components/variations/net/variations_http_header_provider.h

   1 // Copyright 2014 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 COMPONENTS_VARIATIONS_NET_VARIATIONS_HTTP_HEADER_PROVIDER_H_
   6 #define COMPONENTS_VARIATIONS_NET_VARIATIONS_HTTP_HEADER_PROVIDER_H_
   7
   8 #include <set>
   9 #include <string>
  10 #include <vector>
  11
  12 #include "base/basictypes.h"
  13 #include "base/gtest_prod_util.h"
  14 #include "base/metrics/field_trial.h"
  15 #include "base/synchronization/lock.h"
  16 #include "components/metrics/metrics_service.h"
  17 #include "components/variations/variations_associated_data.h"
  18
  19 namespace content {
  20 class ResourceContext;
  21 }
  22
  23 namespace net {
  24 class HttpRequestHeaders;
  25 }
  26
  27 class GURL;
  28
  29 namespace base {
  30 template <typename T> struct DefaultSingletonTraits;
  31 }
  32
  33 namespace variations {
  34
  35 // A helper class for maintaining client experiments and metrics state
  36 // transmitted in custom HTTP request headers.
  37 // This class is a thread-safe singleton.
  38 class VariationsHttpHeaderProvider : public base::FieldTrialList::Observer,
  39                                      public metrics::SyntheticTrialObserver {
  40  public:
  41   static VariationsHttpHeaderProvider* GetInstance();
  42
  43   // Adds Chrome experiment and metrics state as custom headers to |headers|.
  44   // Some headers may not be set given the |incognito| mode or whether
  45   // the user has |uma_enabled|.  Also, we never transmit headers to non-Google
  46   // sites, which is checked based on the destination |url|.
  47   void AppendHeaders(const GURL& url,
  48                      bool incognito,
  49                      bool uma_enabled,
  50                      net::HttpRequestHeaders* headers);
  51
  52   // Sets *additional* variation ids and trigger variation ids to be encoded in
  53   // the X-Client-Data request header.  This is intended for development use to
  54   // force a server side experiment id.  |variation_ids| should be a
  55   // comma-separated string of numeric experiment ids.  If an id is prefixed
  56   // with "t" it will be treated as a trigger experiment id.
  57   bool SetDefaultVariationIds(const std::string& variation_ids);
  58
  59   // Returns the HTTP header names which are added in this class.
  60   std::set<std::string> GetVariationHeaderNames() const;
  61
  62   // Resets any cached state for tests.
  63   void ResetForTesting();
  64
  65  private:
  66   friend struct base::DefaultSingletonTraits<VariationsHttpHeaderProvider>;
  67
  68   FRIEND_TEST_ALL_PREFIXES(VariationsHttpHeaderProviderTest,
  69                            ShouldAppendHeaders);
  70   FRIEND_TEST_ALL_PREFIXES(VariationsHttpHeaderProviderTest,
  71                            SetDefaultVariationIds_Valid);
  72   FRIEND_TEST_ALL_PREFIXES(VariationsHttpHeaderProviderTest,
  73                            SetDefaultVariationIds_Invalid);
  74   FRIEND_TEST_ALL_PREFIXES(VariationsHttpHeaderProviderTest,
  75                            OnFieldTrialGroupFinalized);
  76
  77   VariationsHttpHeaderProvider();
  78   ~VariationsHttpHeaderProvider() override;
  79
  80   // base::FieldTrialList::Observer:
  81   // This will add the variation ID associated with |trial_name| and
  82   // |group_name| to the variation ID cache.
  83   void OnFieldTrialGroupFinalized(const std::string& trial_name,
  84                                   const std::string& group_name) override;
  85
  86   // metrics::SyntheticTrialObserver:
  87   void OnSyntheticTrialsChanged(
  88       const std::vector<metrics::SyntheticTrialGroup>& groups) override;
  89
  90   // Prepares the variation IDs cache with initial values if not already done.
  91   // This method also registers the caller with the FieldTrialList to receive
  92   // new variation IDs.
  93   void InitVariationIDsCacheIfNeeded();
  94
  95   // Takes whatever is currently in |variation_ids_set_| and recreates
  96   // |variation_ids_header_| with it.  Assumes the the |lock_| is currently
  97   // held.
  98   void UpdateVariationIDsHeaderValue();
  99
 100   // Checks whether variation headers should be appended to requests to the
 101   // specified |url|. Returns true for google.<TLD> and youtube.<TLD> URLs.
 102   static bool ShouldAppendHeaders(const GURL& url);
 103
 104   // Guards |variation_ids_cache_initialized_|, |variation_ids_set_| and
 105   // |variation_ids_header_|.
 106   base::Lock lock_;
 107
 108   // Whether or not we've initialized the cache.
 109   bool variation_ids_cache_initialized_;
 110
 111   // Keep a cache of variation IDs that are transmitted in headers to Google.
 112   // This consists of a list of valid IDs, and the actual transmitted header.
 113   std::set<VariationID> variation_ids_set_;
 114   std::set<VariationID> variation_trigger_ids_set_;
 115
 116   // Provides the google experiment ids forced from command line.
 117   std::set<VariationID> default_variation_ids_set_;
 118   std::set<VariationID> default_trigger_id_set_;
 119
 120   // Variations ids from synthetic field trials.
 121   std::set<VariationID> synthetic_variation_ids_set_;
 122
 123   std::string variation_ids_header_;
 124
 125   DISALLOW_COPY_AND_ASSIGN(VariationsHttpHeaderProvider);
 126 };
 127
 128 }  // namespace variations
 129
 130 #endif  // COMPONENTS_VARIATIONS_NET_VARIATIONS_HTTP_HEADER_PROVIDER_H_