| // |
| // ======================================================================== |
| // Copyright (c) 1995-2017 Mort Bay Consulting Pty. Ltd. |
| // ------------------------------------------------------------------------ |
| // All rights reserved. This program and the accompanying materials |
| // are made available under the terms of the Eclipse Public License v1.0 |
| // and Apache License v2.0 which accompanies this distribution. |
| // |
| // The Eclipse Public License is available at |
| // http://www.eclipse.org/legal/epl-v10.html |
| // |
| // The Apache License v2.0 is available at |
| // http://www.opensource.org/licenses/apache2.0.php |
| // |
| // You may elect to redistribute this code under either of these licenses. |
| // ======================================================================== |
| // |
| |
| package org.eclipse.jetty.client; |
| |
| import java.io.IOException; |
| import java.util.HashMap; |
| import java.util.Map; |
| import java.util.concurrent.TimeUnit; |
| import java.util.concurrent.atomic.AtomicBoolean; |
| |
| import org.eclipse.jetty.client.api.Connection; |
| import org.eclipse.jetty.client.api.Destination; |
| import org.eclipse.jetty.util.Callback; |
| import org.eclipse.jetty.util.annotation.ManagedAttribute; |
| import org.eclipse.jetty.util.component.ContainerLifeCycle; |
| import org.eclipse.jetty.util.log.Log; |
| import org.eclipse.jetty.util.log.Logger; |
| import org.eclipse.jetty.util.thread.Scheduler; |
| |
| /** |
| * <p>A connection pool that validates connections before |
| * making them available for use.</p> |
| * <p>Connections that have just been opened are not validated. |
| * Connections that are {@link #release(Connection) released} will |
| * be validated.</p> |
| * <p>Validation by reading from the EndPoint is not reliable, |
| * since the TCP FIN may arrive just after the validation read.</p> |
| * <p>This class validates connections by putting them in a |
| * "quarantine" for a configurable timeout, where they cannot |
| * be used to send requests. When the timeout expires, the |
| * quarantined connection is made idle and therefore available |
| * to send requests.</p> |
| * <p>The existing HttpClient mechanism to detect server closes |
| * will trigger and close quarantined connections, before they |
| * are made idle (and reusable) again.</p> |
| * <p>There still is a small chance that the timeout expires, |
| * the connection is made idle and available again, it is used |
| * to send a request exactly when the server decides to close. |
| * This case is however unavoidable and may be mitigated by |
| * tuning the idle timeout of the servers to be larger than |
| * that of the client.</p> |
| */ |
| public class ValidatingConnectionPool extends ConnectionPool |
| { |
| private static final Logger LOG = Log.getLogger(ValidatingConnectionPool.class); |
| |
| private final Scheduler scheduler; |
| private final long timeout; |
| private final Map<Connection, Holder> quarantine; |
| |
| public ValidatingConnectionPool(Destination destination, int maxConnections, Callback requester, Scheduler scheduler, long timeout) |
| { |
| super(destination, maxConnections, requester); |
| this.scheduler = scheduler; |
| this.timeout = timeout; |
| this.quarantine = new HashMap<>(maxConnections); |
| } |
| |
| @ManagedAttribute(value = "The number of validating connections", readonly = true) |
| public int getValidatingConnectionCount() |
| { |
| return quarantine.size(); |
| } |
| |
| @Override |
| public boolean release(Connection connection) |
| { |
| lock(); |
| try |
| { |
| if (!getActiveConnections().remove(connection)) |
| return false; |
| Holder holder = new Holder(connection); |
| holder.task = scheduler.schedule(holder, timeout, TimeUnit.MILLISECONDS); |
| quarantine.put(connection, holder); |
| if (LOG.isDebugEnabled()) |
| LOG.debug("Validating for {}ms {}", timeout, connection); |
| } |
| finally |
| { |
| unlock(); |
| } |
| |
| released(connection); |
| return true; |
| } |
| |
| @Override |
| public boolean remove(Connection connection) |
| { |
| Holder holder; |
| lock(); |
| try |
| { |
| holder = quarantine.remove(connection); |
| } |
| finally |
| { |
| unlock(); |
| } |
| |
| if (holder == null) |
| return super.remove(connection); |
| |
| if (LOG.isDebugEnabled()) |
| LOG.debug("Removed while validating {}", connection); |
| |
| boolean cancelled = holder.cancel(); |
| if (cancelled) |
| return remove(connection, true); |
| |
| return super.remove(connection); |
| } |
| |
| @Override |
| public void dump(Appendable out, String indent) throws IOException |
| { |
| super.dump(out, indent); |
| ContainerLifeCycle.dump(out, indent, quarantine.values()); |
| } |
| |
| @Override |
| public String toString() |
| { |
| int size; |
| lock(); |
| try |
| { |
| size = quarantine.size(); |
| } |
| finally |
| { |
| unlock(); |
| } |
| return String.format("%s[v=%d]", super.toString(), size); |
| } |
| |
| private class Holder implements Runnable |
| { |
| private final long timestamp = System.nanoTime(); |
| private final AtomicBoolean latch = new AtomicBoolean(); |
| private final Connection connection; |
| public Scheduler.Task task; |
| |
| public Holder(Connection connection) |
| { |
| this.connection = connection; |
| } |
| |
| @Override |
| public void run() |
| { |
| if (latch.compareAndSet(false, true)) |
| { |
| boolean idle; |
| lock(); |
| try |
| { |
| quarantine.remove(connection); |
| idle = offerIdle(connection); |
| if (LOG.isDebugEnabled()) |
| LOG.debug("Validated {}", connection); |
| } |
| finally |
| { |
| unlock(); |
| } |
| |
| if (idle(connection, idle)) |
| proceed(); |
| } |
| } |
| |
| public boolean cancel() |
| { |
| if (latch.compareAndSet(false, true)) |
| { |
| task.cancel(); |
| return true; |
| } |
| return false; |
| } |
| |
| @Override |
| public String toString() |
| { |
| return String.format("%s[validationLeft=%dms]", |
| connection, |
| timeout - TimeUnit.NANOSECONDS.toMillis(System.nanoTime() - timestamp) |
| ); |
| } |
| } |
| } |