HTTPCLIENT-1127: a better fix for the deal-lock between SingleClientConnManager.releaseConnection() and SingleClientConnManager.shutdown(); previous fix may have broken ThreadSafeClientConnManager

git-svn-id: https://svn.apache.org/repos/asf/httpcomponents/httpclient/trunk@1180361 13f79535-47bb-0310-9956-ffa450edef68

httpclient/src/main/java/org/apache/http/impl/conn/AbstractClientConnAdapter.java

@@ -112,7 +112,7 @@ public abstract class AbstractClientConnAdapter implements ManagedClientConnecti
      * Detaches this adapter from the wrapped connection.
      * This adapter becomes useless.
      */
-    protected void detach() {
+    protected synchronized void detach() {
         wrappedConnection = null;
         duration = Long.MAX_VALUE;
     }
@@ -300,18 +300,15 @@ public abstract class AbstractClientConnAdapter implements ManagedClientConnecti
         }
     }
 
-    public void releaseConnection() {
+    public synchronized void releaseConnection() {
-        synchronized (connManager) {
         if (released) {
             return;
         }
         released = true;
         connManager.releaseConnection(this, duration, TimeUnit.MILLISECONDS);
     }
-    }
 
-    public void abortConnection() {
+    public synchronized void abortConnection() {
-        synchronized (connManager) {
         if (released) {
             return;
         }
@@ -323,7 +320,6 @@ public abstract class AbstractClientConnAdapter implements ManagedClientConnecti
         }
         connManager.releaseConnection(this, duration, TimeUnit.MILLISECONDS);
     }
-    }
 
     public Object getAttribute(final String id) {
         OperatedClientConnection conn = getWrappedConnection();

httpclient/src/main/java/org/apache/http/impl/conn/AbstractPooledConnAdapter.java

@@ -105,7 +105,7 @@ public abstract class AbstractPooledConnAdapter extends AbstractClientConnAdapte
      * This adapter becomes useless.
      */
     @Override
-    protected void detach() {
+    protected synchronized void detach() {
         poolEntry = null;
         super.detach();
     }

httpclient/src/main/java/org/apache/http/impl/conn/SingleClientConnManager.java

@@ -82,19 +82,19 @@ public class SingleClientConnManager implements ClientConnectionManager {
 
     /** The one and only entry in this pool. */
     @GuardedBy("this")
-    protected PoolEntry uniquePoolEntry;
+    protected volatile PoolEntry uniquePoolEntry;
 
     /** The currently issued managed connection, if any. */
     @GuardedBy("this")
-    protected ConnAdapter managedConn;
+    protected volatile ConnAdapter managedConn;
 
     /** The time of the last connection release, or -1. */
     @GuardedBy("this")
-    protected long lastReleaseTime;
+    protected volatile long lastReleaseTime;
 
     /** The time the last released connection expires and shouldn't be reused. */
     @GuardedBy("this")
-    protected long connectionExpiresTime;
+    protected volatile long connectionExpiresTime;
 
     /** Indicates whether this connection manager is shut down. */
     protected volatile boolean isShutDown;
@@ -205,7 +205,7 @@ public class SingleClientConnManager implements ClientConnectionManager {
      * @return  a connection that can be used to communicate
      *          along the given route
      */
-    public synchronized ManagedClientConnection getConnection(HttpRoute route, Object state) {
+    public ManagedClientConnection getConnection(HttpRoute route, Object state) {
         if (route == null) {
             throw new IllegalArgumentException("Route may not be null.");
         }
@@ -215,6 +215,7 @@ public class SingleClientConnManager implements ClientConnectionManager {
             log.debug("Get connection for route " + route);
         }
 
+        synchronized (this) {
             if (managedConn != null)
                 throw new IllegalStateException(MISUSE_MESSAGE);
 
@@ -254,8 +255,9 @@ public class SingleClientConnManager implements ClientConnectionManager {
 
             return managedConn;
         }
+    }
 
-    public synchronized void releaseConnection(
+    public void releaseConnection(
             ManagedClientConnection conn,
             long validDuration, TimeUnit timeUnit) {
         assertStillUp();
@@ -271,6 +273,7 @@ public class SingleClientConnManager implements ClientConnectionManager {
         }
 
         ConnAdapter sca = (ConnAdapter) conn;
+        synchronized (sca) {
             if (sca.poolEntry == null)
                 return; // already released
             ClientConnectionManager manager = sca.getManager();
@@ -278,7 +281,6 @@ public class SingleClientConnManager implements ClientConnectionManager {
                 throw new IllegalArgumentException
                     ("Connection not obtained from this manager.");
             }
-
             try {
                 // make sure that the response has been read completely
                 if (sca.isOpen() && (this.alwaysShutDown ||
@@ -300,6 +302,7 @@ public class SingleClientConnManager implements ClientConnectionManager {
                               iox);
             } finally {
                 sca.detach();
+                synchronized (this) {
                     managedConn = null;
                     lastReleaseTime = System.currentTimeMillis();
                     if(validDuration > 0)
@@ -308,14 +311,17 @@ public class SingleClientConnManager implements ClientConnectionManager {
                         connectionExpiresTime = Long.MAX_VALUE;
                 }
             }
+        }
+    }
 
-    public synchronized void closeExpiredConnections() {
+    public void closeExpiredConnections() {
-        if(System.currentTimeMillis() >= connectionExpiresTime) {
+        long time = connectionExpiresTime;
+        if (System.currentTimeMillis() >= time) {
             closeIdleConnections(0, TimeUnit.MILLISECONDS);
         }
     }
 
-    public synchronized void closeIdleConnections(long idletime, TimeUnit tunit) {
+    public void closeIdleConnections(long idletime, TimeUnit tunit) {
         assertStillUp();
 
         // idletime can be 0 or negative, no problem there
@@ -323,6 +329,7 @@ public class SingleClientConnManager implements ClientConnectionManager {
             throw new IllegalArgumentException("Time unit must not be null.");
         }
 
+        synchronized (this) {
             if ((managedConn == null) && uniquePoolEntry.connection.isOpen()) {
                 final long cutoff =
                     System.currentTimeMillis() - tunit.toMillis(idletime);
@@ -336,14 +343,16 @@ public class SingleClientConnManager implements ClientConnectionManager {
                 }
             }
         }
+    }
 
-    public synchronized void shutdown() {
+    public void shutdown() {
-
         this.isShutDown = true;
 
-        if (managedConn != null)
+        ConnAdapter conn = managedConn;
-            managedConn.detach();
+        if (conn != null)
+            conn.detach();
 
+        synchronized (this) {
             try {
                 if (uniquePoolEntry != null) // and connection open?
                     uniquePoolEntry.shutdown();
@@ -352,6 +361,8 @@ public class SingleClientConnManager implements ClientConnectionManager {
                 log.debug("Problem while shutting down manager.", iox);
             } finally {
                 uniquePoolEntry = null;
+                managedConn = null;
+            }
         }
     }
 
@@ -359,10 +370,13 @@ public class SingleClientConnManager implements ClientConnectionManager {
      * @deprecated no longer used
      */
     @Deprecated
-    protected synchronized void revokeConnection() {
+    protected void revokeConnection() {
-        if (managedConn == null)
+        ConnAdapter conn = managedConn;
+        if (conn == null)
             return;
-        managedConn.detach();
+        conn.detach();
+
+        synchronized (this) {
             try {
                 uniquePoolEntry.shutdown();
             } catch (IOException iox) {
@@ -370,6 +384,7 @@ public class SingleClientConnManager implements ClientConnectionManager {
                 log.debug("Problem while shutting down connection.", iox);
             }
         }
+    }
 
     /**
      * The pool entry for this connection manager.