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/*
* Copyright 2020 The gRPC Authors
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package io.grpc.internal;
import static com.google.common.base.Preconditions.checkNotNull;
import static com.google.common.base.Preconditions.checkState;
import static java.util.concurrent.TimeUnit.NANOSECONDS;
import com.google.common.annotations.VisibleForTesting;
import com.google.common.base.MoreObjects;
import io.grpc.Attributes;
import io.grpc.ClientCall;
import io.grpc.Context;
import io.grpc.Deadline;
import io.grpc.Metadata;
import io.grpc.Status;
import java.util.ArrayList;
import java.util.List;
import java.util.Locale;
import java.util.concurrent.Executor;
import java.util.concurrent.ScheduledExecutorService;
import java.util.concurrent.ScheduledFuture;
import java.util.concurrent.TimeUnit;
import java.util.logging.Level;
import java.util.logging.Logger;
import javax.annotation.Nullable;
import javax.annotation.concurrent.GuardedBy;
/**
* A call that queues requests before a real call is ready to be delegated to.
*
* {@code ClientCall} itself doesn't require thread-safety. However, the state of {@code
* DelayedCall} may be internally altered by different threads, thus internal synchronization is
* necessary.
*/
public class DelayedClientCall extends ClientCall {
private static final Logger logger = Logger.getLogger(DelayedClientCall.class.getName());
/**
* A timer to monitor the initial deadline. The timer must be cancelled on transition to the real
* call.
*/
@Nullable
private final ScheduledFuture initialDeadlineMonitor;
private final Executor callExecutor;
private final Context context;
/** {@code true} once realCall is valid and all pending calls have been drained. */
private volatile boolean passThrough;
/**
* Non-{@code null} iff start has been called. Used to assert methods are called in appropriate
* order, but also used if an error occurs before {@code realCall} is set.
*/
private Listener listener;
// Must hold {@code this} lock when setting.
private ClientCall realCall;
@GuardedBy("this")
private Status error;
@GuardedBy("this")
private List pendingRunnables = new ArrayList<>();
@GuardedBy("this")
private DelayedListener delayedListener;
protected DelayedClientCall(
Executor callExecutor, ScheduledExecutorService scheduler, @Nullable Deadline deadline) {
this.callExecutor = checkNotNull(callExecutor, "callExecutor");
checkNotNull(scheduler, "scheduler");
context = Context.current();
initialDeadlineMonitor = scheduleDeadlineIfNeeded(scheduler, deadline);
}
@Nullable
private ScheduledFuture scheduleDeadlineIfNeeded(
ScheduledExecutorService scheduler, @Nullable Deadline deadline) {
Deadline contextDeadline = context.getDeadline();
if (deadline == null && contextDeadline == null) {
return null;
}
long remainingNanos = Long.MAX_VALUE;
if (deadline != null) {
remainingNanos = Math.min(remainingNanos, deadline.timeRemaining(NANOSECONDS));
}
if (contextDeadline != null && contextDeadline.timeRemaining(NANOSECONDS) < remainingNanos) {
remainingNanos = contextDeadline.timeRemaining(NANOSECONDS);
if (logger.isLoggable(Level.FINE)) {
StringBuilder builder =
new StringBuilder(
String.format(
"Call timeout set to '%d' ns, due to context deadline.", remainingNanos));
if (deadline == null) {
builder.append(" Explicit call timeout was not set.");
} else {
long callTimeout = deadline.timeRemaining(TimeUnit.NANOSECONDS);
builder.append(String.format(" Explicit call timeout was '%d' ns.", callTimeout));
}
logger.fine(builder.toString());
}
}
long seconds = Math.abs(remainingNanos) / TimeUnit.SECONDS.toNanos(1);
long nanos = Math.abs(remainingNanos) % TimeUnit.SECONDS.toNanos(1);
final StringBuilder buf = new StringBuilder();
if (remainingNanos < 0) {
buf.append("ClientCall started after deadline exceeded. Deadline exceeded after -");
} else {
buf.append("Deadline exceeded after ");
}
buf.append(seconds);
buf.append(String.format(Locale.US, ".%09d", nanos));
buf.append("s. ");
/** Cancels the call if deadline exceeded prior to the real call being set. */
class DeadlineExceededRunnable implements Runnable {
@Override
public void run() {
cancel(
Status.DEADLINE_EXCEEDED.withDescription(buf.toString()),
// We should not cancel the call if the realCall is set because there could be a
// race between cancel() and realCall.start(). The realCall will handle deadline by
// itself.
/* onlyCancelPendingCall= */ true);
}
}
return scheduler.schedule(new DeadlineExceededRunnable(), remainingNanos, NANOSECONDS);
}
/**
* Transfers all pending and future requests and mutations to the given call.
*
* No-op if either this method or {@link #cancel} have already been called.
*/
// When this method returns, passThrough is guaranteed to be true
public final void setCall(ClientCall call) {
synchronized (this) {
// If realCall != null, then either setCall() or cancel() has been called.
if (realCall != null) {
return;
}
setRealCall(checkNotNull(call, "call"));
}
drainPendingCalls();
}
@Override
public final void start(Listener listener, final Metadata headers) {
checkState(this.listener == null, "already started");
Status savedError;
boolean savedPassThrough;
synchronized (this) {
this.listener = checkNotNull(listener, "listener");
// If error != null, then cancel() has been called and was unable to close the listener
savedError = error;
savedPassThrough = passThrough;
if (!savedPassThrough) {
listener = delayedListener = new DelayedListener<>(listener);
}
}
if (savedError != null) {
callExecutor.execute(new CloseListenerRunnable(listener, savedError));
return;
}
if (savedPassThrough) {
realCall.start(listener, headers);
} else {
final Listener finalListener = listener;
delayOrExecute(new Runnable() {
@Override
public void run() {
realCall.start(finalListener, headers);
}
});
}
}
// When this method returns, passThrough is guaranteed to be true
@Override
public final void cancel(@Nullable final String message, @Nullable final Throwable cause) {
Status status = Status.CANCELLED;
if (message != null) {
status = status.withDescription(message);
} else {
status = status.withDescription("Call cancelled without message");
}
if (cause != null) {
status = status.withCause(cause);
}
cancel(status, false);
}
/**
* Cancels the call unless {@code realCall} is set and {@code onlyCancelPendingCall} is true.
*/
private void cancel(final Status status, boolean onlyCancelPendingCall) {
boolean delegateToRealCall = true;
Listener listenerToClose = null;
synchronized (this) {
// If realCall != null, then either setCall() or cancel() has been called
if (realCall == null) {
@SuppressWarnings("unchecked")
ClientCall noopCall = (ClientCall) NOOP_CALL;
setRealCall(noopCall);
delegateToRealCall = false;
// If listener == null, then start() will later call listener with 'error'
listenerToClose = listener;
error = status;
} else if (onlyCancelPendingCall) {
return;
}
}
if (delegateToRealCall) {
delayOrExecute(new Runnable() {
@Override
public void run() {
realCall.cancel(status.getDescription(), status.getCause());
}
});
} else {
if (listenerToClose != null) {
callExecutor.execute(new CloseListenerRunnable(listenerToClose, status));
}
drainPendingCalls();
}
callCancelled();
}
protected void callCancelled() {
}
private void delayOrExecute(Runnable runnable) {
synchronized (this) {
if (!passThrough) {
pendingRunnables.add(runnable);
return;
}
}
runnable.run();
}
/**
* Called to transition {@code passThrough} to {@code true}. This method is not safe to be called
* multiple times; the caller must ensure it will only be called once, ever. {@code this} lock
* should not be held when calling this method.
*/
private void drainPendingCalls() {
assert realCall != null;
assert !passThrough;
List toRun = new ArrayList<>();
DelayedListener delayedListener ;
while (true) {
synchronized (this) {
if (pendingRunnables.isEmpty()) {
pendingRunnables = null;
passThrough = true;
delayedListener = this.delayedListener;
break;
}
// Since there were pendingCalls, we need to process them. To maintain ordering we can't set
// passThrough=true until we run all pendingCalls, but new Runnables may be added after we
// drop the lock. So we will have to re-check pendingCalls.
List tmp = toRun;
toRun = pendingRunnables;
pendingRunnables = tmp;
}
for (Runnable runnable : toRun) {
// Must not call transport while lock is held to prevent deadlocks.
// TODO(ejona): exception handling
runnable.run();
}
toRun.clear();
}
if (delayedListener != null) {
final DelayedListener listener = delayedListener;
class DrainListenerRunnable extends ContextRunnable {
DrainListenerRunnable() {
super(context);
}
@Override
public void runInContext() {
listener.drainPendingCallbacks();
}
}
callExecutor.execute(new DrainListenerRunnable());
}
}
@GuardedBy("this")
private void setRealCall(ClientCall realCall) {
checkState(this.realCall == null, "realCall already set to %s", this.realCall);
if (initialDeadlineMonitor != null) {
initialDeadlineMonitor.cancel(false);
}
this.realCall = realCall;
}
@VisibleForTesting
final ClientCall getRealCall() {
return realCall;
}
@Override
public final void sendMessage(final ReqT message) {
if (passThrough) {
realCall.sendMessage(message);
} else {
delayOrExecute(new Runnable() {
@Override
public void run() {
realCall.sendMessage(message);
}
});
}
}
@Override
public final void setMessageCompression(final boolean enable) {
if (passThrough) {
realCall.setMessageCompression(enable);
} else {
delayOrExecute(new Runnable() {
@Override
public void run() {
realCall.setMessageCompression(enable);
}
});
}
}
@Override
public final void request(final int numMessages) {
if (passThrough) {
realCall.request(numMessages);
} else {
delayOrExecute(new Runnable() {
@Override
public void run() {
realCall.request(numMessages);
}
});
}
}
@Override
public final void halfClose() {
delayOrExecute(new Runnable() {
@Override
public void run() {
realCall.halfClose();
}
});
}
@Override
public final boolean isReady() {
if (passThrough) {
return realCall.isReady();
} else {
return false;
}
}
@Override
public final Attributes getAttributes() {
ClientCall savedRealCall;
synchronized (this) {
savedRealCall = realCall;
}
if (savedRealCall != null) {
return savedRealCall.getAttributes();
} else {
return Attributes.EMPTY;
}
}
@Override
public String toString() {
return MoreObjects.toStringHelper(this)
.add("realCall", realCall)
.toString();
}
private final class CloseListenerRunnable extends ContextRunnable {
final Listener listener;
final Status status;
CloseListenerRunnable(Listener listener, Status status) {
super(context);
this.listener = listener;
this.status = status;
}
@Override
public void runInContext() {
listener.onClose(status, new Metadata());
}
}
private static final class DelayedListener extends Listener {
private final Listener realListener;
private volatile boolean passThrough;
@GuardedBy("this")
private List pendingCallbacks = new ArrayList<>();
public DelayedListener(Listener listener) {
this.realListener = listener;
}
private void delayOrExecute(Runnable runnable) {
synchronized (this) {
if (!passThrough) {
pendingCallbacks.add(runnable);
return;
}
}
runnable.run();
}
@Override
public void onHeaders(final Metadata headers) {
if (passThrough) {
realListener.onHeaders(headers);
} else {
delayOrExecute(new Runnable() {
@Override
public void run() {
realListener.onHeaders(headers);
}
});
}
}
@Override
public void onMessage(final RespT message) {
if (passThrough) {
realListener.onMessage(message);
} else {
delayOrExecute(new Runnable() {
@Override
public void run() {
realListener.onMessage(message);
}
});
}
}
@Override
public void onClose(final Status status, final Metadata trailers) {
delayOrExecute(new Runnable() {
@Override
public void run() {
realListener.onClose(status, trailers);
}
});
}
@Override
public void onReady() {
if (passThrough) {
realListener.onReady();
} else {
delayOrExecute(new Runnable() {
@Override
public void run() {
realListener.onReady();
}
});
}
}
void drainPendingCallbacks() {
assert !passThrough;
List toRun = new ArrayList<>();
while (true) {
synchronized (this) {
if (pendingCallbacks.isEmpty()) {
pendingCallbacks = null;
passThrough = true;
break;
}
// Since there were pendingCallbacks, we need to process them. To maintain ordering we
// can't set passThrough=true until we run all pendingCallbacks, but new Runnables may be
// added after we drop the lock. So we will have to re-check pendingCallbacks.
List tmp = toRun;
toRun = pendingCallbacks;
pendingCallbacks = tmp;
}
for (Runnable runnable : toRun) {
// Avoid calling listener while lock is held to prevent deadlocks.
// TODO(ejona): exception handling
runnable.run();
}
toRun.clear();
}
}
}
private static final ClientCall NOOP_CALL = new ClientCall() {
@Override
public void start(Listener