| // Copyright 2014 The Chromium Authors. All rights reserved. |
| // Use of this source code is governed by a BSD-style license that can be |
| // found in the LICENSE file. |
| |
| #include "components/variations/variations_http_header_provider.h" |
| |
| #include <stddef.h> |
| |
| #include <set> |
| #include <string> |
| #include <vector> |
| |
| #include "base/base64.h" |
| #include "base/memory/singleton.h" |
| #include "base/metrics/histogram_macros.h" |
| #include "base/strings/string_number_conversions.h" |
| #include "base/strings/string_split.h" |
| #include "base/strings/string_util.h" |
| #include "base/threading/thread_task_runner_handle.h" |
| #include "components/variations/proto/client_variations.pb.h" |
| |
| namespace variations { |
| |
| // static |
| VariationsHttpHeaderProvider* VariationsHttpHeaderProvider::GetInstance() { |
| return base::Singleton<VariationsHttpHeaderProvider>::get(); |
| } |
| |
| std::string VariationsHttpHeaderProvider::GetClientDataHeader() { |
| // Lazily initialize the header, if not already done, before attempting to |
| // transmit it. |
| InitVariationIDsCacheIfNeeded(); |
| |
| std::string variation_ids_header_copy; |
| { |
| base::AutoLock scoped_lock(lock_); |
| variation_ids_header_copy = variation_ids_header_; |
| } |
| return variation_ids_header_copy; |
| } |
| |
| std::string VariationsHttpHeaderProvider::GetVariationsString() { |
| InitVariationIDsCacheIfNeeded(); |
| |
| // Construct a space-separated string with leading and trailing spaces from |
| // the variations set. Note: The ids in it will be in sorted order per the |
| // std::set contract. |
| std::string ids_string = " "; |
| { |
| base::AutoLock scoped_lock(lock_); |
| for (VariationID id : GetAllVariationIds()) { |
| ids_string.append(base::IntToString(id)); |
| ids_string.push_back(' '); |
| } |
| } |
| return ids_string; |
| } |
| |
| bool VariationsHttpHeaderProvider::SetDefaultVariationIds( |
| const std::string& variation_ids) { |
| default_variation_ids_set_.clear(); |
| default_trigger_id_set_.clear(); |
| for (const base::StringPiece& entry : base::SplitStringPiece( |
| variation_ids, ",", base::TRIM_WHITESPACE, base::SPLIT_WANT_ALL)) { |
| if (entry.empty()) { |
| default_variation_ids_set_.clear(); |
| default_trigger_id_set_.clear(); |
| return false; |
| } |
| bool trigger_id = |
| base::StartsWith(entry, "t", base::CompareCase::SENSITIVE); |
| // Remove the "t" prefix if it's there. |
| base::StringPiece trimmed_entry = trigger_id ? entry.substr(1) : entry; |
| |
| int variation_id = 0; |
| if (!base::StringToInt(trimmed_entry, &variation_id)) { |
| default_variation_ids_set_.clear(); |
| default_trigger_id_set_.clear(); |
| return false; |
| } |
| if (trigger_id) |
| default_trigger_id_set_.insert(variation_id); |
| else |
| default_variation_ids_set_.insert(variation_id); |
| } |
| return true; |
| } |
| |
| void VariationsHttpHeaderProvider::ResetForTesting() { |
| base::AutoLock scoped_lock(lock_); |
| |
| // Stop observing field trials so that it can be restarted when this is |
| // re-inited. Note: This is a no-op if this is not currently observing. |
| base::FieldTrialList::RemoveObserver(this); |
| variation_ids_cache_initialized_ = false; |
| } |
| |
| VariationsHttpHeaderProvider::VariationsHttpHeaderProvider() |
| : variation_ids_cache_initialized_(false) {} |
| |
| VariationsHttpHeaderProvider::~VariationsHttpHeaderProvider() {} |
| |
| void VariationsHttpHeaderProvider::OnFieldTrialGroupFinalized( |
| const std::string& trial_name, |
| const std::string& group_name) { |
| VariationID new_id = |
| GetGoogleVariationID(GOOGLE_WEB_PROPERTIES, trial_name, group_name); |
| VariationID new_trigger_id = GetGoogleVariationID( |
| GOOGLE_WEB_PROPERTIES_TRIGGER, trial_name, group_name); |
| if (new_id == EMPTY_ID && new_trigger_id == EMPTY_ID) |
| return; |
| |
| base::AutoLock scoped_lock(lock_); |
| if (new_id != EMPTY_ID) |
| variation_ids_set_.insert(new_id); |
| if (new_trigger_id != EMPTY_ID) |
| variation_trigger_ids_set_.insert(new_trigger_id); |
| |
| UpdateVariationIDsHeaderValue(); |
| } |
| |
| void VariationsHttpHeaderProvider::OnSyntheticTrialsChanged( |
| const std::vector<SyntheticTrialGroup>& groups) { |
| base::AutoLock scoped_lock(lock_); |
| |
| synthetic_variation_ids_set_.clear(); |
| for (const SyntheticTrialGroup& group : groups) { |
| const VariationID id = |
| GetGoogleVariationIDFromHashes(GOOGLE_WEB_PROPERTIES, group.id); |
| if (id != EMPTY_ID) |
| synthetic_variation_ids_set_.insert(id); |
| } |
| UpdateVariationIDsHeaderValue(); |
| } |
| |
| void VariationsHttpHeaderProvider::InitVariationIDsCacheIfNeeded() { |
| base::AutoLock scoped_lock(lock_); |
| if (variation_ids_cache_initialized_) |
| return; |
| |
| // Register for additional cache updates. This is done first to avoid a race |
| // that could cause registered FieldTrials to be missed. |
| DCHECK(base::ThreadTaskRunnerHandle::IsSet()); |
| base::FieldTrialList::AddObserver(this); |
| |
| base::TimeTicks before_time = base::TimeTicks::Now(); |
| |
| base::FieldTrial::ActiveGroups initial_groups; |
| base::FieldTrialList::GetActiveFieldTrialGroups(&initial_groups); |
| |
| for (const auto& entry : initial_groups) { |
| const VariationID id = |
| GetGoogleVariationID(GOOGLE_WEB_PROPERTIES, entry.trial_name, |
| entry.group_name); |
| if (id != EMPTY_ID) |
| variation_ids_set_.insert(id); |
| |
| const VariationID trigger_id = |
| GetGoogleVariationID(GOOGLE_WEB_PROPERTIES_TRIGGER, entry.trial_name, |
| entry.group_name); |
| |
| if (trigger_id != EMPTY_ID) |
| variation_trigger_ids_set_.insert(trigger_id); |
| } |
| UpdateVariationIDsHeaderValue(); |
| |
| UMA_HISTOGRAM_CUSTOM_COUNTS( |
| "Variations.HeaderConstructionTime", |
| (base::TimeTicks::Now() - before_time).InMicroseconds(), 0, |
| base::TimeDelta::FromSeconds(1).InMicroseconds(), 50); |
| |
| variation_ids_cache_initialized_ = true; |
| } |
| |
| void VariationsHttpHeaderProvider::UpdateVariationIDsHeaderValue() { |
| lock_.AssertAcquired(); |
| |
| // The header value is a serialized protobuffer of Variation IDs which is |
| // base64 encoded before transmitting as a string. |
| variation_ids_header_.clear(); |
| |
| if (variation_ids_set_.empty() && default_variation_ids_set_.empty() && |
| variation_trigger_ids_set_.empty() && default_trigger_id_set_.empty() && |
| synthetic_variation_ids_set_.empty()) { |
| return; |
| } |
| |
| // This is the bottleneck for the creation of the header, so validate the size |
| // here. Force a hard maximum on the ID count in case the Variations server |
| // returns too many IDs and DOSs receiving servers with large requests. |
| const size_t total_id_count = |
| variation_ids_set_.size() + variation_trigger_ids_set_.size(); |
| DCHECK_LE(total_id_count, 10U); |
| UMA_HISTOGRAM_COUNTS_100("Variations.Headers.ExperimentCount", |
| total_id_count); |
| if (total_id_count > 20) |
| return; |
| |
| std::set<VariationID> all_variation_ids_set = GetAllVariationIds(); |
| std::set<VariationID> all_trigger_ids_set = default_trigger_id_set_; |
| for (VariationID id : variation_trigger_ids_set_) |
| all_trigger_ids_set.insert(id); |
| |
| ClientVariations proto; |
| for (VariationID id : all_variation_ids_set) |
| proto.add_variation_id(id); |
| for (VariationID id : all_trigger_ids_set) |
| proto.add_trigger_variation_id(id); |
| |
| std::string serialized; |
| proto.SerializeToString(&serialized); |
| |
| std::string hashed; |
| base::Base64Encode(serialized, &hashed); |
| // If successful, swap the header value with the new one. |
| // Note that the list of IDs and the header could be temporarily out of sync |
| // if IDs are added as the header is recreated. The receiving servers are OK |
| // with such discrepancies. |
| variation_ids_header_ = hashed; |
| } |
| |
| std::set<VariationID> VariationsHttpHeaderProvider::GetAllVariationIds() { |
| lock_.AssertAcquired(); |
| |
| std::set<VariationID> all_variation_ids_set = default_variation_ids_set_; |
| for (VariationID id : variation_ids_set_) |
| all_variation_ids_set.insert(id); |
| for (VariationID id : synthetic_variation_ids_set_) |
| all_variation_ids_set.insert(id); |
| return all_variation_ids_set; |
| } |
| |
| } // namespace variations |