When an idle socket is added back to a socket pool, check for stalled jobs in lower pools

net/socket/client_socket_pool.h

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef NET_SOCKET_CLIENT_SOCKET_POOL_H_
 #define NET_SOCKET_CLIENT_SOCKET_POOL_H_
 
 #include <deque>
 #include <string>
 
@@ skipping 12 matching lines @@
 }
 
 namespace net {
 
 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 NET_EXPORT LayeredPool {
+class NET_EXPORT HigherLayeredPool {
  public:
-  virtual ~LayeredPool() {};
+  virtual ~HigherLayeredPool() {}
 
-  // Instructs the LayeredPool to close an idle connection. Return true if one
-  // was closed.
+  // Instructs the HigherLayeredPool to close an idle connection. Return true if
+  // one was closed.  Closing an idle connection will call into the lower layer
+  // pool it came from, so must be careful of re-entrancy when using this.
   virtual bool CloseOneIdleConnection() = 0;
 };
 
+// ClientSocketPools are layered. This defines an interface for higher level
+// socket pools to communicate with lower layer pools.
+class NET_EXPORT LowerLayeredPool {
+ public:
+  virtual ~LowerLayeredPool() {}
+
+  // Returns true if a there is currently a request blocked on the per-pool
+  // (not per-host) max socket limit, either in this pool, or one that it is
+  // layered on top of.
+  virtual bool IsStalled() const = 0;
+
+  // Called to add or remove a higher layer pool on top of |this|.  A higher
+  // layer pool may be added at most once to |this|, and must be removed prior
+  // to destruction of |this|.
+  virtual void AddHigherLayeredPool(HigherLayeredPool* higher_pool) = 0;
+  virtual void RemoveHigherLayeredPool(HigherLayeredPool* higher_pool) = 0;
+};
+
 // A ClientSocketPool is used to restrict the number of sockets open at a time.
 // It also maintains a list of idle persistent sockets.
 //
-class NET_EXPORT ClientSocketPool {
+class NET_EXPORT ClientSocketPool : public LowerLayeredPool {
  public:
   // Requests a connected socket for a group_name.
   //
   // There are five possible results from calling this function:
   // 1) RequestSocket returns OK and initializes |handle| with a reused socket.
   // 2) RequestSocket returns OK with a newly connected socket.
   // 3) RequestSocket returns ERR_IO_PENDING.  The handle will be added to a
   // wait list until a socket is available to reuse or a new socket finishes
   // connecting.  |priority| will determine the placement into the wait list.
   // 4) An error occurred early on, so RequestSocket returns an error code.
@@ skipping 58 matching lines @@
                              StreamSocket* socket,
                              int id) = 0;
 
   // This flushes all state from the ClientSocketPool.  This means that all
   // idle and connecting sockets are discarded with the given |error|.
   // Active sockets being held by ClientSocketPool clients will be discarded
   // when released back to the pool.
   // Does not flush any pools wrapped by |this|.
   virtual void FlushWithError(int error) = 0;
 
-  // Returns true if a there is currently a request blocked on the
-  // 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;
 
   // The total number of idle sockets in the pool.
   virtual int IdleSocketCount() const = 0;
 
   // The total number of idle sockets in a connection group.
   virtual int IdleSocketCountInGroup(const std::string& group_name) const = 0;
 
   // Determine the LoadState of a connecting ClientSocketHandle.
   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
   // ClientSocketPools will be included.
   virtual base::DictionaryValue* GetInfoAsValue(
       const std::string& name,
       const std::string& type,
       bool include_nested_pools) const = 0;
 
   // Returns the maximum amount of time to wait before retrying a connect.
@@ skipping 54 matching lines @@
                            const scoped_refptr<SocketParams>& params,
                            int num_sockets,
                            const BoundNetLog& net_log) {
   CheckIsValidSocketParamsForPool<PoolType, SocketParams>();
   pool->RequestSockets(group_name, &params, num_sockets, net_log);
 }
 
 }  // namespace net
 
 #endif  // NET_SOCKET_CLIENT_SOCKET_POOL_H_