| // Copyright 2021 The Bazel Authors. All rights reserved. |
| // |
| // 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 |
| // |
| // http://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.devtools.build.lib.remote.grpc; |
| |
| import com.google.devtools.build.lib.concurrent.ThreadSafety.ThreadSafe; |
| import io.grpc.CallOptions; |
| import io.grpc.ClientCall; |
| import io.grpc.MethodDescriptor; |
| import io.reactivex.rxjava3.core.Single; |
| import io.reactivex.rxjava3.disposables.Disposable; |
| import io.reactivex.rxjava3.functions.Action; |
| import io.reactivex.rxjava3.subjects.AsyncSubject; |
| import java.io.IOException; |
| import java.util.ArrayList; |
| import java.util.List; |
| import java.util.concurrent.atomic.AtomicReference; |
| import javax.annotation.Nullable; |
| import javax.annotation.concurrent.GuardedBy; |
| |
| /** |
| * A {@link ConnectionPool} that creates one connection using provided {@link ConnectionFactory} and |
| * shares the connection upto {@code maxConcurrency}. |
| * |
| * <p>This is useful if underlying connection maintains a connection pool internally. (such as |
| * {@code Channel} in gRPC) |
| * |
| * <p>Connections must be closed with {@link Connection#close()} in order to be reused later. |
| */ |
| @ThreadSafe |
| public class SharedConnectionFactory implements ConnectionPool { |
| private final TokenBucket<Integer> tokenBucket; |
| private final ConnectionFactory factory; |
| |
| @Nullable |
| @GuardedBy("this") |
| private AsyncSubject<Connection> connectionAsyncSubject = null; |
| |
| private final AtomicReference<Disposable> connectionCreationDisposable = |
| new AtomicReference<>(null); |
| |
| public SharedConnectionFactory(ConnectionFactory factory, int maxConcurrency) { |
| this.factory = factory; |
| |
| List<Integer> initialTokens = new ArrayList<>(maxConcurrency); |
| for (int i = 0; i < maxConcurrency; ++i) { |
| initialTokens.add(i); |
| } |
| this.tokenBucket = new TokenBucket<>(initialTokens); |
| } |
| |
| @Override |
| public void close() throws IOException { |
| tokenBucket.close(); |
| |
| Disposable d = connectionCreationDisposable.getAndSet(null); |
| if (d != null && !d.isDisposed()) { |
| d.dispose(); |
| } |
| |
| synchronized (this) { |
| if (connectionAsyncSubject != null) { |
| Connection connection = connectionAsyncSubject.getValue(); |
| if (connection != null) { |
| connection.close(); |
| } |
| |
| if (!connectionAsyncSubject.hasComplete()) { |
| connectionAsyncSubject.onError(new IllegalStateException("closed")); |
| } |
| } |
| } |
| } |
| |
| private AsyncSubject<Connection> createUnderlyingConnectionIfNot() { |
| synchronized (this) { |
| if (connectionAsyncSubject == null || connectionAsyncSubject.hasThrowable()) { |
| connectionAsyncSubject = |
| factory |
| .create() |
| .doOnSubscribe(connectionCreationDisposable::set) |
| .toObservable() |
| .subscribeWith(AsyncSubject.create()); |
| } |
| |
| return connectionAsyncSubject; |
| } |
| } |
| |
| private Single<? extends Connection> acquireConnection() { |
| return Single.fromObservable(createUnderlyingConnectionIfNot()); |
| } |
| |
| /** |
| * Reuses the underlying {@link Connection} and wait for it to be released if is exceeding {@code |
| * maxConcurrency}. |
| */ |
| @Override |
| public Single<SharedConnection> create() { |
| return tokenBucket |
| .acquireToken() |
| .flatMap( |
| token -> |
| acquireConnection() |
| .doOnError(ignored -> tokenBucket.addToken(token)) |
| .doOnDispose(() -> tokenBucket.addToken(token)) |
| .map( |
| conn -> |
| new SharedConnection( |
| conn, /* onClose= */ () -> tokenBucket.addToken(token)))); |
| } |
| |
| /** Returns current number of available connections. */ |
| public int numAvailableConnections() { |
| return tokenBucket.size(); |
| } |
| |
| /** A {@link Connection} which wraps an underlying connection and is shared between consumers. */ |
| public static class SharedConnection implements Connection { |
| private final Connection connection; |
| private final Action onClose; |
| |
| public SharedConnection(Connection connection, Action onClose) { |
| this.connection = connection; |
| this.onClose = onClose; |
| } |
| |
| @Override |
| public <ReqT, RespT> ClientCall<ReqT, RespT> call( |
| MethodDescriptor<ReqT, RespT> method, CallOptions options) { |
| return connection.call(method, options); |
| } |
| |
| @Override |
| public void close() throws IOException { |
| try { |
| onClose.run(); |
| } catch (Throwable t) { |
| throw new IOException(t); |
| } |
| } |
| |
| /** Returns the underlying connection this shared connection built on */ |
| public Connection getUnderlyingConnection() { |
| return connection; |
| } |
| } |
| } |