tor-browser

The Tor Browser
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environment_factory.cc (4550B)

      1 /*
      2 *  Copyright 2023 The WebRTC project authors. All Rights Reserved.
      3 *
      4 *  Use of this source code is governed by a BSD-style license
      5 *  that can be found in the LICENSE file in the root of the source
      6 *  tree. An additional intellectual property rights grant can be found
      7 *  in the file PATENTS.  All contributing project authors may
      8 *  be found in the AUTHORS file in the root of the source tree.
      9 */
     10 
     11 #include "api/environment/environment_factory.h"
     12 
     13 #include <memory>
     14 #include <utility>
     15 
     16 #include "absl/base/nullability.h"
     17 #include "api/environment/deprecated_global_field_trials.h"
     18 #include "api/environment/environment.h"
     19 #include "api/field_trials_view.h"
     20 #include "api/make_ref_counted.h"
     21 #include "api/ref_counted_base.h"
     22 #include "api/rtc_event_log/rtc_event_log.h"
     23 #include "api/scoped_refptr.h"
     24 #include "api/task_queue/default_task_queue_factory.h"
     25 #include "api/task_queue/task_queue_factory.h"
     26 #include "rtc_base/checks.h"
     27 #include "system_wrappers/include/clock.h"
     28 
     29 namespace webrtc {
     30 namespace {
     31 
     32 template <typename T>
     33 void Store(absl_nonnull std::unique_ptr<T> value,
     34           scoped_refptr<const RefCountedBase>& leaf) {
     35  class StorageNode : public RefCountedBase {
     36   public:
     37    StorageNode(scoped_refptr<const RefCountedBase> parent,
     38                absl_nonnull std::unique_ptr<T> value)
     39        : parent_(std::move(parent)), value_(std::move(value)) {}
     40 
     41    StorageNode(const StorageNode&) = delete;
     42    StorageNode& operator=(const StorageNode&) = delete;
     43 
     44    ~StorageNode() override = default;
     45 
     46   private:
     47    scoped_refptr<const RefCountedBase> parent_;
     48    absl_nonnull std::unique_ptr<T> value_;
     49  };
     50 
     51  // Utilities provided with ownership form a tree:
     52  // Root is nullptr, each node keeps an ownership of one utility.
     53  // Each child node has a link to the parent, but parent is unaware of its
     54  // children. Each `EnvironmentFactory` and `Environment` keep a reference to a
     55  // 'leaf_' - node with the last provided utility. This way `Environment` keeps
     56  // ownership of a single branch of the storage tree with each used utiltity
     57  // owned by one of the nodes on that branch.
     58  leaf = make_ref_counted<StorageNode>(std::move(leaf), std::move(value));
     59 }
     60 
     61 }  // namespace
     62 
     63 EnvironmentFactory::EnvironmentFactory(const Environment& env)
     64    : leaf_(env.storage_),
     65      field_trials_(env.field_trials_),
     66      clock_(env.clock_),
     67      task_queue_factory_(env.task_queue_factory_),
     68      event_log_(env.event_log_) {}
     69 
     70 void EnvironmentFactory::Set(
     71    absl_nullable std::unique_ptr<const FieldTrialsView> utility) {
     72  if (utility != nullptr) {
     73    field_trials_ = utility.get();
     74    Store(std::move(utility), leaf_);
     75  }
     76 }
     77 
     78 void EnvironmentFactory::Set(absl_nullable std::unique_ptr<Clock> utility) {
     79  if (utility != nullptr) {
     80    clock_ = utility.get();
     81    Store(std::move(utility), leaf_);
     82  }
     83 }
     84 
     85 void EnvironmentFactory::Set(
     86    absl_nullable std::unique_ptr<TaskQueueFactory> utility) {
     87  if (utility != nullptr) {
     88    task_queue_factory_ = utility.get();
     89    Store(std::move(utility), leaf_);
     90  }
     91 }
     92 
     93 void EnvironmentFactory::Set(
     94    absl_nullable std::unique_ptr<RtcEventLog> utility) {
     95  if (utility != nullptr) {
     96    event_log_ = utility.get();
     97    Store(std::move(utility), leaf_);
     98  }
     99 }
    100 
    101 Environment EnvironmentFactory::CreateWithDefaults() && {
    102  if (field_trials_ == nullptr) {
    103    Set(std::make_unique<DeprecatedGlobalFieldTrials>());
    104  }
    105 #if defined(WEBRTC_MOZILLA_BUILD)
    106  // We want to use our clock, not GetRealTimeClockRaw, and we avoid
    107  // building the code under third_party/libwebrtc/task_queue.  To
    108  // ensure we're setting up things correctly, namely providing an
    109  // Environment object with a preset task_queue_factory and clock,
    110  // we'll do a release assert here.
    111  RTC_CHECK(clock_);
    112  RTC_CHECK(task_queue_factory_);
    113 #else
    114  if (clock_ == nullptr) {
    115    Set(Clock::GetRealTimeClock());
    116  }
    117  if (task_queue_factory_ == nullptr) {
    118    Set(CreateDefaultTaskQueueFactory(field_trials_));
    119  }
    120 #endif
    121  if (event_log_ == nullptr) {
    122    Set(std::make_unique<RtcEventLogNull>());
    123  }
    124 
    125  RTC_DCHECK(field_trials_ != nullptr);
    126  RTC_DCHECK(clock_ != nullptr);
    127  RTC_DCHECK(task_queue_factory_ != nullptr);
    128  RTC_DCHECK(event_log_ != nullptr);
    129  return Environment(std::move(leaf_),  //
    130                     field_trials_, clock_, task_queue_factory_, event_log_);
    131 }
    132 
    133 Environment EnvironmentFactory::Create() const {
    134  // Create a temporary copy to avoid mutating `this` with default utilities.
    135  return EnvironmentFactory(*this).CreateWithDefaults();
    136 }
    137 
    138 }  // namespace webrtc