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core: use SynchronizationContext.schedule() for NameResolver refresh (#5089) 

This also fixes the bug where NameResolverRefresh is not run from
syncContext if run from ScheduledExecutorService.
This commit is contained in:
Kun Zhang 2018-11-28 09:42:29 -08:00 committed by GitHub
parent 3ff4790212
commit 98ae834dfa
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GPG Key ID: 4AEE18F83AFDEB23
2 changed files with 12 additions and 24 deletions
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33
core/src/main/java/io/grpc/internal/ManagedChannelImpl.java
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@ -62,6 +62,7 @@ import io.grpc.MethodDescriptor;
import io.grpc.NameResolver; import io.grpc.NameResolver;
import io.grpc.Status; import io.grpc.Status;
import io.grpc.SynchronizationContext; import io.grpc.SynchronizationContext;
import io.grpc.SynchronizationContext.ScheduledHandle;
import io.grpc.internal.ClientCallImpl.ClientTransportProvider; import io.grpc.internal.ClientCallImpl.ClientTransportProvider;
import io.grpc.internal.RetriableStream.ChannelBufferMeter; import io.grpc.internal.RetriableStream.ChannelBufferMeter;
import io.grpc.internal.RetriableStream.Throttle; import io.grpc.internal.RetriableStream.Throttle;
@ -394,17 +395,8 @@ final class ManagedChannelImpl extends ManagedChannel implements
// Run from syncContext // Run from syncContext
@VisibleForTesting @VisibleForTesting
class NameResolverRefresh implements Runnable { class NameResolverRefresh implements Runnable {
// Only mutated from syncContext
boolean cancelled;
@Override @Override
public void run() { public void run() {
if (cancelled) {
// Race detected: this task was scheduled on syncContext before
// cancelNameResolverBackoff() could cancel the timer.
return;
}
nameResolverRefreshFuture = null;
nameResolverRefresh = null; nameResolverRefresh = null;
if (nameResolver != null) { if (nameResolver != null) {
nameResolver.refresh(); nameResolver.refresh();
@ -413,19 +405,15 @@ final class ManagedChannelImpl extends ManagedChannel implements
} }
// Must be used from syncContext // Must be used from syncContext
@Nullable private ScheduledFuture<?> nameResolverRefreshFuture; @Nullable private ScheduledHandle nameResolverRefresh;
// Must be used from syncContext
@Nullable private NameResolverRefresh nameResolverRefresh;
// The policy to control backoff between name resolution attempts. Non-null when an attempt is // The policy to control backoff between name resolution attempts. Non-null when an attempt is
// scheduled. Must be used from syncContext // scheduled. Must be used from syncContext
@Nullable private BackoffPolicy nameResolverBackoffPolicy; @Nullable private BackoffPolicy nameResolverBackoffPolicy;
// Must be run from syncContext // Must be run from syncContext
private void cancelNameResolverBackoff() { private void cancelNameResolverBackoff() {
if (nameResolverRefreshFuture != null) { if (nameResolverRefresh != null) {
nameResolverRefreshFuture.cancel(false); nameResolverRefresh.cancel();
nameResolverRefresh.cancelled = true;
nameResolverRefreshFuture = null;
nameResolverRefresh = null; nameResolverRefresh = null;
nameResolverBackoffPolicy = null; nameResolverBackoffPolicy = null;
} }
@ -869,7 +857,7 @@ final class ManagedChannelImpl extends ManagedChannel implements
if (shutdown.get()) { if (shutdown.get()) {
return; return;
} }
if (nameResolverRefreshFuture != null) { if (nameResolverRefresh != null && nameResolverRefresh.isPending()) {
checkState(nameResolverStarted, "name resolver must be started"); checkState(nameResolverStarted, "name resolver must be started");
cancelNameResolverBackoff(); cancelNameResolverBackoff();
nameResolver.refresh(); nameResolver.refresh();
@ -1317,7 +1305,7 @@ final class ManagedChannelImpl extends ManagedChannel implements
return; return;
} }
helper.lb.handleNameResolutionError(error); helper.lb.handleNameResolutionError(error);
if (nameResolverRefreshFuture != null) { if (nameResolverRefresh != null && nameResolverRefresh.isPending()) {
// The name resolver may invoke onError multiple times, but we only want to // The name resolver may invoke onError multiple times, but we only want to
// schedule one backoff attempt // schedule one backoff attempt
// TODO(ericgribkoff) Update contract of NameResolver.Listener or decide if we // TODO(ericgribkoff) Update contract of NameResolver.Listener or decide if we
@ -1331,11 +1319,10 @@ final class ManagedChannelImpl extends ManagedChannel implements
channelLogger.log( channelLogger.log(
ChannelLogLevel.DEBUG, ChannelLogLevel.DEBUG,
"Scheduling DNS resolution backoff for {0} ns", delayNanos); "Scheduling DNS resolution backoff for {0} ns", delayNanos);
nameResolverRefresh = new NameResolverRefresh(); nameResolverRefresh =
nameResolverRefreshFuture = syncContext.schedule(
transportFactory new NameResolverRefresh(), delayNanos, TimeUnit.NANOSECONDS,
.getScheduledExecutorService() transportFactory .getScheduledExecutorService());
.schedule(nameResolverRefresh, delayNanos, TimeUnit.NANOSECONDS);
} }
} }

3
core/src/test/java/io/grpc/internal/ManagedChannelImplTest.java
View File

@ -175,7 +175,8 @@ public class ManagedChannelImplTest {
new FakeClock.TaskFilter() { new FakeClock.TaskFilter() {
@Override @Override
public boolean shouldAccept(Runnable command) { public boolean shouldAccept(Runnable command) {
return command instanceof ManagedChannelImpl.NameResolverRefresh; return command.toString().contains(
ManagedChannelImpl.NameResolverRefresh.class.getName());
} }
}; };