Define ChainedChannel{Sender, Receiver} wrappers

unified-scheduler-pool/src/lib.rs

@@ -10,7 +10,7 @@
 
 use {
     assert_matches::assert_matches,
-    crossbeam_channel::{select, unbounded, Receiver, Sender},
+    crossbeam_channel::{select, unbounded, Receiver, SendError, Sender},
     log::*,
     solana_ledger::blockstore_processor::{
         execute_batch, TransactionBatchWithIndexes, TransactionStatusSender,
@@ -247,36 +247,138 @@ type ExecutedTaskPayload = SubchanneledPayload<Box<ExecutedTask>, ()>;
 // minimum at the cost of a single heap allocation per switching for the sake of Box-ing the Self
 // type to avoid infinite mem::size_of() due to the recursive type structure. Needless to say, such
 // an allocation can be amortized to be negligible.
-enum ChainedChannel<P1, P2> {
-    Payload(P1),
-    PayloadAndChannel(Box<dyn WithChannelAndPayload<P1, P2>>),
-}
+mod chained_channel {
+    use super::*;
 
-trait WithChannelAndPayload<P1, P2>: Send + Sync {
-    fn payload_and_channel(self: Box<Self>) -> PayloadAndChannelInner<P1, P2>;
-}
+    // hide variants by putting this inside newtype
+    enum ChainedChannelPrivate<P, C> {
+        Payload(P),
+        ContextAndChannel(Box<dyn WithContextAndPayload<P, C>>),
+    }
 
-type PayloadAndChannelInner<P1, P2> = (P2, Receiver<ChainedChannel<P1, P2>>);
+    pub(super) struct ChainedChannel<P, C>(ChainedChannelPrivate<P, C>);
 
-struct PayloadAndChannelWrapper<P1, P2>(PayloadAndChannelInner<P1, P2>);
+    trait WithContextAndPayload<P, C>: Send + Sync {
+        fn context_and_channel(self: Box<Self>) -> ContextAndChannelInner<P, C>;
+    }
 
-impl<P1, P2> WithChannelAndPayload<P1, P2> for PayloadAndChannelWrapper<P1, P2>
-where
-    P1: Send + Sync,
-    P2: Send + Sync,
-{
-    fn payload_and_channel(self: Box<Self>) -> PayloadAndChannelInner<P1, P2> {
-        self.0
+    type ContextAndChannelInner<P, C> = (C, Receiver<ChainedChannel<P, C>>);
+
+    struct ContextAndChannelWrapper<P, C>(ContextAndChannelInner<P, C>);
+
+    impl<P, C> WithContextAndPayload<P, C> for ContextAndChannelWrapper<P, C>
+    where
+        P: Send + Sync,
+        C: Send + Sync,
+    {
+        fn context_and_channel(self: Box<Self>) -> ContextAndChannelInner<P, C> {
+            self.0
+        }
     }
-}
 
-impl<P1, P2> ChainedChannel<P1, P2>
-where
-    P1: Send + Sync + 'static,
-    P2: Send + Sync + 'static,
-{
-    fn chain_to_new_channel(payload: P2, receiver: Receiver<Self>) -> Self {
-        Self::PayloadAndChannel(Box::new(PayloadAndChannelWrapper((payload, receiver))))
+    impl<P, C> ChainedChannel<P, C>
+    where
+        P: Send + Sync + 'static,
+        C: Send + Sync + 'static,
+    {
+        fn chain_to_new_channel(context: C, receiver: Receiver<Self>) -> Self {
+            Self(ChainedChannelPrivate::ContextAndChannel(Box::new(
+                ContextAndChannelWrapper((context, receiver)),
+            )))
+        }
+    }
+
+    pub(super) struct ChainedChannelSender<P, C> {
+        sender: Sender<ChainedChannel<P, C>>,
+    }
+
+    impl<P, C> ChainedChannelSender<P, C>
+    where
+        P: Send + Sync + 'static,
+        C: Send + Sync + 'static + Clone,
+    {
+        fn new(sender: Sender<ChainedChannel<P, C>>) -> Self {
+            Self { sender }
+        }
+
+        pub(super) fn send_payload(
+            &self,
+            payload: P,
+        ) -> std::result::Result<(), SendError<ChainedChannel<P, C>>> {
+            self.sender
+                .send(ChainedChannel(ChainedChannelPrivate::Payload(payload)))
+        }
+
+        pub(super) fn send_chained_channel(
+            &mut self,
+            context: C,
+            count: usize,
+        ) -> std::result::Result<(), SendError<ChainedChannel<P, C>>> {
+            let (chained_sender, chained_receiver) = crossbeam_channel::unbounded();
+            for _ in 0..count {
+                self.sender.send(ChainedChannel::chain_to_new_channel(
+                    context.clone(),
+                    chained_receiver.clone(),
+                ))?
+            }
+            self.sender = chained_sender;
+            Ok(())
+        }
+    }
+
+    pub(super) struct ChainedChannelReceiver<P, C: Clone> {
+        receiver: Receiver<ChainedChannel<P, C>>,
+        context: C,
+    }
+
+    impl<P, C: Clone> Clone for ChainedChannelReceiver<P, C> {
+        fn clone(&self) -> Self {
+            Self {
+                receiver: self.receiver.clone(),
+                context: self.context.clone(),
+            }
+        }
+    }
+
+    impl<P, C: Clone> ChainedChannelReceiver<P, C> {
+        fn new(receiver: Receiver<ChainedChannel<P, C>>, initial_context: C) -> Self {
+            Self {
+                receiver,
+                context: initial_context,
+            }
+        }
+
+        pub(super) fn context(&self) -> &C {
+            &self.context
+        }
+
+        pub(super) fn for_select(&self) -> &Receiver<ChainedChannel<P, C>> {
+            &self.receiver
+        }
+
+        pub(super) fn after_select(&mut self, message: ChainedChannel<P, C>) -> Option<P> {
+            match message.0 {
+                ChainedChannelPrivate::Payload(payload) => Some(payload),
+                ChainedChannelPrivate::ContextAndChannel(new_context_and_channel) => {
+                    (self.context, self.receiver) = new_context_and_channel.context_and_channel();
+                    None
+                }
+            }
+        }
+    }
+
+    pub(super) fn unbounded<P, C>(
+        initial_context: C,
+    ) -> (ChainedChannelSender<P, C>, ChainedChannelReceiver<P, C>)
+    where
+        P: Send + Sync + 'static,
+        C: Send + Sync + 'static + Clone,
+    {
+        let (sender, receiver) = crossbeam_channel::unbounded();
+        (
+            ChainedChannelSender::new(sender),
+            ChainedChannelReceiver::new(receiver, initial_context),
+        )
     }
 }
 
@@ -369,23 +471,6 @@ impl<S: SpawnableScheduler<TH>, TH: TaskHandler> ThreadManager<S, TH> {
         );
     }
 
-    fn propagate_context_to_handler_threads(
-        runnable_task_sender: &mut Sender<ChainedChannel<Task, SchedulingContext>>,
-        context: SchedulingContext,
-        handler_count: usize,
-    ) {
-        let (next_sessioned_task_sender, runnable_task_receiver) = unbounded();
-        for _ in 0..handler_count {
-            runnable_task_sender
-                .send(ChainedChannel::chain_to_new_channel(
-                    context.clone(),
-                    runnable_task_receiver.clone(),
-                ))
-                .unwrap();
-        }
-        *runnable_task_sender = next_sessioned_task_sender;
-    }
-
     fn take_session_result_with_timings(&mut self) -> ResultWithTimings {
         self.session_result_with_timings.take().unwrap()
     }
@@ -399,8 +484,8 @@ impl<S: SpawnableScheduler<TH>, TH: TaskHandler> ThreadManager<S, TH> {
     }
 
     fn start_threads(&mut self, context: &SchedulingContext) {
-        let (runnable_task_sender, runnable_task_receiver) =
-            unbounded::<ChainedChannel<Task, SchedulingContext>>();
+        let (mut runnable_task_sender, runnable_task_receiver) =
+            chained_channel::unbounded::<Task, SchedulingContext>(context.clone());
         let (executed_task_sender, executed_task_receiver) = unbounded::<ExecutedTaskPayload>();
         let (finished_task_sender, finished_task_receiver) = unbounded::<Box<ExecutedTask>>();
         let (accumulated_result_sender, accumulated_result_receiver) =
@@ -422,7 +507,6 @@ impl<S: SpawnableScheduler<TH>, TH: TaskHandler> ThreadManager<S, TH> {
             let handler_count = self.handler_count;
             let session_result_sender = self.session_result_sender.clone();
             let new_task_receiver = self.new_task_receiver.clone();
-            let mut runnable_task_sender = runnable_task_sender.clone();
 
             let mut session_ending = false;
             let mut active_task_count: usize = 0;
@@ -481,17 +565,16 @@ impl<S: SpawnableScheduler<TH>, TH: TaskHandler> ThreadManager<S, TH> {
                                     // be resolved in the case of single-threaded FIFO like this.
                                     active_task_count = active_task_count.checked_add(1).unwrap();
                                     runnable_task_sender
-                                        .send(ChainedChannel::Payload(task))
+                                        .send_payload(task)
                                         .unwrap();
                                 }
                                 NewTaskPayload::OpenSubchannel(context) => {
                                     // signal about new SchedulingContext to both handler and
                                     // accumulator threads
-                                    Self::propagate_context_to_handler_threads(
-                                        &mut runnable_task_sender,
+                                    runnable_task_sender.send_chained_channel(
                                         context,
                                         handler_count
-                                    );
+                                    ).unwrap();
                                     executed_task_sender
                                         .send(ExecutedTaskPayload::OpenSubchannel(()))
                                         .unwrap();
@@ -528,28 +611,25 @@ impl<S: SpawnableScheduler<TH>, TH: TaskHandler> ThreadManager<S, TH> {
 
         let handler_main_loop = || {
             let pool = self.pool.clone();
-            let mut bank = context.bank().clone();
             let mut runnable_task_receiver = runnable_task_receiver.clone();
             let finished_task_sender = finished_task_sender.clone();
 
             move || loop {
                 let (task, sender) = select! {
-                    recv(runnable_task_receiver) -> message => {
-                        match message.unwrap() {
-                            ChainedChannel::Payload(task) => {
-                                (task, &finished_task_sender)
-                            }
-                            ChainedChannel::PayloadAndChannel(new_channel) => {
-                                let new_context;
-                                (new_context, runnable_task_receiver) = new_channel.payload_and_channel();
-                                bank = new_context.bank().clone();
-                                continue;
-                            }
+                    recv(runnable_task_receiver.for_select()) -> message => {
+                        if let Some(task) = runnable_task_receiver.after_select(message.unwrap()) {
+                            (task, &finished_task_sender)
+                        } else {
+                            continue;
                         }
                     },
                 };
                 let mut task = ExecutedTask::new_boxed(task);
-                Self::execute_task_with_handler(&bank, &mut task, &pool.handler_context);
+                Self::execute_task_with_handler(
+                    runnable_task_receiver.context().bank(),
+                    &mut task,
+                    &pool.handler_context,
+                );
                 sender.send(task).unwrap();
             }
         };