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core: Provide DEADLINE_EXCEEDED insights for context deadline
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We provided extra details when the RPC is killed by CallOptions'
Deadline, but didn't do the same for Context.

To avoid duplicating code, things were restructured, including the
threading. There are more code flows now, but I think the
multi-threading came out more obvious and less error-prone. I didn't
change the status when the deadline is already expired, because the
text is shared with DelayedClientCall and AbstractInteropTest doesn't
distinguish between the two cases.

This is a roll-forward that avoids a NPE when cancel() is called
without an earlier call to start().

As seen at b/300991330
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@ejona86
ejona86 authored Mar 22, 2024
1 parent 51f811d commit 3abab95
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170 changes: 78 additions & 92 deletions core/src/main/java/io/grpc/internal/ClientCallImpl.java
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Original file line number Diff line number Diff line change
Expand Up @@ -28,7 +28,6 @@
import static io.grpc.internal.GrpcUtil.CONTENT_LENGTH_KEY;
import static io.grpc.internal.GrpcUtil.MESSAGE_ACCEPT_ENCODING_KEY;
import static io.grpc.internal.GrpcUtil.MESSAGE_ENCODING_KEY;
import static java.lang.Math.max;

import com.google.common.annotations.VisibleForTesting;
import com.google.common.base.MoreObjects;
Expand Down Expand Up @@ -62,6 +61,7 @@
import java.util.concurrent.ScheduledExecutorService;
import java.util.concurrent.ScheduledFuture;
import java.util.concurrent.TimeUnit;
import java.util.concurrent.TimeoutException;
import java.util.logging.Level;
import java.util.logging.Logger;
import javax.annotation.Nullable;
Expand All @@ -82,16 +82,13 @@ final class ClientCallImpl<ReqT, RespT> extends ClientCall<ReqT, RespT> {
private final boolean callExecutorIsDirect;
private final CallTracer channelCallsTracer;
private final Context context;
private volatile ScheduledFuture<?> deadlineCancellationFuture;
private CancellationHandler cancellationHandler;
private final boolean unaryRequest;
private CallOptions callOptions;
private ClientStream stream;
private volatile boolean cancelListenersShouldBeRemoved;
private boolean cancelCalled;
private boolean halfCloseCalled;
private final ClientStreamProvider clientStreamProvider;
private final ContextCancellationListener cancellationListener =
new ContextCancellationListener();
private final ScheduledExecutorService deadlineCancellationExecutor;
private boolean fullStreamDecompression;
private DecompressorRegistry decompressorRegistry = DecompressorRegistry.getDefaultInstance();
Expand Down Expand Up @@ -128,13 +125,6 @@ final class ClientCallImpl<ReqT, RespT> extends ClientCall<ReqT, RespT> {
PerfMark.event("ClientCall.<init>", tag);
}

private final class ContextCancellationListener implements CancellationListener {
@Override
public void cancelled(Context context) {
stream.cancel(statusFromCancelled(context));
}
}

/**
* Provider of {@link ClientStream}s.
*/
Expand Down Expand Up @@ -252,21 +242,21 @@ public void runInContext() {
prepareHeaders(headers, decompressorRegistry, compressor, fullStreamDecompression);

Deadline effectiveDeadline = effectiveDeadline();
boolean deadlineExceeded = effectiveDeadline != null && effectiveDeadline.isExpired();
boolean contextIsDeadlineSource = effectiveDeadline != null
&& effectiveDeadline.equals(context.getDeadline());
cancellationHandler = new CancellationHandler(effectiveDeadline, contextIsDeadlineSource);
boolean deadlineExceeded = effectiveDeadline != null && cancellationHandler.remainingNanos <= 0;
if (!deadlineExceeded) {
logIfContextNarrowedTimeout(
effectiveDeadline, context.getDeadline(), callOptions.getDeadline());
stream = clientStreamProvider.newStream(method, callOptions, headers, context);
} else {
ClientStreamTracer[] tracers =
GrpcUtil.getClientStreamTracers(callOptions, headers, 0, false);
String deadlineName =
isFirstMin(callOptions.getDeadline(), context.getDeadline()) ? "CallOptions" : "Context";
String deadlineName = contextIsDeadlineSource ? "Context" : "CallOptions";
Long nameResolutionDelay = callOptions.getOption(NAME_RESOLUTION_DELAYED);
String description = String.format(
"ClientCall started after %s deadline was exceeded %.9f seconds ago. "
+ "Name resolution delay %.9f seconds.", deadlineName,
effectiveDeadline.timeRemaining(TimeUnit.NANOSECONDS) / NANO_TO_SECS,
cancellationHandler.remainingNanos / NANO_TO_SECS,
nameResolutionDelay == null ? 0 : nameResolutionDelay / NANO_TO_SECS);
stream = new FailingClientStream(DEADLINE_EXCEEDED.withDescription(description), tracers);
}
Expand Down Expand Up @@ -298,21 +288,7 @@ public void runInContext() {
// they receive cancel before start. Issue #1343 has more details

// Propagate later Context cancellation to the remote side.
context.addListener(cancellationListener, directExecutor());
if (effectiveDeadline != null
// If the context has the effective deadline, we don't need to schedule an extra task.
&& !effectiveDeadline.equals(context.getDeadline())
// If the channel has been terminated, we don't need to schedule an extra task.
&& deadlineCancellationExecutor != null) {
deadlineCancellationFuture = startDeadlineTimer(effectiveDeadline);
}
if (cancelListenersShouldBeRemoved) {
// Race detected! ClientStreamListener.closed may have been called before
// deadlineCancellationFuture was set / context listener added, thereby preventing the future
// and listener from being cancelled. Go ahead and cancel again, just to be sure it
// was cancelled.
removeContextListenerAndCancelDeadlineFuture();
}
cancellationHandler.setUp();
}

private void applyMethodConfig() {
Expand Down Expand Up @@ -354,75 +330,96 @@ private void applyMethodConfig() {
}
}

private static void logIfContextNarrowedTimeout(
Deadline effectiveDeadline, @Nullable Deadline outerCallDeadline,
@Nullable Deadline callDeadline) {
if (!log.isLoggable(Level.FINE) || effectiveDeadline == null
|| !effectiveDeadline.equals(outerCallDeadline)) {
return;
private final class CancellationHandler implements Runnable, CancellationListener {
private final boolean contextIsDeadlineSource;
private final boolean hasDeadline;
private final long remainingNanos;
private volatile ScheduledFuture<?> deadlineCancellationFuture;
private volatile boolean tearDownCalled;

CancellationHandler(Deadline deadline, boolean contextIsDeadlineSource) {
this.contextIsDeadlineSource = contextIsDeadlineSource;
if (deadline == null) {
hasDeadline = false;
remainingNanos = 0;
} else {
hasDeadline = true;
remainingNanos = deadline.timeRemaining(TimeUnit.NANOSECONDS);
}
}

long effectiveTimeout = max(0, effectiveDeadline.timeRemaining(TimeUnit.NANOSECONDS));
StringBuilder builder = new StringBuilder(String.format(
Locale.US,
"Call timeout set to '%d' ns, due to context deadline.", effectiveTimeout));
if (callDeadline == null) {
builder.append(" Explicit call timeout was not set.");
} else {
long callTimeout = callDeadline.timeRemaining(TimeUnit.NANOSECONDS);
builder.append(String.format(Locale.US, " Explicit call timeout was '%d' ns.", callTimeout));
void setUp() {
if (tearDownCalled) {
return;
}
if (hasDeadline
// If the context has the effective deadline, we don't need to schedule an extra task.
&& !contextIsDeadlineSource
// If the channel has been terminated, we don't need to schedule an extra task.
&& deadlineCancellationExecutor != null) {
deadlineCancellationFuture = deadlineCancellationExecutor.schedule(
new LogExceptionRunnable(this), remainingNanos, TimeUnit.NANOSECONDS);
}
context.addListener(this, directExecutor());
if (tearDownCalled) {
// Race detected! Re-run to make sure the future is cancelled and context listener removed
tearDown();
}
}

log.fine(builder.toString());
}

private void removeContextListenerAndCancelDeadlineFuture() {
context.removeListener(cancellationListener);
ScheduledFuture<?> f = deadlineCancellationFuture;
if (f != null) {
f.cancel(false);
// May be called multiple times, and race with setUp()
void tearDown() {
tearDownCalled = true;
ScheduledFuture<?> deadlineCancellationFuture = this.deadlineCancellationFuture;
if (deadlineCancellationFuture != null) {
deadlineCancellationFuture.cancel(false);
}
context.removeListener(this);
}
}

private class DeadlineTimer implements Runnable {
private final long remainingNanos;

DeadlineTimer(long remainingNanos) {
this.remainingNanos = remainingNanos;
@Override
public void cancelled(Context context) {
if (hasDeadline && contextIsDeadlineSource
&& context.cancellationCause() instanceof TimeoutException) {
stream.cancel(formatDeadlineExceededStatus());
return;
}
stream.cancel(statusFromCancelled(context));
}

@Override
public void run() {
InsightBuilder insight = new InsightBuilder();
stream.appendTimeoutInsight(insight);
stream.cancel(formatDeadlineExceededStatus());
}

Status formatDeadlineExceededStatus() {
// DelayedStream.cancel() is safe to call from a thread that is different from where the
// stream is created.
long seconds = Math.abs(remainingNanos) / TimeUnit.SECONDS.toNanos(1);
long nanos = Math.abs(remainingNanos) % TimeUnit.SECONDS.toNanos(1);

StringBuilder buf = new StringBuilder();
buf.append("deadline exceeded after ");
buf.append(contextIsDeadlineSource ? "Context" : "CallOptions");
buf.append(" deadline exceeded after ");
if (remainingNanos < 0) {
buf.append('-');
}
buf.append(seconds);
buf.append(String.format(Locale.US, ".%09d", nanos));
buf.append("s. ");
Long nsDelay = callOptions.getOption(NAME_RESOLUTION_DELAYED);
buf.append(String.format(Locale.US, "Name resolution delay %.9f seconds. ",
buf.append(String.format(Locale.US, "Name resolution delay %.9f seconds.",
nsDelay == null ? 0 : nsDelay / NANO_TO_SECS));
buf.append(insight);
stream.cancel(DEADLINE_EXCEEDED.augmentDescription(buf.toString()));
if (stream != null) {
InsightBuilder insight = new InsightBuilder();
stream.appendTimeoutInsight(insight);
buf.append(" ");
buf.append(insight);
}
return DEADLINE_EXCEEDED.withDescription(buf.toString());
}
}

private ScheduledFuture<?> startDeadlineTimer(Deadline deadline) {
long remainingNanos = deadline.timeRemaining(TimeUnit.NANOSECONDS);
return deadlineCancellationExecutor.schedule(
new LogExceptionRunnable(
new DeadlineTimer(remainingNanos)), remainingNanos, TimeUnit.NANOSECONDS);
}

@Nullable
private Deadline effectiveDeadline() {
// Call options and context are immutable, so we don't need to cache the deadline.
Expand All @@ -440,16 +437,6 @@ private static Deadline min(@Nullable Deadline deadline0, @Nullable Deadline dea
return deadline0.minimum(deadline1);
}

private static boolean isFirstMin(@Nullable Deadline deadline0, @Nullable Deadline deadline1) {
if (deadline0 == null) {
return false;
}
if (deadline1 == null) {
return true;
}
return deadline0.isBefore(deadline1);
}

@Override
public void request(int numMessages) {
try (TaskCloseable ignore = PerfMark.traceTask("ClientCall.request")) {
Expand Down Expand Up @@ -493,7 +480,10 @@ private void cancelInternal(@Nullable String message, @Nullable Throwable cause)
stream.cancel(status);
}
} finally {
removeContextListenerAndCancelDeadlineFuture();
// start() might not have been called
if (cancellationHandler != null) {
cancellationHandler.tearDown();
}
}
}

Expand Down Expand Up @@ -699,10 +689,7 @@ private void closedInternal(
// description. Since our timer may be delayed in firing, we double-check the deadline and
// turn the failure into the likely more helpful DEADLINE_EXCEEDED status.
if (deadline.isExpired()) {
InsightBuilder insight = new InsightBuilder();
stream.appendTimeoutInsight(insight);
status = DEADLINE_EXCEEDED.augmentDescription(
"ClientCall was cancelled at or after deadline. " + insight);
status = cancellationHandler.formatDeadlineExceededStatus();
// Replace trailers to prevent mixing sources of status and trailers.
trailers = new Metadata();
}
Expand All @@ -725,6 +712,7 @@ public void runInContext() {
}

private void runInternal() {
cancellationHandler.tearDown();
Status status = savedStatus;
Metadata trailers = savedTrailers;
if (exceptionStatus != null) {
Expand All @@ -737,11 +725,9 @@ private void runInternal() {
// Replace trailers to prevent mixing sources of status and trailers.
trailers = new Metadata();
}
cancelListenersShouldBeRemoved = true;
try {
closeObserver(observer, status, trailers);
} finally {
removeContextListenerAndCancelDeadlineFuture();
channelCallsTracer.reportCallEnded(status.isOk());
}
}
Expand Down
21 changes: 19 additions & 2 deletions core/src/test/java/io/grpc/internal/ClientCallImplTest.java
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Original file line number Diff line number Diff line change
Expand Up @@ -926,7 +926,7 @@ public void expiredDeadlineCancelsStream_CallOptions() {
verify(stream, times(1)).cancel(statusCaptor.capture());
assertEquals(Status.Code.DEADLINE_EXCEEDED, statusCaptor.getValue().getCode());
assertThat(statusCaptor.getValue().getDescription())
.matches("deadline exceeded after [0-9]+\\.[0-9]+s. "
.matches("CallOptions deadline exceeded after [0-9]+\\.[0-9]+s. "
+ "Name resolution delay 0.000000000 seconds. \\[remote_addr=127\\.0\\.0\\.1:443\\]");
}

Expand Down Expand Up @@ -954,7 +954,24 @@ public void expiredDeadlineCancelsStream_Context() {

verify(stream, times(1)).cancel(statusCaptor.capture());
assertEquals(Status.Code.DEADLINE_EXCEEDED, statusCaptor.getValue().getCode());
assertThat(statusCaptor.getValue().getDescription()).isEqualTo("context timed out");
assertThat(statusCaptor.getValue().getDescription())
.matches("Context deadline exceeded after [0-9]+\\.[0-9]+s. "
+ "Name resolution delay 0.000000000 seconds. \\[remote_addr=127\\.0\\.0\\.1:443\\]");
}

@Test
public void cancelWithoutStart() {
fakeClock.forwardTime(System.nanoTime(), TimeUnit.NANOSECONDS);

ClientCallImpl<Void, Void> call = new ClientCallImpl<>(
method,
MoreExecutors.directExecutor(),
baseCallOptions.withDeadline(Deadline.after(1, TimeUnit.SECONDS)),
clientStreamProvider,
deadlineCancellationExecutor,
channelCallTracer, configSelector);
// Nothing happens as a result, but it shouldn't throw
call.cancel("canceled", null);
}

@Test
Expand Down
2 changes: 1 addition & 1 deletion interop-testing/src/main/java/io/grpc/testing/integration/AbstractInteropTest.java
View file
Original file line number Diff line number Diff line change
Expand Up @@ -1190,7 +1190,7 @@ public void deadlineExceeded() throws Exception {
assertTrue(desc,
// There is a race between client and server-side deadline expiration.
// If client expires first, it'd generate this message
Pattern.matches("deadline exceeded after .*s. \\[.*\\]", desc)
Pattern.matches("CallOptions deadline exceeded after .*s. \\[.*\\]", desc)
// If server expires first, it'd reset the stream and client would generate a different
// message
|| desc.startsWith("ClientCall was cancelled at or after deadline."));
Expand Down

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