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