Java tutorial
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See the License for the * specific language governing permissions and limitations * under the License. * ==================================================================== * * This software consists of voluntary contributions made by many * individuals on behalf of the Apache Software Foundation. For more * information on the Apache Software Foundation, please see * <http://www.apache.org/>. * */ package org.apache.http.impl.conn.tsccm; import java.io.IOException; import java.util.Date; import java.util.HashMap; import java.util.Iterator; import java.util.LinkedList; import java.util.Map; import java.util.Queue; import java.util.Set; import java.util.concurrent.TimeUnit; import java.util.concurrent.locks.Condition; import java.util.concurrent.locks.Lock; import org.apache.commons.logging.Log; import org.apache.commons.logging.LogFactory; import org.apache.http.conn.ClientConnectionOperator; import org.apache.http.conn.ConnectionPoolTimeoutException; import org.apache.http.conn.OperatedClientConnection; import org.apache.http.conn.params.ConnManagerParams; import org.apache.http.conn.params.ConnPerRoute; import org.apache.http.conn.routing.HttpRoute; import org.apache.http.params.HttpParams; import org.apache.http.util.Args; import org.apache.http.util.Asserts; /** * A connection pool that maintains connections by route. * This class is derived from <code>MultiThreadedHttpConnectionManager</code> * in HttpClient 3.x, see there for original authors. It implements the same * algorithm for connection re-use and connection-per-host enforcement: * <ul> * <li>connections are re-used only for the exact same route</li> * <li>connection limits are enforced per route rather than per host</li> * </ul> * Note that access to the pool data structures is synchronized via the * {@link AbstractConnPool#poolLock poolLock} in the base class, * not via <code>synchronized</code> methods. * * @since 4.0 * * @deprecated (4.2) use {@link org.apache.http.pool.AbstractConnPool} */ @Deprecated public class ConnPoolByRoute extends AbstractConnPool { private final Log log = LogFactory.getLog(getClass()); private final Lock poolLock; /** Connection operator for this pool */ protected final ClientConnectionOperator operator; /** Connections per route lookup */ protected final ConnPerRoute connPerRoute; /** References to issued connections */ protected final Set<BasicPoolEntry> leasedConnections; /** The list of free connections */ protected final Queue<BasicPoolEntry> freeConnections; /** The list of WaitingThreads waiting for a connection */ protected final Queue<WaitingThread> waitingThreads; /** Map of route-specific pools */ protected final Map<HttpRoute, RouteSpecificPool> routeToPool; private final long connTTL; private final TimeUnit connTTLTimeUnit; protected volatile boolean shutdown; protected volatile int maxTotalConnections; protected volatile int numConnections; /** * Creates a new connection pool, managed by route. * * @since 4.1 */ public ConnPoolByRoute(final ClientConnectionOperator operator, final ConnPerRoute connPerRoute, final int maxTotalConnections) { this(operator, connPerRoute, maxTotalConnections, -1, TimeUnit.MILLISECONDS); } /** * @since 4.1 */ public ConnPoolByRoute(final ClientConnectionOperator operator, final ConnPerRoute connPerRoute, final int maxTotalConnections, final long connTTL, final TimeUnit connTTLTimeUnit) { super(); Args.notNull(operator, "Connection operator"); Args.notNull(connPerRoute, "Connections per route"); this.poolLock = super.poolLock; this.leasedConnections = super.leasedConnections; this.operator = operator; this.connPerRoute = connPerRoute; this.maxTotalConnections = maxTotalConnections; this.freeConnections = createFreeConnQueue(); this.waitingThreads = createWaitingThreadQueue(); this.routeToPool = createRouteToPoolMap(); this.connTTL = connTTL; this.connTTLTimeUnit = connTTLTimeUnit; } protected Lock getLock() { return this.poolLock; } /** * Creates a new connection pool, managed by route. * * @deprecated (4.1) use {@link ConnPoolByRoute#ConnPoolByRoute(ClientConnectionOperator, ConnPerRoute, int)} */ @Deprecated public ConnPoolByRoute(final ClientConnectionOperator operator, final HttpParams params) { this(operator, ConnManagerParams.getMaxConnectionsPerRoute(params), ConnManagerParams.getMaxTotalConnections(params)); } /** * Creates the queue for {@link #freeConnections}. * Called once by the constructor. * * @return a queue */ protected Queue<BasicPoolEntry> createFreeConnQueue() { return new LinkedList<BasicPoolEntry>(); } /** * Creates the queue for {@link #waitingThreads}. * Called once by the constructor. * * @return a queue */ protected Queue<WaitingThread> createWaitingThreadQueue() { return new LinkedList<WaitingThread>(); } /** * Creates the map for {@link #routeToPool}. * Called once by the constructor. * * @return a map */ protected Map<HttpRoute, RouteSpecificPool> createRouteToPoolMap() { return new HashMap<HttpRoute, RouteSpecificPool>(); } /** * Creates a new route-specific pool. * Called by {@link #getRoutePool} when necessary. * * @param route the route * * @return the new pool */ protected RouteSpecificPool newRouteSpecificPool(final HttpRoute route) { return new RouteSpecificPool(route, this.connPerRoute); } /** * Creates a new waiting thread. * Called by {@link #getRoutePool} when necessary. * * @param cond the condition to wait for * @param rospl the route specific pool, or <code>null</code> * * @return a waiting thread representation */ protected WaitingThread newWaitingThread(final Condition cond, final RouteSpecificPool rospl) { return new WaitingThread(cond, rospl); } private void closeConnection(final BasicPoolEntry entry) { final OperatedClientConnection conn = entry.getConnection(); if (conn != null) { try { conn.close(); } catch (final IOException ex) { log.debug("I/O error closing connection", ex); } } } /** * Get a route-specific pool of available connections. * * @param route the route * @param create whether to create the pool if it doesn't exist * * @return the pool for the argument route, * never <code>null</code> if <code>create</code> is <code>true</code> */ protected RouteSpecificPool getRoutePool(final HttpRoute route, final boolean create) { RouteSpecificPool rospl = null; poolLock.lock(); try { rospl = routeToPool.get(route); if ((rospl == null) && create) { // no pool for this route yet (or anymore) rospl = newRouteSpecificPool(route); routeToPool.put(route, rospl); } } finally { poolLock.unlock(); } return rospl; } public int getConnectionsInPool(final HttpRoute route) { poolLock.lock(); try { // don't allow a pool to be created here! final RouteSpecificPool rospl = getRoutePool(route, false); return (rospl != null) ? rospl.getEntryCount() : 0; } finally { poolLock.unlock(); } } public int getConnectionsInPool() { poolLock.lock(); try { return numConnections; } finally { poolLock.unlock(); } } @Override public PoolEntryRequest requestPoolEntry(final HttpRoute route, final Object state) { final WaitingThreadAborter aborter = new WaitingThreadAborter(); return new PoolEntryRequest() { public void abortRequest() { poolLock.lock(); try { aborter.abort(); } finally { poolLock.unlock(); } } public BasicPoolEntry getPoolEntry(final long timeout, final TimeUnit tunit) throws InterruptedException, ConnectionPoolTimeoutException { return getEntryBlocking(route, state, timeout, tunit, aborter); } }; } /** * Obtains a pool entry with a connection within the given timeout. * If a {@link WaitingThread} is used to block, {@link WaitingThreadAborter#setWaitingThread(WaitingThread)} * must be called before blocking, to allow the thread to be interrupted. * * @param route the route for which to get the connection * @param timeout the timeout, 0 or negative for no timeout * @param tunit the unit for the <code>timeout</code>, * may be <code>null</code> only if there is no timeout * @param aborter an object which can abort a {@link WaitingThread}. * * @return pool entry holding a connection for the route * * @throws ConnectionPoolTimeoutException * if the timeout expired * @throws InterruptedException * if the calling thread was interrupted */ protected BasicPoolEntry getEntryBlocking(final HttpRoute route, final Object state, final long timeout, final TimeUnit tunit, final WaitingThreadAborter aborter) throws ConnectionPoolTimeoutException, InterruptedException { Date deadline = null; if (timeout > 0) { deadline = new Date(System.currentTimeMillis() + tunit.toMillis(timeout)); } BasicPoolEntry entry = null; poolLock.lock(); try { RouteSpecificPool rospl = getRoutePool(route, true); WaitingThread waitingThread = null; while (entry == null) { Asserts.check(!shutdown, "Connection pool shut down"); if (log.isDebugEnabled()) { log.debug("[" + route + "] total kept alive: " + freeConnections.size() + ", total issued: " + leasedConnections.size() + ", total allocated: " + numConnections + " out of " + maxTotalConnections); } // the cases to check for: // - have a free connection for that route // - allowed to create a free connection for that route // - can delete and replace a free connection for another route // - need to wait for one of the things above to come true entry = getFreeEntry(rospl, state); if (entry != null) { break; } final boolean hasCapacity = rospl.getCapacity() > 0; if (log.isDebugEnabled()) { log.debug("Available capacity: " + rospl.getCapacity() + " out of " + rospl.getMaxEntries() + " [" + route + "][" + state + "]"); } if (hasCapacity && numConnections < maxTotalConnections) { entry = createEntry(rospl, operator); } else if (hasCapacity && !freeConnections.isEmpty()) { deleteLeastUsedEntry(); // if least used entry's route was the same as rospl, // rospl is now out of date : we preemptively refresh rospl = getRoutePool(route, true); entry = createEntry(rospl, operator); } else { if (log.isDebugEnabled()) { log.debug("Need to wait for connection" + " [" + route + "][" + state + "]"); } if (waitingThread == null) { waitingThread = newWaitingThread(poolLock.newCondition(), rospl); aborter.setWaitingThread(waitingThread); } boolean success = false; try { rospl.queueThread(waitingThread); waitingThreads.add(waitingThread); success = waitingThread.await(deadline); } finally { // In case of 'success', we were woken up by the // connection pool and should now have a connection // waiting for us, or else we're shutting down. // Just continue in the loop, both cases are checked. rospl.removeThread(waitingThread); waitingThreads.remove(waitingThread); } // check for spurious wakeup vs. timeout if (!success && (deadline != null) && (deadline.getTime() <= System.currentTimeMillis())) { throw new ConnectionPoolTimeoutException("Timeout waiting for connection from pool"); } } } // while no entry } finally { poolLock.unlock(); } return entry; } @Override public void freeEntry(final BasicPoolEntry entry, final boolean reusable, final long validDuration, final TimeUnit timeUnit) { final HttpRoute route = entry.getPlannedRoute(); if (log.isDebugEnabled()) { log.debug("Releasing connection" + " [" + route + "][" + entry.getState() + "]"); } poolLock.lock(); try { if (shutdown) { // the pool is shut down, release the // connection's resources and get out of here closeConnection(entry); return; } // no longer issued, we keep a hard reference now leasedConnections.remove(entry); final RouteSpecificPool rospl = getRoutePool(route, true); if (reusable && rospl.getCapacity() >= 0) { if (log.isDebugEnabled()) { final String s; if (validDuration > 0) { s = "for " + validDuration + " " + timeUnit; } else { s = "indefinitely"; } log.debug("Pooling connection" + " [" + route + "][" + entry.getState() + "]; keep alive " + s); } rospl.freeEntry(entry); entry.updateExpiry(validDuration, timeUnit); freeConnections.add(entry); } else { closeConnection(entry); rospl.dropEntry(); numConnections--; } notifyWaitingThread(rospl); } finally { poolLock.unlock(); } } /** * If available, get a free pool entry for a route. * * @param rospl the route-specific pool from which to get an entry * * @return an available pool entry for the given route, or * <code>null</code> if none is available */ protected BasicPoolEntry getFreeEntry(final RouteSpecificPool rospl, final Object state) { BasicPoolEntry entry = null; poolLock.lock(); try { boolean done = false; while (!done) { entry = rospl.allocEntry(state); if (entry != null) { if (log.isDebugEnabled()) { log.debug("Getting free connection" + " [" + rospl.getRoute() + "][" + state + "]"); } freeConnections.remove(entry); if (entry.isExpired(System.currentTimeMillis())) { // If the free entry isn't valid anymore, get rid of it // and loop to find another one that might be valid. if (log.isDebugEnabled()) { log.debug("Closing expired free connection" + " [" + rospl.getRoute() + "][" + state + "]"); } closeConnection(entry); // We use dropEntry instead of deleteEntry because the entry // is no longer "free" (we just allocated it), and deleteEntry // can only be used to delete free entries. rospl.dropEntry(); numConnections--; } else { leasedConnections.add(entry); done = true; } } else { done = true; if (log.isDebugEnabled()) { log.debug("No free connections" + " [" + rospl.getRoute() + "][" + state + "]"); } } } } finally { poolLock.unlock(); } return entry; } /** * Creates a new pool entry. * This method assumes that the new connection will be handed * out immediately. * * @param rospl the route-specific pool for which to create the entry * @param op the operator for creating a connection * * @return the new pool entry for a new connection */ protected BasicPoolEntry createEntry(final RouteSpecificPool rospl, final ClientConnectionOperator op) { if (log.isDebugEnabled()) { log.debug("Creating new connection [" + rospl.getRoute() + "]"); } // the entry will create the connection when needed final BasicPoolEntry entry = new BasicPoolEntry(op, rospl.getRoute(), connTTL, connTTLTimeUnit); poolLock.lock(); try { rospl.createdEntry(entry); numConnections++; leasedConnections.add(entry); } finally { poolLock.unlock(); } return entry; } /** * Deletes a given pool entry. * This closes the pooled connection and removes all references, * so that it can be GCed. * * <p><b>Note:</b> Does not remove the entry from the freeConnections list. * It is assumed that the caller has already handled this step.</p> * <!-- @@@ is that a good idea? or rather fix it? --> * * @param entry the pool entry for the connection to delete */ protected void deleteEntry(final BasicPoolEntry entry) { final HttpRoute route = entry.getPlannedRoute(); if (log.isDebugEnabled()) { log.debug("Deleting connection" + " [" + route + "][" + entry.getState() + "]"); } poolLock.lock(); try { closeConnection(entry); final RouteSpecificPool rospl = getRoutePool(route, true); rospl.deleteEntry(entry); numConnections--; if (rospl.isUnused()) { routeToPool.remove(route); } } finally { poolLock.unlock(); } } /** * Delete an old, free pool entry to make room for a new one. * Used to replace pool entries with ones for a different route. */ protected void deleteLeastUsedEntry() { poolLock.lock(); try { final BasicPoolEntry entry = freeConnections.remove(); if (entry != null) { deleteEntry(entry); } else if (log.isDebugEnabled()) { log.debug("No free connection to delete"); } } finally { poolLock.unlock(); } } @Override protected void handleLostEntry(final HttpRoute route) { poolLock.lock(); try { final RouteSpecificPool rospl = getRoutePool(route, true); rospl.dropEntry(); if (rospl.isUnused()) { routeToPool.remove(route); } numConnections--; notifyWaitingThread(rospl); } finally { poolLock.unlock(); } } /** * Notifies a waiting thread that a connection is available. * This will wake a thread waiting in the specific route pool, * if there is one. * Otherwise, a thread in the connection pool will be notified. * * @param rospl the pool in which to notify, or <code>null</code> */ protected void notifyWaitingThread(final RouteSpecificPool rospl) { //@@@ while this strategy provides for best connection re-use, //@@@ is it fair? only do this if the connection is open? // Find the thread we are going to notify. We want to ensure that // each waiting thread is only interrupted once, so we will remove // it from all wait queues before interrupting. WaitingThread waitingThread = null; poolLock.lock(); try { if ((rospl != null) && rospl.hasThread()) { if (log.isDebugEnabled()) { log.debug("Notifying thread waiting on pool" + " [" + rospl.getRoute() + "]"); } waitingThread = rospl.nextThread(); } else if (!waitingThreads.isEmpty()) { if (log.isDebugEnabled()) { log.debug("Notifying thread waiting on any pool"); } waitingThread = waitingThreads.remove(); } else if (log.isDebugEnabled()) { log.debug("Notifying no-one, there are no waiting threads"); } if (waitingThread != null) { waitingThread.wakeup(); } } finally { poolLock.unlock(); } } @Override public void deleteClosedConnections() { poolLock.lock(); try { final Iterator<BasicPoolEntry> iter = freeConnections.iterator(); while (iter.hasNext()) { final BasicPoolEntry entry = iter.next(); if (!entry.getConnection().isOpen()) { iter.remove(); deleteEntry(entry); } } } finally { poolLock.unlock(); } } /** * Closes idle connections. * * @param idletime the time the connections should have been idle * in order to be closed now * @param tunit the unit for the <code>idletime</code> */ @Override public void closeIdleConnections(final long idletime, final TimeUnit tunit) { Args.notNull(tunit, "Time unit"); final long t = idletime > 0 ? idletime : 0; if (log.isDebugEnabled()) { log.debug("Closing connections idle longer than " + t + " " + tunit); } // the latest time for which connections will be closed final long deadline = System.currentTimeMillis() - tunit.toMillis(t); poolLock.lock(); try { final Iterator<BasicPoolEntry> iter = freeConnections.iterator(); while (iter.hasNext()) { final BasicPoolEntry entry = iter.next(); if (entry.getUpdated() <= deadline) { if (log.isDebugEnabled()) { log.debug("Closing connection last used @ " + new Date(entry.getUpdated())); } iter.remove(); deleteEntry(entry); } } } finally { poolLock.unlock(); } } @Override public void closeExpiredConnections() { log.debug("Closing expired connections"); final long now = System.currentTimeMillis(); poolLock.lock(); try { final Iterator<BasicPoolEntry> iter = freeConnections.iterator(); while (iter.hasNext()) { final BasicPoolEntry entry = iter.next(); if (entry.isExpired(now)) { if (log.isDebugEnabled()) { log.debug("Closing connection expired @ " + new Date(entry.getExpiry())); } iter.remove(); deleteEntry(entry); } } } finally { poolLock.unlock(); } } @Override public void shutdown() { poolLock.lock(); try { if (shutdown) { return; } shutdown = true; // close all connections that are issued to an application final Iterator<BasicPoolEntry> iter1 = leasedConnections.iterator(); while (iter1.hasNext()) { final BasicPoolEntry entry = iter1.next(); iter1.remove(); closeConnection(entry); } // close all free connections final Iterator<BasicPoolEntry> iter2 = freeConnections.iterator(); while (iter2.hasNext()) { final BasicPoolEntry entry = iter2.next(); iter2.remove(); if (log.isDebugEnabled()) { log.debug( "Closing connection" + " [" + entry.getPlannedRoute() + "][" + entry.getState() + "]"); } closeConnection(entry); } // wake up all waiting threads final Iterator<WaitingThread> iwth = waitingThreads.iterator(); while (iwth.hasNext()) { final WaitingThread waiter = iwth.next(); iwth.remove(); waiter.wakeup(); } routeToPool.clear(); } finally { poolLock.unlock(); } } /** * since 4.1 */ public void setMaxTotalConnections(final int max) { poolLock.lock(); try { maxTotalConnections = max; } finally { poolLock.unlock(); } } /** * since 4.1 */ public int getMaxTotalConnections() { return maxTotalConnections; } }