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/*
* Copyright (C) 2015 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.internal.http;
import com.squareup.okhttp.Address;
import com.squareup.okhttp.ConnectionPool;
import com.squareup.okhttp.Route;
import com.squareup.okhttp.internal.Internal;
import com.squareup.okhttp.internal.RouteDatabase;
import com.squareup.okhttp.internal.Util;
import com.squareup.okhttp.internal.io.RealConnection;
import java.io.IOException;
import java.io.InterruptedIOException;
import java.lang.ref.Reference;
import java.lang.ref.WeakReference;
import java.net.ProtocolException;
import java.net.SocketTimeoutException;
import java.security.cert.CertificateException;
import javax.net.ssl.SSLHandshakeException;
import javax.net.ssl.SSLPeerUnverifiedException;
import okio.Sink;
import static java.util.concurrent.TimeUnit.MILLISECONDS;
/**
* This class coordinates the relationship between three entities:
*
* <ul>
* <li><strong>Connections:</strong> physical socket connections to remote servers. These are
* potentially slow to establish so it is necessary to be able to cancel a connection
* currently being connected.
* <li><strong>Streams:</strong> logical HTTP request/response pairs that are layered on
* connections. Each connection has its own allocation limit, which defines how many
* concurrent streams that connection can carry. HTTP/1.x connections can carry 1 stream
* at a time, SPDY and HTTP/2 typically carry multiple.
* <li><strong>Calls:</strong> a logical sequence of streams, typically an initial request and
* its follow up requests. We prefer to keep all streams of a single call on the same
* connection for better behavior and locality.
* </ul>
*
* <p>Instances of this class act on behalf of the call, using one or more streams over one or
* more connections. This class has APIs to release each of the above resources:
*
* <ul>
* <li>{@link #noNewStreams()} prevents the connection from being used for new streams in the
* future. Use this after a {@code Connection: close} header, or when the connection may be
* inconsistent.
* <li>{@link #streamFinished streamFinished()} releases the active stream from this allocation.
* Note that only one stream may be active at a given time, so it is necessary to call {@link
* #streamFinished streamFinished()} before creating a subsequent stream with {@link
* #newStream newStream()}.
* <li>{@link #release()} removes the call's hold on the connection. Note that this won't
* immediately free the connection if there is a stream still lingering. That happens when a
* call is complete but its response body has yet to be fully consumed.
* </ul>
*
* <p>This class supports {@linkplain #cancel asynchronous canceling}. This is intended to have
* the smallest blast radius possible. If an HTTP/2 stream is active, canceling will cancel that
* stream but not the other streams sharing its connection. But if the TLS handshake is still in
* progress then canceling may break the entire connection.
*/
public final class StreamAllocation {
public final Address address;
private final ConnectionPool connectionPool;
// State guarded by connectionPool.
private RouteSelector routeSelector;
private RealConnection connection;
private boolean released;
private boolean canceled;
private HttpStream stream;
public StreamAllocation(ConnectionPool connectionPool, Address address) {
this.connectionPool = connectionPool;
this.address = address;
}
public HttpStream newStream(int connectTimeout, int readTimeout, int writeTimeout,
boolean connectionRetryEnabled, boolean doExtensiveHealthChecks)
throws RouteException, IOException {
try {
RealConnection resultConnection = findHealthyConnection(connectTimeout, readTimeout,
writeTimeout, connectionRetryEnabled, doExtensiveHealthChecks);
HttpStream resultStream;
if (resultConnection.framedConnection != null) {
resultStream = new Http2xStream(this, resultConnection.framedConnection);
} else {
resultConnection.getSocket().setSoTimeout(readTimeout);
resultConnection.source.timeout().timeout(readTimeout, MILLISECONDS);
resultConnection.sink.timeout().timeout(writeTimeout, MILLISECONDS);
resultStream = new Http1xStream(this, resultConnection.source, resultConnection.sink);
}
synchronized (connectionPool) {
resultConnection.streamCount++;
stream = resultStream;
return resultStream;
}
} catch (IOException e) {
throw new RouteException(e);
}
}
/**
* Finds a connection and returns it if it is healthy. If it is unhealthy the process is repeated
* until a healthy connection is found.
*/
private RealConnection findHealthyConnection(int connectTimeout, int readTimeout,
int writeTimeout, boolean connectionRetryEnabled, boolean doExtensiveHealthChecks)
throws IOException, RouteException {
while (true) {
RealConnection candidate = findConnection(connectTimeout, readTimeout, writeTimeout,
connectionRetryEnabled);
// If this is a brand new connection, we can skip the extensive health checks.
synchronized (connectionPool) {
if (candidate.streamCount == 0) {
return candidate;
}
}
// Otherwise do a potentially-slow check to confirm that the pooled connection is still good.
if (candidate.isHealthy(doExtensiveHealthChecks)) {
return candidate;
}
connectionFailed();
}
}
/**
* Returns a connection to host a new stream. This prefers the existing connection if it exists,
* then the pool, finally building a new connection.
*/
private RealConnection findConnection(int connectTimeout, int readTimeout, int writeTimeout,
boolean connectionRetryEnabled) throws IOException, RouteException {
synchronized (connectionPool) {
if (released) throw new IllegalStateException("released");
if (stream != null) throw new IllegalStateException("stream != null");
if (canceled) throw new IOException("Canceled");
RealConnection allocatedConnection = this.connection;
if (allocatedConnection != null && !allocatedConnection.noNewStreams) {
return allocatedConnection;
}
// Attempt to get a connection from the pool.
RealConnection pooledConnection = Internal.instance.get(connectionPool, address, this);
if (pooledConnection != null) {
this.connection = pooledConnection;
return pooledConnection;
}
// Attempt to create a connection.
if (routeSelector == null) {
routeSelector = new RouteSelector(address, routeDatabase());
}
}
Route route = routeSelector.next();
RealConnection newConnection = new RealConnection(route);
acquire(newConnection);
synchronized (connectionPool) {
Internal.instance.put(connectionPool, newConnection);
this.connection = newConnection;
if (canceled) throw new IOException("Canceled");
}
newConnection.connect(connectTimeout, readTimeout, writeTimeout, address.getConnectionSpecs(),
connectionRetryEnabled);
routeDatabase().connected(newConnection.getRoute());
return newConnection;
}
public void streamFinished(HttpStream stream) {
synchronized (connectionPool) {
if (stream == null || stream != this.stream) {
throw new IllegalStateException("expected " + this.stream + " but was " + stream);
}
}
deallocate(false, false, true);
}
public HttpStream stream() {
synchronized (connectionPool) {
return stream;
}
}
private RouteDatabase routeDatabase() {
return Internal.instance.routeDatabase(connectionPool);
}
public synchronized RealConnection connection() {
return connection;
}
public void release() {
deallocate(false, true, false);
}
/** Forbid new streams from being created on the connection that hosts this allocation. */
public void noNewStreams() {
deallocate(true, false, false);
}
/**
* Releases resources held by this allocation. If sufficient resources are allocated, the
* connection will be detached or closed.
*/
private void deallocate(boolean noNewStreams, boolean released, boolean streamFinished) {
RealConnection connectionToClose = null;
synchronized (connectionPool) {
if (streamFinished) {
this.stream = null;
}
if (released) {
this.released = true;
}
if (connection != null) {
if (noNewStreams) {
connection.noNewStreams = true;
}
if (this.stream == null && (this.released || connection.noNewStreams)) {
release(connection);
if (connection.streamCount > 0) {
routeSelector = null;
}
if (connection.allocations.isEmpty()) {
connection.idleAtNanos = System.nanoTime();
if (Internal.instance.connectionBecameIdle(connectionPool, connection)) {
connectionToClose = connection;
}
}
connection = null;
}
}
}
if (connectionToClose != null) {
Util.closeQuietly(connectionToClose.getSocket());
}
}
public void cancel() {
HttpStream streamToCancel;
RealConnection connectionToCancel;
synchronized (connectionPool) {
canceled = true;
streamToCancel = stream;
connectionToCancel = connection;
}
if (streamToCancel != null) {
streamToCancel.cancel();
} else if (connectionToCancel != null) {
connectionToCancel.cancel();
}
}
private void connectionFailed(IOException e) {
synchronized (connectionPool) {
if (routeSelector != null) {
if (connection.streamCount == 0) {
// Record the failure on a fresh route.
Route failedRoute = connection.getRoute();
routeSelector.connectFailed(failedRoute, e);
} else {
// We saw a failure on a recycled connection, reset this allocation with a fresh route.
routeSelector = null;
}
}
}
connectionFailed();
}
/** Finish the current stream and prevent new streams from being created. */
public void connectionFailed() {
deallocate(true, false, true);
}
/**
* Use this allocation to hold {@code connection}. Each call to this must be paired with a call to
* {@link #release} on the same connection.
*/
public void acquire(RealConnection connection) {
connection.allocations.add(new WeakReference<>(this));
}
/** Remove this allocation from the connection's list of allocations. */
private void release(RealConnection connection) {
for (int i = 0, size = connection.allocations.size(); i < size; i++) {
Reference<StreamAllocation> reference = connection.allocations.get(i);
if (reference.get() == this) {
connection.allocations.remove(i);
return;
}
}
throw new IllegalStateException();
}
public boolean recover(RouteException e) {
// Android-changed: Canceled StreamAllocations can never recover http://b/33763156
if (canceled) {
return false;
}
if (connection != null) {
connectionFailed(e.getLastConnectException());
}
if ((routeSelector != null && !routeSelector.hasNext()) // No more routes to attempt.
|| !isRecoverable(e)) {
return false;
}
return true;
}
public boolean recover(IOException e, Sink requestBodyOut) {
if (connection != null) {
int streamCount = connection.streamCount;
connectionFailed(e);
if (streamCount == 1) {
// This isn't a recycled connection.
// TODO(jwilson): find a better way for this.
return false;
}
}
boolean canRetryRequestBody = requestBodyOut == null || requestBodyOut instanceof RetryableSink;
if ((routeSelector != null && !routeSelector.hasNext()) // No more routes to attempt.
|| !isRecoverable(e)
|| !canRetryRequestBody) {
return false;
}
return true;
}
private boolean isRecoverable(IOException e) {
// If there was a protocol problem, don't recover.
if (e instanceof ProtocolException) {
return false;
}
// If there was an interruption or timeout, don't recover.
if (e instanceof InterruptedIOException) {
return false;
}
return true;
}
private boolean isRecoverable(RouteException e) {
// Problems with a route may mean the connection can be retried with a new route, or may
// indicate a client-side or server-side issue that should not be retried. To tell, we must look
// at the cause.
IOException ioe = e.getLastConnectException();
// If there was a protocol problem, don't recover.
if (ioe instanceof ProtocolException) {
return false;
}
// If there was an interruption don't recover, but if there was a timeout
// we should try the next route (if there is one).
if (ioe instanceof InterruptedIOException) {
return ioe instanceof SocketTimeoutException;
}
// Look for known client-side or negotiation errors that are unlikely to be fixed by trying
// again with a different route.
if (ioe instanceof SSLHandshakeException) {
// If the problem was a CertificateException from the X509TrustManager,
// do not retry.
if (ioe.getCause() instanceof CertificateException) {
return false;
}
}
if (ioe instanceof SSLPeerUnverifiedException) {
// e.g. a certificate pinning error.
return false;
}
// An example of one we might want to retry with a different route is a problem connecting to a
// proxy and would manifest as a standard IOException. Unless it is one we know we should not
// retry, we return true and try a new route.
return true;
}
@Override public String toString() {
return address.toString();
}
}