Close idle connections / SPDY sessions when needed.

Due to the idle connection state being held by different socket pools, it's possible for one socket pool to hold an idle socket in a lower layer socket pool. From the lower level socket pool's perspective, the socket is being "actively" used. From the higher socket pool's (including SpdySession, which is more of a connection manager) perspective, the connection is idle and can be closed if we have hit a limit.

Normally this isn't a big deal, except when we have a lot of idle SPDY connections and are connecting via a proxy, so we have low connection limits through the proxy server. We address this problem by allowing lower-level socket pools to tell higher level socket pools to close a socket. 

BUG=62364,92244
TEST=none


Review URL: http://codereview.chromium.org/8340012

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@112130 0039d316-1c4b-4281-b951-d872f2087c98

1 files changed, 19 insertions, 0 deletions

diff --git a/net/socket/client_socket_pool.h b/net/socket/client_socket_pool.h
index 5f618cd..917446d 100644
--- a/net/socket/client_socket_pool.h
+++ b/net/socket/client_socket_pool.h
@@ -29,6 +29,15 @@ class ClientSocketHandle;
 class ClientSocketPoolHistograms;
 class StreamSocket;
 
+// ClientSocketPools are layered. This defines an interface for lower level
+// socket pools to communicate with higher layer pools.
+class LayeredPool {
+ public:
+  // Instructs the LayeredPool to close an idle connection. Return true if one
+  // was closed.
+  virtual bool CloseOneIdleConnection() = 0;
+};
+
 // A ClientSocketPool is used to restrict the number of sockets open at a time.
 // It also maintains a list of idle persistent sockets.
 //
@@ -110,6 +119,10 @@ class NET_EXPORT ClientSocketPool {
   // the pool.  Does not flush any pools wrapped by |this|.
   virtual void Flush() = 0;
 
+  // Returns true if a new request may hit a per-pool (not per-host) max socket
+  // limit.
+  virtual bool IsStalled() const = 0;
+
   // Called to close any idle connections held by the connection manager.
   virtual void CloseIdleSockets() = 0;
 
@@ -123,6 +136,12 @@ class NET_EXPORT ClientSocketPool {
   virtual LoadState GetLoadState(const std::string& group_name,
                                  const ClientSocketHandle* handle) const = 0;
 
+  // Adds a LayeredPool on top of |this|.
+  virtual void AddLayeredPool(LayeredPool* layered_pool) = 0;
+
+  // Removes a LayeredPool from |this|.
+  virtual void RemoveLayeredPool(LayeredPool* layered_pool) = 0;
+
   // Retrieves information on the current state of the pool as a
   // DictionaryValue.  Caller takes possession of the returned value.
   // If |include_nested_pools| is true, the states of any nested