| /* |
| * 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 |
| * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, |
| * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT |
| * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, |
| * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY |
| * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT |
| * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE |
| * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. |
| */ |
| |
| package io.grpc; |
| |
| import com.google.common.base.Preconditions; |
| import java.util.ArrayList; |
| import java.util.Arrays; |
| import java.util.Collections; |
| import java.util.List; |
| |
| /** |
| * Utility methods for working with {@link ClientInterceptor}s. |
| */ |
| public class ClientInterceptors { |
| |
| // Prevent instantiation |
| private ClientInterceptors() {} |
| |
| /** |
| * Create a new {@link Channel} that will call {@code interceptors} before starting a call on the |
| * given channel. The first interceptor will have its {@link ClientInterceptor#interceptCall} |
| * called first. |
| * |
| * @param channel the underlying channel to intercept. |
| * @param interceptors array of interceptors to bind to {@code channel}. |
| * @return a new channel instance with the interceptors applied. |
| */ |
| public static Channel interceptForward(Channel channel, ClientInterceptor... interceptors) { |
| return interceptForward(channel, Arrays.asList(interceptors)); |
| } |
| |
| /** |
| * Create a new {@link Channel} that will call {@code interceptors} before starting a call on the |
| * given channel. The first interceptor will have its {@link ClientInterceptor#interceptCall} |
| * called first. |
| * |
| * @param channel the underlying channel to intercept. |
| * @param interceptors a list of interceptors to bind to {@code channel}. |
| * @return a new channel instance with the interceptors applied. |
| */ |
| public static Channel interceptForward(Channel channel, |
| List<? extends ClientInterceptor> interceptors) { |
| List<? extends ClientInterceptor> copy = new ArrayList<ClientInterceptor>(interceptors); |
| Collections.reverse(copy); |
| return intercept(channel, copy); |
| } |
| |
| /** |
| * Create a new {@link Channel} that will call {@code interceptors} before starting a call on the |
| * given channel. The last interceptor will have its {@link ClientInterceptor#interceptCall} |
| * called first. |
| * |
| * @param channel the underlying channel to intercept. |
| * @param interceptors array of interceptors to bind to {@code channel}. |
| * @return a new channel instance with the interceptors applied. |
| */ |
| public static Channel intercept(Channel channel, ClientInterceptor... interceptors) { |
| return intercept(channel, Arrays.asList(interceptors)); |
| } |
| |
| /** |
| * Create a new {@link Channel} that will call {@code interceptors} before starting a call on the |
| * given channel. The last interceptor will have its {@link ClientInterceptor#interceptCall} |
| * called first. |
| * |
| * @param channel the underlying channel to intercept. |
| * @param interceptors a list of interceptors to bind to {@code channel}. |
| * @return a new channel instance with the interceptors applied. |
| */ |
| public static Channel intercept(Channel channel, List<? extends ClientInterceptor> interceptors) { |
| Preconditions.checkNotNull(channel, "channel"); |
| for (ClientInterceptor interceptor : interceptors) { |
| channel = new InterceptorChannel(channel, interceptor); |
| } |
| return channel; |
| } |
| |
| private static class InterceptorChannel extends Channel { |
| private final Channel channel; |
| private final ClientInterceptor interceptor; |
| |
| private InterceptorChannel(Channel channel, ClientInterceptor interceptor) { |
| this.channel = channel; |
| this.interceptor = Preconditions.checkNotNull(interceptor, "interceptor"); |
| } |
| |
| @Override |
| public <ReqT, RespT> ClientCall<ReqT, RespT> newCall( |
| MethodDescriptor<ReqT, RespT> method, CallOptions callOptions) { |
| return interceptor.interceptCall(method, callOptions, channel); |
| } |
| |
| @Override |
| public String authority() { |
| return channel.authority(); |
| } |
| } |
| |
| private static final ClientCall<Object, Object> NOOP_CALL = new ClientCall<Object, Object>() { |
| @Override |
| public void start(Listener<Object> responseListener, Metadata headers) {} |
| |
| @Override |
| public void request(int numMessages) {} |
| |
| @Override |
| public void cancel(String message, Throwable cause) {} |
| |
| @Override |
| public void halfClose() {} |
| |
| @Override |
| public void sendMessage(Object message) {} |
| |
| /** |
| * Always returns {@code false}, since this is only used when the startup of the {@link |
| * ClientCall} fails (i.e. the {@link ClientCall} is closed). |
| */ |
| @Override |
| public boolean isReady() { |
| return false; |
| } |
| }; |
| |
| /** |
| * A {@link io.grpc.ForwardingClientCall} that delivers exceptions from its start logic to the |
| * call listener. |
| * |
| * <p>{@link ClientCall#start(ClientCall.Listener, Metadata)} should not throw any |
| * exception other than those caused by misuse, e.g., {@link IllegalStateException}. {@code |
| * CheckedForwardingClientCall} provides {@code checkedStart()} in which throwing exceptions is |
| * allowed. |
| */ |
| public abstract static class CheckedForwardingClientCall<ReqT, RespT> |
| extends io.grpc.ForwardingClientCall<ReqT, RespT> { |
| |
| private ClientCall<ReqT, RespT> delegate; |
| |
| /** |
| * Subclasses implement the start logic here that would normally belong to {@code start()}. |
| * |
| * <p>Implementation should call {@code this.delegate().start()} in the normal path. Exceptions |
| * may safely be thrown prior to calling {@code this.delegate().start()}. Such exceptions will |
| * be handled by {@code CheckedForwardingClientCall} and be delivered to {@code |
| * responseListener}. Exceptions <em>must not</em> be thrown after calling {@code |
| * this.delegate().start()}, as this can result in {@link ClientCall.Listener#onClose} being |
| * called multiple times. |
| */ |
| protected abstract void checkedStart(Listener<RespT> responseListener, Metadata headers) |
| throws Exception; |
| |
| protected CheckedForwardingClientCall(ClientCall<ReqT, RespT> delegate) { |
| this.delegate = delegate; |
| } |
| |
| @Override |
| protected final ClientCall<ReqT, RespT> delegate() { |
| return delegate; |
| } |
| |
| @Override |
| @SuppressWarnings("unchecked") |
| public final void start(Listener<RespT> responseListener, Metadata headers) { |
| try { |
| checkedStart(responseListener, headers); |
| } catch (Exception e) { |
| // Because start() doesn't throw, the caller may still try to call other methods on this |
| // call object. Passing these invocations to the original delegate will cause |
| // IllegalStateException because delegate().start() was not called. We switch the delegate |
| // to a NO-OP one to prevent the IllegalStateException. The user will finally get notified |
| // about the error through the listener. |
| delegate = (ClientCall<ReqT, RespT>) NOOP_CALL; |
| responseListener.onClose(Status.fromThrowable(e), new Metadata()); |
| } |
| } |
| } |
| } |