net/url_request/url_request_job_manager.h

   1 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 #ifndef NET_URL_REQUEST_URL_REQUEST_JOB_MANAGER_H_
   6 #define NET_URL_REQUEST_URL_REQUEST_JOB_MANAGER_H_
   7
   8 #include <string>
   9 #include <vector>
  10
  11 #include "base/synchronization/lock.h"
  12 #include "base/threading/platform_thread.h"
  13 #include "net/base/net_export.h"
  14 #include "net/url_request/url_request.h"
  15
  16 template <typename T> struct DefaultSingletonTraits;
  17
  18 namespace net {
  19
  20 // This class is responsible for managing the set of protocol factories and
  21 // request interceptors that determine how an URLRequestJob gets created to
  22 // handle an URLRequest.
  23 //
  24 // MULTI-THREADING NOTICE:
  25 //   URLRequest is designed to have all consumers on a single thread, and
  26 //   so no attempt is made to support Interceptor instances being
  27 //   registered/unregistered or in any way poked on multiple threads.
  28 class NET_EXPORT URLRequestJobManager {
  29  public:
  30   // Returns the singleton instance.
  31   static URLRequestJobManager* GetInstance();
  32
  33   // Instantiate an URLRequestJob implementation based on the registered
  34   // interceptors and protocol factories.  This will always succeed in
  35   // returning a job unless we are--in the extreme case--out of memory.
  36   URLRequestJob* CreateJob(URLRequest* request,
  37                            NetworkDelegate* network_delegate) const;
  38
  39   // Allows interceptors to hijack the request after examining the new location
  40   // of a redirect. Returns NULL if no interceptor intervenes.
  41   URLRequestJob* MaybeInterceptRedirect(URLRequest* request,
  42                                         NetworkDelegate* network_delegate,
  43                                         const GURL& location) const;
  44
  45   // Allows interceptors to hijack the request after examining the response
  46   // status and headers. This is also called when there is no server response
  47   // at all to allow interception of failed requests due to network errors.
  48   // Returns NULL if no interceptor intervenes.
  49   URLRequestJob* MaybeInterceptResponse(
  50       URLRequest* request, NetworkDelegate* network_delegate) const;
  51
  52   // Returns true if the manager has a built-in handler for |scheme|.
  53   static bool SupportsScheme(const std::string& scheme);
  54
  55  private:
  56   friend struct DefaultSingletonTraits<URLRequestJobManager>;
  57
  58   URLRequestJobManager();
  59   ~URLRequestJobManager();
  60
  61   // The first guy to call this function sets the allowed thread.  This way we
  62   // avoid needing to define that thread externally.  Since we expect all
  63   // callers to be on the same thread, we don't worry about threads racing to
  64   // set the allowed thread.
  65   bool IsAllowedThread() const {
  66 #if 0
  67     if (!allowed_thread_initialized_) {
  68       allowed_thread_ = base::PlatformThread::CurrentId();
  69       allowed_thread_initialized_ = true;
  70     }
  71     return allowed_thread_ == base::PlatformThread::CurrentId();
  72 #else
  73     // The previous version of this check used GetCurrentThread on Windows to
  74     // get thread handles to compare. Unfortunately, GetCurrentThread returns
  75     // a constant pseudo-handle (0xFFFFFFFE), and therefore IsAllowedThread
  76     // always returned true. The above code that's turned off is the correct
  77     // code, but causes the tree to turn red because some caller isn't
  78     // respecting our thread requirements. We're turning off the check for now;
  79     // bug http://b/issue?id=1338969 has been filed to fix things and turn the
  80     // check back on.
  81     return true;
  82   }
  83
  84   // We use this to assert that CreateJob and the registration functions all
  85   // run on the same thread.
  86   mutable base::PlatformThreadId allowed_thread_;
  87   mutable bool allowed_thread_initialized_;
  88 #endif
  89
  90   mutable base::Lock lock_;
  91
  92   DISALLOW_COPY_AND_ASSIGN(URLRequestJobManager);
  93 };
  94
  95 }  // namespace net
  96
  97 #endif  // NET_URL_REQUEST_URL_REQUEST_JOB_MANAGER_H_