nl.topicus.jdbc.shaded.io.grpc.internal.ExponentialBackoffPolicy Maven / Gradle / Ivy
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package nl.topicus.jdbc.shaded.io.grpc.internal;
import static nl.topicus.jdbc.shaded.com.google.nl.topicus.jdbc.shaded.com.on.base.Preconditions.checkArgument;
import nl.topicus.jdbc.shaded.com.google.nl.topicus.jdbc.shaded.com.on.annotations.VisibleForTesting;
import java.util.Random;
import java.util.concurrent.TimeUnit;
/**
* Retry Policy for Transport reconnection. Initial parameters from
* https://github.nl.topicus.jdbc.shaded.com.grpc/grpc/blob/master/doc/connection-backoff.md
*
* TODO(carl-mastrangelo): add unit tests for this class
*/
final class ExponentialBackoffPolicy implements BackoffPolicy {
static final class Provider implements BackoffPolicy.Provider {
@Override
public BackoffPolicy get() {
return new ExponentialBackoffPolicy();
}
}
private Random random = new Random();
private long initialBackoffNanos = TimeUnit.SECONDS.toNanos(1);
private long maxBackoffNanos = TimeUnit.MINUTES.toNanos(2);
private double multiplier = 1.6;
private double jitter = .2;
private long nextBackoffNanos = initialBackoffNanos;
@Override
public long nextBackoffNanos() {
long currentBackoffNanos = nextBackoffNanos;
nextBackoffNanos = Math.min((long) (currentBackoffNanos * multiplier), maxBackoffNanos);
return currentBackoffNanos
+ uniformRandom(-jitter * currentBackoffNanos, jitter * currentBackoffNanos);
}
private long uniformRandom(double low, double high) {
checkArgument(high >= low);
double mag = high - low;
return (long) (random.nextDouble() * mag + low);
}
/*
* No guice and no flags means we get to implement these setters for testing ourselves. Do not
* call these from non-test code.
*/
@VisibleForTesting
ExponentialBackoffPolicy setRandom(Random random) {
this.random = random;
return this;
}
@VisibleForTesting
ExponentialBackoffPolicy setInitialBackoffNanos(long initialBackoffNanos) {
this.initialBackoffNanos = initialBackoffNanos;
return this;
}
@VisibleForTesting
ExponentialBackoffPolicy setMaxBackoffNanos(long maxBackoffNanos) {
this.maxBackoffNanos = maxBackoffNanos;
return this;
}
@VisibleForTesting
ExponentialBackoffPolicy setMultiplier(double multiplier) {
this.multiplier = multiplier;
return this;
}
@VisibleForTesting
ExponentialBackoffPolicy setJitter(double jitter) {
this.jitter = jitter;
return this;
}
}