org.apache.beam.runners.fnexecution.state.GrpcStateService Maven / Gradle / Ivy
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*
* http://www.apache.org/licenses/LICENSE-2.0
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package org.apache.beam.runners.fnexecution.state;
import org.apache.beam.model.fnexecution.v1.BeamFnApi.StateRequest;
import org.apache.beam.model.fnexecution.v1.BeamFnApi.StateResponse;
import org.apache.beam.model.fnexecution.v1.BeamFnStateGrpc;
import org.apache.beam.sdk.fn.server.FnService;
import org.apache.beam.vendor.grpc.v1p43p2.io.grpc.stub.ServerCallStreamObserver;
import org.apache.beam.vendor.grpc.v1p43p2.io.grpc.stub.StreamObserver;
import java.util.concurrent.CompletableFuture;
import java.util.concurrent.CompletionStage;
import java.util.concurrent.ConcurrentHashMap;
import java.util.concurrent.ConcurrentLinkedQueue;
import java.util.concurrent.ConcurrentMap;
import static org.apache.beam.vendor.guava.v26_0_jre.com.google.common.base.Throwables.getStackTraceAsString;
/** An implementation of the Beam Fn State service. */
public class GrpcStateService extends BeamFnStateGrpc.BeamFnStateImplBase
implements StateDelegator, FnService {
/** Create a new {@link GrpcStateService}. */
public static GrpcStateService create() {
return new GrpcStateService();
}
private final ConcurrentLinkedQueue clients;
private final ConcurrentMap requestHandlers;
private GrpcStateService() {
this.requestHandlers = new ConcurrentHashMap<>();
this.clients = new ConcurrentLinkedQueue<>();
}
@Override
public void close() throws Exception {
Exception thrown = null;
for (Inbound inbound : clients) {
try {
// the call may be cancelled because the sdk harness hung up
// (we terminate the environment before terminating the service endpoints)
if (inbound.outboundObserver instanceof ServerCallStreamObserver) {
if (((ServerCallStreamObserver) inbound.outboundObserver).isCancelled()) {
// skip to avoid call already closed exception
continue;
}
}
inbound.outboundObserver.onCompleted();
} catch (Exception t) {
if (thrown == null) {
thrown = t;
} else {
thrown.addSuppressed(t);
}
}
}
if (thrown != null) {
throw thrown;
}
}
@Override
public StreamObserver state(StreamObserver responseObserver) {
Inbound rval = new Inbound(responseObserver);
clients.add(rval);
return rval;
}
@Override
public StateDelegator.Registration registerForProcessBundleInstructionId(
String processBundleInstructionId, StateRequestHandler handler) {
requestHandlers.putIfAbsent(processBundleInstructionId, handler);
return new Registration(processBundleInstructionId);
}
private class Registration implements StateDelegator.Registration {
private final String processBundleInstructionId;
private Registration(String processBundleInstructionId) {
this.processBundleInstructionId = processBundleInstructionId;
}
@Override
public void deregister() {
requestHandlers.remove(processBundleInstructionId);
}
@Override
public void abort() {
deregister();
// TODO: Abort in-flight state requests. Flag this processBundleInstructionId as a fail.
}
}
/**
* An inbound {@link StreamObserver} which delegates requests to registered handlers.
*
* Is only threadsafe if the outbound observer is threadsafe.
*
*
TODO: Handle when the client indicates completion or an error on the inbound stream and
* there are pending requests.
*/
private class Inbound implements StreamObserver {
private final StreamObserver outboundObserver;
Inbound(StreamObserver outboundObserver) {
this.outboundObserver = outboundObserver;
}
@Override
public void onNext(StateRequest request) {
StateRequestHandler handler =
requestHandlers.getOrDefault(request.getInstructionId(), this::handlerNotFound);
try {
CompletionStage result = handler.handle(request);
result.whenComplete(
(StateResponse.Builder responseBuilder, Throwable t) ->
// note that this is threadsafe if and only if outboundObserver is
// threadsafe.
outboundObserver.onNext(
t == null
? responseBuilder.setId(request.getId()).build()
: createErrorResponse(request.getId(), t)));
} catch (Exception e) {
outboundObserver.onNext(createErrorResponse(request.getId(), e));
}
}
@Override
public void onError(Throwable t) {
if (!t.getMessage().contains("cancelled before receiving half close")) {
// ignore the exception "cancelled before receiving half close" as we don't care
// about it.
outboundObserver.onError(t);
}
}
@Override
public void onCompleted() {
outboundObserver.onCompleted();
}
private CompletionStage handlerNotFound(StateRequest request) {
CompletableFuture result = new CompletableFuture<>();
result.complete(
StateResponse.newBuilder()
.setError(
String.format(
"Unknown process bundle instruction id '%s'",
request.getInstructionId())));
return result;
}
private StateResponse createErrorResponse(String id, Throwable t) {
return StateResponse.newBuilder().setId(id).setError(getStackTraceAsString(t)).build();
}
}
}