forked from chromium/chromium
-
Notifications
You must be signed in to change notification settings - Fork 2
Commit
This commit does not belong to any branch on this repository, and may belong to a fork outside of the repository.
Create a notifier class for system DNS config changes
Essentially a thread-safe notifier wrapping around DnsConfigService, intended (but not yet used) for NetworkChangeNotifier and HostResolverManager(s) to listen to a shared object for system DNS config changes. In subsequent CLs, this will allow us to divorce HostResolverManager from listening to NetworkChangeNotifier and be able to apply Chrome-internal config changes on top of the system-only changes currently triggerring change notifications. In non-test, will generally be expected to be broadly shared and leaked on shutdown. Sequence-safe destruction is still implemented (using an internal Core class with an OnTaskRunnerDeleter) for any special cases and for tests. Note that some of the internal workings of the new class work similarly to base::ObserverListThreadSafe, but it was too difficult to make that work with the requirement that we always be able to get an initial config once ready, whether read before or after adding observers. Bug: 971411 Change-Id: Iac79dba9f74018ae6b9559c27df60174bf4edc93 Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1654881 Reviewed-by: Matt Menke <mmenke@chromium.org> Commit-Queue: Eric Orth <ericorth@chromium.org> Cr-Commit-Position: refs/heads/master@{#672087}
- Loading branch information
Eric Orth
authored and
Commit Bot
committed
Jun 25, 2019
1 parent
ba345fe
commit de0c566
Showing
10 changed files
with
650 additions
and
34 deletions.
There are no files selected for viewing
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,188 @@ | ||
| // Copyright 2019 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 "net/dns/system_dns_config_change_notifier.h" | ||
|
|
||
| #include <map> | ||
| #include <utility> | ||
|
|
||
| #include "base/bind.h" | ||
| #include "base/location.h" | ||
| #include "base/logging.h" | ||
| #include "base/memory/weak_ptr.h" | ||
| #include "base/sequence_checker.h" | ||
| #include "base/sequenced_task_runner.h" | ||
| #include "base/synchronization/lock.h" | ||
| #include "base/task/post_task.h" | ||
| #include "base/task/task_traits.h" | ||
| #include "base/threading/sequenced_task_runner_handle.h" | ||
| #include "net/dns/dns_config_service.h" | ||
|
|
||
| namespace net { | ||
|
|
||
| namespace { | ||
|
|
||
| // Internal information and handling for a registered Observer. Handles | ||
| // posting to and DCHECKing the correct sequence for the Observer. | ||
| class WrappedObserver { | ||
| public: | ||
| explicit WrappedObserver(SystemDnsConfigChangeNotifier::Observer* observer) | ||
| : task_runner_(base::SequencedTaskRunnerHandle::Get()), | ||
| observer_(observer), | ||
| weak_ptr_factory_(this) {} | ||
|
|
||
| ~WrappedObserver() { DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_); } | ||
|
|
||
| void OnNotifyThreadsafe(base::Optional<DnsConfig> config) { | ||
| task_runner_->PostTask( | ||
| FROM_HERE, | ||
| base::BindOnce(&WrappedObserver::OnNotify, | ||
| weak_ptr_factory_.GetWeakPtr(), std::move(config))); | ||
| } | ||
|
|
||
| void OnNotify(base::Optional<DnsConfig> config) { | ||
| DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_); | ||
| DCHECK(!config || config.value().IsValid()); | ||
|
|
||
| observer_->OnSystemDnsConfigChanged(std::move(config)); | ||
| } | ||
|
|
||
| private: | ||
| scoped_refptr<base::SequencedTaskRunner> task_runner_; | ||
| SystemDnsConfigChangeNotifier::Observer* const observer_; | ||
|
|
||
| SEQUENCE_CHECKER(sequence_checker_); | ||
| base::WeakPtrFactory<WrappedObserver> weak_ptr_factory_; | ||
|
|
||
| DISALLOW_COPY_AND_ASSIGN(WrappedObserver); | ||
| }; | ||
|
|
||
| } // namespace | ||
|
|
||
| // Internal core to be destroyed via base::OnTaskRunnerDeleter to ensure | ||
| // sequence safety. | ||
| class SystemDnsConfigChangeNotifier::Core { | ||
| public: | ||
| Core(scoped_refptr<base::SequencedTaskRunner> task_runner, | ||
| std::unique_ptr<DnsConfigService> dns_config_service) | ||
| : task_runner_(std::move(task_runner)), | ||
| dns_config_service_(std::move(dns_config_service)), | ||
| weak_ptr_factory_(this) { | ||
| DCHECK(task_runner_); | ||
| DCHECK(dns_config_service_); | ||
|
|
||
| DETACH_FROM_SEQUENCE(sequence_checker_); | ||
|
|
||
| task_runner_->PostTask( | ||
| FROM_HERE, | ||
| base::BindOnce(&Core::StartWatching, weak_ptr_factory_.GetWeakPtr())); | ||
| } | ||
|
|
||
| ~Core() { | ||
| DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_); | ||
| DCHECK(wrapped_observers_.empty()); | ||
| } | ||
|
|
||
| void AddObserver(Observer* observer) { | ||
| // Create wrapped observer outside locking in case construction requires | ||
| // complex side effects. | ||
| auto wrapped_observer = std::make_unique<WrappedObserver>(observer); | ||
|
|
||
| { | ||
| base::AutoLock lock(lock_); | ||
|
|
||
| if (config_) { | ||
| // Even though this is the same sequence as the observer, use the | ||
| // threadsafe OnNotify to post the notification for both lock and | ||
| // reentrancy safety. | ||
| wrapped_observer->OnNotifyThreadsafe(config_); | ||
| } | ||
|
|
||
| DCHECK_EQ(0u, wrapped_observers_.count(observer)); | ||
| wrapped_observers_.emplace(observer, std::move(wrapped_observer)); | ||
| } | ||
| } | ||
|
|
||
| void RemoveObserver(Observer* observer) { | ||
| // Destroy wrapped observer outside locking in case destruction requires | ||
| // complex side effects. | ||
| std::unique_ptr<WrappedObserver> removed_wrapped_observer; | ||
|
|
||
| { | ||
| base::AutoLock lock(lock_); | ||
| auto it = wrapped_observers_.find(observer); | ||
| DCHECK(it != wrapped_observers_.end()); | ||
| removed_wrapped_observer = std::move(it->second); | ||
| wrapped_observers_.erase(it); | ||
| } | ||
| } | ||
|
|
||
| private: | ||
| void StartWatching() { | ||
| DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_); | ||
|
|
||
| dns_config_service_->WatchConfig(base::BindRepeating( | ||
| &Core::OnConfigChanged, weak_ptr_factory_.GetWeakPtr())); | ||
| } | ||
|
|
||
| void OnConfigChanged(const DnsConfig& config) { | ||
| DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_); | ||
| base::AutoLock lock(lock_); | ||
|
|
||
| // |config_| is |base::nullopt| if most recent config was invalid (or no | ||
| // valid config has yet been read), so convert |config| to a similar form | ||
| // before comparing for change. | ||
| base::Optional<DnsConfig> new_config; | ||
| if (config.IsValid()) | ||
| new_config = config; | ||
|
|
||
| if (config_ == new_config) | ||
| return; | ||
|
|
||
| config_ = std::move(new_config); | ||
|
|
||
| for (auto& wrapped_observer : wrapped_observers_) { | ||
| wrapped_observer.second->OnNotifyThreadsafe(config_); | ||
| } | ||
| } | ||
|
|
||
| // Fields that may be accessed from any sequence. Must protect access using | ||
| // |lock_|. | ||
| mutable base::Lock lock_; | ||
| // Only stores valid configs. |base::nullopt| if most recent config was | ||
| // invalid (or no valid config has yet been read). | ||
| base::Optional<DnsConfig> config_; | ||
| std::map<Observer*, std::unique_ptr<WrappedObserver>> wrapped_observers_; | ||
|
|
||
| // Fields valid only on |task_runner_|. | ||
| scoped_refptr<base::SequencedTaskRunner> task_runner_; | ||
| SEQUENCE_CHECKER(sequence_checker_); | ||
| std::unique_ptr<DnsConfigService> dns_config_service_; | ||
| base::WeakPtrFactory<Core> weak_ptr_factory_; | ||
|
|
||
| DISALLOW_COPY_AND_ASSIGN(Core); | ||
| }; | ||
|
|
||
| SystemDnsConfigChangeNotifier::SystemDnsConfigChangeNotifier() | ||
| : SystemDnsConfigChangeNotifier( | ||
| base::CreateSequencedTaskRunnerWithTraits({base::MayBlock()}), | ||
| DnsConfigService::CreateSystemService()) {} | ||
|
|
||
| SystemDnsConfigChangeNotifier::SystemDnsConfigChangeNotifier( | ||
| scoped_refptr<base::SequencedTaskRunner> task_runner, | ||
| std::unique_ptr<DnsConfigService> dns_config_service) | ||
| : core_(new Core(task_runner, std::move(dns_config_service)), | ||
| base::OnTaskRunnerDeleter(task_runner)) {} | ||
|
|
||
| SystemDnsConfigChangeNotifier::~SystemDnsConfigChangeNotifier() = default; | ||
|
|
||
| void SystemDnsConfigChangeNotifier::AddObserver(Observer* observer) { | ||
| core_->AddObserver(observer); | ||
| } | ||
|
|
||
| void SystemDnsConfigChangeNotifier::RemoveObserver(Observer* observer) { | ||
| core_->RemoveObserver(observer); | ||
| } | ||
|
|
||
| } // namespace net |
Oops, something went wrong.