com.squareup.okhttp.Dispatcher Maven / Gradle / Ivy
/*
* Copyright (C) 2013 Square, Inc.
*
* 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.squareup.okhttp;
import com.squareup.okhttp.Call.AsyncCall;
import com.squareup.okhttp.internal.Util;
import com.squareup.okhttp.internal.http.HttpEngine;
import java.util.ArrayDeque;
import java.util.Deque;
import java.util.Iterator;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.LinkedBlockingQueue;
import java.util.concurrent.ThreadPoolExecutor;
import java.util.concurrent.TimeUnit;
/**
* Policy on when async requests are executed.
*
* Each dispatcher uses an {@link ExecutorService} to run calls internally. If you
* supply your own executor, it should be able to run {@linkplain #getMaxRequests the
* configured maximum} number of calls concurrently.
*/
public final class Dispatcher {
private int maxRequests = 64;
private int maxRequestsPerHost = 5;
/** Executes calls. Created lazily. */
private ExecutorService executorService;
/** Ready calls in the order they'll be run. */
private final Deque readyCalls = new ArrayDeque<>();
/** Running calls. Includes canceled calls that haven't finished yet. */
private final Deque runningCalls = new ArrayDeque<>();
/** In-flight synchronous calls. Includes canceled calls that haven't finished yet. */
private final Deque executedCalls = new ArrayDeque<>();
public Dispatcher(ExecutorService executorService) {
this.executorService = executorService;
}
public Dispatcher() {
}
public synchronized ExecutorService getExecutorService() {
if (executorService == null) {
executorService = new ThreadPoolExecutor(0, Integer.MAX_VALUE, 60, TimeUnit.SECONDS,
new LinkedBlockingQueue(), Util.threadFactory("OkHttp Dispatcher", false));
}
return executorService;
}
/**
* Set the maximum number of requests to execute concurrently. Above this
* requests queue in memory, waiting for the running calls to complete.
*
* If more than {@code maxRequests} requests are in flight when this is
* invoked, those requests will remain in flight.
*/
public synchronized void setMaxRequests(int maxRequests) {
if (maxRequests < 1) {
throw new IllegalArgumentException("max < 1: " + maxRequests);
}
this.maxRequests = maxRequests;
promoteCalls();
}
public synchronized int getMaxRequests() {
return maxRequests;
}
/**
* Set the maximum number of requests for each host to execute concurrently.
* This limits requests by the URL's host name. Note that concurrent requests
* to a single IP address may still exceed this limit: multiple hostnames may
* share an IP address or be routed through the same HTTP proxy.
*
*
If more than {@code maxRequestsPerHost} requests are in flight when this
* is invoked, those requests will remain in flight.
*/
public synchronized void setMaxRequestsPerHost(int maxRequestsPerHost) {
if (maxRequestsPerHost < 1) {
throw new IllegalArgumentException("max < 1: " + maxRequestsPerHost);
}
this.maxRequestsPerHost = maxRequestsPerHost;
promoteCalls();
}
public synchronized int getMaxRequestsPerHost() {
return maxRequestsPerHost;
}
synchronized void enqueue(AsyncCall call) {
if (runningCalls.size() < maxRequests && runningCallsForHost(call) < maxRequestsPerHost) {
runningCalls.add(call);
getExecutorService().execute(call);
} else {
readyCalls.add(call);
}
}
/** Cancel all calls with the tag {@code tag}. */
public synchronized void cancel(Object tag) {
for (AsyncCall call : readyCalls) {
if (Util.equal(tag, call.tag())) {
call.cancel();
}
}
for (AsyncCall call : runningCalls) {
if (Util.equal(tag, call.tag())) {
call.get().canceled = true;
HttpEngine engine = call.get().engine;
if (engine != null) engine.disconnect();
}
}
for (Call call : executedCalls) {
if (Util.equal(tag, call.tag())) {
call.cancel();
}
}
}
/** Used by {@code AsyncCall#run} to signal completion. */
synchronized void finished(AsyncCall call) {
if (!runningCalls.remove(call)) throw new AssertionError("AsyncCall wasn't running!");
promoteCalls();
}
private void promoteCalls() {
if (runningCalls.size() >= maxRequests) return; // Already running max capacity.
if (readyCalls.isEmpty()) return; // No ready calls to promote.
for (Iterator i = readyCalls.iterator(); i.hasNext(); ) {
AsyncCall call = i.next();
if (runningCallsForHost(call) < maxRequestsPerHost) {
i.remove();
runningCalls.add(call);
getExecutorService().execute(call);
}
if (runningCalls.size() >= maxRequests) return; // Reached max capacity.
}
}
/** Returns the number of running calls that share a host with {@code call}. */
private int runningCallsForHost(AsyncCall call) {
int result = 0;
for (AsyncCall c : runningCalls) {
if (c.host().equals(call.host())) result++;
}
return result;
}
/** Used by {@code Call#execute} to signal it is in-flight. */
synchronized void executed(Call call) {
executedCalls.add(call);
}
/** Used by {@code Call#execute} to signal completion. */
synchronized void finished(Call call) {
if (!executedCalls.remove(call)) throw new AssertionError("Call wasn't in-flight!");
}
}