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  33 // clean out outdated entries.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   virtual ~URLRequestThrottlerManager();
  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   // Adds the given host to a list of sites for which exponential back-off
  51   // throttling will be disabled.  Subdomains are not included, so they
  52   // must be added separately.
  53   void AddToOptOutList(const std::string& host);
  54
  55   // Registers a new entry in this service and overrides the existing entry (if
  56   // any) for the URL. The service will hold a reference to the entry.
  57   // It is only used by unit tests.
  58   void OverrideEntryForTests(const GURL& url, URLRequestThrottlerEntry* entry);
  59
  60   // Explicitly erases an entry.
  61   // This is useful to remove those entries which have got infinite lifetime and
  62   // thus won't be garbage collected.
  63   // It is only used by unit tests.
  64   void EraseEntryForTests(const GURL& url);
  65
  66   // Turns threading model verification on or off.  Any code that correctly
  67   // uses the network stack should preferably call this function to enable
  68   // verification of correct adherence to the network stack threading model.
  69   void set_enable_thread_checks(bool enable);
  70   bool enable_thread_checks() const;
  71
  72   // Whether throttling is enabled or not.
  73   void set_enforce_throttling(bool enforce);
  74   bool enforce_throttling();
  75
  76   // Sets the NetLog instance to use.
  77   void set_net_log(NetLog* net_log);
  78   NetLog* net_log() const;
  79
  80   // IPAddressObserver interface.
  81   virtual void OnIPAddressChanged() OVERRIDE;
  82
  83   // ConnectionTypeObserver interface.
  84   virtual void OnConnectionTypeChanged(
  85       NetworkChangeNotifier::ConnectionType type) OVERRIDE;
  86
  87   // Method that allows us to transform a URL into an ID that can be used in our
  88   // map. Resulting IDs will be lowercase and consist of the scheme, host, port
  89   // and path (without query string, fragment, etc.).
  90   // If the URL is invalid, the invalid spec will be returned, without any
  91   // transformation.
  92   std::string GetIdFromUrl(const GURL& url) const;
  93
  94   // Method that ensures the map gets cleaned from time to time. The period at
  95   // which garbage collecting happens is adjustable with the
  96   // kRequestBetweenCollecting constant.
  97   void GarbageCollectEntriesIfNecessary();
  98
  99   // Method that does the actual work of garbage collecting.
 100   void GarbageCollectEntries();
 101
 102   // When we switch from online to offline or change IP addresses, we
 103   // clear all back-off history. This is a precaution in case the change in
 104   // online state now lets us communicate without error with servers that
 105   // we were previously getting 500 or 503 responses from (perhaps the
 106   // responses are from a badly-written proxy that should have returned a
 107   // 502 or 504 because it's upstream connection was down or it had no route
 108   // to the server).
 109   void OnNetworkChange();
 110
 111   // Used by tests.
 112   int GetNumberOfEntriesForTests() const { return url_entries_.size(); }
 113
 114  private:
 115   // From each URL we generate an ID composed of the scheme, host, port and path
 116   // that allows us to uniquely map an entry to it.
 117   typedef std::map<std::string, scoped_refptr<URLRequestThrottlerEntry> >
 118       UrlEntryMap;
 119
 120   // We maintain a set of hosts that have opted out of exponential
 121   // back-off throttling.
 122   typedef std::set<std::string> OptOutHosts;
 123
 124   // Maximum number of entries that we are willing to collect in our map.
 125   static const unsigned int kMaximumNumberOfEntries;
 126   // Number of requests that will be made between garbage collection.
 127   static const unsigned int kRequestsBetweenCollecting;
 128
 129   // Map that contains a list of URL ID and their matching
 130   // URLRequestThrottlerEntry.
 131   UrlEntryMap url_entries_;
 132
 133   // Set of hosts that have opted out.
 134   OptOutHosts opt_out_hosts_;
 135
 136   // This keeps track of how many requests have been made. Used with
 137   // GarbageCollectEntries.
 138   unsigned int requests_since_last_gc_;
 139
 140   // Valid after construction.
 141   GURL::Replacements url_id_replacements_;
 142
 143   // Certain tests do not obey the net component's threading policy, so we
 144   // keep track of whether we're being used by tests, and turn off certain
 145   // checks.
 146   //
 147   // TODO(joi): See if we can fix the offending unit tests and remove this
 148   // workaround.
 149   bool enable_thread_checks_;
 150
 151   // Initially false, switches to true once we have logged because of back-off
 152   // being disabled for localhost.
 153   bool logged_for_localhost_disabled_;
 154
 155   // NetLog to use, if configured.
 156   BoundNetLog net_log_;
 157
 158   // Valid once we've registered for network notifications.
 159   base::PlatformThreadId registered_from_thread_;
 160
 161   DISALLOW_COPY_AND_ASSIGN(URLRequestThrottlerManager);
 162 };
 163
 164 }  // namespace net
 165
 166 #endif  // NET_URL_REQUEST_URL_REQUEST_THROTTLER_MANAGER_H_