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| 1 // Copyright 2015 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 BASE_PROFILER_STACK_SAMPLING_PROFILER_H_ | |
| 6 #define BASE_PROFILER_STACK_SAMPLING_PROFILER_H_ | |
| 7 | |
| 8 #include <string> | |
| 9 #include <vector> | |
| 10 | |
| 11 #include "base/base_export.h" | |
| 12 #include "base/callback.h" | |
| 13 #include "base/files/file_path.h" | |
| 14 #include "base/memory/scoped_ptr.h" | |
| 15 #include "base/strings/string16.h" | |
| 16 #include "base/synchronization/waitable_event.h" | |
| 17 #include "base/threading/platform_thread.h" | |
| 18 #include "base/time/time.h" | |
| 19 | |
| 20 namespace base { | |
| 21 | |
| 22 class NativeStackSampler; | |
| 23 | |
| 24 // StackSamplingProfiler periodically stops a thread to sample its stack, for | |
| 25 // the purpose of collecting information about which code paths are | |
| 26 // executing. This information is used in aggregate by UMA to identify hot | |
| 27 // and/or janky code paths. | |
| 28 // | |
| 29 // Sample StackSamplingProfiler usage: | |
| 30 // | |
| 31 // // Create and customize params as desired. | |
| 32 // base::StackStackSamplingProfiler::SamplingParams params; | |
| 33 // // Any thread's ID may be passed as the target. | |
| 34 // base::StackSamplingProfiler profiler(base::PlatformThread::CurrentId()), | |
| 35 // params); | |
| 36 // | |
| 37 // // Or, to process the profiles within Chrome rather than via UMA, use a | |
| 38 // // custom completed callback: | |
| 39 // base::StackStackSamplingProfiler::CompletedCallback | |
| 40 // thread_safe_callback = ...; | |
| 41 // base::StackSamplingProfiler profiler(base::PlatformThread::CurrentId()), | |
| 42 // params, thread_safe_callback); | |
| 43 // | |
| 44 // profiler.Start(); | |
| 45 // // ... work being done on the target thread here ... | |
| 46 // profiler.Stop(); // optional, stops collection before complete per params | |
| 47 // | |
| 48 // The default SamplingParams causes stacks to be recorded in a single burst at | |
| 49 // a 10Hz interval for a total of 30 seconds. All of these parameters may be | |
| 50 // altered as desired. | |
| 51 // | |
| 52 // When all call stack profiles are complete or the profiler is stopped, if the | |
| 53 // custom completed callback was set it is called from a thread created by the | |
| 54 // profiler with the completed profiles. A profile is considered complete if all | |
| 55 // requested samples were recorded for the profile (i.e. it was not stopped | |
| 56 // prematurely). If no callback was set, the default completed callback will be | |
| 57 // called with the profiles. It is expected that the the default completed | |
| 58 // callback is set by the metrics system to allow profiles to be provided via | |
| 59 // UMA. | |
| 60 // | |
| 61 // The results of the profiling are passed to the completed callback and consist | |
| 62 // of a vector of CallStackProfiles. Each CallStackProfile corresponds to a | |
| 63 // burst as specified in SamplingParams and contains a set of Samples and | |
| 64 // Modules. One Sample corresponds to a single recorded stack, and the Modules | |
| 65 // record those modules associated with the recorded stack frames. | |
| 66 class BASE_EXPORT StackSamplingProfiler { | |
| 67 public: | |
| 68 // Module represents the module (DLL or exe) corresponding to a stack frame. | |
| 69 struct BASE_EXPORT Module { | |
| 70 Module(); | |
| 71 Module(const void* base_address, const std::string& id, | |
| 72 const FilePath& filename); | |
| 73 ~Module(); | |
| 74 | |
| 75 // Points to the base address of the module. | |
| 76 const void* base_address; | |
| 77 | |
| 78 // An opaque binary string that uniquely identifies a particular program | |
| 79 // version with high probability. This is parsed from headers of the loaded | |
| 80 // module. | |
| 81 // For binaries generated by GNU tools: | |
| 82 // Contents of the .note.gnu.build-id field. | |
| 83 // On Windows: | |
| 84 // GUID + AGE in the debug image headers of a module. | |
| 85 std::string id; | |
| 86 | |
| 87 // The filename of the module. | |
| 88 FilePath filename; | |
| 89 }; | |
| 90 | |
| 91 // Frame represents an individual sampled stack frame with module information. | |
| 92 struct BASE_EXPORT Frame { | |
| 93 // Identifies an unknown module. | |
| 94 static const size_t kUnknownModuleIndex = static_cast<size_t>(-1); | |
| 95 | |
| 96 Frame(const void* instruction_pointer, size_t module_index); | |
| 97 ~Frame(); | |
| 98 | |
| 99 // The sampled instruction pointer within the function. | |
| 100 const void* instruction_pointer; | |
| 101 | |
| 102 // Index of the module in CallStackProfile::modules. We don't represent | |
| 103 // module state directly here to save space. | |
| 104 size_t module_index; | |
| 105 }; | |
| 106 | |
| 107 // Sample represents a set of stack frames. | |
| 108 using Sample = std::vector<Frame>; | |
| 109 | |
| 110 // CallStackProfile represents a set of samples. | |
| 111 struct BASE_EXPORT CallStackProfile { | |
| 112 CallStackProfile(); | |
| 113 ~CallStackProfile(); | |
| 114 | |
| 115 std::vector<Module> modules; | |
| 116 std::vector<Sample> samples; | |
| 117 | |
| 118 // Duration of this profile. | |
| 119 TimeDelta profile_duration; | |
| 120 | |
| 121 // Time between samples. | |
| 122 TimeDelta sampling_period; | |
| 123 | |
| 124 // True if sample ordering is important and should be preserved if and when | |
| 125 // this profile is compressed and processed. | |
| 126 bool preserve_sample_ordering; | |
| 127 | |
| 128 // User data associated with this profile. | |
| 129 uintptr_t user_data; | |
| 130 }; | |
| 131 | |
| 132 using CallStackProfiles = std::vector<CallStackProfile>; | |
| 133 | |
| 134 // Represents parameters that configure the sampling. | |
| 135 struct BASE_EXPORT SamplingParams { | |
| 136 SamplingParams(); | |
| 137 | |
| 138 // Time to delay before first samples are taken. Defaults to 0. | |
| 139 TimeDelta initial_delay; | |
| 140 | |
| 141 // Number of sampling bursts to perform. Defaults to 1. | |
| 142 int bursts; | |
| 143 | |
| 144 // Interval between sampling bursts. This is the desired duration from the | |
| 145 // start of one burst to the start of the next burst. Defaults to 10s. | |
| 146 TimeDelta burst_interval; | |
| 147 | |
| 148 // Number of samples to record per burst. Defaults to 300. | |
| 149 int samples_per_burst; | |
| 150 | |
| 151 // Interval between samples during a sampling burst. This is the desired | |
| 152 // duration from the start of one sample to the start of the next | |
| 153 // sample. Defaults to 100ms. | |
| 154 TimeDelta sampling_interval; | |
| 155 | |
| 156 // True if sample ordering is important and should be preserved if and when | |
| 157 // this profile is compressed and processed. Defaults to false. | |
| 158 bool preserve_sample_ordering; | |
| 159 | |
| 160 // User data associated with this profile. | |
| 161 uintptr_t user_data; | |
| 162 }; | |
| 163 | |
| 164 // The callback type used to collect completed profiles. | |
| 165 // | |
| 166 // IMPORTANT NOTE: the callback is invoked on a thread the profiler | |
| 167 // constructs, rather than on the thread used to construct the profiler and | |
| 168 // set the callback, and thus the callback must be callable on any thread. For | |
| 169 // threads with message loops that create StackSamplingProfilers, posting a | |
| 170 // task to the message loop with a copy of the profiles is the recommended | |
| 171 // thread-safe callback implementation. | |
| 172 using CompletedCallback = Callback<void(const CallStackProfiles&)>; | |
| 173 | |
| 174 // Creates a profiler that sends completed profiles to the default completed | |
| 175 // callback. | |
| 176 StackSamplingProfiler(PlatformThreadId thread_id, | |
| 177 const SamplingParams& params); | |
| 178 // Creates a profiler that sends completed profiles to |completed_callback|. | |
| 179 StackSamplingProfiler(PlatformThreadId thread_id, | |
| 180 const SamplingParams& params, | |
| 181 CompletedCallback callback); | |
| 182 ~StackSamplingProfiler(); | |
| 183 | |
| 184 // Initializes the profiler and starts sampling. | |
| 185 void Start(); | |
| 186 | |
| 187 // Stops the profiler and any ongoing sampling. Calling this function is | |
| 188 // optional; if not invoked profiling terminates when all the profiling bursts | |
| 189 // specified in the SamplingParams are completed. | |
| 190 void Stop(); | |
| 191 | |
| 192 // Sets a callback to process profiles collected by profiler instances without | |
| 193 // a completed callback. Profiles are queued internally until a non-null | |
| 194 // callback is provided to this function, | |
| 195 // | |
| 196 // The callback is typically called on a thread created by the profiler. If | |
| 197 // completed profiles are queued when set, however, it will also be called | |
| 198 // immediately on the calling thread. | |
| 199 static void SetDefaultCompletedCallback(CompletedCallback callback); | |
| 200 | |
| 201 private: | |
| 202 // SamplingThread is a separate thread used to suspend and sample stacks from | |
| 203 // the target thread. | |
| 204 class SamplingThread : public PlatformThread::Delegate { | |
| 205 public: | |
| 206 // Samples stacks using |native_sampler|. When complete, invokes | |
| 207 // |completed_callback| with the collected call stack profiles. | |
| 208 // |completed_callback| must be callable on any thread. | |
| 209 SamplingThread(scoped_ptr<NativeStackSampler> native_sampler, | |
| 210 const SamplingParams& params, | |
| 211 CompletedCallback completed_callback); | |
| 212 ~SamplingThread() override; | |
| 213 | |
| 214 // PlatformThread::Delegate: | |
| 215 void ThreadMain() override; | |
| 216 | |
| 217 void Stop(); | |
| 218 | |
| 219 private: | |
| 220 // Collects a call stack profile from a single burst. Returns true if the | |
| 221 // profile was collected, or false if collection was stopped before it | |
| 222 // completed. | |
| 223 bool CollectProfile(CallStackProfile* profile, TimeDelta* elapsed_time); | |
| 224 | |
| 225 // Collects call stack profiles from all bursts, or until the sampling is | |
| 226 // stopped. If stopped before complete, |call_stack_profiles| will contain | |
| 227 // only full bursts. | |
| 228 void CollectProfiles(CallStackProfiles* profiles); | |
| 229 | |
| 230 scoped_ptr<NativeStackSampler> native_sampler_; | |
| 231 const SamplingParams params_; | |
| 232 | |
| 233 // If Stop() is called, it signals this event to force the sampling to | |
| 234 // terminate before all the samples specified in |params_| are collected. | |
| 235 WaitableEvent stop_event_; | |
| 236 | |
| 237 const CompletedCallback completed_callback_; | |
| 238 | |
| 239 DISALLOW_COPY_AND_ASSIGN(SamplingThread); | |
| 240 }; | |
| 241 | |
| 242 // The thread whose stack will be sampled. | |
| 243 PlatformThreadId thread_id_; | |
| 244 | |
| 245 const SamplingParams params_; | |
| 246 | |
| 247 scoped_ptr<SamplingThread> sampling_thread_; | |
| 248 PlatformThreadHandle sampling_thread_handle_; | |
| 249 | |
| 250 const CompletedCallback completed_callback_; | |
| 251 | |
| 252 DISALLOW_COPY_AND_ASSIGN(StackSamplingProfiler); | |
| 253 }; | |
| 254 | |
| 255 // The metrics provider code wants to put Samples in a map and compare them, | |
| 256 // which requires us to define a few operators. | |
| 257 BASE_EXPORT bool operator==(const StackSamplingProfiler::Frame& a, | |
| 258 const StackSamplingProfiler::Frame& b); | |
| 259 BASE_EXPORT bool operator<(const StackSamplingProfiler::Frame& a, | |
| 260 const StackSamplingProfiler::Frame& b); | |
| 261 | |
| 262 } // namespace base | |
| 263 | |
| 264 #endif // BASE_PROFILER_STACK_SAMPLING_PROFILER_H_ | |
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