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/*
* Copyright 2017 Google LLC
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are
* met:
*
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* notice, this list of conditions and the following disclaimer.
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*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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package com.google.api.gax.grpc;
import com.google.api.client.util.Preconditions;
import com.google.api.core.AbstractApiFuture;
import com.google.api.core.ApiFuture;
import com.google.api.core.BetaApi;
import com.google.api.gax.rpc.ApiCallContext;
import com.google.api.gax.tracing.ApiTracer.Scope;
import io.grpc.CallOptions;
import io.grpc.Channel;
import io.grpc.ClientCall;
import io.grpc.ClientInterceptor;
import io.grpc.ClientInterceptors;
import io.grpc.Deadline;
import io.grpc.Metadata;
import io.grpc.MethodDescriptor;
import io.grpc.Status;
import io.grpc.stub.MetadataUtils;
import java.util.concurrent.TimeUnit;
import java.util.logging.Level;
import java.util.logging.Logger;
/**
* {@code GrpcClientCalls} creates a new {@code ClientCall} from the given call context.
*
* Package-private for internal use.
*/
class GrpcClientCalls {
private static final Logger LOGGER = Logger.getLogger(GrpcDirectCallable.class.getName());
private GrpcClientCalls() {};
public static ClientCall newCall(
MethodDescriptor descriptor, ApiCallContext context) {
if (!(context instanceof GrpcCallContext)) {
throw new IllegalArgumentException(
"context must be an instance of GrpcCallContext, but found "
+ context.getClass().getName());
}
GrpcCallContext grpcContext = (GrpcCallContext) context;
Preconditions.checkNotNull(grpcContext.getChannel());
CallOptions callOptions = grpcContext.getCallOptions();
Preconditions.checkNotNull(callOptions);
// Try to convert the timeout into a deadline and use it if it occurs before the actual deadline
if (grpcContext.getTimeoutDuration() != null) {
Deadline newDeadline =
Deadline.after(grpcContext.getTimeoutDuration().toMillis(), TimeUnit.MILLISECONDS);
Deadline oldDeadline = callOptions.getDeadline();
if (oldDeadline == null || newDeadline.isBefore(oldDeadline)) {
callOptions = callOptions.withDeadline(newDeadline);
}
}
Channel channel = grpcContext.getChannel();
if (grpcContext.getChannelAffinity() != null && channel instanceof ChannelPool) {
channel = ((ChannelPool) channel).getChannel(grpcContext.getChannelAffinity());
}
if (!grpcContext.getExtraHeaders().isEmpty()) {
ClientInterceptor interceptor =
MetadataUtils.newAttachHeadersInterceptor(grpcContext.getMetadata());
channel = ClientInterceptors.intercept(channel, interceptor);
}
// Validate the Universe Domain prior to the call. Only allow the call to go through
// if the Universe Domain is valid.
grpcContext.validateUniverseDomain();
try (Scope ignored = grpcContext.getTracer().inScope()) {
return channel.newCall(descriptor, callOptions);
}
}
/**
* A work-alike of {@link io.grpc.stub.ClientCalls#futureUnaryCall(ClientCall, Object)}.
*
* The only difference is that unlike grpc-stub's implementation. This implementation doesn't
* wait for trailers to resolve a unary RPC. This can save milliseconds when the server is
* overloaded.
*/
@BetaApi
static ApiFuture eagerFutureUnaryCall(
ClientCall clientCall, RequestT request) {
// Start the call
GrpcFuture future = new GrpcFuture<>(clientCall);
clientCall.start(new EagerFutureListener<>(future), new Metadata());
// Send the request
try {
clientCall.sendMessage(request);
clientCall.halfClose();
// Request an extra message to detect misconfigured servers
clientCall.request(2);
} catch (Throwable sendError) {
// Cancel if anything goes wrong
try {
clientCall.cancel(null, sendError);
} catch (Throwable cancelError) {
LOGGER.log(Level.SEVERE, "Error encountered while closing it", sendError);
}
throw sendError;
}
return future;
}
/** Thin wrapper around an ApiFuture that will cancel the underlying ClientCall. */
private static class GrpcFuture extends AbstractApiFuture {
private final ClientCall call;
private GrpcFuture(ClientCall call) {
this.call = call;
}
@Override
protected void interruptTask() {
call.cancel("GrpcFuture was cancelled", null);
}
@Override
public boolean set(T value) {
return super.set(value);
}
@Override
public boolean setException(Throwable throwable) {
return super.setException(throwable);
}
}
/**
* A bridge between gRPC's ClientCall.Listener to an ApiFuture.
*
* The Listener will eagerly resolve the future when the first message is received and will not
* wait for the trailers. This should cut down on the latency at the expense of safety. If the
* server is misconfigured and sends a second response for a unary call, the error will be logged,
* but the future will still be successful.
*/
private static class EagerFutureListener extends ClientCall.Listener {
private final GrpcFuture future;
private EagerFutureListener(GrpcFuture future) {
this.future = future;
}
@Override
public void onMessage(T message) {
if (!future.set(message)) {
throw Status.INTERNAL
.withDescription("More than one value received for unary call")
.asRuntimeException();
}
}
@Override
public void onClose(Status status, Metadata trailers) {
if (!future.isDone()) {
future.setException(
Status.INTERNAL
.withDescription("No value received for unary call")
.asException(trailers));
}
if (!status.isOk()) {
LOGGER.log(
Level.WARNING, "Received error for unary call after receiving a successful response");
}
}
}
}