io.grpc.internal.BackoffPolicyRetryScheduler Maven / Gradle / Ivy
/*
* Copyright 2023 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 io.grpc.SynchronizationContext;
import io.grpc.SynchronizationContext.ScheduledHandle;
import java.util.concurrent.ScheduledExecutorService;
import java.util.concurrent.TimeUnit;
import java.util.logging.Level;
import java.util.logging.Logger;
/**
* Schedules a retry operation according to a {@link BackoffPolicy}. The retry is run within a
* {@link SynchronizationContext}. At most one retry is scheduled at a time.
*/
final class BackoffPolicyRetryScheduler implements RetryScheduler {
private final ScheduledExecutorService scheduledExecutorService;
private final SynchronizationContext syncContext;
private final BackoffPolicy.Provider policyProvider;
private BackoffPolicy policy;
private ScheduledHandle scheduledHandle;
private static final Logger logger = Logger.getLogger(
BackoffPolicyRetryScheduler.class.getName());
BackoffPolicyRetryScheduler(BackoffPolicy.Provider policyProvider,
ScheduledExecutorService scheduledExecutorService,
SynchronizationContext syncContext) {
this.policyProvider = policyProvider;
this.scheduledExecutorService = scheduledExecutorService;
this.syncContext = syncContext;
}
/**
* Schedules a future retry operation. Only allows one retry to be scheduled at any given time.
*/
@Override
public void schedule(Runnable retryOperation) {
syncContext.throwIfNotInThisSynchronizationContext();
if (policy == null) {
policy = policyProvider.get();
}
// If a retry is already scheduled, take no further action.
if (scheduledHandle != null && scheduledHandle.isPending()) {
return;
}
long delayNanos = policy.nextBackoffNanos();
scheduledHandle = syncContext.schedule(retryOperation, delayNanos, TimeUnit.NANOSECONDS,
scheduledExecutorService);
logger.log(Level.FINE, "Scheduling DNS resolution backoff for {0}ns", delayNanos);
}
/**
* Resets the {@link BackoffPolicyRetryScheduler} and cancels any pending retry task. The policy
* will be cleared thus also resetting any state associated with it (e.g. a backoff multiplier).
*/
@Override
public void reset() {
syncContext.throwIfNotInThisSynchronizationContext();
syncContext.execute(() -> {
if (scheduledHandle != null && scheduledHandle.isPending()) {
scheduledHandle.cancel();
}
policy = null;
});
}
}