Chromium Code Reviews
chromiumcodereview-hr@appspot.gserviceaccount.com (chromiumcodereview-hr) | Please choose your nickname with Settings | Help | Chromium Project | Gerrit Changes | Sign out
(2)

Side by Side Diff: chrome/browser/metrics/histogram_synchronizer.h

Issue 10454086: Histograms - Support histograms for Plugins, GPU (Closed) Base URL: svn://chrome-svn/chrome/trunk/src/
Patch Set: Created 8 years, 5 months ago
Use n/p to move between diff chunks; N/P to move between comments. Draft comments are only viewable by you.
Jump to:
View unified diff | Download patch | Annotate | Revision Log
« no previous file with comments | « chrome/browser/chrome_browser_main.cc ('k') | chrome/browser/metrics/histogram_synchronizer.cc » ('j') | no next file with comments »
Toggle Intra-line Diffs ('i') | Expand Comments ('e') | Collapse Comments ('c') | Show Comments Hide Comments ('s')
OLDNEW
(Empty)
1 // Copyright (c) 2012 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_METRICS_HISTOGRAM_SYNCHRONIZER_H_
6 #define CHROME_BROWSER_METRICS_HISTOGRAM_SYNCHRONIZER_H_
7
8 #include <string>
9 #include <vector>
10
11 #include "base/basictypes.h"
12 #include "base/callback.h"
13 #include "base/memory/ref_counted.h"
14 #include "base/synchronization/condition_variable.h"
15 #include "base/synchronization/lock.h"
16 #include "base/time.h"
17
18 class MessageLoop;
19
20 // This class maintains state that is used to upload histogram data from the
21 // various renderer processes, into the browser process. Such transactions are
22 // usually instigated by the browser. In general, a renderer process will
23 // respond by gathering snapshots of all internal histograms, calculating what
24 // has changed since its last upload, and transmitting a pickled collection of
25 // deltas.
26 //
27 // There are actually two modes of update request. One is synchronous (and
28 // blocks the UI thread, waiting to populate an about:histograms tab) and the
29 // other is asynchronous, and used by the metrics services in preparation for a
30 // log upload.
31 //
32 // To assure that all the renderers have responded, a counter is maintained (for
33 // each mode) to indicate the number of pending (not yet responsive) renderers.
34 // To avoid confusion about a response (i.e., is the renderer responding to a
35 // current request for an update, or to an old request for an update) we tag
36 // each group of requests with a sequence number. When an update arrives we can
37 // ignore it (relative to the counter) if it does not relate to a current
38 // outstanding sequence number.
39 //
40 // There is one final mode of use, where a renderer spontaneously decides to
41 // transmit a collection of histogram data. This is designed for use when the
42 // renderer is terminating. Unfortunately, renders may be terminated without
43 // warning, and the best we can do is periodically acquire data from a tab, such
44 // as when a page load has completed. In this mode, the renderer uses a
45 // reserved sequence number, different from any sequence number that might be
46 // specified by a browser request. Since this sequence number can't match an
47 // outstanding sequence number, the pickled data is accepted into the browser,
48 // but there is no impact on the counters.
49
50 class HistogramSynchronizer : public
51 base::RefCountedThreadSafe<HistogramSynchronizer> {
52 public:
53
54 enum RendererHistogramRequester {
55 ASYNC_HISTOGRAMS,
56 SYNCHRONOUS_HISTOGRAMS
57 };
58
59 // Construction also sets up the global singleton instance. This instance is
60 // used to communicate between the IO and UI thread, and is destroyed only
61 // as the main thread (browser_main) terminates, which means the IO thread has
62 // already completed, and will not need this instance any further.
63 HistogramSynchronizer();
64
65 // Return pointer to the singleton instance, which is allocated and
66 // deallocated on the main UI thread (during system startup and teardown).
67 static HistogramSynchronizer* CurrentSynchronizer();
68
69 // Contact all renderers, and get them to upload to the browser any/all
70 // changes to histograms. Return when all changes have been acquired, or when
71 // the wait time expires (whichever is sooner). This method is called on the
72 // main UI thread from about:histograms.
73 void FetchRendererHistogramsSynchronously(base::TimeDelta wait_time);
74
75 // Contact all renderers, and get them to upload to the browser any/all
76 // changes to histograms. When all changes have been acquired, or when the
77 // wait time expires (whichever is sooner), post the callback to the
78 // specified message loop. Note the callback is posted exactly once.
79 static void FetchRendererHistogramsAsynchronously(
80 MessageLoop* callback_thread,
81 const base::Closure& callback,
82 base::TimeDelta wait_time);
83
84 // This method is called on the IO thread. Deserializes the histograms and
85 // records that we have received histograms from a renderer process.
86 static void DeserializeHistogramList(
87 int sequence_number, const std::vector<std::string>& histograms);
88
89 private:
90 friend class base::RefCountedThreadSafe<HistogramSynchronizer>;
91
92 ~HistogramSynchronizer();
93
94 // Establish a new sequence_number_, and use it to notify all the renderers of
95 // the need to supply, to the browser, any changes in their histograms.
96 // The argument indicates whether this will set async_sequence_number_ or
97 // synchronous_sequence_number_.
98 // Return the sequence number that was used.
99 int NotifyAllRenderers(RendererHistogramRequester requester);
100
101 // Records that we are waiting for one less histogram from a renderer for the
102 // given sequence number. If we have received a response from all renderers,
103 // either signal the waiting process or call the callback function.
104 void DecrementPendingRenderers(int sequence_number);
105
106 // Set the callback_thread_ and callback_ members. If these members already
107 // had values, then as a side effect, post the old callback_ to the old
108 // callaback_thread_. This side effect should not generally happen, but is in
109 // place to assure correctness (that any tasks that were set, are eventually
110 // called, and never merely discarded).
111 void SetCallbackTaskAndThread(MessageLoop* callback_thread,
112 const base::Closure& callback);
113
114 void ForceHistogramSynchronizationDoneCallback(int sequence_number);
115
116 // Gets a new sequence number to be sent to renderers from browser process and
117 // set the number of pending responses for the given type to renderer_count.
118 int GetNextAvailableSequenceNumber(RendererHistogramRequester requster,
119 int renderer_count);
120
121 // Internal helper function, to post task, and record callback stats.
122 void InternalPostTask(MessageLoop* thread,
123 const base::Closure& callback,
124 int unresponsive_renderers,
125 const base::TimeTicks& started);
126
127 // This lock_ protects access to all members.
128 base::Lock lock_;
129
130 // This condition variable is used to block caller of the synchronous request
131 // to update histograms, and to signal that thread when updates are completed.
132 base::ConditionVariable received_all_renderer_histograms_;
133
134 // When a request is made to asynchronously update the histograms, we store
135 // the task and thread we use to post a completion notification in
136 // callback_ and callback_thread_.
137 base::Closure callback_;
138 MessageLoop* callback_thread_;
139
140 // We don't track the actual renderers that are contacted for an update, only
141 // the count of the number of renderers, and we can sometimes time-out and
142 // give up on a "slow to respond" renderer. We use a sequence_number to be
143 // sure a response from a renderer is associated with the current round of
144 // requests (and not merely a VERY belated prior response).
145 // All sequence numbers used are non-negative.
146 // last_used_sequence_number_ is the most recently used number (used to avoid
147 // reuse for a long time).
148 int last_used_sequence_number_;
149
150 // The sequence number used by the most recent asynchronous update request to
151 // contact all renderers.
152 int async_sequence_number_;
153
154 // The number of renderers that have not yet responded to requests (as part of
155 // an asynchronous update).
156 int async_renderers_pending_;
157
158 // The time when we were told to start the fetch histograms asynchronously
159 // from renderers.
160 base::TimeTicks async_callback_start_time_;
161
162 // The sequence number used by the most recent synchronous update request to
163 // contact all renderers.
164 int synchronous_sequence_number_;
165
166 // The number of renderers that have not yet responded to requests (as part of
167 // a synchronous update).
168 int synchronous_renderers_pending_;
169
170 // This singleton instance should be started during the single threaded
171 // portion of main(). It initializes globals to provide support for all future
172 // calls. This object is created on the UI thread, and it is destroyed after
173 // all the other threads have gone away. As a result, it is ok to call it
174 // from the UI thread (for UMA uploads), or for about:histograms.
175 static HistogramSynchronizer* histogram_synchronizer_;
176
177 DISALLOW_COPY_AND_ASSIGN(HistogramSynchronizer);
178 };
179
180 #endif // CHROME_BROWSER_METRICS_HISTOGRAM_SYNCHRONIZER_H_
OLDNEW
« no previous file with comments | « chrome/browser/chrome_browser_main.cc ('k') | chrome/browser/metrics/histogram_synchronizer.cc » ('j') | no next file with comments »

Powered by Google App Engine
This is Rietveld 408576698