Fix retry race condition that can lead to double decrementing inFlightSubStreams and so miss calling closed (grpc#11026)

Author: larry-safran

core/src/main/java/io/grpc/internal/RetriableStream.java

@@ -149,11 +149,10 @@ public void uncaughtException(Thread t, Throwable e) {
     this.throttle = throttle;
   }
 
-  @SuppressWarnings("GuardedBy")
+  @SuppressWarnings("GuardedBy")  // TODO(b/145386688) this.lock==ScheduledCancellor.lock so ok
   @Nullable // null if already committed
   @CheckReturnValue
   private Runnable commit(final Substream winningSubstream) {
-
     synchronized (lock) {
       if (state.winningSubstream != null) {
         return null;
@@ -165,10 +164,9 @@ private Runnable commit(final Substream winningSubstream) {
       // subtract the share of this RPC from channelBufferUsed.
       channelBufferUsed.addAndGet(-perRpcBufferUsed);
 
+      final boolean wasCancelled = (scheduledRetry != null) ? scheduledRetry.isCancelled() : false;
       final Future<?> retryFuture;
       if (scheduledRetry != null) {
-        // TODO(b/145386688): This access should be guarded by 'this.scheduledRetry.lock'; instead
-        // found: 'this.lock'
         retryFuture = scheduledRetry.markCancelled();
         scheduledRetry = null;
       } else {
@@ -177,8 +175,6 @@ private Runnable commit(final Substream winningSubstream) {
       // cancel the scheduled hedging if it is scheduled prior to the commitment
       final Future<?> hedgingFuture;
       if (scheduledHedging != null) {
-        // TODO(b/145386688): This access should be guarded by 'this.scheduledHedging.lock'; instead
-        // found: 'this.lock'
         hedgingFuture = scheduledHedging.markCancelled();
         scheduledHedging = null;
       } else {
@@ -195,11 +191,22 @@ public void run() {
             }
           }
           if (retryFuture != null) {
-            boolean cancelled = retryFuture.cancel(false);
-            if (cancelled) {
-              inFlightSubStreams.decrementAndGet();
+            retryFuture.cancel(false);
+            if (!wasCancelled && inFlightSubStreams.decrementAndGet() == Integer.MIN_VALUE) {
+              assert savedCloseMasterListenerReason != null;
+              listenerSerializeExecutor.execute(
+                  new Runnable() {
+                    @Override
+                    public void run() {
+                      isClosed = true;
+                      masterListener.closed(savedCloseMasterListenerReason.status,
+                          savedCloseMasterListenerReason.progress,
+                          savedCloseMasterListenerReason.metadata);
+                    }
+                  });
             }
           }
+
           if (hedgingFuture != null) {
             hedgingFuture.cancel(false);
           }
@@ -418,7 +425,7 @@ public final void start(ClientStreamListener listener) {
     drain(substream);
   }
 
-  @SuppressWarnings("GuardedBy")
+  @SuppressWarnings("GuardedBy")  // TODO(b/145386688) this.lock==ScheduledCancellor.lock so ok
   private void pushbackHedging(@Nullable Integer delayMillis) {
     if (delayMillis == null) {
       return;
@@ -437,8 +444,6 @@ private void pushbackHedging(@Nullable Integer delayMillis) {
         return;
       }
 
-      // TODO(b/145386688): This access should be guarded by 'this.scheduledHedging.lock'; instead
-      // found: 'this.lock'
       futureToBeCancelled = scheduledHedging.markCancelled();
       scheduledHedging = future = new FutureCanceller(lock);
     }
@@ -472,16 +477,13 @@ public void run() {
       }
       callExecutor.execute(
           new Runnable() {
-            @SuppressWarnings("GuardedBy")
+            @SuppressWarnings("GuardedBy")  //TODO(b/145386688) lock==ScheduledCancellor.lock so ok
             @Override
             public void run() {
               boolean cancelled = false;
               FutureCanceller future = null;
 
               synchronized (lock) {
-                // TODO(b/145386688): This access should be guarded by
-                // 'HedgingRunnable.this.scheduledHedgingRef.lock'; instead found:
-                // 'RetriableStream.this.lock'
                 if (scheduledHedgingRef.isCancelled()) {
                   cancelled = true;
                 } else {
@@ -813,13 +815,11 @@ private boolean hasPotentialHedging(State state) {
         && !state.hedgingFrozen;
   }
 
-  @SuppressWarnings("GuardedBy")
+  @SuppressWarnings("GuardedBy")  // TODO(b/145386688) this.lock==ScheduledCancellor.lock so ok
   private void freezeHedging() {
     Future<?> futureToBeCancelled = null;
     synchronized (lock) {
       if (scheduledHedging != null) {
-        // TODO(b/145386688): This access should be guarded by 'this.scheduledHedging.lock'; instead
-        // found: 'this.lock'
         futureToBeCancelled = scheduledHedging.markCancelled();
         scheduledHedging = null;
       }
@@ -1002,9 +1002,19 @@ public void run() {
               synchronized (lock) {
                 scheduledRetry = scheduledRetryCopy = new FutureCanceller(lock);
               }
+
               class RetryBackoffRunnable implements Runnable {
                 @Override
+                @SuppressWarnings("FutureReturnValueIgnored")
                 public void run() {
+                  synchronized (scheduledRetryCopy.lock) {
+                    if (scheduledRetryCopy.isCancelled()) {
+                      return;
+                    } else {
+                      scheduledRetryCopy.markCancelled();
+                    }
+                  }
+
                   callExecutor.execute(
                       new Runnable() {
                         @Override
@@ -1566,11 +1576,16 @@ private static final class FutureCanceller {
     }
 
     void setFuture(Future<?> future) {
+      boolean wasCancelled;
       synchronized (lock) {
-        if (!cancelled) {
+        wasCancelled = cancelled;
+        if (!wasCancelled) {
           this.future = future;
         }
       }
+      if (wasCancelled) {
+        future.cancel(false);
+      }
     }
 
     @GuardedBy("lock")

core/src/test/java/io/grpc/internal/RetriableStreamTest.java

@@ -705,6 +705,7 @@ public void retry_unretriableClosed_cancel() {
     // cancel
     retriableStream.cancel(Status.CANCELLED);
     inOrder.verify(retriableStreamRecorder, never()).postCommit();
+    verify(masterListener, times(1)).closed(any(), any(), any());
   }
 
   @Test
@@ -733,6 +734,7 @@ public void retry_cancelWhileBackoff() {
 
     verifyNoMoreInteractions(mockStream1);
     verifyNoMoreInteractions(mockStream2);
+    verify(masterListener, times(1)).closed(any(), any(), any());
   }
 
   @Test