| // Copyright 2020 The Chromium Authors |
| // Use of this source code is governed by a BSD-style license that can be |
| // found in the LICENSE file. |
| |
| #ifndef CHROME_BROWSER_ASH_PROCESS_SNAPSHOT_SERVER_H_ |
| #define CHROME_BROWSER_ASH_PROCESS_SNAPSHOT_SERVER_H_ |
| |
| #include "base/lazy_instance.h" |
| #include "base/memory/scoped_refptr.h" |
| #include "base/memory/weak_ptr.h" |
| #include "base/observer_list.h" |
| #include "base/observer_list_types.h" |
| #include "base/process/process_iterator.h" |
| #include "base/task/sequenced_task_runner.h" |
| #include "base/time/time.h" |
| #include "base/timer/timer.h" |
| |
| namespace ash { |
| |
| // Provides an interface to regularly getting a full snapshot of the running |
| // processes on the system. |
| // The process snapshot will be refreshed at the highest refresh rate (i.e. |
| // lowest desired refresh time) requested by all clients. |
| // This system is useful for clients that regularly need a process snapshot but |
| // don't care if it's stale for a short amount of time. This is to avoid |
| // multiple clients building a separate process snapshot individually which can |
| // lead to performance issues. |
| // (See b/154362057 and https://crbug.com/). |
| // TODO(afakhry): Currently, this is only used by chome-os-specific task manager |
| // providers (for VM/Crostini and ARC++ tasks). Consider moving this server |
| // outside chrome/browser/chromeos/ so that other non-chrome-os clients can use |
| // it. |
| class ProcessSnapshotServer { |
| public: |
| class Observer : public base::CheckedObserver { |
| public: |
| explicit Observer(base::TimeDelta desired_refresh_time); |
| |
| base::TimeDelta desired_refresh_time() const { |
| return desired_refresh_time_; |
| } |
| |
| // Called when the process |snapshot| is refreshed. This may be called with |
| // intervals shorter than |desired_refresh_time_| as there might be other |
| // observers demanding higher refresh rates. |
| virtual void OnProcessSnapshotRefreshed( |
| const base::ProcessIterator::ProcessEntries& snapshot) = 0; |
| |
| protected: |
| ~Observer() override = default; |
| |
| private: |
| // The desired time between two successive refreshes of the process |
| // snapshot. The server will use the value from the observer which is |
| // minimum among all other observers. |
| const base::TimeDelta desired_refresh_time_; |
| }; |
| |
| ProcessSnapshotServer(const ProcessSnapshotServer&) = delete; |
| ProcessSnapshotServer& operator=(const ProcessSnapshotServer&) = delete; |
| ~ProcessSnapshotServer(); |
| |
| static ProcessSnapshotServer* Get(); |
| |
| const base::ProcessIterator::ProcessEntries& snapshot() const { |
| return snapshot_; |
| } |
| |
| // If the added |observer| has a lower |desired_refresh_time_| than all |
| // current observers, the refresh rate will be adjusted to match that, |
| // otherwise, the server will continue at the same current refresh rate. |
| // |
| // The first |observer| to be added will trigger an immediate refresh of the |
| // process snapshot regardless of the |desired_refresh_time_|. |
| void AddObserver(Observer* observer); |
| |
| // If the removed |observer| used to have the lowset |desired_refresh_time_|, |
| // the refresh rate will be adjusted according to the remaining observers. |
| // If |observer| is the last one to be removed, then refreshing will stop. |
| void RemoveObserver(Observer* observer); |
| |
| const base::RepeatingTimer& GetTimerForTesting() const { return timer_; } |
| |
| private: |
| friend struct base::LazyInstanceTraitsBase<ProcessSnapshotServer>; |
| |
| ProcessSnapshotServer(); |
| |
| // Triggers a refresh of the process snapshot on |task_runner_|. |
| void RefreshSnapshot(); |
| |
| // Called on the UI thread when the process snapshot is refreshed. |
| void OnSnapshotRefreshed(base::ProcessIterator::ProcessEntries snapshot); |
| |
| // Updates the current refresh rate based on |new_refresh_time| which could |
| // also lead to stopping the timer if |base::TimeDelta::Max()| is provided. |
| void RefreshTimer(base::TimeDelta new_refresh_time); |
| |
| // The current cached process snapshot. It's only valid if the |timer_| is |
| // running and it's being refreshed regularly. Depending on the current |
| // refresh rate, it can be too stale. |
| base::ProcessIterator::ProcessEntries snapshot_; |
| |
| base::RepeatingTimer timer_; |
| |
| base::ObserverList<Observer> observers_; |
| |
| scoped_refptr<base::SequencedTaskRunner> task_runner_; |
| |
| base::WeakPtrFactory<ProcessSnapshotServer> weak_ptr_factory_; |
| }; |
| |
| } // namespace ash |
| |
| #endif // CHROME_BROWSER_ASH_PROCESS_SNAPSHOT_SERVER_H_ |