// 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>
#include "base/basictypes.h"
#include "base/memory/ref_counted.h"
#include "base/memory/scoped_ptr.h"
#include "base/template_util.h"
#include "base/time/time.h"
#include "net/base/completion_callback.h"
#include "net/base/load_states.h"
#include "net/base/net_export.h"
#include "net/base/request_priority.h"
#include "net/dns/host_resolver.h"
namespace base {
class DictionaryValue;
}
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 HigherLayeredPool {
public:
virtual ~HigherLayeredPool() {}
// 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 : public LowerLayeredPool {
public:
// Subclasses must also have an inner class SocketParams which is
// the type for the |params| argument in RequestSocket() and
// RequestSockets() below.
// 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.
// 5) A recoverable error occurred while setting up the socket. An error
// code is returned, but the |handle| is initialized with the new socket.
// The caller must recover from the error before using the connection, or
// Disconnect the socket before releasing or resetting the |handle|.
// The current recoverable errors are: the errors accepted by
// IsCertificateError(err) and PROXY_AUTH_REQUESTED, or
// HTTPS_PROXY_TUNNEL_RESPONSE when reported by HttpProxyClientSocketPool.
//
// If this function returns OK, then |handle| is initialized upon return.
// The |handle|'s is_initialized method will return true in this case. If a
// StreamSocket was reused, then ClientSocketPool will call
// |handle|->set_reused(true). In either case, the socket will have been
// allocated and will be connected. A client might want to know whether or
// not the socket is reused in order to request a new socket if he encounters
// an error with the reused socket.
//
// If ERR_IO_PENDING is returned, then the callback will be used to notify the
// client of completion.
//
// Profiling information for the request is saved to |net_log| if non-NULL.
virtual int RequestSocket(const std::string& group_name,
const void* params,
RequestPriority priority,
ClientSocketHandle* handle,
const CompletionCallback& callback,
const BoundNetLog& net_log) = 0;
// RequestSockets is used to request that |num_sockets| be connected in the
// connection group for |group_name|. If the connection group already has
// |num_sockets| idle sockets / active sockets / currently connecting sockets,
// then this function doesn't do anything. Otherwise, it will start up as
// many connections as necessary to reach |num_sockets| total sockets for the
// group. It uses |params| to control how to connect the sockets. The
// ClientSocketPool will assign a priority to the new connections, if any.
// This priority will probably be lower than all others, since this method
// is intended to make sure ahead of time that |num_sockets| sockets are
// available to talk to a host.
virtual void RequestSockets(const std::string& group_name,
const void* params,
int num_sockets,
const BoundNetLog& net_log) = 0;
// Called to cancel a RequestSocket call that returned ERR_IO_PENDING. The
// same handle parameter must be passed to this method as was passed to the
// RequestSocket call being cancelled. The associated CompletionCallback is
// not run. However, for performance, we will let one ConnectJob complete
// and go idle.
virtual void CancelRequest(const std::string& group_name,
ClientSocketHandle* handle) = 0;
// Called to release a socket once the socket is no longer needed. If the
// socket still has an established connection, then it will be added to the
// set of idle sockets to be used to satisfy future RequestSocket calls.
// Otherwise, the StreamSocket is destroyed. |id| is used to differentiate
// between updated versions of the same pool instance. The pool's id will
// change when it flushes, so it can use this |id| to discard sockets with
// mismatched ids.
virtual void ReleaseSocket(const std::string& group_name,
scoped_ptr<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;
// 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;
// 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.
static const int kMaxConnectRetryIntervalMs = 250;
// The set of histograms specific to this pool. We can't use the standard
// UMA_HISTOGRAM_* macros because they are callsite static.
virtual ClientSocketPoolHistograms* histograms() const = 0;
static base::TimeDelta unused_idle_socket_timeout();
static void set_unused_idle_socket_timeout(base::TimeDelta timeout);
static base::TimeDelta used_idle_socket_timeout();
static void set_used_idle_socket_timeout(base::TimeDelta timeout);
protected:
ClientSocketPool();
virtual ~ClientSocketPool();
// Return the connection timeout for this pool.
virtual base::TimeDelta ConnectionTimeout() const = 0;
private:
DISALLOW_COPY_AND_ASSIGN(ClientSocketPool);
};
template <typename PoolType>
void RequestSocketsForPool(
PoolType* pool,
const std::string& group_name,
const scoped_refptr<typename PoolType::SocketParams>& params,
int num_sockets,
const BoundNetLog& net_log) {
pool->RequestSockets(group_name, ¶ms, num_sockets, net_log);
}
} // namespace net
#endif // NET_SOCKET_CLIENT_SOCKET_POOL_H_