// Copyright (c) 2013 The Chromium Authors. All rights reserved. // Use of this source code is governed by a BSD-style license that can be // found in the LICENSE file. // Trace events are for tracking application performance and resource usage. // Macros are provided to track: // Begin and end of function calls // Counters // // Events are issued against categories. Whereas LOG's // categories are statically defined, TRACE categories are created // implicitly with a string. For example: // TRACE_EVENT_INSTANT("MY_SUBSYSTEM", "SomeImportantEvent") // // Events can be INSTANT, or can be pairs of BEGIN and END in the same scope: // TRACE_EVENT_BEGIN("MY_SUBSYSTEM", "SomethingCostly") // doSomethingCostly() // TRACE_EVENT_END("MY_SUBSYSTEM", "SomethingCostly") // Note: our tools can't always determine the correct BEGIN/END pairs unless // these are used in the same scope. Use ASYNC_BEGIN/ASYNC_END macros if you need them // to be in separate scopes. // // A common use case is to trace entire function scopes. This // issues a trace BEGIN and END automatically: // void doSomethingCostly() { // TRACE_EVENT("MY_SUBSYSTEM", "doSomethingCostly"); // ... // } // // Additional parameters can be associated with an event: // void doSomethingCostly2(int howMuch) { // TRACE_EVENT("MY_SUBSYSTEM", "doSomethingCostly", "howMuch", howMuch); // ... // } // // The trace system will automatically add to this information the // current process id, thread id, and a timestamp in microseconds. // // To trace an asynchronous procedure such as an IPC send/receive, use ASYNC_BEGIN and // ASYNC_END: // [single threaded sender code] // static int send_count = 0; // ++send_count; // TRACE_EVENT_ASYNC_BEGIN("ipc", "message", send_count); // Send(new MyMessage(send_count)); // [receive code] // void OnMyMessage(send_count) { // TRACE_EVENT_ASYNC_END("ipc", "message", send_count); // } // The third parameter is a unique ID to match ASYNC_BEGIN/ASYNC_END pairs. // ASYNC_BEGIN and ASYNC_END can occur on any thread of any traced process. Pointers can // be used for the ID parameter, and they will be mangled internally so that // the same pointer on two different processes will not match. For example: // class MyTracedClass { // public: // MyTracedClass() { // TRACE_EVENT_ASYNC_BEGIN("category", "MyTracedClass", this); // } // ~MyTracedClass() { // TRACE_EVENT_ASYNC_END("category", "MyTracedClass", this); // } // } // // Trace event also supports counters, which is a way to track a quantity // as it varies over time. Counters are created with the following macro: // TRACE_COUNTER1("MY_SUBSYSTEM", "myCounter", g_myCounterValue); // // Counters are process-specific. The macro itself can be issued from any // thread, however. // // Sometimes, you want to track two counters at once. You can do this with two // counter macros: // TRACE_COUNTER1("MY_SUBSYSTEM", "myCounter0", g_myCounterValue[0]); // TRACE_COUNTER1("MY_SUBSYSTEM", "myCounter1", g_myCounterValue[1]); // Or you can do it with a combined macro: // TRACE_COUNTER2("MY_SUBSYSTEM", "myCounter", // "bytesPinned", g_myCounterValue[0], // "bytesAllocated", g_myCounterValue[1]); // This indicates to the tracing UI that these counters should be displayed // in a single graph, as a summed area chart. // // Since counters are in a global namespace, you may want to disambiguate with a // unique ID, by using the TRACE_COUNTER_ID* variations. // // By default, trace collection is compiled in, but turned off at runtime. // Collecting trace data is the responsibility of the embedding // application. In Chrome's case, navigating to about:tracing will turn on // tracing and display data collected across all active processes. // // // Memory scoping note: // Tracing copies the pointers, not the string content, of the strings passed // in for category, name, and arg_names. Thus, the following code will // cause problems: // char* str = strdup("impprtantName"); // TRACE_EVENT_INSTANT("SUBSYSTEM", str); // BAD! // free(str); // Trace system now has dangling pointer // // To avoid this issue with the |name| and |arg_name| parameters, use the // TRACE_EVENT_COPY_XXX overloads of the macros at additional runtime overhead. // Notes: The category must always be in a long-lived char* (i.e. static const). // The |arg_values|, when used, are always deep copied with the _COPY // macros. // // When are string argument values copied: // const char* arg_values are only referenced by default: // TRACE_EVENT("category", "name", // "arg1", "literal string is only referenced"); // Use TRACE_STR_COPY to force copying of a const char*: // TRACE_EVENT("category", "name", // "arg1", TRACE_STR_COPY("string will be copied")); // std::string arg_values are always copied: // TRACE_EVENT("category", "name", // "arg1", std::string("string will be copied")); // // // Thread Safety: // A thread safe singleton and mutex are used for thread safety. Category // enabled flags are used to limit the performance impact when the system // is not enabled. // // TRACE_EVENT macros first cache a pointer to a category. The categories are // statically allocated and safe at all times, even after exit. Fetching a // category is protected by the TraceLog::lock_. Multiple threads initializing // the static variable is safe, as they will be serialized by the lock and // multiple calls will return the same pointer to the category. // // Then the category_enabled flag is checked. This is a unsigned char, and // not intended to be multithread safe. It optimizes access to addTraceEvent // which is threadsafe internally via TraceLog::lock_. The enabled flag may // cause some threads to incorrectly call or skip calling addTraceEvent near // the time of the system being enabled or disabled. This is acceptable as // we tolerate some data loss while the system is being enabled/disabled and // because addTraceEvent is threadsafe internally and checks the enabled state // again under lock. // // Without the use of these static category pointers and enabled flags all // trace points would carry a significant performance cost of aquiring a lock // and resolving the category. #ifndef COMMON_TRACE_EVENT_H_ #define COMMON_TRACE_EVENT_H_ #include <string> #include "common/event_tracer.h" // By default, const char* argument values are assumed to have long-lived scope // and will not be copied. Use this macro to force a const char* to be copied. #define TRACE_STR_COPY(str) … // Records a pair of begin and end events called "name" for the current // scope, optionally with associated arguments. // Each argument must have a name and a value. // If the category is not enabled, then this does nothing. // - category and name strings must have application lifetime (statics or // literals). They may not include " chars. #define TRACE_EVENT(platform, category, name, ...) … // Deprecated, use `TRACE_EVENT` instead #define TRACE_EVENT0(platform, category, name) … #define TRACE_EVENT1(platform, category, name, arg1_name, arg1_val) … #define TRACE_EVENT2(category, name, arg1_name, arg1_val, arg2_name, arg2_val) … // Records a single event called "name" immediately, optionally with associated arguments. // Each argument must have a name and a value. // If the category is not enabled, then this does nothing. // - category and name strings must have application lifetime (statics or // literals). They may not include " chars. #define TRACE_EVENT_INSTANT(platform, category, name, ...) … #define TRACE_EVENT_COPY_INSTANT(platform, category, name, ...) … // Deprecated, use `TRACE_EVENT_INSTANT` instead #define TRACE_EVENT_INSTANT0(platform, category, name) … #define TRACE_EVENT_INSTANT1(platform, category, name, arg1_name, arg1_val) … #define TRACE_EVENT_INSTANT2(platform, category, name, arg1_name, arg1_val, arg2_name, arg2_val) … // Deprecated, use `TRACE_EVENT_COPY_INSTANT` instead #define TRACE_EVENT_COPY_INSTANT0(platform, category, name) … #define TRACE_EVENT_COPY_INSTANT1(platform, category, name, arg1_name, arg1_val) … #define TRACE_EVENT_COPY_INSTANT2(platform, category, name, arg1_name, arg1_val, arg2_name, \ arg2_val) … // Records a single BEGIN event called "name" immediately, optionally with associated arguments. // Each argument must have a name and a value. // If the category is not enabled, then this does nothing. // - category and name strings must have application lifetime (statics or // literals). They may not include " chars. #define TRACE_EVENT_BEGIN(platform, category, name, ...) … #define TRACE_EVENT_COPY_BEGIN(platform, category, name, ...) … // Deprecated, use TRACE_EVENT_BEGIN #define TRACE_EVENT_BEGIN0(platform, category, name) … #define TRACE_EVENT_BEGIN1(platform, category, name, arg1_name, arg1_val) … #define TRACE_EVENT_BEGIN2(platform, category, name, arg1_name, arg1_val, arg2_name, arg2_val) … // Deprecated, use TRACE_EVENT_COPY_BEGIN #define TRACE_EVENT_COPY_BEGIN0(platform, category, name) … #define TRACE_EVENT_COPY_BEGIN1(platform, category, name, arg1_name, arg1_val) … #define TRACE_EVENT_COPY_BEGIN2(platform, category, name, arg1_name, arg1_val, arg2_name, \ arg2_val) … // Records a single END event for "name" immediately. If the category // is not enabled, then this does nothing. // - category and name strings must have application lifetime (statics or // literals). They may not include " chars. #define TRACE_EVENT_END(platform, category, name, ...) … #define TRACE_EVENT_COPY_END(platform, category, name, ...) … // Deprecated, use TRACE_EVENT_END #define TRACE_EVENT_END0(platform, category, name) … #define TRACE_EVENT_END1(platform, category, name, arg1_name, arg1_val) … #define TRACE_EVENT_END2(platform, category, name, arg1_name, arg1_val, arg2_name, arg2_val) … // Deprecated, use TRACE_EVENT_COPY_END #define TRACE_EVENT_COPY_END0(platform, category, name) … #define TRACE_EVENT_COPY_END1(platform, category, name, arg1_name, arg1_val) … #define TRACE_EVENT_COPY_END2(platform, category, name, arg1_name, arg1_val, arg2_name, arg2_val) … // Records the value of a counter called "name" immediately. Value // must be representable as a 32 bit integer. // - category and name strings must have application lifetime (statics or // literals). They may not include " chars. #define TRACE_COUNTER1(platform, category, name, value) … #define TRACE_COPY_COUNTER1(platform, category, name, value) … // Records the values of a multi-parted counter called "name" immediately. // The UI will treat value1 and value2 as parts of a whole, displaying their // values as a stacked-bar chart. // - category and name strings must have application lifetime (statics or // literals). They may not include " chars. #define TRACE_COUNTER2(platform, category, name, value1_name, value1_val, value2_name, value2_val) … #define TRACE_COPY_COUNTER2(platform, category, name, value1_name, value1_val, value2_name, \ value2_val) … // Records the value of a counter called "name" immediately. Value // must be representable as a 32 bit integer. // - category and name strings must have application lifetime (statics or // literals). They may not include " chars. // - |id| is used to disambiguate counters with the same name. It must either // be a pointer or an integer value up to 64 bits. If it's a pointer, the bits // will be xored with a hash of the process ID so that the same pointer on // two different processes will not collide. #define TRACE_COUNTER_ID1(platform, category, name, id, value) … #define TRACE_COPY_COUNTER_ID1(platform, category, name, id, value) … // Records the values of a multi-parted counter called "name" immediately. // The UI will treat value1 and value2 as parts of a whole, displaying their // values as a stacked-bar chart. // - category and name strings must have application lifetime (statics or // literals). They may not include " chars. // - |id| is used to disambiguate counters with the same name. It must either // be a pointer or an integer value up to 64 bits. If it's a pointer, the bits // will be xored with a hash of the process ID so that the same pointer on // two different processes will not collide. #define TRACE_COUNTER_ID2(platform, category, name, id, value1_name, value1_val, value2_name, \ value2_val) … #define TRACE_COPY_COUNTER_ID2(platform, category, name, id, value1_name, value1_val, value2_name, \ value2_val) … // Records a single ASYNC_BEGIN event called "name" immediately, with 0, 1 or 2 // associated arguments. If the category is not enabled, then this // does nothing. // - category and name strings must have application lifetime (statics or // literals). They may not include " chars. // - |id| is used to match the ASYNC_BEGIN event with the ASYNC_END event. ASYNC // events are considered to match if their category, name and id values all // match. |id| must either be a pointer or an integer value up to 64 bits. If // it's a pointer, the bits will be xored with a hash of the process ID so // that the same pointer on two different processes will not collide. // An asynchronous operation can consist of multiple phases. The first phase is // defined by the ASYNC_BEGIN calls. Additional phases can be defined using the // ASYNC_STEP_BEGIN macros. When the operation completes, call ASYNC_END. // An async operation can span threads and processes, but all events in that // operation must use the same |name| and |id|. Each event can have its own // args. #define TRACE_EVENT_ASYNC_BEGIN0(platform, category, name, id) … #define TRACE_EVENT_ASYNC_BEGIN1(platform, category, name, id, arg1_name, arg1_val) … #define TRACE_EVENT_ASYNC_BEGIN2(platform, category, name, id, arg1_name, arg1_val, arg2_name, \ arg2_val) … #define TRACE_EVENT_COPY_ASYNC_BEGIN0(platform, category, name, id) … #define TRACE_EVENT_COPY_ASYNC_BEGIN1(platform, category, name, id, arg1_name, arg1_val) … #define TRACE_EVENT_COPY_ASYNC_BEGIN2(platform, category, name, id, arg1_name, arg1_val, \ arg2_name, arg2_val) … // Records a single ASYNC_STEP event for |step| immediately. If the category // is not enabled, then this does nothing. The |name| and |id| must match the // ASYNC_BEGIN event above. The |step| param identifies this step within the // async event. This should be called at the beginning of the next phase of an // asynchronous operation. #define TRACE_EVENT_ASYNC_STEP0(platform, category, name, id, step) … #define TRACE_EVENT_ASYNC_STEP1(platform, category, name, id, step, arg1_name, arg1_val) … #define TRACE_EVENT_COPY_ASYNC_STEP0(platform, category, name, id, step) … #define TRACE_EVENT_COPY_ASYNC_STEP1(platform, category, name, id, step, arg1_name, arg1_val) … // Records a single ASYNC_END event for "name" immediately. If the category // is not enabled, then this does nothing. #define TRACE_EVENT_ASYNC_END0(platform, category, name, id) … #define TRACE_EVENT_ASYNC_END1(platform, category, name, id, arg1_name, arg1_val) … #define TRACE_EVENT_ASYNC_END2(platform, category, name, id, arg1_name, arg1_val, arg2_name, \ arg2_val) … #define TRACE_EVENT_COPY_ASYNC_END0(platform, category, name, id) … #define TRACE_EVENT_COPY_ASYNC_END1(platform, category, name, id, arg1_name, arg1_val) … #define TRACE_EVENT_COPY_ASYNC_END2(platform, category, name, id, arg1_name, arg1_val, arg2_name, \ arg2_val) … // Creates a scope of a sampling state with the given category and name (both must // be constant strings). These states are intended for a sampling profiler. // Implementation note: we store category and name together because we don't // want the inconsistency/expense of storing two pointers. // |thread_bucket| is [0..2] and is used to statically isolate samples in one // thread from others. // // { // The sampling state is set within this scope. // TRACE_EVENT_SAMPLING_STATE_SCOPE_FOR_BUCKET(0, "category", "name"); // ...; // } #define TRACE_EVENT_SCOPED_SAMPLING_STATE_FOR_BUCKET(bucket_number, category, name) … // Returns a current sampling state of the given bucket. // The format of the returned string is "category\0name". #define TRACE_EVENT_GET_SAMPLING_STATE_FOR_BUCKET(bucket_number) … // Sets a current sampling state of the given bucket. // |category| and |name| have to be constant strings. #define TRACE_EVENT_SET_SAMPLING_STATE_FOR_BUCKET(bucket_number, category, name) … // Sets a current sampling state of the given bucket. // |categoryAndName| doesn't need to be a constant string. // The format of the string is "category\0name". #define TRACE_EVENT_SET_NONCONST_SAMPLING_STATE_FOR_BUCKET(bucket_number, categoryAndName) … // Syntactic sugars for the sampling tracing in the main thread. #define TRACE_EVENT_SCOPED_SAMPLING_STATE(category, name) … #define TRACE_EVENT_GET_SAMPLING_STATE() … #define TRACE_EVENT_SET_SAMPLING_STATE(category, name) … #define TRACE_EVENT_SET_NONCONST_SAMPLING_STATE(categoryAndName) … //////////////////////////////////////////////////////////////////////////////// // Implementation specific tracing API definitions. // Get a pointer to the enabled state of the given trace category. Only // long-lived literal strings should be given as the category name. The returned // pointer can be held permanently in a local static for example. If the // unsigned char is non-zero, tracing is enabled. If tracing is enabled, // TRACE_EVENT_API_ADD_TRACE_EVENT can be called. It's OK if tracing is disabled // between the load of the tracing state and the call to // TRACE_EVENT_API_ADD_TRACE_EVENT, because this flag only provides an early out // for best performance when tracing is disabled. // const unsigned char* // TRACE_EVENT_API_GET_CATEGORY_ENABLED(const char* category_name) #define TRACE_EVENT_API_GET_CATEGORY_ENABLED … // Add a trace event to the platform tracing system. // void TRACE_EVENT_API_ADD_TRACE_EVENT( // char phase, // const unsigned char* category_enabled, // const char* name, // unsigned long long id, // int num_args, // const char** arg_names, // const unsigned char* arg_types, // const unsigned long long* arg_values, // unsigned char flags) #define TRACE_EVENT_API_ADD_TRACE_EVENT … //////////////////////////////////////////////////////////////////////////////// // Implementation detail: trace event macros create temporary variables // to keep instrumentation overhead low. These macros give each temporary // variable a unique name based on the line number to prevent name collissions. #define INTERNAL_TRACE_EVENT_UID3(a, b) … #define INTERNAL_TRACE_EVENT_UID2(a, b) … #define INTERNALTRACEEVENTUID(name_prefix) … // Implementation detail: internal macro to create static category. #define INTERNAL_TRACE_EVENT_GET_CATEGORY_INFO(platform, category) … // Implementation detail: internal macro to create static category and add // event if the category is enabled. #define INTERNAL_TRACE_EVENT_ADD(platform, phase, category, name, flags, ...) … // Implementation detail: internal macro to create static category and add begin // event if the category is enabled. Also adds the end event when the scope // ends. #define INTERNAL_TRACE_EVENT_ADD_SCOPED(platform, category, name, ...) … // Implementation detail: internal macro to create static category and add // event if the category is enabled. #define INTERNAL_TRACE_EVENT_ADD_WITH_ID(platform, phase, category, name, id, flags, ...) … // Notes regarding the following definitions: // New values can be added and propagated to third party libraries, but existing // definitions must never be changed, because third party libraries may use old // definitions. // Phase indicates the nature of an event entry. E.g. part of a begin/end pair. #define TRACE_EVENT_PHASE_BEGIN … #define TRACE_EVENT_PHASE_END … #define TRACE_EVENT_PHASE_INSTANT … #define TRACE_EVENT_PHASE_ASYNC_BEGIN … #define TRACE_EVENT_PHASE_ASYNC_STEP … #define TRACE_EVENT_PHASE_ASYNC_END … #define TRACE_EVENT_PHASE_METADATA … #define TRACE_EVENT_PHASE_COUNTER … #define TRACE_EVENT_PHASE_SAMPLE … // Flags for changing the behavior of TRACE_EVENT_API_ADD_TRACE_EVENT. #define TRACE_EVENT_FLAG_NONE … #define TRACE_EVENT_FLAG_COPY … #define TRACE_EVENT_FLAG_HAS_ID … #define TRACE_EVENT_FLAG_MANGLE_ID … // Type values for identifying types in the TraceValue union. #define TRACE_VALUE_TYPE_BOOL … #define TRACE_VALUE_TYPE_UINT … #define TRACE_VALUE_TYPE_INT … #define TRACE_VALUE_TYPE_DOUBLE … #define TRACE_VALUE_TYPE_POINTER … #define TRACE_VALUE_TYPE_STRING … #define TRACE_VALUE_TYPE_COPY_STRING … namespace gl { TraceEvent // namespace TraceEvent } // namespace gl #endif
Codebase Browser
chromium