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      1 // Copyright (c) 2011 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 #pragma once
      8 
      9 #include <map>
     10 #include <string>
     11 #include <vector>
     12 
     13 #include "base/synchronization/lock.h"
     14 #include "base/threading/platform_thread.h"
     15 #include "net/url_request/url_request.h"
     16 
     17 template <typename T> struct DefaultSingletonTraits;
     18 
     19 namespace net {
     20 
     21 // This class is responsible for managing the set of protocol factories and
     22 // request interceptors that determine how an URLRequestJob gets created to
     23 // handle an URLRequest.
     24 //
     25 // MULTI-THREADING NOTICE:
     26 //   URLRequest is designed to have all consumers on a single thread, and
     27 //   so no attempt is made to support ProtocolFactory or Interceptor instances
     28 //   being registered/unregistered or in any way poked on multiple threads.
     29 //   However, we do support checking for supported schemes FROM ANY THREAD
     30 //   (i.e., it is safe to call SupportsScheme on any thread).
     31 //
     32 class URLRequestJobManager {
     33  public:
     34   // Returns the singleton instance.
     35   static URLRequestJobManager* GetInstance();
     36 
     37   // Instantiate an URLRequestJob implementation based on the registered
     38   // interceptors and protocol factories.  This will always succeed in
     39   // returning a job unless we are--in the extreme case--out of memory.
     40   URLRequestJob* CreateJob(URLRequest* request) const;
     41 
     42   // Allows interceptors to hijack the request after examining the new location
     43   // of a redirect. Returns NULL if no interceptor intervenes.
     44   URLRequestJob* MaybeInterceptRedirect(URLRequest* request,
     45                                              const GURL& location) const;
     46 
     47   // Allows interceptors to hijack the request after examining the response
     48   // status and headers. This is also called when there is no server response
     49   // at all to allow interception of failed requests due to network errors.
     50   // Returns NULL if no interceptor intervenes.
     51   URLRequestJob* MaybeInterceptResponse(URLRequest* request) const;
     52 
     53   // Returns true if there is a protocol factory registered for the given
     54   // scheme.  Note: also returns true if there is a built-in handler for the
     55   // given scheme.
     56   bool SupportsScheme(const std::string& scheme) const;
     57 
     58   // Register a protocol factory associated with the given scheme.  The factory
     59   // parameter may be null to clear any existing association.  Returns the
     60   // previously registered protocol factory if any.
     61   URLRequest::ProtocolFactory* RegisterProtocolFactory(
     62       const std::string& scheme, URLRequest::ProtocolFactory* factory);
     63 
     64   // Register/unregister a request interceptor.
     65   void RegisterRequestInterceptor(URLRequest::Interceptor* interceptor);
     66   void UnregisterRequestInterceptor(URLRequest::Interceptor* interceptor);
     67 
     68   void set_enable_file_access(bool enable) { enable_file_access_ = enable; }
     69   bool enable_file_access() const { return enable_file_access_; }
     70 
     71  private:
     72   typedef std::map<std::string, URLRequest::ProtocolFactory*> FactoryMap;
     73   typedef std::vector<URLRequest::Interceptor*> InterceptorList;
     74   friend struct DefaultSingletonTraits<URLRequestJobManager>;
     75 
     76   URLRequestJobManager();
     77   ~URLRequestJobManager();
     78 
     79 #ifndef NDEBUG
     80   // The first guy to call this function sets the allowed thread.  This way we
     81   // avoid needing to define that thread externally.  Since we expect all
     82   // callers to be on the same thread, we don't worry about threads racing to
     83   // set the allowed thread.
     84   bool IsAllowedThread() const {
     85 #if 0
     86     if (!allowed_thread_initialized_) {
     87       allowed_thread_ = base::PlatformThread::CurrentId();
     88       allowed_thread_initialized_ = true;
     89     }
     90     return allowed_thread_ == base::PlatformThread::CurrentId();
     91 #else
     92     // The previous version of this check used GetCurrentThread on Windows to
     93     // get thread handles to compare. Unfortunately, GetCurrentThread returns
     94     // a constant psuedo-handle (0xFFFFFFFE), and therefore IsAllowedThread
     95     // always returned true. The above code that's turned off is the correct
     96     // code, but causes the tree to turn red because some caller isn't
     97     // respecting our thread requirements. We're turning off the check for now;
     98     // bug http://b/issue?id=1338969 has been filed to fix things and turn the
     99     // check back on.
    100     return true;
    101 #endif
    102   }
    103 
    104   // We use this to assert that CreateJob and the registration functions all
    105   // run on the same thread.
    106   mutable base::PlatformThreadId allowed_thread_;
    107   mutable bool allowed_thread_initialized_;
    108 #endif
    109 
    110   mutable base::Lock lock_;
    111   FactoryMap factories_;
    112   InterceptorList interceptors_;
    113   bool enable_file_access_;
    114 
    115   DISALLOW_COPY_AND_ASSIGN(URLRequestJobManager);
    116 };
    117 
    118 }  // namespace net
    119 
    120 #endif  // NET_URL_REQUEST_URL_REQUEST_JOB_MANAGER_H_
    121