CSY/reowolf Changeset - a99ae23c30ec · Centrum Wiskunde & Informatica (CWI)

Changeset - a99ae23c30ec

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mh - 4 years ago 2021-11-18 11:36:29
contact@maxhenger.nl

WIP on consensus error handling

5 files changed with 147 insertions and 26 deletions:

src/protocol/eval/executor.rs

src/runtime2/connector.rs

src/runtime2/consensus.rs

src/runtime2/inbox.rs

src/runtime2/scheduler.rs

0 comments (0 inline, 0 general)

src/protocol/eval/executor.rs

➞

Show inline comments

@@ @@ -953,97 +953,115 @@ impl Prompt { @@
                 debug_assert!(prev_stack_idx >= 0);
                 // Return to original state of stack frame
                 self.store.cur_stack_boundary = prev_stack_idx as usize;
                 let cur_frame = self.frames.last_mut().unwrap();
                 cur_frame.expr_values.push_back(return_value);
                 // We just returned to the previous frame, which might be in
                 // the middle of evaluating expressions for a particular
                 // statement. So we don't want to enter the code below.
                 return Ok(EvalContinuation::Stepping);
             },
             Statement::Goto(stmt) => {
                 cur_frame.position = stmt.target.unwrap().upcast();
                 Ok(EvalContinuation::Stepping)
             },
             Statement::New(stmt) => {
                 let call_expr = &heap[stmt.expression];
                 debug_assert!(heap[call_expr.definition].is_component());
                 debug_assert_eq!(
                     cur_frame.expr_values.len(), heap[call_expr.definition].parameters().len(),
                     "mismatch in expr stack size and number of arguments for new statement"
                 );
                 let mono_data = types.get_procedure_expression_data(&cur_frame.definition, cur_frame.monomorph_idx);
                 let expr_data = &mono_data.expr_data[call_expr.unique_id_in_definition as usize];
                 // Note that due to expression value evaluation they exist in
                 // reverse order on the stack.
                 // TODO: Revise this code, keep it as is to be compatible with current runtime
                 let mut args = Vec::new();
                 while let Some(value) = cur_frame.expr_values.pop_front() {
                     args.push(value);
+                }
                 // Construct argument group, thereby copying heap regions
                 let argument_group = ValueGroup::from_store(&self.store, &args);
                 // println!("Creating {} with\n{:#?}", heap[call_expr.definition].identifier().value.as_str(), argument_group);
                 // Clear any heap regions
                 for arg in &args {
                     self.store.drop_value(arg.get_heap_pos());
+                }
                 cur_frame.position = stmt.next;
                 Ok(EvalContinuation::NewComponent(call_expr.definition, expr_data.field_or_monomorph_idx, argument_group))
             },
             Statement::Expression(stmt) => {
                 // The expression has just been completely evaluated. Some
                 // values might have remained on the expression value stack.
                 // cur_frame.expr_values.clear(); PROPER CLEARING
                 cur_frame.position = stmt.next;
                 Ok(EvalContinuation::Stepping)
             },
         };
         assert!(
             cur_frame.expr_values.is_empty(),
             "This is a debugging assertion that will fail if you perform expressions without \
             assigning to anything. This should be completely valid, and this assertion should be \
             replaced by something that clears the expression values if needed, but I'll keep this \
             in for now for debugging purposes."
         );
         // If the next statement requires evaluating expressions then we push
         // these onto the expression stack. This way we will evaluate this
         // stack in the next loop, then evaluate the statement using the result
         // from the expression evaluation.
         if !cur_frame.position.is_invalid() {
             let stmt = &heap[cur_frame.position];
             match stmt {
                 Statement::If(stmt) => cur_frame.prepare_single_expression(heap, stmt.test),
                 Statement::While(stmt) => cur_frame.prepare_single_expression(heap, stmt.test),
                 Statement::Return(stmt) => {
                     debug_assert_eq!(stmt.expressions.len(), 1); // TODO: @ReturnValues
                     cur_frame.prepare_single_expression(heap, stmt.expressions[0]);
                 },
                 Statement::New(stmt) => {
                     // Note that we will end up not evaluating the call itself.
                     // Rather we will evaluate its expressions and then
                     // instantiate the component upon reaching the "new" stmt.
                     let call_expr = &heap[stmt.expression];
                     cur_frame.prepare_multiple_expressions(heap, &call_expr.arguments);
                 },
                 Statement::Expression(stmt) => {
                     cur_frame.prepare_single_expression(heap, stmt.expression);
+                }
                 _ => {},
+            }
+        }
         return_value
+    }
     /// Constructs an error at the current expression that lives at the top of
     /// the expression stack. Falls back to constructing an error at the current
     /// statement if there is no expression.
     pub(crate) fn new_error_at_expr(&self, modules: &[Module], heap: &Heap, error_message: String) -> EvalError {
         let last_frame = self.frames.last().unwrap();
         for instruction in last_frame.expr_stack.iter().rev() {
             if let ExprInstruction::EvalExpr(expression_id) = instruction {
                 return EvalError::new_error_at_expr(
                     self, modules, heap, *expression_id, error_message
                 );
+            }
+        }
         // If here then expression stack was empty (cannot have just rotate
         // instructions)
         panic!("attempted to construct evaluation error without any expressions to evaluate in frame");
+    }
+}
@@ \ No newline at end of file @@

src/runtime2/connector.rs

➞

Show inline comments

 // connector.rs
 //
 // Represents a component. A component (and the scheduler that is running it)
 // has many properties that are not easy to subdivide into aspects that are
 // conceptually handled by particular data structures. That is to say: the code
 // that we run governs: running PDL code, keeping track of ports, instantiating
 // new components and transports (i.e. interacting with the runtime), running
 // a consensus algorithm, etc. But on the other hand, our data is rather
 // simple: we have a speculative execution tree, a set of ports that we own,
 // and a bit of code that we should run.
 //
 // So currently the code is organized as following:
 // - The scheduler that is running the component is the authoritative source on
 //     ports during *non-sync* mode. The consensus algorithm is the
 //     authoritative source during *sync* mode. They retrieve each other's
 //     state during the transitions. Hence port data exists duplicated between
 //     these two datastructures.
 // - The execution tree is where executed branches reside. But the execution
 //     tree is only aware of the tree shape itself (and keeps track of some
 //     queues of branches that are in a particular state), and tends to store
 //     the PDL program state. The consensus algorithm is also somewhat aware
 //     of the execution tree, but only in terms of what is needed to complete
 //     a sync round (for now, that means the port mapping in each branch).
 //     Hence once more we have properties conceptually associated with branches
 //     in two places.
 // - TODO: Write about handling messages, consensus wrapping data
 // - TODO: Write about way information is exchanged between PDL/component and scheduler through ctx
 use std::collections::HashMap;
 use std::sync::atomic::AtomicBool;
 use crate::{PortId, ProtocolDescription};
 use crate::common::ComponentState;
 use crate::protocol::eval::{EvalContinuation, EvalError, Prompt, Value, ValueGroup};
 use crate::protocol::{RunContext, RunResult};
 use crate::runtime2::branch::PreparedStatement;
 use super::branch::{BranchId, ExecTree, QueueKind, SpeculativeState};
 use super::consensus::{Consensus, Consistency, find_ports_in_value_group};
 use super::inbox::{DataMessage, DataContent, Message, SyncMessage, PublicInbox};
 use super::native::Connector;
 use super::port::{PortKind, PortIdLocal};
 use super::scheduler::{ComponentCtx, SchedulerCtx};
 pub(crate) struct ConnectorPublic {
     pub inbox: PublicInbox,
     pub sleeping: AtomicBool,
+}
 impl ConnectorPublic {
     pub fn new(initialize_as_sleeping: bool) -> Self {
         ConnectorPublic{
             inbox: PublicInbox::new(),
             sleeping: AtomicBool::new(initialize_as_sleeping),
+        }
+    }
+}
 #[derive(Debug, PartialEq, Eq, Copy)]
 enum Mode {
     NonSync,    // running non-sync code
     Sync,       // running sync code (in potentially multiple branches)
     SyncError,  // encountered an unrecoverable error in sync mode
     Error,      // encountered an error in non-sync mode (or finished handling the sync mode error).
+}
 #[derive(Debug)]
 pub(crate) enum ConnectorScheduling {
     Immediate,          // Run again, immediately
     Later,              // Schedule for running, at some later point in time
     NotNow,             // Do not reschedule for running
     Exit,               // Connector has exited
     Error(EvalError),   // Connector has experienced a fatal error
+}
 pub(crate) struct ConnectorPDL {
     mode: Mode,
     eval_error: Option<EvalError>,
     tree: ExecTree,
     consensus: Consensus,
     last_finished_handled: Option<BranchId>,
+}
 // TODO: Remove remaining fields once 'fires()' is removed from language.
 struct ConnectorRunContext<'a> {
     branch_id: BranchId,
     consensus: &'a Consensus,
     prepared: PreparedStatement,
+}
 impl<'a> RunContext for ConnectorRunContext<'a>{
     fn performed_put(&mut self, _port: PortId) -> bool {
         return match self.prepared.take() {
             PreparedStatement::None => false,
             PreparedStatement::PerformedPut => true,
             taken => unreachable!("prepared statement is '{:?}' during 'performed_put()'", taken)
         };
+    }
     fn performed_get(&mut self, _port: PortId) -> Option<ValueGroup> {
         return match self.prepared.take() {
             PreparedStatement::None => None,
             PreparedStatement::PerformedGet(value) => Some(value),
             taken => unreachable!("prepared statement is '{:?}' during 'performed_get()'", taken),
         };
+    }
     fn fires(&mut self, port: PortId) -> Option<Value> {
         let port_id = PortIdLocal::new(port.0.u32_suffix);
         let annotation = self.consensus.get_annotation(self.branch_id, port_id);
         return annotation.expected_firing.map(|v| Value::Bool(v));
+    }
     fn created_channel(&mut self) -> Option<(Value, Value)> {
         return match self.prepared.take() {
             PreparedStatement::None => None,
             PreparedStatement::CreatedChannel(ports) => Some(ports),
             taken => unreachable!("prepared statement is '{:?}' during 'created_channel)_'", taken),
         };
+    }
     fn performed_fork(&mut self) -> Option<bool> {
         return match self.prepared.take() {
             PreparedStatement::None => None,
             PreparedStatement::ForkedExecution(path) => Some(path),
             taken => unreachable!("prepared statement is '{:?}' during 'performed_fork()'", taken),
         };
+    }
+}
 impl Connector for ConnectorPDL {
     fn run(&mut self, sched_ctx: SchedulerCtx, comp_ctx: &mut ComponentCtx) -> ConnectorScheduling {
         self.handle_new_messages(comp_ctx);
         if self.tree.is_in_sync() {
             // Run in sync mode
             let scheduling = self.run_in_sync_mode(sched_ctx, comp_ctx);
             // Handle any new finished branches
             let mut iter_id = self.last_finished_handled.or(self.tree.get_queue_first(QueueKind::FinishedSync));
             while let Some(branch_id) = iter_id {
                 iter_id = self.tree.get_queue_next(branch_id);
                 self.last_finished_handled = Some(branch_id);
         match self.mode {
             Mode::Sync => {
                 // Run in sync mode
                 let scheduling = self.run_in_sync_mode(sched_ctx, comp_ctx);
                 // Handle any new finished branches
                 let mut iter_id = self.last_finished_handled.or(self.tree.get_queue_first(QueueKind::FinishedSync));
                 while let Some(branch_id) = iter_id {
                     iter_id = self.tree.get_queue_next(branch_id);
                     self.last_finished_handled = Some(branch_id);
                     if let Some(solution_branch_id) = self.consensus.handle_new_finished_sync_branch(branch_id, comp_ctx) {
                         // Actually found a solution
                         self.enter_non_sync_mode(solution_branch_id, comp_ctx);
                         return ConnectorScheduling::Immediate;
+                    }
                 if let Some(solution_branch_id) = self.consensus.handle_new_finished_sync_branch(branch_id, comp_ctx) {
                     // Actually found a solution
                     self.collapse_sync_to_solution_branch(solution_branch_id, comp_ctx);
                     return ConnectorScheduling::Immediate;
                     self.last_finished_handled = Some(branch_id);
+                }
                 self.last_finished_handled = Some(branch_id);
+            }
             return scheduling;
         } else {
             let scheduling = self.run_in_deterministic_mode(sched_ctx, comp_ctx);
             return scheduling;
                 return scheduling;
             },
             Mode::NonSync => {
                 let scheduling = self.run_in_deterministic_mode(sched_ctx, comp_ctx);
                 return scheduling;
             },
             Mode::SyncError => {
                 todo!("write");
                 return ConnectorScheduling::Exit;
             },
             Mode::Error => {
                 // This shouldn't really be called. Because when we reach exit
                 // mode the scheduler should not run the component anymore
                 unreachable!("called component run() during error-mode");
             },
+        }
+    }
+}
 impl ConnectorPDL {
     pub fn new(initial: Prompt) -> Self {
         Self{
             mode: Mode::NonSync,
             eval_error: None,
             tree: ExecTree::new(initial),
             consensus: Consensus::new(),
             last_finished_handled: None,
+        }
+    }
     // --- Handling messages
     pub fn handle_new_messages(&mut self, ctx: &mut ComponentCtx) {
         while let Some(message) = ctx.read_next_message() {
             match message {
                 Message::Data(message) => self.handle_new_data_message(message, ctx),
                 Message::Sync(message) => self.handle_new_sync_message(message, ctx),
                 Message::Control(_) => unreachable!("control message in component"),
+            }
+        }
+    }
     pub fn handle_new_data_message(&mut self, message: DataMessage, ctx: &mut ComponentCtx) {
         // Go through all branches that are awaiting new messages and see if
         // there is one that can receive this message.
         if !self.consensus.handle_new_data_message(&message, ctx) {
             // Old message, so drop it
             return;
+        }
         let mut iter_id = self.tree.get_queue_first(QueueKind::AwaitingMessage);
         while let Some(branch_id) = iter_id {
             iter_id = self.tree.get_queue_next(branch_id);
             let branch = &self.tree[branch_id];
             if branch.awaiting_port != message.data_header.target_port { continue; }
             if !self.consensus.branch_can_receive(branch_id, &message) { continue; }
             // This branch can receive, so fork and given it the message
             let receiving_branch_id = self.tree.fork_branch(branch_id);
             self.consensus.notify_of_new_branch(branch_id, receiving_branch_id);
             let receiving_branch = &mut self.tree[receiving_branch_id];
             debug_assert!(receiving_branch.awaiting_port == message.data_header.target_port);
             receiving_branch.awaiting_port = PortIdLocal::new_invalid();
             receiving_branch.prepared = PreparedStatement::PerformedGet(message.content.as_message().unwrap().clone());
             self.consensus.notify_of_received_message(receiving_branch_id, &message);
             // And prepare the branch for running
             self.tree.push_into_queue(QueueKind::Runnable, receiving_branch_id);
+        }
+    }
     pub fn handle_new_sync_message(&mut self, message: SyncMessage, ctx: &mut ComponentCtx) {
         if let Some(solution_branch_id) = self.consensus.handle_new_sync_message(message, ctx) {
-            self.collapse_sync_to_solution_branch(solution_branch_id, ctx);
+            self.enter_non_sync_mode(solution_branch_id, ctx);
+        }
+    }
     // --- Running code
     pub fn run_in_sync_mode(&mut self, sched_ctx: SchedulerCtx, comp_ctx: &mut ComponentCtx) -> ConnectorScheduling {
         // Check if we have any branch that needs running
         debug_assert!(self.tree.is_in_sync() && self.consensus.is_in_sync());
         let branch_id = self.tree.pop_from_queue(QueueKind::Runnable);
         if branch_id.is_none() {
             return ConnectorScheduling::NotNow;
+        }
         // Retrieve the branch and run it
         let branch_id = branch_id.unwrap();
         let branch = &mut self.tree[branch_id];
         let mut run_context = ConnectorRunContext{
             branch_id,
             consensus: &self.consensus,
             prepared: branch.prepared.take(),
         };
         let run_result = Self::run_prompt(&mut branch.code_state, &sched_ctx.runtime.protocol_description, &mut run_context);
         if let Err(eval_error) = run_result {
             return ConnectorScheduling::Error(eval_error);
+        }
         let run_result = run_result.unwrap();
         // Handle the returned result. Note that this match statement contains
         // explicit returns in case the run result requires that the component's
         // code is ran again immediately
         match run_result {
             EvalContinuation::BranchInconsistent => {
                 // Branch became inconsistent
                 branch.sync_state = SpeculativeState::Inconsistent;
             },
             EvalContinuation::BlockFires(port_id) => {
                 // Branch called `fires()` on a port that has not been used yet.
                 let port_id = PortIdLocal::new(port_id.0.u32_suffix);
                 // Create two forks, one that assumes the port will fire, and
                 // one that assumes the port remains silent
                 branch.sync_state = SpeculativeState::HaltedAtBranchPoint;
                 let firing_branch_id = self.tree.fork_branch(branch_id);
                 let silent_branch_id = self.tree.fork_branch(branch_id);
                 self.consensus.notify_of_new_branch(branch_id, firing_branch_id);
                 let _result = self.consensus.notify_of_speculative_mapping(firing_branch_id, port_id, true);
                 debug_assert_eq!(_result, Consistency::Valid);
                 self.consensus.notify_of_new_branch(branch_id, silent_branch_id);
                 let _result = self.consensus.notify_of_speculative_mapping(silent_branch_id, port_id, false);
                 debug_assert_eq!(_result, Consistency::Valid);
                 // Somewhat important: we push the firing one first, such that
                 // that branch is ran again immediately.
                 self.tree.push_into_queue(QueueKind::Runnable, firing_branch_id);
                 self.tree.push_into_queue(QueueKind::Runnable, silent_branch_id);
                 return ConnectorScheduling::Immediate;
             },
             EvalContinuation::BlockGet(port_id) => {
                 // Branch performed a `get()` on a port that does not have a
                 // received message on that port.
                 let port_id = PortIdLocal::new(port_id.0.u32_suffix);
                 branch.sync_state = SpeculativeState::HaltedAtBranchPoint;
                 branch.awaiting_port = port_id;
                 self.tree.push_into_queue(QueueKind::AwaitingMessage, branch_id);
                 // Note: we only know that a branch is waiting on a message when
                 // it reaches the `get` call. But we might have already received
                 // a message that targets this branch, so check now.
                 let mut any_message_received = false;
                 for message in comp_ctx.get_read_data_messages(port_id) {
                     if self.consensus.branch_can_receive(branch_id, &message) {
                         // This branch can receive the message, so we do the
                         // fork-and-receive dance
                         let receiving_branch_id = self.tree.fork_branch(branch_id);
                         let branch = &mut self.tree[receiving_branch_id];
                         branch.awaiting_port = PortIdLocal::new_invalid();
                         branch.prepared = PreparedStatement::PerformedGet(message.content.as_message().unwrap().clone());
                         self.consensus.notify_of_new_branch(branch_id, receiving_branch_id);
                         self.consensus.notify_of_received_message(receiving_branch_id, &message);
                         self.tree.push_into_queue(QueueKind::Runnable, receiving_branch_id);
                         any_message_received = true;
+                    }
+                }
                 if any_message_received {
                     return ConnectorScheduling::Immediate;
+                }
+            }
             EvalContinuation::SyncBlockEnd => {
                 let consistency = self.consensus.notify_of_finished_branch(branch_id);
                 if consistency == Consistency::Valid {
                     branch.sync_state = SpeculativeState::ReachedSyncEnd;
                     self.tree.push_into_queue(QueueKind::FinishedSync, branch_id);
                 } else {
                     branch.sync_state = SpeculativeState::Inconsistent;
+                }
             },
             EvalContinuation::NewFork => {
                 // Like the `NewChannel` result. This means we're setting up
                 // a branch and putting a marker inside the RunContext for the
                 // next time we run the PDL code
                 let left_id = branch_id;
                 let right_id = self.tree.fork_branch(left_id);
                 self.consensus.notify_of_new_branch(left_id, right_id);
                 self.tree.push_into_queue(QueueKind::Runnable, left_id);
                 self.tree.push_into_queue(QueueKind::Runnable, right_id);
                 let left_branch = &mut self.tree[left_id];
                 left_branch.prepared = PreparedStatement::ForkedExecution(true);
                 let right_branch = &mut self.tree[right_id];
                 right_branch.prepared = PreparedStatement::ForkedExecution(false);
+            }
             EvalContinuation::Put(port_id, content) => {
                 // Branch is attempting to send data
                 let port_id = PortIdLocal::new(port_id.0.u32_suffix);
                 let (sync_header, data_header) = self.consensus.handle_message_to_send(branch_id, port_id, &content, comp_ctx);
                 comp_ctx.submit_message(Message::Data(DataMessage {
+                if let Err(_) = comp_ctx.submit_message(Message::Data(DataMessage {
                     sync_header, data_header,
                     content: DataContent::Message(content),
                 }));
                 })) {
                     // We don't own the port
                     let pd = &sched_ctx.runtime.protocol_description;
                     let eval_error = branch.code_state.new_error_at_expr(
                         &pd.modules, &pd.heap,
                         String::from("attempted to 'put' on port that is no longer owned")
                     );
                     self.mode = Mode::SyncError(eval_error);
+                }
                 branch.prepared = PreparedStatement::PerformedPut;
                 self.tree.push_into_queue(QueueKind::Runnable, branch_id);
                 return ConnectorScheduling::Immediate;
             },
             _ => unreachable!("unexpected run result {:?} in sync mode", run_result),
+        }
         // If here then the run result did not require a particular action. We
         // return whether we have more active branches to run or not.
         if self.tree.queue_is_empty(QueueKind::Runnable) {
             return ConnectorScheduling::NotNow;
         } else {
             return ConnectorScheduling::Later;
+        }
+    }
     pub fn run_in_deterministic_mode(&mut self, sched_ctx: SchedulerCtx, comp_ctx: &mut ComponentCtx) -> ConnectorScheduling {
         debug_assert!(!self.tree.is_in_sync() && !self.consensus.is_in_sync());
         let branch = self.tree.base_branch_mut();
         debug_assert!(branch.sync_state == SpeculativeState::RunningNonSync);
         let mut run_context = ConnectorRunContext{
             branch_id: branch.id,
             consensus: &self.consensus,
             prepared: branch.prepared.take(),
         };
         let run_result = Self::run_prompt(&mut branch.code_state, &sched_ctx.runtime.protocol_description, &mut run_context);
         if let Err(eval_error) = run_result {
             return ConnectorScheduling::Error(eval_error);
+        }
         let run_result = run_result.unwrap();
         match run_result {
             EvalContinuation::ComponentTerminated => {
                 branch.sync_state = SpeculativeState::Finished;
                 return ConnectorScheduling::Exit;
             },
             EvalContinuation::SyncBlockStart => {
                 comp_ctx.notify_sync_start();
                 let sync_branch_id = self.tree.start_sync();
                 debug_assert!(self.last_finished_handled.is_none());
                 self.consensus.start_sync(comp_ctx);
                 self.consensus.notify_of_new_branch(BranchId::new_invalid(), sync_branch_id);
                 self.tree.push_into_queue(QueueKind::Runnable, sync_branch_id);
                 return ConnectorScheduling::Immediate;
             },
             EvalContinuation::NewComponent(definition_id, monomorph_idx, arguments) => {
                 // Note: we're relinquishing ownership of ports. But because
                 // we are in non-sync mode the scheduler will handle and check
                 // port ownership transfer.
                 debug_assert!(comp_ctx.workspace_ports.is_empty());
                 find_ports_in_value_group(&arguments, &mut comp_ctx.workspace_ports);
                 let new_prompt = Prompt::new(
                     &sched_ctx.runtime.protocol_description.types,
                     &sched_ctx.runtime.protocol_description.heap,
                     definition_id, monomorph_idx, arguments
                 );
                 let new_component = ConnectorPDL::new(new_prompt);
                 comp_ctx.push_component(new_component, comp_ctx.workspace_ports.clone());
                 comp_ctx.workspace_ports.clear();
                 return ConnectorScheduling::Later;
             },
             EvalContinuation::NewChannel => {
                 let (getter, putter) = sched_ctx.runtime.create_channel(comp_ctx.id);
                 debug_assert!(getter.kind == PortKind::Getter && putter.kind == PortKind::Putter);
                 branch.prepared = PreparedStatement::CreatedChannel((
                     Value::Output(PortId::new(putter.self_id.index)),
                     Value::Input(PortId::new(getter.self_id.index)),
                 ));
                 comp_ctx.push_port(putter);
                 comp_ctx.push_port(getter);
                 return ConnectorScheduling::Immediate;
             },
             _ => unreachable!("unexpected run result '{:?}' while running in non-sync mode", run_result),
+        }
+    }
     pub fn collapse_sync_to_solution_branch(&mut self, solution_branch_id: BranchId, ctx: &mut ComponentCtx) {
     /// Helper that moves the component's state back into non-sync mode, using
     /// the provided solution branch ID as the branch that should be comitted to
     /// memory.
     fn enter_non_sync_mode(&mut self, solution_branch_id: BranchId, ctx: &mut ComponentCtx) {
         debug_assert!(self.mode == Mode::Sync || self.mode == Mode::SyncError);
         let mut fake_vec = Vec::new();
         self.tree.end_sync(solution_branch_id);
         self.consensus.end_sync(solution_branch_id, &mut fake_vec);
         for port in fake_vec {
             // TODO: Handle sent/received ports
             debug_assert!(ctx.get_port_by_id(port).is_some());
+        }
         ctx.notify_sync_end(&[]);
         self.last_finished_handled = None;
         self.eval_error = None; // in case we came from the SyncError mode
         self.mode = Mode::NonSync;
+    }
     /// Helper that moves the component's state into sync-error mode, sending
     /// the appropriate errors where needed. The branch that caused the fatal
     /// error and the evaluation error should be provided.
     fn enter_sync_error_mode(&mut self, failing_branch_id: BranchId, ctx: &mut ComponentCtx, eval_error: EvalError) {
         debug_assert!(self.mode == Mode::Sync);
         debug_assert!(self.eval_error.is_none());
         self.mode = Mode::SyncError;
         self.eval_error = Some(eval_error);
         let failing_branch = &mut self.tree[failing_branch_id];
         failing_branch.sync_state = SpeculativeState::Error;
+    }
     /// Runs the prompt repeatedly until some kind of execution-blocking
     /// condition appears.
     #[inline]
     fn run_prompt(prompt: &mut Prompt, pd: &ProtocolDescription, ctx: &mut ConnectorRunContext) -> Result<EvalContinuation, EvalError> {
         loop {
             let result = prompt.step(&pd.types, &pd.heap, &pd.modules, ctx);
             if let Ok(EvalContinuation::Stepping) = result {
                 continue;
+            }
             return result;
+        }
+    }
+}
@@ \ No newline at end of file @@

src/runtime2/consensus.rs

➞

Show inline comments

@@ @@ -51,192 +51,211 @@ struct Peer { @@
 //  performed on the same port to prevent repeated lookups
 // TODO: A lot of stuff should be batched. Like checking all the sync headers
 //  and sending "I have a higher ID" messages. Should reduce locking by quite a
 //  bit.
 pub(crate) struct Consensus {
     // --- State that is cleared after each round
     // Local component's state
     highest_connector_id: ConnectorId,
     branch_annotations: Vec<BranchAnnotation>, // index is branch ID
     branch_markers: Vec<BranchId>, // index is branch marker, maps to branch
     // Gathered state from communication
     encountered_ports: VecSet<PortIdLocal>, // to determine if we should send "port remains silent" messages.
     solution_combiner: SolutionCombiner,
     // --- Persistent state
     peers: Vec<Peer>,
     sync_round: u32,
     // --- Workspaces
     workspace_ports: Vec<PortIdLocal>,
+}
 #[derive(Debug, Clone, Copy, PartialEq, Eq)]
 pub(crate) enum Consistency {
     Valid,
     Inconsistent,
+}
 impl Consensus {
     pub fn new() -> Self {
         return Self {
             highest_connector_id: ConnectorId::new_invalid(),
             branch_annotations: Vec::new(),
             branch_markers: Vec::new(),
             encountered_ports: VecSet::new(),
             solution_combiner: SolutionCombiner::new(),
             peers: Vec::new(),
             sync_round: 0,
             workspace_ports: Vec::new(),
+        }
+    }
     // --- Controlling sync round and branches
     /// Returns whether the consensus algorithm is running in sync mode
     pub fn is_in_sync(&self) -> bool {
         return !self.branch_annotations.is_empty();
+    }
     /// TODO: Remove this once multi-fire is in place
     pub fn get_annotation(&self, branch_id: BranchId, port_id: PortIdLocal) -> &PortAnnotation {
         let branch = &self.branch_annotations[branch_id.index as usize];
         let port = branch.port_mapping.iter().find(|v| v.port_id == port_id).unwrap();
         return port;
+    }
     /// Sets up the consensus algorithm for a new synchronous round. The
     /// provided ports should be the ports the component owns at the start of
     /// the sync round.
     pub fn start_sync(&mut self, ctx: &ComponentCtx) {
         debug_assert!(!self.highest_connector_id.is_valid());
         debug_assert!(self.branch_annotations.is_empty());
         debug_assert!(self.solution_combiner.local.is_empty());
         // We'll use the first "branch" (the non-sync one) to store our ports,
         // this allows cloning if we created a new branch.
         self.branch_annotations.push(BranchAnnotation{
             port_mapping: ctx.get_ports().iter()
                 .map(|v| PortAnnotation{
                     port_id: v.self_id,
                     registered_id: None,
                     expected_firing: None,
                 })
                 .collect(),
             cur_marker: BranchMarker::new_invalid(),
         });
         self.branch_markers.push(BranchId::new_invalid());
         self.highest_connector_id = ctx.id;
+    }
     /// Notifies the consensus algorithm that a new branch has appeared. Must be
     /// called for each forked branch in the execution tree.
     pub fn notify_of_new_branch(&mut self, parent_branch_id: BranchId, new_branch_id: BranchId) {
         // If called correctly. Then each time we are notified the new branch's
         // index is the length in `branch_annotations`.
         debug_assert!(self.branch_annotations.len() == new_branch_id.index as usize);
         let parent_branch_annotations = &self.branch_annotations[parent_branch_id.index as usize];
         let new_marker = BranchMarker::new(self.branch_markers.len() as u32);
         let new_branch_annotations = BranchAnnotation{
             port_mapping: parent_branch_annotations.port_mapping.clone(),
             cur_marker: new_marker,
         };
         self.branch_annotations.push(new_branch_annotations);
         self.branch_markers.push(new_branch_id);
+    }
     /// Notifies the consensus algorithm that a particular branch has
     /// encountered an unrecoverable error. If the return value is `false`, then
     /// the caller can enter a "normal" exit mode instead of the special "sync"
     /// exit mode.
     pub fn notify_of_fatal_branch(&mut self, failed_branch_id: BranchId) -> bool {
         debug_assert!(self.is_in_sync());
         // Check for trivial case, where branch has not yet communicated within
         // the consensus algorithm
         let branch = &self.branch_annotations[failed_branch_id.index as usize];
         if branch.port_mapping.iter().all(|v| v.registered_id.is_none()) {
             return false;
+        }
         // Branch has communicated. Since we need to discover the entire
         return true;
+    }
     /// Notifies the consensus algorithm that a branch has reached the end of
     /// the sync block. A final check for consistency will be performed that the
     /// caller has to handle. Note that
     pub fn notify_of_finished_branch(&self, branch_id: BranchId) -> Consistency {
         debug_assert!(self.is_in_sync());
         let branch = &self.branch_annotations[branch_id.index as usize];
         for mapping in &branch.port_mapping {
             match mapping.expected_firing {
                 Some(expected) => {
                     if expected != mapping.registered_id.is_some() {
                         // Inconsistent speculative state and actual state
                         debug_assert!(mapping.registered_id.is_none()); // because if we did fire on a silent port, we should've caught that earlier
                         return Consistency::Inconsistent;
+                    }
                 },
                 None => {},
+            }
+        }
         return Consistency::Valid;
+    }
     /// Notifies the consensus algorithm that a particular branch has assumed
     /// a speculative value for its port mapping.
     pub fn notify_of_speculative_mapping(&mut self, branch_id: BranchId, port_id: PortIdLocal, does_fire: bool) -> Consistency {
         debug_assert!(self.is_in_sync());
         let branch = &mut self.branch_annotations[branch_id.index as usize];
         for mapping in &mut branch.port_mapping {
             if mapping.port_id == port_id {
                 match mapping.expected_firing {
                     None => {
                         // Not yet mapped, perform speculative mapping
                         mapping.expected_firing = Some(does_fire);
                         return Consistency::Valid;
                     },
                     Some(current) => {
                         // Already mapped
                         if current == does_fire {
                             return Consistency::Valid;
                         } else {
                             return Consistency::Inconsistent;
+                        }
+                    }
+                }
+            }
+        }
         unreachable!("notify_of_speculative_mapping called with unowned port");
+    }
     /// Generates a new local solution from a finished branch. If the component
     /// is not the leader of the sync region then it will be sent to the
     /// appropriate component. If it is the leader then there is a chance that
     /// this solution completes a global solution. In that case the solution
     /// branch ID will be returned.
     pub(crate) fn handle_new_finished_sync_branch(&mut self, branch_id: BranchId, ctx: &mut ComponentCtx) -> Option<BranchId> {
         // Turn the port mapping into a local solution
         let source_mapping = &self.branch_annotations[branch_id.index as usize].port_mapping;
         let mut target_mapping = Vec::with_capacity(source_mapping.len());
         for port in source_mapping {
             // Note: if the port is silent, and we've never communicated
             // over the port, then we need to do so now, to let the peer
             // component know about our sync leader state.
             let port_desc = ctx.get_port_by_id(port.port_id).unwrap();
             let peer_port_id = port_desc.peer_id;
             let channel_id = port_desc.channel_id;
             if !self.encountered_ports.contains(&port.port_id) {
                 ctx.submit_message(Message::Data(DataMessage {
                     sync_header: SyncHeader{
                         sending_component_id: ctx.id,
                         highest_component_id: self.highest_connector_id,
                         sync_round: self.sync_round
                     },
                     data_header: DataHeader{
                         expected_mapping: source_mapping.clone(),
                         sending_port: port.port_id,
                         target_port: peer_port_id,
                         new_mapping: BranchMarker::new_invalid(),
                     },
                     content: DataContent::SilentPortNotification,
                 }));
                 self.encountered_ports.push(port.port_id);
+            }
             target_mapping.push((
                 channel_id,
                 port.registered_id.unwrap_or(BranchMarker::new_invalid())
             ));
+        }
         let local_solution = LocalSolution{
             component: ctx.id,
             final_branch_id: branch_id,
             port_mapping: target_mapping,

src/runtime2/inbox.rs

➞

Show inline comments

@@ @@ -34,127 +34,140 @@ impl BranchMarker { @@
+    }
     #[inline]
     pub(crate) fn new_invalid() -> Self {
         return Self{ marker: 0 }
+    }
+}
 /// The header added by the synchronization algorithm to all.
 #[derive(Debug, Clone)]
 pub(crate) struct SyncHeader {
     pub sending_component_id: ConnectorId,
     pub highest_component_id: ConnectorId,
     pub sync_round: u32,
+}
 /// The header added to data messages
 #[derive(Debug, Clone)]
 pub(crate) struct DataHeader {
     pub expected_mapping: Vec<PortAnnotation>,
     pub sending_port: PortIdLocal,
     pub target_port: PortIdLocal,
     pub new_mapping: BranchMarker,
+}
 // TODO: Very much on the fence about this. On one hand I thought making it a
 //  data message was neat because "silent port notification" should be rerouted
 //  like any other data message to determine the component ID of the receiver
 //  and to make it part of the leader election algorithm for the sync leader.
 //  However: it complicates logic quite a bit. Really it might be easier to
 //  create `Message::SyncAtComponent` and `Message::SyncAtPort` messages...
 #[derive(Debug, Clone)]
 pub(crate) enum DataContent {
     SilentPortNotification,
     Message(ValueGroup),
+}
 impl DataContent {
     pub(crate) fn as_message(&self) -> Option<&ValueGroup> {
         match self {
             DataContent::SilentPortNotification => None,
             DataContent::Message(message) => Some(message),
+        }
+    }
+}
 /// A data message is a message that is intended for the receiver's PDL code,
 /// but will also be handled by the consensus algorithm
 #[derive(Debug, Clone)]
 pub(crate) struct DataMessage {
     pub sync_header: SyncHeader,
     pub data_header: DataHeader,
     pub content: DataContent,
+}
 #[derive(Debug)]
 pub(crate) enum SyncContent {
     LocalSolution(LocalSolution), // sending a local solution to the leader
     GlobalSolution(GlobalSolution), // broadcasting to everyone
     Notification, // just a notification (so purpose of message is to send the SyncHeader)
+}
 /// A sync message is a message that is intended only for the consensus
 /// algorithm.
 #[derive(Debug)]
 pub(crate) struct SyncMessage {
     pub sync_header: SyncHeader,
     pub target_component_id: ConnectorId,
     pub content: SyncContent,
+}
 /// A control message is a message intended for the scheduler that is executing
 /// a component.
 #[derive(Debug)]
 pub(crate) struct ControlMessage {
     pub id: u32, // generic identifier, used to match request to response
     pub sending_component_id: ConnectorId,
     pub content: ControlContent,
+}
 #[derive(Debug)]
 pub(crate) enum ControlContent {
     PortPeerChanged(PortIdLocal, ConnectorId),
     CloseChannel(PortIdLocal),
     Ack,
     Ping,
+}
 /// Combination of data message and control messages.
 #[derive(Debug)]
 pub(crate) enum Message {
     Data(DataMessage),
     Sync(SyncMessage),
     Control(ControlMessage),
+}
 impl Message {
     /// If the message is sent through a particular channel, then this function
     /// returns the port through which the message was sent.
     pub(crate) fn source_port(&self) -> Option<PortIdLocal> {
         // Currently only data messages have a source port
         if let Message::Data(message) = self {
             return Some(message.data_header.sending_port);
         } else {
             return None;
+        }
+    }
+}
 /// The public inbox of a connector. The thread running the connector that owns
 /// this inbox may retrieved from it. Non-owning threads may only put new
 /// messages inside of it.
 // TODO: @Optimize, lazy concurrency. Probably ringbuffer with read/write heads.
 //  Should behave as a MPSC queue.
 pub struct PublicInbox {
     messages: Mutex<VecDeque<Message>>,
+}
 impl PublicInbox {
     pub fn new() -> Self {
         Self{
             messages: Mutex::new(VecDeque::new()),
+        }
+    }
     pub(crate) fn insert_message(&self, message: Message) {
         let mut lock = self.messages.lock().unwrap();
         lock.push_back(message);
+    }
     pub(crate) fn take_message(&self) -> Option<Message> {
         let mut lock = self.messages.lock().unwrap();
         return lock.pop_front();
+    }
     pub fn is_empty(&self) -> bool {
         let lock = self.messages.lock().unwrap();
         return lock.is_empty();
+    }
+}
@@ \ No newline at end of file @@

src/runtime2/scheduler.rs

➞

Show inline comments

 use std::collections::VecDeque;
 use std::sync::Arc;
 use std::sync::atomic::Ordering;
 use crate::protocol::eval::EvalError;
 use super::{ScheduledConnector, RuntimeInner, ConnectorId, ConnectorKey};
 use super::port::{Port, PortState, PortIdLocal};
 use super::native::Connector;
 use super::branch::{BranchId};
 use super::connector::{ConnectorPDL, ConnectorScheduling};
 use super::inbox::{Message, DataMessage, ControlMessage, ControlContent};
 // Because it contains pointers we're going to do a copy by value on this one
 #[derive(Clone, Copy)]
 pub(crate) struct SchedulerCtx<'a> {
     pub(crate) runtime: &'a RuntimeInner
+}
 pub(crate) struct Scheduler {
     runtime: Arc<RuntimeInner>,
     scheduler_id: u32,
+}
 impl Scheduler {
     pub fn new(runtime: Arc<RuntimeInner>, scheduler_id: u32) -> Self {
         return Self{ runtime, scheduler_id };
+    }
     pub fn run(&mut self) {
         // Setup global storage and workspaces that are reused for every
         // connector that we run
         'thread_loop: loop {
             // Retrieve a unit of work
             self.debug("Waiting for work");
             let connector_key = self.runtime.wait_for_work();
             if connector_key.is_none() {
                 // We should exit
                 self.debug(" ... No more work, quitting");
                 break 'thread_loop;
+            }
             // We have something to do
             let connector_key = connector_key.unwrap();
             let connector_id = connector_key.downcast();
             self.debug_conn(connector_id, &format!(" ... Got work, running {}", connector_key.index));
             let scheduled = self.runtime.get_component_private(&connector_key);
             // Keep running until we should no longer immediately schedule the
             // connector.
             let mut cur_schedule = ConnectorScheduling::Immediate;
             while let ConnectorScheduling::Immediate = cur_schedule {
                 self.handle_inbox_messages(scheduled);
                 // Run the main behaviour of the connector, depending on its
                 // current state.
                 if scheduled.shutting_down {
                     // Nothing to do. But we're stil waiting for all our pending
                     // control messages to be answered.
                     self.debug_conn(connector_id, &format!("Shutting down, {} Acks remaining", scheduled.router.num_pending_acks()));
                     if scheduled.router.num_pending_acks() == 0 {
                         // We're actually done, we can safely destroy the
                         // currently running connector
                         self.runtime.destroy_component(connector_key);
                         continue 'thread_loop;
                     } else {
                         cur_schedule = ConnectorScheduling::NotNow;
+                    }
                 } else {
                     self.debug_conn(connector_id, "Running ...");
                     let scheduler_ctx = SchedulerCtx{ runtime: &*self.runtime };
                     let new_schedule = scheduled.connector.run(scheduler_ctx, &mut scheduled.ctx);
                     self.debug_conn(connector_id, "Finished running");
                     // Handle all of the output from the current run: messages to
                     // send and connectors to instantiate.
                     self.handle_changes_in_context(scheduled);
                     cur_schedule = new_schedule;
+                }
+            }
             // If here then the connector does not require immediate execution.
             // So enqueue it if requested, and otherwise put it in a sleeping
             // state.
             match cur_schedule {
                 ConnectorScheduling::Immediate => unreachable!(),
                 ConnectorScheduling::Later => {
                     // Simply queue it again later
                     self.runtime.push_work(connector_key);
                 },
                 ConnectorScheduling::NotNow => {
                     // Need to sleep, note that we are the only ones which are
                     // allows to set the sleeping state to `true`, and since
                     // we're running it must currently be `false`.
                     self.try_go_to_sleep(connector_key, scheduled);
                 },
                 ConnectorScheduling::Exit => {
                     // Prepare for exit. Set the shutdown flag and broadcast
                     // messages to notify peers of closing channels
@@ @@ -300,264 +301,281 @@ impl Scheduler { @@
         if scheduled.ctx.changed_in_sync {
             if scheduled.ctx.is_in_sync {
                 // Just entered sync region
             } else {
                 // Just left sync region. So clear inbox up until the last
                 // message that was read.
                 scheduled.ctx.inbox_messages.drain(0..scheduled.ctx.inbox_len_read);
                 scheduled.ctx.inbox_len_read = 0;
+            }
             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.0);
         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)
+            }
+        }
+    }
     #[inline]
     fn get_message_target_port(message: &Message) -> Option<PortIdLocal> {
         match message {
             Message::Data(data) => return Some(data.data_header.target_port),
             Message::Sync(_) => {},
             Message::Control(control) => {
                 match &control.content {
                     ControlContent::PortPeerChanged(port_id, _) => return Some(*port_id),
                     ControlContent::CloseChannel(port_id) => return Some(*port_id),
                     ControlContent::Ping | ControlContent::Ack => {},
+                }
             },
+        }
         return None
+    }
     // TODO: Remove, this is debugging stuff
     fn debug(&self, message: &str) {
         // println!("DEBUG [thrd:{:02} conn:  ]: {}", self.scheduler_id, message);
+    }
     fn debug_conn(&self, conn: ConnectorId, message: &str) {
         // println!("DEBUG [thrd:{:02} conn:{:02}]: {}", self.scheduler_id, conn.0, 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_messages: Vec<Message>,
     inbox_len_read: usize,
     // 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_messages: Vec::new(),
             inbox_len_read: 0,
             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) {
+    }
     #[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);
+    }
     fn get_port_mut_by_id(&mut self, id: PortIdLocal) -> Option<&mut Port> {
         return self.ports.iter_mut().find(|v| v.self_id == id);
+    }
     /// Notify that component will enter a sync block. Note that after calling
     /// this function you must allow the scheduler to pick up the changes in the
     /// context by exiting your code-executing loop, and to continue executing
     /// code the next time the scheduler picks up the component.
     pub(crate) fn notify_sync_start(&mut self) {
         debug_assert!(!self.is_in_sync);
         self.is_in_sync = true;
         self.changed_in_sync = true;
+    }
     #[inline]
     pub(crate) fn is_in_sync(&self) -> bool {
         return self.is_in_sync;
+    }
     /// Submit a message for the scheduler to send to the appropriate receiver.
     /// May only be called inside of a sync block.
     pub(crate) fn submit_message(&mut self, contents: Message) {
+    pub(crate) fn submit_message(&mut self, contents: Message) -> Result<(), ()> {
         debug_assert!(self.is_in_sync);
         if let Some(port_id) = contents.source_port() {
             if self.get_port_by_id(port_id).is_none() {
                 // We don't own the port
                 return Err(());
+            }
+        }
         self.outbox.push_back(contents);
         return Ok(());
+    }
     /// Notify that component just finished a sync block. Like
     /// `notify_sync_start`: drop out of the `Component::Run` function.
     pub(crate) fn notify_sync_end(&mut self, changed_ports: &[ComponentPortChange]) {
         debug_assert!(self.is_in_sync);
         self.is_in_sync = false;
         self.changed_in_sync = true;
         self.state_changes.reserve(changed_ports.len());
         for changed_port in changed_ports {
             self.state_changes.push_back(ComponentStateChange::ChangedPort(changed_port.clone()));
+        }
+    }
     /// Retrieves messages matching a particular port and branch id. But only
     /// those messages that have been previously received with
     /// `read_next_message`.
     pub(crate) fn get_read_data_messages(&self, match_port_id: PortIdLocal) -> MessagesIter {
         return MessagesIter {
             messages: &self.inbox_messages,
             next_index: 0,
             max_index: self.inbox_len_read,
             match_port_id
         };
+    }
     /// Retrieves the next unread message from the inbox `None` if there are no
     /// (new) messages to read.
     // TODO: Fix the clone of the data message, entirely unnecessary
     pub(crate) fn read_next_message(&mut self) -> Option<Message> {
         if !self.is_in_sync { return None; }
         if self.inbox_len_read == self.inbox_messages.len() { return None; }
         // We want to keep data messages in the inbox, because we need to check
         // them in the future. We don't want to keep sync messages around, we
         // should only handle them once. Control messages should never be in
         // here.
         let message = &self.inbox_messages[self.inbox_len_read];
         match message {
             Message::Data(content) => {
                 self.inbox_len_read += 1;
                 return Some(Message::Data(content.clone()));
             },
             Message::Sync(_) => {
                 let message = self.inbox_messages.remove(self.inbox_len_read);
                 return Some(message);
             },
             Message::Control(_) => unreachable!("control message ended up in component inbox"),
+        }
+    }
+}
 pub(crate) struct MessagesIter<'a> {
     messages: &'a [Message],
     next_index: usize,
     max_index: usize,
     match_port_id: PortIdLocal,
+}
 impl<'a> Iterator for MessagesIter<'a> {
     type Item = &'a DataMessage;
     fn next(&mut self) -> Option<Self::Item> {
         // Loop until match is found or at end of messages
         while self.next_index < self.max_index {
             let message = &self.messages[self.next_index];
             if let Message::Data(message) = &message {
                 if message.data_header.target_port == self.match_port_id {
                     // Found a match
                     self.next_index += 1;
                     return Some(message);
+                }
             } else {
                 // Unreachable because:
                 //  1. We only iterate over messages that were previously retrieved by `read_next_message`.
                 //  2. Inbox does not contain control/ping messages.
                 //  3. If `read_next_message` encounters anything else than a data message, it is removed from the inbox.
                 unreachable!();
+            }
             self.next_index += 1;
+        }
         // No more messages
         return None;
+    }
+}
 // -----------------------------------------------------------------------------
 // Control messages
 // -----------------------------------------------------------------------------
 struct ControlEntry {
     id: u32,

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