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1 // Copyright 2016 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 CHROME_BROWSER_MEMORY_MEMORY_KILLS_MONITOR_H_ | |
6 #define CHROME_BROWSER_MEMORY_MEMORY_KILLS_MONITOR_H_ | |
7 | |
8 #include <memory> | |
9 | |
10 #include "base/files/scoped_file.h" | |
11 #include "base/macros.h" | |
12 #include "base/memory/ref_counted.h" | |
13 #include "base/synchronization/atomic_flag.h" | |
14 #include "base/synchronization/lock.h" | |
15 #include "base/threading/simple_thread.h" | |
16 #include "base/time/time.h" | |
17 | |
18 namespace memory { | |
19 | |
20 // Traces kernel OOM kill events and Low memory kill events (by Chrome | |
21 // TabManagr). | |
22 // | |
23 // For OOM kill events, it listens to kernel message (/dev/kmsg) in a blocking | |
24 // manner. It runs in a non-joinable thread in order to avoid blocking shutdown. | |
25 // There should be only one MemoryKillsMonitor instance globally at any given | |
26 // time, otherwise UMA would receive duplicate events. | |
27 // | |
28 // For Low memory kills events, chrome calls the single global instance of | |
29 // MemoryKillsMonitor synchronously. Note that it would be from a browser thread | |
30 // other than the listening thread. | |
31 // | |
32 // For every events, it reports to UMA and optionally a local file specified by | |
33 // --memory-kills-log. The log file is useful if we want to analyze low memory | |
34 // kills. If the flag is not given, it won't write to any file. | |
35 class MemoryKillsMonitor : public base::DelegateSimpleThread::Delegate { | |
36 public: | |
37 // A handle representing the MemoryKillsMonitor's lifetime (the monitor itself | |
38 // can't be destroyed per being a non-joinable Thread). | |
39 class Handle { | |
hidehiko
2016/11/25 10:13:21
Looks like this is RAII, so should this be non-cop
cylee1
2016/11/29 20:28:41
Looks like so (It's added by gab@).
It requires a
| |
40 public: | |
41 // Constructs a handle that will flag |outer| as shutting down on | |
42 // destruction. | |
43 explicit Handle(MemoryKillsMonitor* outer); | |
44 | |
45 ~Handle(); | |
46 | |
47 private: | |
48 MemoryKillsMonitor* const outer_; | |
49 }; | |
50 | |
51 // Instantiates the MemoryKillsMonitor instance and starts it. This must only | |
52 // be invoked once per process. | |
53 static Handle StartMonitoring(); | |
54 | |
55 // Logs a low memory kill event. | |
56 static void LogLowMemoryKill(int estimated_freed_kb); | |
57 | |
58 // Writes an OOM kill event or low memory kill event to file. | |
59 void WriteToFile(base::Time time_stamp, const char* event); | |
60 | |
61 private: | |
62 MemoryKillsMonitor(); | |
63 ~MemoryKillsMonitor() override; | |
64 | |
65 // Overridden from base::DelegateSimpleThread::Delegate: | |
66 void Run() override; | |
67 | |
68 // A flag set when MemoryKillsMonitor is shutdown so that its thread can poll | |
69 // it and attempt to wind down from that point (to avoid unnecessary work, not | |
70 // because it blocks shutdown). | |
71 base::AtomicFlag is_shutting_down_; | |
72 | |
73 // The underlying worker thread which is non-joinable to avoid blocking | |
74 // shutdown. | |
75 std::unique_ptr<base::DelegateSimpleThread> non_joinable_worker_thread_; | |
76 | |
77 // The handle to the optional log file to write to. | |
78 base::ScopedFILE log_file_; | |
79 // Multiple threads may want to write to the log file, so we need a lock to | |
80 // ensure thread-safety. | |
81 mutable base::Lock log_file_lock_; | |
82 | |
83 DISALLOW_COPY_AND_ASSIGN(MemoryKillsMonitor); | |
84 }; | |
85 | |
86 } // namespace memory | |
87 | |
88 #endif // CHROME_BROWSER_MEMORY_MEMORY_KILLS_MONITOR_H_ | |
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