content/browser/loader/offline_policy.cc

   1 // Copyright (c) 2013 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 #include "content/browser/loader/offline_policy.h"
   6
   7 #include "base/command_line.h"
   8 #include "base/metrics/histogram.h"
   9 #include "content/public/common/content_switches.h"
  10 #include "net/base/load_flags.h"
  11 #include "net/http/http_response_info.h"
  12 #include "net/url_request/url_request.h"
  13
  14 namespace content {
  15
  16 OfflinePolicy::OfflinePolicy()
  17     : enabled_(CommandLine::ForCurrentProcess()->HasSwitch(
  18           switches::kEnableOfflineCacheAccess)),
  19       state_(INIT),
  20       resource_loads_initiated_(0),
  21       resource_loads_successfully_started_(0) {}
  22
  23 OfflinePolicy::~OfflinePolicy() {
  24   RecordAndResetStats();
  25 }
  26
  27 void OfflinePolicy::RecordAndResetStats() {
  28   if (enabled_ && OFFLINE == state_ && 0 != resource_loads_initiated_) {
  29     UMA_HISTOGRAM_PERCENTAGE(
  30         "OfflinePolicy.SuccessfulResourceLoadPercentage",
  31         (resource_loads_successfully_started_ * 100 /
  32          resource_loads_initiated_));
  33   }
  34   resource_loads_initiated_ = 0;
  35   resource_loads_successfully_started_ = 0;
  36 }
  37
  38 int OfflinePolicy::GetAdditionalLoadFlags(int current_flags,
  39                                           bool reset_state) {
  40   // Don't do anything if offline mode is disabled.
  41   if (!enabled_)
  42     return 0;
  43
  44   if (reset_state) {
  45     RecordAndResetStats();
  46     state_ = INIT;
  47   }
  48
  49   ++resource_loads_initiated_;
  50
  51   // If a consumer has requested something contradictory, it wins; we
  52   // don't modify the load flags.
  53   if (current_flags &
  54       (net::LOAD_BYPASS_CACHE | net::LOAD_PREFERRING_CACHE |
  55        net::LOAD_ONLY_FROM_CACHE | net::LOAD_FROM_CACHE_IF_OFFLINE |
  56        net::LOAD_DISABLE_CACHE)) {
  57     return 0;
  58   }
  59
  60   switch(state_) {
  61     case INIT:
  62       return net::LOAD_FROM_CACHE_IF_OFFLINE;
  63     case ONLINE:
  64       return 0;
  65     case OFFLINE:
  66       return net::LOAD_ONLY_FROM_CACHE;
  67   }
  68   NOTREACHED();
  69   return 0;
  70 }
  71
  72 void OfflinePolicy::UpdateStateForSuccessfullyStartedRequest(
  73     const net::HttpResponseInfo& response_info) {
  74   // Don't do anything if offline mode is disabled.
  75   if (!enabled_)
  76     return;
  77
  78   // If we get here, we're going to be providing some amount of information
  79   // to the renderer.
  80   ++resource_loads_successfully_started_;
  81
  82   if (state_ != INIT)
  83     // We've already made the decision for the rest of this set
  84     // of navigations.
  85     return;
  86
  87   if (response_info.server_data_unavailable) {
  88     state_ = OFFLINE;
  89   } else if (response_info.network_accessed) {
  90     // If we got the response from the network or validated it as part
  91     // of this request, that means our connection to the host is working.
  92     state_ = ONLINE;
  93   }
  94 }
  95
  96 }  // namespace content