net/url_request/url_request_throttler_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_THROTTLER_MANAGER_H_
   6 #define NET_URL_REQUEST_URL_REQUEST_THROTTLER_MANAGER_H_
   7
   8 #include <map>
   9 #include <set>
  10 #include <string>
  11
  12 #include "base/basictypes.h"
  13 #include "base/memory/ref_counted.h"
  14 #include "base/threading/non_thread_safe.h"
  15 #include "base/threading/platform_thread.h"
  16 #include "net/base/net_export.h"
  17 #include "net/base/network_change_notifier.h"
  18 #include "net/url_request/url_request_throttler_entry.h"
  19 #include "url/gurl.h"
  20
  21 namespace net {
  22
  23 class BoundNetLog;
  24 class NetLog;
  25
  26 // Class that registers URL request throttler entries for URLs being accessed
  27 // in order to supervise traffic. URL requests for HTTP contents should
  28 // register their URLs in this manager on each request.
  29 //
  30 // URLRequestThrottlerManager maintains a map of URL IDs to URL request
  31 // throttler entries. It creates URL request throttler entries when new URLs
  32 // are registered, and does garbage collection from time to time in order to
  33 // clean out outdated entries. URL ID consists of lowercased scheme, host, port
  34 // and path. All URLs converted to the same ID will share the same entry.
  35 class NET_EXPORT URLRequestThrottlerManager
  36     : NON_EXPORTED_BASE(public base::NonThreadSafe),
  37       public NetworkChangeNotifier::IPAddressObserver,
  38       public NetworkChangeNotifier::ConnectionTypeObserver {
  39  public:
  40   URLRequestThrottlerManager();
  41   ~URLRequestThrottlerManager() override;
  42
  43   // Must be called for every request, returns the URL request throttler entry
  44   // associated with the URL. The caller must inform this entry of some events.
  45   // Please refer to url_request_throttler_entry_interface.h for further
  46   // informations.
  47   scoped_refptr<URLRequestThrottlerEntryInterface> RegisterRequestUrl(
  48       const GURL& url);
  49
  50   // Registers a new entry in this service and overrides the existing entry (if
  51   // any) for the URL. The service will hold a reference to the entry.
  52   // It is only used by unit tests.
  53   void OverrideEntryForTests(const GURL& url, URLRequestThrottlerEntry* entry);
  54
  55   // Explicitly erases an entry.
  56   // This is useful to remove those entries which have got infinite lifetime and
  57   // thus won't be garbage collected.
  58   // It is only used by unit tests.
  59   void EraseEntryForTests(const GURL& url);
  60
  61   // Turns threading model verification on or off.  Any code that correctly
  62   // uses the network stack should preferably call this function to enable
  63   // verification of correct adherence to the network stack threading model.
  64   void set_enable_thread_checks(bool enable);
  65   bool enable_thread_checks() const;
  66
  67   // Whether throttling is enabled or not.
  68   void set_enforce_throttling(bool enforce);
  69   bool enforce_throttling();
  70
  71   // Sets the NetLog instance to use.
  72   void set_net_log(NetLog* net_log);
  73   NetLog* net_log() const;
  74
  75   // IPAddressObserver interface.
  76   void OnIPAddressChanged() override;
  77
  78   // ConnectionTypeObserver interface.
  79   void OnConnectionTypeChanged(
  80       NetworkChangeNotifier::ConnectionType type) override;
  81
  82   // Method that allows us to transform a URL into an ID that can be used in our
  83   // map. Resulting IDs will be lowercase and consist of the scheme, host, port
  84   // and path (without query string, fragment, etc.).
  85   // If the URL is invalid, the invalid spec will be returned, without any
  86   // transformation.
  87   std::string GetIdFromUrl(const GURL& url) const;
  88
  89   // Method that ensures the map gets cleaned from time to time. The period at
  90   // which garbage collecting happens is adjustable with the
  91   // kRequestBetweenCollecting constant.
  92   void GarbageCollectEntriesIfNecessary();
  93
  94   // Method that does the actual work of garbage collecting.
  95   void GarbageCollectEntries();
  96
  97   // When we switch from online to offline or change IP addresses, we
  98   // clear all back-off history. This is a precaution in case the change in
  99   // online state now lets us communicate without error with servers that
 100   // we were previously getting 500 or 503 responses from (perhaps the
 101   // responses are from a badly-written proxy that should have returned a
 102   // 502 or 504 because it's upstream connection was down or it had no route
 103   // to the server).
 104   void OnNetworkChange();
 105
 106   // Used by tests.
 107   int GetNumberOfEntriesForTests() const { return url_entries_.size(); }
 108
 109  private:
 110   // From each URL we generate an ID composed of the scheme, host, port and path
 111   // that allows us to uniquely map an entry to it.
 112   typedef std::map<std::string, scoped_refptr<URLRequestThrottlerEntry> >
 113       UrlEntryMap;
 114
 115   // Maximum number of entries that we are willing to collect in our map.
 116   static const unsigned int kMaximumNumberOfEntries;
 117   // Number of requests that will be made between garbage collection.
 118   static const unsigned int kRequestsBetweenCollecting;
 119
 120   // Map that contains a list of URL ID and their matching
 121   // URLRequestThrottlerEntry.
 122   UrlEntryMap url_entries_;
 123
 124   // This keeps track of how many requests have been made. Used with
 125   // GarbageCollectEntries.
 126   unsigned int requests_since_last_gc_;
 127
 128   // Valid after construction.
 129   GURL::Replacements url_id_replacements_;
 130
 131   // Certain tests do not obey the net component's threading policy, so we
 132   // keep track of whether we're being used by tests, and turn off certain
 133   // checks.
 134   //
 135   // TODO(joi): See if we can fix the offending unit tests and remove this
 136   // workaround.
 137   bool enable_thread_checks_;
 138
 139   // Initially false, switches to true once we have logged because of back-off
 140   // being disabled for localhost.
 141   bool logged_for_localhost_disabled_;
 142
 143   // NetLog to use, if configured.
 144   BoundNetLog net_log_;
 145
 146   // Valid once we've registered for network notifications.
 147   base::PlatformThreadId registered_from_thread_;
 148
 149   DISALLOW_COPY_AND_ASSIGN(URLRequestThrottlerManager);
 150 };
 151
 152 }  // namespace net
 153
 154 #endif  // NET_URL_REQUEST_URL_REQUEST_THROTTLER_MANAGER_H_