 
        let self_id = self.id;
 
        let port = self.get_port_mut(port_handle);
 
        debug_assert_eq!(port.peer_comp_id, peer_comp_id);
 
        debug_assert!(!port.associated_with_peer);
 
        dbg_code!(assert!(!port.associated_with_peer));
 
        if !Self::requires_peer_reference(port, self_id, false) {
 
            return;
 
        }
 

	
 
        dbg_code!(port.associated_with_peer = true);
 
        match self.get_peer_index_by_id(peer_comp_id) {
 
            Some(peer_index) => {
 
                let peer = &mut self.peers[peer_index];
 
                peer.num_associated_ports += 1;
 
            },
 
            None => {
 
                let handle = match handle {
 
                    Some(handle) => handle.clone(),
 
                    None => sched_ctx.runtime.get_component_public(peer_comp_id)
 
                };
 
                self.peers.push(Peer{
 
                    id: peer_comp_id,
 
                    num_associated_ports: 1,
 
                    handle,
 
                });
 
            }
 
        }
 
    }
 

	
 
    /// Removes a peer associated with a port.
 
    pub(crate) fn remove_peer(&mut self, sched_ctx: &SchedulerCtx, port_handle: LocalPortHandle, peer_id: CompId, also_remove_if_closed: bool) {
 
        let self_id = self.id;
 
        let port = self.get_port_mut(port_handle);
 
        debug_assert_eq!(port.peer_comp_id, peer_id);
 
        if !Self::requires_peer_reference(port, self_id, also_remove_if_closed) {
 
            return;
 
        }
 

	
 
        debug_assert!(port.associated_with_peer);
 
        dbg_code!(assert!(port.associated_with_peer));
 
        dbg_code!(port.associated_with_peer = false);
 
        let peer_index = self.get_peer_index_by_id(peer_id).unwrap();
 
        let peer = &mut self.peers[peer_index];
 
        peer.num_associated_ports -= 1;
 
        if peer.num_associated_ports == 0 {
 
            let mut peer = self.peers.remove(peer_index);
 
            if let Some(key) = peer.handle.decrement_users() {
 
                debug_assert_ne!(key.downgrade(), self.id); // should be upheld by the code that shuts down a component
 
                sched_ctx.runtime.destroy_component(key);
 
            }
 
        }
 
    }
 

	
 
    pub(crate) fn set_port_state(&mut self, port_handle: LocalPortHandle, new_state: PortState) {
 
        let port_info = self.get_port_mut(port_handle);
 
        debug_assert_ne!(port_info.state, PortState::Closed); // because then we do not expect to change the state
 
        port_info.state = new_state;
 
    }
 

	
 
    pub(crate) fn get_port_handle(&self, port_id: PortId) -> LocalPortHandle {
 
        return LocalPortHandle(port_id);
 
    }
 

	
 
    // should perhaps be revised, used in main inbox
 
    pub(crate) fn get_port_index(&self, port_handle: LocalPortHandle) -> usize {
 
        return self.must_get_port_index(port_handle);
 
    }
 

	
 
    pub(crate) fn get_peer_handle(&self, peer_id: CompId) -> LocalPeerHandle {
 
        return LocalPeerHandle(peer_id);
 
    }
 

	
 
    pub(crate) fn get_port(&self, port_handle: LocalPortHandle) -> &Port {
 
        let index = self.must_get_port_index(port_handle);
 
        return &self.ports[index];
 
    }
 

	
 
    pub(crate) fn get_port_mut(&mut self, port_handle: LocalPortHandle) -> &mut Port {
 
        let index = self.must_get_port_index(port_handle);
 
        return &mut self.ports[index];
 
    }
 

	
 
    pub(crate) fn get_port_by_index_mut(&mut self, index: usize) -> &mut Port {
 
        return &mut self.ports[index];
 
    }
 

	
 
    pub(crate) fn get_peer(&self, peer_handle: LocalPeerHandle) -> &Peer {
 
        let index = self.must_get_peer_index(peer_handle);
 
        return &self.peers[index];
 
    }
 

	
 
    pub(crate) fn get_peer_mut(&mut self, peer_handle: LocalPeerHandle) -> &mut Peer {
 
        let index = self.must_get_peer_index(peer_handle);
 
        return &mut self.peers[index];
 
    }
 

	
 
    #[inline]
 
    pub(crate) fn iter_ports(&self) -> impl Iterator<Item=&Port> {
 
        return self.ports.iter();
 
    }
 

	
 
    #[inline]
 
    pub(crate) fn iter_ports_mut(&mut self) -> impl Iterator<Item=&mut Port> {
 
        return self.ports.iter_mut();
 
    }
 

	
 
    #[inline]
 
    pub(crate) fn iter_peers(&self) -> impl Iterator<Item=&Peer> {
 
        return self.peers.iter();
 
    }
 

	
 
    #[inline]
 
    pub(crate) fn num_ports(&self) -> usize {
 
        return self.ports.len();
 
    }
 

	
 
    // -------------------------------------------------------------------------
 
    // Local utilities
 
    // -------------------------------------------------------------------------
 

	
 
    #[inline]
 
    fn requires_peer_reference(port: &Port, self_id: CompId, required_if_closed: bool) -> bool {
 
        return (port.state != PortState::Closed || required_if_closed) && port.peer_comp_id != self_id;
 
    }
 

	
 
    fn must_get_port_index(&self, handle: LocalPortHandle) -> usize {
 
        for (index, port) in self.ports.iter().enumerate() {
 
            if port.self_id == handle.0 {
 
                return index;
 
            }
 
        }
 

	
 
        unreachable!()
 
    }
 

	
 
    fn must_get_peer_index(&self, handle: LocalPeerHandle) -> usize {
src/runtime2/runtime.rs
Show inline comments
 
@@ -16,228 +16,228 @@ use super::scheduler::*;
 
/// Key to a component. Type system somewhat ensures that there can only be one
 
/// of these. Only with a key one may retrieve privately-accessible memory for
 
/// a component. Practically just a generational index, like `CompId` is.
 
#[derive(Debug, Copy, Clone, PartialEq, Eq)]
 
pub(crate) struct CompKey(pub u32);
 

	
 
impl CompKey {
 
    pub(crate) fn downgrade(&self) -> CompId {
 
        return CompId(self.0);
 
    }
 
}
 

	
 
/// Generational ID of a component
 
#[derive(Debug, Copy, Clone, PartialEq, Eq)]
 
pub struct CompId(pub u32);
 

	
 
impl CompId {
 
    pub(crate) fn new_invalid() -> CompId {
 
        return CompId(u32::MAX);
 
    }
 

	
 
    /// Upgrade component ID to component key. Unsafe because the caller needs
 
    /// to make sure that only one component key can exist at a time (to ensure
 
    /// a component can only be scheduled/executed by one thread).
 
    pub(crate) unsafe fn upgrade(&self) -> CompKey {
 
        return CompKey(self.0);
 
    }
 
}
 

	
 
/// Handle to a component that is being created.
 
pub(crate) struct CompReserved {
 
    reservation: ComponentReservation,
 
}
 

	
 
impl CompReserved {
 
    pub(crate) fn id(&self) -> CompId {
 
        return CompId(self.reservation.index)
 
    }
 
}
 

	
 
/// Private fields of a component, may only be modified by a single thread at
 
/// a time.
 
pub(crate) struct RuntimeComp {
 
    pub public: CompPublic,
 
    pub code: CompPDL,
 
    pub ctx: CompCtx,
 
    pub inbox: QueueDynMpsc<Message>,
 
    pub exiting: bool,
 
}
 

	
 
/// Should contain everything that is accessible in a thread-safe manner
 
// TODO: Do something about the `num_handles` thing. This needs to be a bit more
 
//  "foolproof" to lighten the mental burden of using the `num_handles`
 
//  variable.
 
pub(crate) struct CompPublic {
 
    pub sleeping: AtomicBool,
 
    pub num_handles: AtomicU32, // manually modified (!)
 
    inbox: QueueDynProducer<Message>,
 
}
 

	
 
/// Handle to public part of a component. Would be nice if we could
 
/// automagically manage the `num_handles` counter. But when it reaches zero we
 
/// need to manually remove the handle from the runtime. So we just have debug
 
/// code to make sure this actually happens.
 
pub(crate) struct CompHandle {
 
    target: *const CompPublic,
 
    id: CompId, // TODO: @Remove after debugging
 
    #[cfg(debug_assertions)] decremented: bool,
 
}
 

	
 
impl CompHandle {
 
    fn new(id: CompId, public: &CompPublic) -> CompHandle {
 
        let handle = CompHandle{
 
            target: public,
 
            id,
 
            #[cfg(debug_assertions)] decremented: false,
 
        };
 
        handle.increment_users();
 
        return handle;
 
    }
 

	
 
    pub(crate) fn send_message(&self, sched_ctx: &SchedulerCtx, message: Message, try_wake_up: bool) {
 
        sched_ctx.log(&format!("Sending message to [c:{:03}, wakeup:{}]: {:?}", self.id.0, try_wake_up, message));
 
        self.inbox.push(message);
 
        if try_wake_up {
 
            wake_up_if_sleeping(sched_ctx, self.id, self);
 
        }
 
    }
 

	
 
    fn increment_users(&self) {
 
        let old_count = self.num_handles.fetch_add(1, Ordering::AcqRel);
 
        debug_assert!(old_count > 0); // because we should never be able to retrieve a handle when the component is (being) destroyed
 
    }
 

	
 
    /// Returns the `CompKey` to the component if it should be destroyed
 
    pub(crate) fn decrement_users(&mut self) -> Option<CompKey> {
 
        debug_assert!(!self.decremented, "illegal to 'decrement_users' twice");
 
        dbg_code!(assert!(self.decremented, "illegal to 'decrement_users' twice"));
 
        let old_count = self.num_handles.fetch_sub(1, Ordering::AcqRel);
 
        let new_count = old_count - 1;
 
        dbg_code!(self.decremented = true);
 
        if new_count == 0 {
 
            return Some(unsafe{ self.id.upgrade() });
 
        }
 

	
 
        return None;
 
    }
 
}
 

	
 
impl Clone for CompHandle {
 
    fn clone(&self) -> Self {
 
        debug_assert!(!self.decremented, "illegal to clone after 'decrement_users'");
 
        dbg_code!(assert!(!self.decremented, "illegal to clone after 'decrement_users'"));
 
        self.increment_users();
 
        return CompHandle{
 
            target: self.target,
 
            id: self.id,
 
            #[cfg(debug_assertions)] decremented: false,
 
        };
 
    }
 
}
 

	
 
impl std::ops::Deref for CompHandle {
 
    type Target = CompPublic;
 

	
 
    fn deref(&self) -> &Self::Target {
 
        debug_assert!(!self.decremented); // cannot access if control is relinquished
 
        dbg_code!(assert!(!self.decremented)); // cannot access if control is relinquished
 
        return unsafe{ &*self.target };
 
    }
 
}
 

	
 
impl Drop for CompHandle {
 
    fn drop(&mut self) {
 
        debug_assert!(self.decremented, "need call to 'decrement_users' before dropping");
 
        dbg_code!(assert!(self.decremented, "need call to 'decrement_users' before dropping"));
 
    }
 
}
 

	
 
// -----------------------------------------------------------------------------
 
// Runtime
 
// -----------------------------------------------------------------------------
 

	
 
pub struct Runtime {
 
    pub(crate) inner: Arc<RuntimeInner>,
 
    threads: Vec<std::thread::JoinHandle<()>>,
 
}
 

	
 
impl Runtime {
 
    // TODO: debug_logging should be removed at some point
 
    pub fn new(num_threads: u32, debug_logging: bool, protocol_description: ProtocolDescription) -> Runtime {
 
        assert!(num_threads > 0, "need a thread to perform work");
 
        let runtime_inner = Arc::new(RuntimeInner {
 
            protocol: protocol_description,
 
            components: ComponentStore::new(128),
 
            work_queue: Mutex::new(VecDeque::with_capacity(128)),
 
            work_condvar: Condvar::new(),
 
            active_elements: AtomicU32::new(1),
 
        });
 
        let mut runtime = Runtime {
 
            inner: runtime_inner,
 
            threads: Vec::with_capacity(num_threads as usize),
 
        };
 

	
 
        for thread_index in 0..num_threads {
 
            let mut scheduler = Scheduler::new(runtime.inner.clone(), thread_index, debug_logging);
 
            let thread_handle = std::thread::spawn(move || {
 
                scheduler.run();
 
            });
 

	
 
            runtime.threads.push(thread_handle);
 
        }
 

	
 
        return runtime;
 
    }
 

	
 
    pub fn create_component(&self, module_name: &[u8], routine_name: &[u8]) -> Result<(), ComponentCreationError> {
 
        use crate::protocol::eval::ValueGroup;
 
        let prompt = self.inner.protocol.new_component(
 
            module_name, routine_name,
 
            ValueGroup::new_stack(Vec::new())
 
        )?;
 
        let reserved = self.inner.start_create_pdl_component();
 
        let ctx = CompCtx::new(&reserved);
 
        let (key, _) = self.inner.finish_create_pdl_component(reserved, CompPDL::new(prompt, 0), ctx, false);
 
        self.inner.enqueue_work(key);
 

	
 
        return Ok(())
 
    }
 
}
 

	
 
impl Drop for Runtime {
 
    fn drop(&mut self) {
 
        self.inner.decrement_active_components();
 
        for handle in self.threads.drain(..) {
 
            handle.join().expect("join scheduler thread");
 
        }
 
    }
 
}
 

	
 
/// Memory that is maintained by "the runtime". In practice it is maintained by
 
/// multiple schedulers, and this serves as the common interface to that memory.
 
pub(crate) struct RuntimeInner {
 
    pub protocol: ProtocolDescription,
 
    components: ComponentStore<RuntimeComp>,
 
    work_queue: Mutex<VecDeque<CompKey>>,
 
    work_condvar: Condvar,
 
    active_elements: AtomicU32, // active components and APIs (i.e. component creators)
 
}
 

	
 
impl RuntimeInner {
 
    // Scheduling and retrieving work
 

	
 
    pub(crate) fn take_work(&self) -> Option<CompKey> {
 
        let mut lock = self.work_queue.lock().unwrap();
 
        while lock.is_empty() && self.active_elements.load(Ordering::Acquire) != 0 {
 
            lock = self.work_condvar.wait(lock).unwrap();
 
        }
 

	
 
        // We have work, or the schedulers should exit.
 
        return lock.pop_front();
 
    }
 

	
 
    pub(crate) fn enqueue_work(&self, key: CompKey) {
 
        let mut lock = self.work_queue.lock().unwrap();
 
        lock.push_back(key);
 
        self.work_condvar.notify_one();
 
    }
 

	
 
    // Creating/destroying components
 

	
 
    pub(crate) fn start_create_pdl_component(&self) -> CompReserved {
src/runtime2/scheduler.rs
Show inline comments
 
use std::sync::Arc;
 
use std::sync::atomic::Ordering;
 

	
 
use super::component::*;
 
use super::runtime::*;
 

	
 
/// Data associated with a scheduler thread
 
pub(crate) struct Scheduler {
 
    runtime: Arc<RuntimeInner>,
 
    scheduler_id: u32,
 
    debug_logging: bool,
 
}
 

	
 
pub(crate) struct SchedulerCtx<'a> {
 
    pub runtime: &'a RuntimeInner,
 
    pub id: u32,
 
    pub comp: u32,
 
    pub logging_enabled: bool,
 
}
 

	
 
impl<'a> SchedulerCtx<'a> {
 
    pub fn new(runtime: &'a RuntimeInner, id: u32, logging_enabled: bool) -> Self {
 
        return Self {
 
            runtime,
 
            id,
 
            comp: 0,
 
            logging_enabled,
 
        }
 
    }
 

	
 
    pub(crate) fn log(&self, text: &str) {
 
        if self.logging_enabled {
 
            println!("[s:{:02}, c:{:03}] {}", self.id, self.comp, text);
 
        }
 
    }
 

	
 
    // TODO: Obviously remove, but useful for testing
 
    pub(crate) fn log_special(&self, text: &str) {
 
        if self.logging_enabled {
 
            println!("[s:{:02}, c:{:03}] *** *** {}", self.id, self.comp, text);
 
        }
 
    }
 
}
 

	
 
impl Scheduler {
 
    // public interface to thread
 

	
 
    pub fn new(runtime: Arc<RuntimeInner>, scheduler_id: u32, debug_logging: bool) -> Self {
 
        return Scheduler{ runtime, scheduler_id, debug_logging }
 
    }
 

	
 
    pub fn run(&mut self) {
 
        let mut scheduler_ctx = SchedulerCtx::new(&*self.runtime, self.scheduler_id, self.debug_logging);
 

	
 
        'run_loop: loop {
 
            // Wait until we have something to do (or need to quit)
 
            let comp_key = self.runtime.take_work();
 
            if comp_key.is_none() {
 
                break 'run_loop;
 
            }
 

	
 
            let comp_key = comp_key.unwrap();
 
            let component = self.runtime.get_component(comp_key);
 
            scheduler_ctx.comp = comp_key.0;
 

	
 
            // Run the component until it no longer indicates that it needs to
 
            // be re-executed immediately.
 
            let mut new_scheduling = CompScheduling::Immediate;
 
            while let CompScheduling::Immediate = new_scheduling {
 
                while let Some(message) = component.inbox.pop() {
 
                    component.code.handle_message(&mut scheduler_ctx, &mut component.ctx, message);
 
                }
 
                new_scheduling = component.code.run(&mut scheduler_ctx, &mut component.ctx).expect("TODO: Handle error");
 
            }
 

	
 
            // Handle the new scheduling
 
            match new_scheduling {
 
                CompScheduling::Immediate => unreachable!(),
 
                CompScheduling::Requeue => { self.runtime.enqueue_work(comp_key); },
 
                CompScheduling::Sleep => { self.mark_component_as_sleeping(comp_key, component); },
 
                CompScheduling::Exit => { self.mark_component_as_exiting(&scheduler_ctx, component); }
 
            }
 
        }
 
    }
 

	
 
    // local utilities
 

	
 
    /// Marks component as sleeping, if after marking itself as sleeping the
 
    /// inbox contains messages then the component will be immediately
 
    /// rescheduled. After calling this function the component should not be
 
    /// executed anymore.
 
    fn mark_component_as_sleeping(&self, key: CompKey, component: &mut RuntimeComp) {
 
        debug_assert_eq!(key.downgrade(), component.ctx.id); // make sure component matches key
 
        debug_assert_eq!(component.public.sleeping.load(Ordering::Acquire), false); // we're executing it, so it cannot be sleeping
 

	
 
        component.public.sleeping.store(true, Ordering::Release);
 
        if component.inbox.can_pop() {
 
            let should_reschedule = component.public.sleeping
 
                .compare_exchange(true, false, Ordering::AcqRel, Ordering::Relaxed)
 
                .is_ok();
 

	
 
            if should_reschedule {
 
                self.runtime.enqueue_work(key);
 
            }
 
        }
 
    }
 

	
 
    /// Marks the component as exiting by removing the reference it holds to
 
    /// itself. Afterward the component will enter "normal" sleeping mode (if it
 
    /// has not yet been destroyed)
 
    fn mark_component_as_exiting(&self, sched_ctx: &SchedulerCtx, component: &mut RuntimeComp) {
 
        // If we didn't yet decrement our reference count, do so now
 
        let comp_key = unsafe{ component.ctx.id.upgrade() };
 

	
 
        if !component.exiting {
 
            component.exiting = true;
 

	
 
            let old_count = component.public.num_handles.fetch_sub(1, Ordering::AcqRel);
 
            let new_count = old_count - 1;
 
            if new_count == 0 {
 
                sched_ctx.runtime.destroy_component(comp_key);
 
                return;
 
            }
 
        }
 

	
 
        // Enter "regular" sleeping mode
 
        self.mark_component_as_sleeping(comp_key, component);
 
    }
 
}
 
\ No newline at end of file
src/runtime2/store/component.rs
Show inline comments
 
/*
 
 * Component Store
 
 *
 
 * Concurrent datastructure for creating/destroying/retrieving components using
 
 * their ID. It is essentially a variation on a concurrent freelist. We store an
 
 * array of (potentially null) pointers to data. Indices into this array that
 
 * are unused (but may be left allocated) are in a freelist. So creating a new
 
 * bit of data involves taking an index from this freelist. Destruction involves
 
 * putting the index back.
 
 *
 
 * This datastructure takes care of the threadsafe implementation of the
 
 * freelist and calling the data's destructor when needed. Note that it is not
 
 * completely safe (in Rust's sense of the word) because it is possible to
 
 * get more than one mutable reference to a piece of data. Likewise it is
 
 * possible to put back bogus indices into the freelist, which will destroy the
 
 * integrity of the datastructure.
 
 *
 
 * Some underlying assumptions that led to this design (note that I haven't
 
 * actually checked these conditions or performed any real profiling, yet):
 
 *  - Resizing the freelist should be very rare. The datastructure should grow
 
 *    to some kind of maximum size and stay at that size.
 
 *  - Creation should (preferably) be faster than deletion of data. Reason being
 
 *    that creation implies we're creating a component that has code to be
 
 *    executed. Better to quickly be able to execute code than being able to
 
 *    quickly tear down finished components.
 
 *  - Retrieval is much more likely than creation/destruction.
 
 *
 
 * Some obvious flaws with this implementation:
 
 *  - Because of the freelist implementation we will generally allocate all of
 
 *    the data pointers that are available (i.e. if we have a buffer of size
 
 *    64, but we generally use 33 elements, than we'll have 64 elements
 
 *    allocated), which might be wasteful at larger array sizes (which are
 
 *    always powers of two).
 
 *  - A lot of concurrent operations are not necessary: we may move some of the
 
 *    access to the global concurrent datastructure by an initial access to some
 
 *    kind of thread-local datastructure.
 
 */
 

	
 
use std::mem::transmute;
 
use std::alloc::{dealloc, Layout};
 
use std::ptr;
 
use std::sync::atomic::{AtomicUsize, Ordering};
 

	
 
use super::unfair_se_lock::{UnfairSeLock, UnfairSeLockSharedGuard};
 

	
 
/// Generic store of components. Essentially a resizable freelist (implemented
 
/// as a ringbuffer) combined with an array of actual elements.
 
pub struct ComponentStore<T: Sized> {
 
    inner: UnfairSeLock<Inner<T>>,
 
    read_head: AtomicUsize,
 
    write_head: AtomicUsize,
 
    limit_head: AtomicUsize,
 
}
 

	
 
unsafe impl<T: Sized> Send for ComponentStore<T>{}
 
unsafe impl<T: Sized> Sync for ComponentStore<T>{}
 

	
 
/// Contents of the `ComponentStore` that require a shared/exclusive locking
 
/// mechanism for consistency.
 
struct Inner<T: Sized> {
 
    freelist: Vec<u32>,
 
    data: Vec<*mut T>,
 
    size: usize,
 
    compare_mask: usize,
 
    index_mask: usize,
 
}
 

	
 
type InnerShared<'a, T> = UnfairSeLockSharedGuard<'a, Inner<T>>;
 

	
 
/// Reservation of a slot in the component store. Corresponds to the case where
 
/// an index has been taken from the freelist, but the element has not yet been
 
/// initialized
 
pub struct ComponentReservation {
 
    pub(crate) index: u32,
 
    #[cfg(debug_assertions)] submitted: bool,
 
}
 

	
 
impl ComponentReservation {
 
    fn new(index: u32) -> Self {
 
        return Self{
 
            index,
 
            #[cfg(debug_assertions)] submitted: false,
 
        }
 
    }
 
}
 

	
 
impl Drop for ComponentReservation {
 
    fn drop(&mut self) {
 
        debug_assert!(self.submitted);
 
        dbg_code!( assert!(self.submitted) );
 
    }
 
}
 

	
 
impl<T: Sized> ComponentStore<T> {
 
    pub fn new(initial_size: usize) -> Self {
 
        Self::assert_valid_size(initial_size);
 

	
 
        // Fill initial freelist and preallocate data array
 
        let mut initial_freelist = Vec::with_capacity(initial_size);
 
        for idx in 0..initial_size {
 
            initial_freelist.push(idx as u32)
 
        }
 

	
 
        let mut initial_data = Vec::new();
 
        initial_data.resize(initial_size, ptr::null_mut());
 

	
 
        // Return initial store
 
        return Self{
 
            inner: UnfairSeLock::new(Inner{
 
                freelist: initial_freelist,
 
                data: initial_data,
 
                size: initial_size,
 
                compare_mask: 2*initial_size - 1,
 
                index_mask: initial_size - 1,
 
            }),
 
            read_head: AtomicUsize::new(0),
 
            write_head: AtomicUsize::new(initial_size),
 
            limit_head: AtomicUsize::new(initial_size),
 
        };
 
    }
 

	
 
    /// Creates a new element initialized to the provided `value`. This returns
 
    /// the index at which the element can be retrieved.
 
    pub fn create(&self, value: T) -> u32 {
 
        let lock = self.inner.lock_shared();
 
        let (lock, index) = self.pop_freelist_index(lock);
 
        Self::initialize_at_index(lock, index, value);
 
        return index;
 
    }
 

	
 
    pub fn reserve(&self) -> ComponentReservation {
 
        let lock = self.inner.lock_shared();
 
        let (_lock, index) = self.pop_freelist_index(lock);
 
        return ComponentReservation::new(index);
 
    }
 

	
 
    pub fn submit(&self, mut reservation: ComponentReservation, value: T) -> u32 {
 
        dbg_code!({ reservation.submitted = true; });
 
        let lock = self.inner.lock_shared();
 
        Self::initialize_at_index(lock, reservation.index, value);
 
        return reservation.index;
 
    }
 

	
 
    /// Destroys an element at the provided `index`. The caller must make sure
 
    /// that it does not use any previously received references to the data at
 
    /// this index, and that no more calls to `get` are performed using this
 
    /// index. This is allowed again if the index has been reacquired using
 
    /// `create`.
 
    pub fn destroy(&self, index: u32) {
 
        let lock = self.inner.lock_shared();
 
        self.destruct_at_index(&lock, index);
 
        self.push_freelist_index(&lock, index);
 
    }
 

	
 
    /// Retrieves an element by reference
 
    pub fn get(&self, index: u32) -> &T {
 
        let lock = self.inner.lock_shared();
 
        let value = lock.data[index as usize];
 
        unsafe {
 
            debug_assert!(!value.is_null());
 
            return &*value;
 
        }
 
    }
 

	
 
    /// Retrieves an element by mutable reference. The caller should ensure that
 
    /// use of that mutability is thread-safe
 
    pub fn get_mut(&self, index: u32) -> &mut T {
 
        let lock = self.inner.lock_shared();
 
        let value = lock.data[index as usize];
 
        unsafe {
 
            debug_assert!(!value.is_null());
 
            return &mut *value;
 
        }
 
    }
 

	
 
    #[inline]
 
    fn pop_freelist_index<'a>(&'a self, mut shared_lock: InnerShared<'a, T>) -> (InnerShared<'a, T>, u32) {
 
        'attempt_read: loop {
 
            // Load indices and check for reallocation condition
 
            let current_size = shared_lock.size;
 
            let mut read_index = self.read_head.load(Ordering::Relaxed);
 
            let limit_index = self.limit_head.load(Ordering::Acquire);
 

	
 
            if read_index == limit_index {
 
                shared_lock = self.reallocate(current_size, shared_lock);
 
                continue 'attempt_read;
 
            }
 

	
 
            loop {
 
                let preemptive_read = shared_lock.freelist[read_index & shared_lock.index_mask];
 
                if let Err(actual_read_index) = self.read_head.compare_exchange(
 
                if let Err(_actual_read_index) = self.read_head.compare_exchange(
 
                    read_index, (read_index + 1) & shared_lock.compare_mask,
 
                    Ordering::AcqRel, Ordering::Acquire
 
                ) {
 
                    // We need to try again
 
                    read_index = actual_read_index;
 
                    // TODO: Fix this update loop at some point. When update
 
                    //  loop is disabled, popping the freelist index is not
 
                    //  reliable.
 
                    // read_index = actual_read_index;
 
                    continue 'attempt_read;
 
                }
 

	
 
                // If here then we performed the read
 
                return (shared_lock, preemptive_read);
 
            }
 
        }
 
    }
 

	
 
    #[inline]
 
    fn initialize_at_index(read_lock: InnerShared<T>, index: u32, value: T) {
 
        let mut target_ptr = read_lock.data[index as usize];
 

	
 
        unsafe {
 
            if target_ptr.is_null() {
 
                let layout = Layout::for_value(&value);
 
                target_ptr = std::alloc::alloc(layout).cast();
 
                let rewrite: *mut *mut T = transmute(read_lock.data.as_ptr());
 
                *rewrite.add(index as usize) = target_ptr;
 
            }
 

	
 
            std::ptr::write(target_ptr, value);
 
        }
 
    }
 

	
 
    #[inline]
 
    fn push_freelist_index(&self, read_lock: &InnerShared<T>, index_to_put_back: u32) {
 
        // Acquire an index in the freelist to which we can write
 
        let mut cur_write_index = self.write_head.load(Ordering::Relaxed);
 
        let mut new_write_index = (cur_write_index + 1) & read_lock.compare_mask;
 
        while let Err(actual_write_index) = self.write_head.compare_exchange(
 
            cur_write_index, new_write_index,
 
            Ordering::AcqRel, Ordering::Acquire
 
        ) {
 
            cur_write_index = actual_write_index;
 
            new_write_index = (cur_write_index + 1) & read_lock.compare_mask;
 
        }
 

	
 
        // We own the data at the index, write to it and notify reader through
 
        // limit_head that it can be read from. Note that we cheat around the
 
        // rust mutability system here :)
 
        unsafe {
 
            let target: *mut u32 = transmute(read_lock.freelist.as_ptr());
 
            *(target.add(cur_write_index & read_lock.index_mask)) = index_to_put_back;
 
        }
 

	
 
        // Essentially spinlocking, relaxed failure ordering because the logic
 
        // is that a write first moves the `write_head`, then the `limit_head`.
 
        while let Err(_) = self.limit_head.compare_exchange(
 
            cur_write_index, new_write_index,
 
            Ordering::AcqRel, Ordering::Relaxed
 
        ) {};
 
    }
 

	
 
    #[inline]
 
    fn destruct_at_index(&self, read_lock: &InnerShared<T>, index: u32) {
 
        let target_ptr = read_lock.data[index as usize];
 
        unsafe{ ptr::drop_in_place(target_ptr); }
 
    }
 

	
 
    // NOTE: Bit of a mess, and could have a cleanup with better logic for the
 
    // resizing. Maybe even a different indexing scheme...
 
    fn reallocate(&self, old_size: usize, inner: InnerShared<T>) -> InnerShared<T> {
 
        drop(inner);
 
        {
 
            // After dropping read lock, acquire write lock
 
            let mut lock = self.inner.lock_exclusive();
 

	
 
            if old_size == lock.size {
 
                // We are the thread that is supposed to reallocate
 
                let new_size = old_size * 2;
 
                Self::assert_valid_size(new_size);
 

	
 
                // Note that the atomic indices are in the range [0, new_size)
 
                // already, so we need to be careful
 
                let new_index_mask = new_size - 1;
 
                let new_compare_mask = (2 * new_size) - 1;
 
                lock.data.resize(new_size, ptr::null_mut());
 
                lock.freelist.resize(new_size, 0);
 
                for idx in 0..old_size {
 
                    lock.freelist[old_size + idx] = lock.freelist[idx];
 
                }
 

	
 
                // We need to fill the freelist with the indices of all of the
 
                // new elements that we have just created.
 
                debug_assert_eq!(self.limit_head.load(Ordering::SeqCst), self.write_head.load(Ordering::SeqCst));
 
                let old_read_index = self.read_head.load(Ordering::SeqCst);
 
                let old_write_index = self.write_head.load(Ordering::SeqCst);
 

	
 
                if old_read_index > old_write_index {
 
                    // Read index wraps, so keep it as-is and fill
 
                    let new_read_index = old_read_index + old_size;
 
                    for index in 0..old_size {
 
                        let target_idx = (new_read_index + index) & new_index_mask;
 
                        lock.freelist[target_idx] = (old_size + index) as u32;
 
                    }
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