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/*
* Copyright 2014, Google Inc. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are
* met:
*
* * Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* * Redistributions in binary form must reproduce the above
* copyright notice, this list of conditions and the following disclaimer
* in the documentation and/or other materials provided with the
* distribution.
*
* * Neither the name of Google Inc. nor the names of its
* contributors may be used to endorse or promote products derived from
* this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
* A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
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package org.glowroot.agent.shaded.grpc.internal;
import static org.glowroot.agent.shaded.google.common.base.Preconditions.checkState;
import static org.glowroot.agent.shaded.grpc.internal.GrpcUtil.TIMEOUT_KEY;
import static org.glowroot.agent.shaded.grpc.internal.GrpcUtil.TIMER_SERVICE;
import org.glowroot.agent.shaded.google.common.base.Preconditions;
import org.glowroot.agent.shaded.google.common.base.Throwables;
import org.glowroot.agent.shaded.google.common.util.concurrent.Futures;
import org.glowroot.agent.shaded.google.common.util.concurrent.MoreExecutors;
import org.glowroot.agent.shaded.grpc.CompressorRegistry;
import org.glowroot.agent.shaded.grpc.Context;
import org.glowroot.agent.shaded.grpc.DecompressorRegistry;
import org.glowroot.agent.shaded.grpc.HandlerRegistry;
import org.glowroot.agent.shaded.grpc.Metadata;
import org.glowroot.agent.shaded.grpc.ServerCall;
import org.glowroot.agent.shaded.grpc.ServerMethodDefinition;
import org.glowroot.agent.shaded.grpc.Status;
import java.io.IOException;
import java.io.InputStream;
import java.util.ArrayList;
import java.util.Collection;
import java.util.HashSet;
import java.util.concurrent.Executor;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Future;
import java.util.concurrent.ScheduledExecutorService;
import java.util.concurrent.TimeUnit;
import java.util.concurrent.TimeoutException;
/**
* Default implementation of {@link org.glowroot.agent.shaded.grpc.Server}, for creation by transports.
*
* Expected usage (by a theoretical TCP transport):
*
public class TcpTransportServerFactory {
* public static Server newServer(Executor executor, HandlerRegistry registry,
* String configuration) {
* return new ServerImpl(executor, registry, new TcpTransportServer(configuration));
* }
* }
*
* Starting the server starts the underlying transport for servicing requests. Stopping the
* server stops servicing new requests and waits for all connections to terminate.
*/
public final class ServerImpl extends org.glowroot.agent.shaded.grpc.Server {
private static final ServerStreamListener NOOP_LISTENER = new NoopListener();
private static final Future DEFAULT_TIMEOUT_FUTURE = Futures.immediateCancelledFuture();
private static final TimeoutException TIMEOUT_EXCEPTION =
new TimeoutException("request timed out") {
@Override
public synchronized Throwable fillInStackTrace() {
// Suppress the stack trace as it would be confusing.
return this;
}
};
/** Executor for application processing. */
private Executor executor;
private boolean usingSharedExecutor;
private final HandlerRegistry registry;
private boolean started;
private boolean shutdown;
private boolean terminated;
/** Service encapsulating something similar to an accept() socket. */
private final org.glowroot.agent.shaded.grpc.internal.Server transportServer;
private final Object lock = new Object();
private boolean transportServerTerminated;
/** {@code transportServer} and services encapsulating something similar to a TCP connection. */
private final Collection transports = new HashSet();
private final ScheduledExecutorService timeoutService = SharedResourceHolder.get(TIMER_SERVICE);
private final Context rootContext;
private final DecompressorRegistry decompressorRegistry;
private final CompressorRegistry compressorRegistry;
/**
* Construct a server.
*
* @param executor to call methods on behalf of remote clients
* @param registry of methods to expose to remote clients.
*/
ServerImpl(Executor executor, HandlerRegistry registry, org.glowroot.agent.shaded.grpc.internal.Server transportServer,
Context rootContext, DecompressorRegistry decompressorRegistry,
CompressorRegistry compressorRegistry) {
this.executor = executor;
this.registry = Preconditions.checkNotNull(registry, "registry");
this.transportServer = Preconditions.checkNotNull(transportServer, "transportServer");
// Fork from the passed in context so that it does not propagate cancellation, it only
// inherits values.
this.rootContext = Preconditions.checkNotNull(rootContext).fork();
this.decompressorRegistry = decompressorRegistry;
this.compressorRegistry = compressorRegistry;
}
/**
* Bind and start the server.
*
* @return {@code this} object
* @throws IllegalStateException if already started
* @throws IOException if unable to bind
*/
@Override
public ServerImpl start() throws IOException {
synchronized (lock) {
checkState(!started, "Already started");
checkState(!shutdown, "Shutting down");
usingSharedExecutor = executor == null;
if (usingSharedExecutor) {
executor = SharedResourceHolder.get(GrpcUtil.SHARED_CHANNEL_EXECUTOR);
}
// Start and wait for any port to actually be bound.
transportServer.start(new ServerListenerImpl());
started = true;
return this;
}
}
/**
* Initiates an orderly shutdown in which preexisting calls continue but new calls are rejected.
*/
@Override
public ServerImpl shutdown() {
boolean shutdownTransportServer;
synchronized (lock) {
if (shutdown) {
return this;
}
shutdown = true;
shutdownTransportServer = started;
if (!shutdownTransportServer) {
transportServerTerminated = true;
checkForTermination();
}
}
if (shutdownTransportServer) {
transportServer.shutdown();
}
SharedResourceHolder.release(TIMER_SERVICE, timeoutService);
if (usingSharedExecutor) {
SharedResourceHolder.release(GrpcUtil.SHARED_CHANNEL_EXECUTOR, (ExecutorService) executor);
}
return this;
}
/**
* NOT YET IMPLEMENTED. This method currently behaves identically to shutdown().
*/
// TODO(ejona86): cancel preexisting calls.
@Override
public ServerImpl shutdownNow() {
shutdown();
return this;
}
@Override
public boolean isShutdown() {
synchronized (lock) {
return shutdown;
}
}
@Override
public boolean awaitTermination(long timeout, TimeUnit unit) throws InterruptedException {
synchronized (lock) {
long timeoutNanos = unit.toNanos(timeout);
long endTimeNanos = System.nanoTime() + timeoutNanos;
while (!terminated && (timeoutNanos = endTimeNanos - System.nanoTime()) > 0) {
TimeUnit.NANOSECONDS.timedWait(lock, timeoutNanos);
}
return terminated;
}
}
@Override
public void awaitTermination() throws InterruptedException {
synchronized (lock) {
while (!terminated) {
lock.wait();
}
}
}
@Override
public boolean isTerminated() {
synchronized (lock) {
return terminated;
}
}
/**
* Remove transport service from accounting collection and notify of complete shutdown if
* necessary.
*
* @param transport service to remove
*/
private void transportClosed(ServerTransport transport) {
synchronized (lock) {
if (!transports.remove(transport)) {
throw new AssertionError("Transport already removed");
}
checkForTermination();
}
}
/** Notify of complete shutdown if necessary. */
private void checkForTermination() {
synchronized (lock) {
if (shutdown && transports.isEmpty() && transportServerTerminated) {
if (terminated) {
throw new AssertionError("Server already terminated");
}
terminated = true;
// TODO(carl-mastrangelo): move this outside the synchronized block.
lock.notifyAll();
}
}
}
private class ServerListenerImpl implements ServerListener {
@Override
public ServerTransportListener transportCreated(ServerTransport transport) {
synchronized (lock) {
transports.add(transport);
}
return new ServerTransportListenerImpl(transport);
}
@Override
public void serverShutdown() {
ArrayList copiedTransports;
synchronized (lock) {
// transports collection can be modified during shutdown(), even if we hold the lock, due
// to reentrancy.
copiedTransports = new ArrayList(transports);
}
for (ServerTransport transport : copiedTransports) {
transport.shutdown();
}
synchronized (lock) {
transportServerTerminated = true;
checkForTermination();
}
}
}
private class ServerTransportListenerImpl implements ServerTransportListener {
private final ServerTransport transport;
public ServerTransportListenerImpl(ServerTransport transport) {
this.transport = transport;
}
@Override
public void transportTerminated() {
transportClosed(transport);
}
@Override
public ServerStreamListener streamCreated(final ServerStream stream, final String methodName,
final Metadata headers) {
final Context.CancellableContext context = rootContext.withCancellation();
final Future timeout = scheduleTimeout(stream, headers, context);
final Executor wrappedExecutor;
// This is a performance optimization that avoids the synchronization and queuing overhead
// that comes with SerializingExecutor.
if (executor == MoreExecutors.directExecutor()) {
wrappedExecutor = new SerializeReentrantCallsDirectExecutor();
} else {
wrappedExecutor = new SerializingExecutor(executor);
}
final JumpToApplicationThreadServerStreamListener jumpListener
= new JumpToApplicationThreadServerStreamListener(wrappedExecutor, stream, context);
// Run in wrappedExecutor so jumpListener.setListener() is called before any callbacks
// are delivered, including any errors. Callbacks can still be triggered, but they will be
// queued.
wrappedExecutor.execute(new ContextRunnable(context) {
@Override
public void runInContext() {
ServerStreamListener listener = NOOP_LISTENER;
try {
ServerMethodDefinition method = registry.lookupMethod(methodName);
if (method == null) {
stream.close(
Status.UNIMPLEMENTED.withDescription("Method not found: " + methodName),
new Metadata());
timeout.cancel(true);
return;
}
listener = startCall(stream, methodName, method, timeout, headers, context);
} catch (Throwable t) {
stream.close(Status.fromThrowable(t), new Metadata());
timeout.cancel(true);
throw Throwables.propagate(t);
} finally {
jumpListener.setListener(listener);
}
}
});
return jumpListener;
}
private Future scheduleTimeout(final ServerStream stream, Metadata headers,
final Context.CancellableContext context) {
Long timeoutNanos = headers.get(TIMEOUT_KEY);
if (timeoutNanos == null) {
return DEFAULT_TIMEOUT_FUTURE;
}
return timeoutService.schedule(new Runnable() {
@Override
public void run() {
// This should rarely get run, since the client will likely cancel the stream before
// the timeout is reached.
stream.cancel(Status.DEADLINE_EXCEEDED);
// Cancel the context using a statically created exception as this event may occur
// often enough that stack trace alloc impacts performance.
context.cancel(TIMEOUT_EXCEPTION);
}
},
timeoutNanos,
TimeUnit.NANOSECONDS);
}
/** Never returns {@code null}. */
private ServerStreamListener startCall(ServerStream stream, String fullMethodName,
ServerMethodDefinition methodDef, Future timeout,
Metadata headers, Context.CancellableContext context) {
// TODO(ejona86): should we update fullMethodName to have the canonical path of the method?
ServerCallImpl call = new ServerCallImpl(
stream, methodDef.getMethodDescriptor(), headers, context, decompressorRegistry,
compressorRegistry);
ServerCall.Listener listener = methodDef.getServerCallHandler()
.startCall(methodDef.getMethodDescriptor(), call, headers);
if (listener == null) {
throw new NullPointerException(
"startCall() returned a null listener for method " + fullMethodName);
}
return call.newServerStreamListener(listener, timeout);
}
}
private static class NoopListener implements ServerStreamListener {
@Override
public void messageRead(InputStream value) {
try {
value.close();
} catch (IOException e) {
throw new RuntimeException(e);
}
}
@Override
public void halfClosed() {}
@Override
public void closed(Status status) {}
@Override
public void onReady() {}
}
/**
* Dispatches callbacks onto an application-provided executor and correctly propagates
* exceptions.
*/
private static class JumpToApplicationThreadServerStreamListener implements ServerStreamListener {
private final Executor callExecutor;
private final Context.CancellableContext context;
private final ServerStream stream;
// Only accessed from callExecutor.
private ServerStreamListener listener;
public JumpToApplicationThreadServerStreamListener(Executor executor,
ServerStream stream, Context.CancellableContext context) {
this.callExecutor = executor;
this.stream = stream;
this.context = context;
}
private ServerStreamListener getListener() {
if (listener == null) {
throw new IllegalStateException("listener unset");
}
return listener;
}
private void setListener(ServerStreamListener listener) {
Preconditions.checkNotNull(listener, "listener must not be null");
Preconditions.checkState(this.listener == null, "Listener already set");
this.listener = listener;
}
/**
* Like {@link ServerCall#close(Status, Metadata)}, but thread-safe for internal use.
*/
private void internalClose(Status status, Metadata trailers) {
// TODO(ejona86): this is not thread-safe :)
stream.close(status, trailers);
}
@Override
public void messageRead(final InputStream message) {
callExecutor.execute(new ContextRunnable(context) {
@Override
public void runInContext() {
try {
getListener().messageRead(message);
} catch (Throwable t) {
internalClose(Status.fromThrowable(t), new Metadata());
throw Throwables.propagate(t);
}
}
});
}
@Override
public void halfClosed() {
callExecutor.execute(new ContextRunnable(context) {
@Override
public void runInContext() {
try {
getListener().halfClosed();
} catch (Throwable t) {
internalClose(Status.fromThrowable(t), new Metadata());
throw Throwables.propagate(t);
}
}
});
}
@Override
public void closed(final Status status) {
callExecutor.execute(new ContextRunnable(context) {
@Override
public void runInContext() {
try {
getListener().closed(status);
} finally {
// Regardless of the status code we cancel the context so that listeners
// are aware that the call is done.
context.cancel(status.getCause());
}
}
});
}
@Override
public void onReady() {
callExecutor.execute(new ContextRunnable(context) {
@Override
public void runInContext() {
getListener().onReady();
}
});
}
}
}