Web Inspector: Better handling for large arrays and collections in Object Trees
[WebKit-https.git] / Source / WebCore / page / ResourceUsageThread.cpp
1 /*
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8  *    notice, this list of conditions and the following disclaimer.
9  * 2. Redistributions in binary form must reproduce the above copyright
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11  *    documentation and/or other materials provided with the distribution.
12  *
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24  */
25
26 #include "config.h"
27 #include "ResourceUsageThread.h"
28
29 #if ENABLE(RESOURCE_USAGE)
30
31 #include "CommonVM.h"
32 #include "JSDOMWindow.h"
33 #include <thread>
34 #include <wtf/MainThread.h>
35 #include <wtf/Vector.h>
36
37 namespace WebCore {
38
39 ResourceUsageThread::ResourceUsageThread()
40 {
41 }
42
43 ResourceUsageThread& ResourceUsageThread::singleton()
44 {
45     static NeverDestroyed<ResourceUsageThread> resourceUsageThread;
46     return resourceUsageThread;
47 }
48
49 void ResourceUsageThread::addObserver(void* key, ResourceUsageCollectionMode mode, std::function<void (const ResourceUsageData&)> function)
50 {
51     auto& resourceUsageThread = ResourceUsageThread::singleton();
52     resourceUsageThread.createThreadIfNeeded();
53
54     {
55         LockHolder locker(resourceUsageThread.m_lock);
56         bool wasEmpty = resourceUsageThread.m_observers.isEmpty();
57         resourceUsageThread.m_observers.set(key, std::make_pair(mode, function));
58
59         resourceUsageThread.recomputeCollectionMode();
60
61         if (wasEmpty) {
62             resourceUsageThread.platformSaveStateBeforeStarting();
63             resourceUsageThread.m_condition.notifyAll();
64         }
65     }
66 }
67
68 void ResourceUsageThread::removeObserver(void* key)
69 {
70     auto& resourceUsageThread = ResourceUsageThread::singleton();
71
72     {
73         LockHolder locker(resourceUsageThread.m_lock);
74         resourceUsageThread.m_observers.remove(key);
75
76         resourceUsageThread.recomputeCollectionMode();
77     }
78 }
79
80 void ResourceUsageThread::waitUntilObservers()
81 {
82     LockHolder locker(m_lock);
83     while (m_observers.isEmpty()) {
84         m_condition.wait(m_lock);
85
86         // Wait a bit after waking up for the first time.
87         WTF::sleep(10_ms);
88     }
89 }
90
91 void ResourceUsageThread::notifyObservers(ResourceUsageData&& data)
92 {
93     callOnMainThread([data = WTFMove(data)]() mutable {
94         Vector<std::pair<ResourceUsageCollectionMode, std::function<void (const ResourceUsageData&)>>> pairs;
95
96         {
97             auto& resourceUsageThread = ResourceUsageThread::singleton();
98             LockHolder locker(resourceUsageThread.m_lock);
99             pairs = copyToVector(resourceUsageThread.m_observers.values());
100         }
101
102         for (auto& pair : pairs)
103             pair.second(data);
104     });
105 }
106
107 void ResourceUsageThread::recomputeCollectionMode()
108 {
109     m_collectionMode = None;
110
111     for (auto& pair : m_observers.values())
112         m_collectionMode = static_cast<ResourceUsageCollectionMode>(m_collectionMode | pair.first);
113 }
114
115 void ResourceUsageThread::createThreadIfNeeded()
116 {
117     if (m_thread)
118         return;
119
120     m_vm = &commonVM();
121     m_thread = Thread::create("WebCore: ResourceUsage", [this] {
122         threadBody();
123     });
124 }
125
126 NO_RETURN void ResourceUsageThread::threadBody()
127 {
128     // Wait a bit after waking up for the first time.
129     WTF::sleep(10_ms);
130     
131     while (true) {
132         // Only do work if we have observers.
133         waitUntilObservers();
134
135         auto start = WallTime::now();
136
137         ResourceUsageData data;
138         ResourceUsageCollectionMode mode = m_collectionMode;
139         if (mode & CPU)
140             platformCollectCPUData(m_vm, data);
141         if (mode & Memory)
142             platformCollectMemoryData(m_vm, data);
143
144         notifyObservers(WTFMove(data));
145
146         // NOTE: Web Inspector expects this interval to be 500ms (CPU / Memory timelines),
147         // so if this interval changes Web Inspector may need to change.
148         auto duration = WallTime::now() - start;
149         auto difference = 500_ms - duration;
150         WTF::sleep(difference);
151     }
152 }
153
154 } // namespace WebCore
155
156 #endif // ENABLE(RESOURCE_USAGE)