+ * If the managed connections is released or revoked, the adapter
+ * gets disconnected, but the pool entry still contains the
+ * underlying connection and the established route.
+ *
+ * @since 4.0
+ */
+@NotThreadSafe
+public abstract class AbstractPoolEntry {
+
+ /** The connection operator. */
+ protected final ClientConnectionOperator connOperator;
+
+ /** The underlying connection being pooled or used. */
+ protected final OperatedClientConnection connection;
+
+ /** The route for which this entry gets allocated. */
+ //@@@ currently accessed from connection manager(s) as attribute
+ //@@@ avoid that, derived classes should decide whether update is allowed
+ //@@@ SCCM: yes, TSCCM: no
+ protected volatile HttpRoute route;
+
+ /** Connection state object */
+ protected volatile Object state;
+
+ /** The tracked route, or null before tracking starts. */
+ protected volatile RouteTracker tracker;
+
+
+ /**
+ * Creates a new pool entry.
+ *
+ * @param connOperator the Connection Operator for this entry
+ * @param route the planned route for the connection,
+ * or null
+ */
+ protected AbstractPoolEntry(ClientConnectionOperator connOperator,
+ HttpRoute route) {
+ super();
+ if (connOperator == null) {
+ throw new IllegalArgumentException("Connection operator may not be null");
+ }
+ this.connOperator = connOperator;
+ this.connection = connOperator.createConnection();
+ this.route = route;
+ this.tracker = null;
+ }
+
+ /**
+ * Returns the state object associated with this pool entry.
+ *
+ * @return The state object
+ */
+ public Object getState() {
+ return state;
+ }
+
+ /**
+ * Assigns a state object to this pool entry.
+ *
+ * @param state The state object
+ */
+ public void setState(final Object state) {
+ this.state = state;
+ }
+
+ /**
+ * Opens the underlying connection.
+ *
+ * @param route the route along which to open the connection
+ * @param context the context for opening the connection
+ * @param params the parameters for opening the connection
+ *
+ * @throws IOException in case of a problem
+ */
+ public void open(HttpRoute route,
+ HttpContext context, HttpParams params)
+ throws IOException {
+
+ if (route == null) {
+ throw new IllegalArgumentException
+ ("Route must not be null.");
+ }
+ if (params == null) {
+ throw new IllegalArgumentException
+ ("Parameters must not be null.");
+ }
+ if ((this.tracker != null) && this.tracker.isConnected()) {
+ throw new IllegalStateException("Connection already open.");
+ }
+
+ // - collect the arguments
+ // - call the operator
+ // - update the tracking data
+ // In this order, we can be sure that only a successful
+ // opening of the connection will be tracked.
+
+ this.tracker = new RouteTracker(route);
+ final HttpHost proxy = route.getProxyHost();
+
+ connOperator.openConnection
+ (this.connection,
+ (proxy != null) ? proxy : route.getTargetHost(),
+ route.getLocalAddress(),
+ context, params);
+
+ RouteTracker localTracker = tracker; // capture volatile
+
+ // If this tracker was reset while connecting,
+ // fail early.
+ if (localTracker == null) {
+ throw new IOException("Request aborted");
+ }
+
+ if (proxy == null) {
+ localTracker.connectTarget(this.connection.isSecure());
+ } else {
+ localTracker.connectProxy(proxy, this.connection.isSecure());
+ }
+
+ }
+
+ /**
+ * Tracks tunnelling of the connection to the target.
+ * The tunnel has to be established outside by sending a CONNECT
+ * request to the (last) proxy.
+ *
+ * @param secure true if the tunnel should be
+ * considered secure, false otherwise
+ * @param params the parameters for tunnelling the connection
+ *
+ * @throws IOException in case of a problem
+ */
+ public void tunnelTarget(boolean secure, HttpParams params)
+ throws IOException {
+
+ if (params == null) {
+ throw new IllegalArgumentException
+ ("Parameters must not be null.");
+ }
+
+ if ((this.tracker == null) || !this.tracker.isConnected()) {
+ throw new IllegalStateException("Connection not open.");
+ }
+ if (this.tracker.isTunnelled()) {
+ throw new IllegalStateException
+ ("Connection is already tunnelled.");
+ }
+
+ this.connection.update(null, tracker.getTargetHost(),
+ secure, params);
+ this.tracker.tunnelTarget(secure);
+ }
+
+ /**
+ * Tracks tunnelling of the connection to a chained proxy.
+ * The tunnel has to be established outside by sending a CONNECT
+ * request to the previous proxy.
+ *
+ * @param next the proxy to which the tunnel was established.
+ * See {@link ch.boye.httpclientandroidlib.conn.ManagedClientConnection#tunnelProxy
+ * ManagedClientConnection.tunnelProxy}
+ * for details.
+ * @param secure true if the tunnel should be
+ * considered secure, false otherwise
+ * @param params the parameters for tunnelling the connection
+ *
+ * @throws IOException in case of a problem
+ */
+ public void tunnelProxy(HttpHost next, boolean secure, HttpParams params)
+ throws IOException {
+
+ if (next == null) {
+ throw new IllegalArgumentException
+ ("Next proxy must not be null.");
+ }
+ if (params == null) {
+ throw new IllegalArgumentException
+ ("Parameters must not be null.");
+ }
+
+ //@@@ check for proxy in planned route?
+ if ((this.tracker == null) || !this.tracker.isConnected()) {
+ throw new IllegalStateException("Connection not open.");
+ }
+
+ this.connection.update(null, next, secure, params);
+ this.tracker.tunnelProxy(next, secure);
+ }
+
+ /**
+ * Layers a protocol on top of an established tunnel.
+ *
+ * @param context the context for layering
+ * @param params the parameters for layering
+ *
+ * @throws IOException in case of a problem
+ */
+ public void layerProtocol(HttpContext context, HttpParams params)
+ throws IOException {
+
+ //@@@ is context allowed to be null? depends on operator?
+ if (params == null) {
+ throw new IllegalArgumentException
+ ("Parameters must not be null.");
+ }
+
+ if ((this.tracker == null) || !this.tracker.isConnected()) {
+ throw new IllegalStateException("Connection not open.");
+ }
+ if (!this.tracker.isTunnelled()) {
+ //@@@ allow this?
+ throw new IllegalStateException
+ ("Protocol layering without a tunnel not supported.");
+ }
+ if (this.tracker.isLayered()) {
+ throw new IllegalStateException
+ ("Multiple protocol layering not supported.");
+ }
+
+ // - collect the arguments
+ // - call the operator
+ // - update the tracking data
+ // In this order, we can be sure that only a successful
+ // layering on top of the connection will be tracked.
+
+ final HttpHost target = tracker.getTargetHost();
+
+ connOperator.updateSecureConnection(this.connection, target,
+ context, params);
+
+ this.tracker.layerProtocol(this.connection.isSecure());
+
+ }
+
+ /**
+ * Shuts down the entry.
+ *
+ * If {@link #open(HttpRoute, HttpContext, HttpParams)} is in progress,
+ * this will cause that open to possibly throw an {@link IOException}.
+ */
+ protected void shutdownEntry() {
+ tracker = null;
+ state = null;
+ }
+
+}
+