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