/
HeaderTracerStreamingCallable.java
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/
HeaderTracerStreamingCallable.java
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/*
* Copyright 2020 Google LLC
*
* 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
*
* https://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 com.google.cloud.bigtable.data.v2.stub.metrics;
import com.google.api.core.InternalApi;
import com.google.api.gax.grpc.GrpcResponseMetadata;
import com.google.api.gax.rpc.ApiCallContext;
import com.google.api.gax.rpc.ResponseObserver;
import com.google.api.gax.rpc.ServerStreamingCallable;
import com.google.api.gax.rpc.StreamController;
import com.google.common.base.Preconditions;
import io.grpc.Metadata;
import javax.annotation.Nonnull;
/**
* This callable will inject a {@link GrpcResponseMetadata} to access the headers and trailers
* returned by gRPC methods upon completion. The {@link BigtableTracer} will process metrics that
* were injected in the header/trailer and publish them to OpenCensus. If {@link
* GrpcResponseMetadata#getMetadata()} returned null, it probably means that the request has never
* reached GFE, and it'll increment the gfe_header_missing_counter in this case.
*
* <p>If GFE metrics are not registered in {@link RpcViews}, skip injecting GrpcResponseMetadata.
* This is for the case where direct path is enabled, all the requests won't go through GFE and
* therefore won't have the server-timing header.
*
* <p>This class is considered an internal implementation detail and not meant to be used by
* applications.
*/
@InternalApi
public class HeaderTracerStreamingCallable<RequestT, ResponseT>
extends ServerStreamingCallable<RequestT, ResponseT> {
private final ServerStreamingCallable<RequestT, ResponseT> innerCallable;
public HeaderTracerStreamingCallable(
@Nonnull ServerStreamingCallable<RequestT, ResponseT> callable) {
this.innerCallable = Preconditions.checkNotNull(callable, "Inner callable must be set");
}
@Override
public void call(
RequestT request, ResponseObserver<ResponseT> responseObserver, ApiCallContext context) {
final GrpcResponseMetadata responseMetadata = new GrpcResponseMetadata();
// tracer should always be an instance of bigtable tracer
if (RpcViews.isGfeMetricsRegistered() && context.getTracer() instanceof BigtableTracer) {
HeaderTracerResponseObserver<ResponseT> innerObserver =
new HeaderTracerResponseObserver<>(
responseObserver, (BigtableTracer) context.getTracer(), responseMetadata);
innerCallable.call(request, innerObserver, responseMetadata.addHandlers(context));
} else {
innerCallable.call(request, responseObserver, context);
}
}
private class HeaderTracerResponseObserver<ResponseT> implements ResponseObserver<ResponseT> {
private final BigtableTracer tracer;
private final ResponseObserver<ResponseT> outerObserver;
private final GrpcResponseMetadata responseMetadata;
HeaderTracerResponseObserver(
ResponseObserver<ResponseT> observer,
BigtableTracer tracer,
GrpcResponseMetadata metadata) {
this.tracer = tracer;
this.outerObserver = observer;
this.responseMetadata = metadata;
}
@Override
public void onStart(final StreamController controller) {
outerObserver.onStart(controller);
}
@Override
public void onResponse(ResponseT response) {
outerObserver.onResponse(response);
}
@Override
public void onError(Throwable t) {
// server-timing metric will be added through GrpcResponseMetadata#onHeaders(Metadata),
// so it's not checking trailing metadata here.
Metadata metadata = responseMetadata.getMetadata();
Long latency = Util.getGfeLatency(metadata);
tracer.recordGfeMetadata(latency, t);
outerObserver.onError(t);
}
@Override
public void onComplete() {
Metadata metadata = responseMetadata.getMetadata();
Long latency = Util.getGfeLatency(metadata);
tracer.recordGfeMetadata(latency, null);
outerObserver.onComplete();
}
}
}