1# trace.h 2 3 4## Overview 5 6Defines APIs of the HiTraceMeter module for performance trace. 7 8Example 9 10Synchronous time slice trace event: 11 12 13``` 14OH_HiTrace_StartTrace("hitraceTest"); 15OH_HiTrace_FinishTrace(); 16``` 17 18Output: 19 20 21``` 22<...>-1668 (----—) [003] .... 135.059377: tracing_mark_write: B|1668|H:hitraceTest 23<...>-1668 (----—) [003] .... 135.059415: tracing_mark_write: E|1668| 24``` 25 26Asynchronous time slice trace event: 27 28 29``` 30OH_HiTrace_StartAsyncTrace("hitraceTest", 123); 31OH_HiTrace_FinishAsyncTrace("hitraceTest", 123); 32``` 33 34Output: 35 36 37``` 38<...>-2477 (----—) [001] .... 396.427165: tracing_mark_write: S|2477|H:hitraceTest 123 39<...>-2477 (----—) [001] .... 396.427196: tracing_mark_write: F|2477|H:hitraceTest 123 40``` 41 42Integer value trace event: 43 44 45``` 46OH_HiTrace_CountTrace("hitraceTest", 500); 47``` 48 49Output: 50 51 52``` 53<...>-2638 (----—) [002] .... 458.904382: tracing_mark_write: C|2638|H:hitraceTest 500 54``` 55 56**Since** 57 5810 59 60**Related Modules** 61 62[Hitrace](_hitrace.md) 63 64 65## Summary 66 67 68### Functions 69 70| Name| Description| 71| -------- | -------- | 72| [OH_HiTrace_StartTrace](_hitrace.md#oh_hitrace_starttrace) (const char \*name) | Marks the start of a synchronous trace.| 73| [OH_HiTrace_FinishTrace](_hitrace.md#oh_hitrace_finishtrace) (void) | Marks the end of a synchronous trace.| 74| [OH_HiTrace_StartAsyncTrace](_hitrace.md#oh_hitrace_startasynctrace) (const char \*name, int32_t taskId) | Marks the start of an asynchronous trace.| 75| [OH_HiTrace_FinishAsyncTrace](_hitrace.md#oh_hitrace_finishasynctrace) (const char \*name, int32_t taskId) | Marks the end of an asynchronous trace.| 76| [OH_HiTrace_CountTrace](_hitrace.md#oh_hitrace_counttrace) (const char \*name, int64_t count) | Traces the value change of an integer variable based on its name.| 77