37 lines
2.3 KiB
Markdown
37 lines
2.3 KiB
Markdown
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# Timer
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## Overview
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### Introduction
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This is a timer manager. After "Timer" started, users can register several timed events, which can be continuous or once, to it.
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`#include <timer.h>`
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## Related Interfaces
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### OHOS::Utils::Timer
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#### Public Functions
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| Return Type | Name |
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| -------------- | -------------- |
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| | **Timer**(const std::string& name, int timeoutMs = 1000)<br>Construct Timer. If performance-sensitive, change "timeoutMs" larger before Setup. "timeoutMs" default-value(1000ms), performance-estimate: occupy fixed-100us in every default-value(1000ms). |
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| virtual | **~Timer**() |
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| uint32_t | **Register**(const TimerCallback& callback, uint32_t interval, bool once = false)<br>Regist timed events. |
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| virtual uint32_t | **Setup**()<br>Set up "Timer". Do not set up repeatly before shutdown. |
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| virtual void | **Shutdown**(bool useJoin = true)<br>Shut down "Timer". There are two modes to shut the "Timer" down: blocking and unblocking. Blocking mode will shut "Timer" down until all running events in "Timer" finished. If "timeoutMs" is set as -1, use unblocking mode to avoid deadloop. |
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| void | **Unregister**(uint32_t timerId)<br>Delete a timed events. |
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## Examples
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1. Examples can be seen in base/test/unittest/common/utils_timer_test.cpp
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2. Running unit test：
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- Start developer test framework：[Developer Test - Using Test Framework](https://gitee.com/openharmony/testfwk_developer_test#using-test-framework)
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- Run this command in the test framework to run the tests of `timer.h`
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```bash
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run -t UT -tp utils -ts UtilsTimerTest
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```
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## FAQ
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1. Timer should be set up(via Setup()) before use, and shutdown(via Shutdown()) before its deconstruction.
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1. Timer should be set up first and then shutdown. Avoid delegating them to different threads since it may cause multithreading problem.
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1. Set up Timer again would not reset this Timer, but return `TIMER_ERR_INVALID_VALUE`. If a reset operation is required, shut Timer down first and then set it up.
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1. Parameter in Shutdown() determines whether the thread in Timer would be detach or join. (True(default) --> join; False --> detach). Detach operation would cause possible multithreading problems, thus is not recommended. If a detach operation is required, availability of related objects used in `thread_` should be guaranteed.
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