Revert 51877, since SpdyNetworkTransactionTest.CorruptFrameSessionError start...

net/proxy/multi_threaded_proxy_resolver.h

-// Copyright (c) 2009 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_PROXY_MULTI_THREADED_PROXY_RESOLVER_H_
-#define NET_PROXY_MULTI_THREADED_PROXY_RESOLVER_H_
-
-#include <deque>
-#include <string>
-#include <vector>
-
-#include "base/basictypes.h"
-#include "base/non_thread_safe.h"
-#include "base/ref_counted.h"
-#include "base/scoped_ptr.h"
-#include "net/proxy/proxy_resolver.h"
-
-namespace base {
-class Thread;
-}  // namespace base
-
-namespace net {
-
-// ProxyResolverFactory is an interface for creating ProxyResolver instances.
-class ProxyResolverFactory {
- public:
-  explicit ProxyResolverFactory(bool resolvers_expect_pac_bytes)
-      : resolvers_expect_pac_bytes_(resolvers_expect_pac_bytes) {}
-
-  virtual ~ProxyResolverFactory() {}
-
-  // Creates a new ProxyResolver. The caller is responsible for freeing this
-  // object.
-  virtual ProxyResolver* CreateProxyResolver() = 0;
-
-  bool resolvers_expect_pac_bytes() const {
-    return resolvers_expect_pac_bytes_;
-  }
-
- private:
-  bool resolvers_expect_pac_bytes_;
-  DISALLOW_COPY_AND_ASSIGN(ProxyResolverFactory);
-};
-
-// MultiThreadedProxyResolver is a ProxyResolver implementation that runs
-// synchronous ProxyResolver implementations on worker threads.
-//
-// Threads are created lazily on demand, up to a maximum total. The advantage
-// of having a pool of threads, is faster performance. In particular, being
-// able to keep servicing PAC requests even if one blocks its execution.
-//
-// During initialization (SetPacScript), a single thread is spun up to test
-// the script. If this succeeds, we cache the input script, and will re-use
-// this to lazily provision any new threads as needed.
-//
-// For each new thread that we spawn, a corresponding new ProxyResolver is
-// created using ProxyResolverFactory.
-//
-// Because we are creating multiple ProxyResolver instances, this means we
-// are duplicating script contexts for what is ordinarily seen as being a
-// single script. This can affect compatibility on some classes of PAC
-// script:
-//
-// (a) Scripts whose initialization has external dependencies on network or
-//     time may end up successfully initializing on some threads, but not
-//     others. So depending on what thread services the request, the result
-//     may jump between several possibilities.
-//
-// (b) Scripts whose FindProxyForURL() depends on side-effects may now
-//     work differently. For example, a PAC script which was incrementing
-//     a global counter and using that to make a decision. In the
-//     multi-threaded model, each thread may have a different value for this
-//     counter, so it won't globally be seen as monotonically increasing!
-class MultiThreadedProxyResolver : public ProxyResolver, public NonThreadSafe {
- public:
-  // Creates an asynchronous ProxyResolver that runs requests on up to
-  // |max_num_threads|.
-  //
-  // For each thread that is created, an accompanying synchronous ProxyResolver
-  // will be provisioned using |resolver_factory|. All methods on these
-  // ProxyResolvers will be called on the one thread, with the exception of
-  // ProxyResolver::Shutdown() which will be called from the origin thread
-  // prior to destruction.
-  //
-  // The constructor takes ownership of |resolver_factory|.
-  MultiThreadedProxyResolver(ProxyResolverFactory* resolver_factory,
-                             size_t max_num_threads);
-
-  virtual ~MultiThreadedProxyResolver();
-
-  // ProxyResolver implementation:
-  virtual int GetProxyForURL(const GURL& url,
-                             ProxyInfo* results,
-                             CompletionCallback* callback,
-                             RequestHandle* request,
-                             const BoundNetLog& net_log);
-  virtual void CancelRequest(RequestHandle request);
-  virtual void CancelSetPacScript();
-  virtual void PurgeMemory();
-
- private:
-  class Executor;
-  class Job;
-  class SetPacScriptJob;
-  class GetProxyForURLJob;
-  // FIFO queue of pending jobs waiting to be started.
-  // TODO(eroman): Make this priority queue.
-  typedef std::deque<scoped_refptr<Job> > PendingJobsQueue;
-  typedef std::vector<scoped_refptr<Executor> > ExecutorList;
-
-  // ProxyResolver implementation:
-  virtual int SetPacScript(const GURL& pac_url,
-                           const string16& pac_script,
-                           CompletionCallback* callback);
-
-  // Asserts that there are no outstanding user-initiated jobs on any of the
-  // worker threads.
-  void CheckNoOutstandingUserRequests() const;
-
-  // Stops and deletes all of the worker threads.
-  void ReleaseAllExecutors();
-
-  // Returns an idle worker thread which is ready to receive GetProxyForURL()
-  // requests. If all threads are occupied, returns NULL.
-  Executor* FindIdleExecutor();
-
-  // Creates a new worker thread, and appends it to |executors_|.
-  Executor* AddNewExecutor();
-
-  // Starts the next job from |pending_jobs_| if possible.
-  void OnExecutorReady(Executor* executor);
-
-  const scoped_ptr<ProxyResolverFactory> resolver_factory_;
-  const size_t max_num_threads_;
-  PendingJobsQueue pending_jobs_;
-  ExecutorList executors_;
-  bool was_set_pac_script_called_;
-  GURL current_pac_url_;
-  string16 current_pac_script_;
-};
-
-}  // namespace net
-
-#endif  // NET_PROXY_MULTI_THREADED_PROXY_RESOLVER_H_