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1
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2 .. _timer:
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3
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4 :c:type:`uv_timer_t` --- Timer handle
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5 =====================================
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6
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7 Timer handles are used to schedule callbacks to be called in the future.
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8
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9 Timers are either single-shot or repeating. Repeating timers do not adjust
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10 for overhead but are rearmed relative to the event loop's idea of "now".
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11
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12 Libuv updates its idea of "now" right before executing timer callbacks, and
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13 right after waking up from waiting for I/O. See also :c:func:`uv_update_time`.
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14
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15 Example: a repeating timer with a 50 ms interval whose callback takes 17 ms
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16 to complete, runs again 33 ms later. If other tasks take longer than 33 ms,
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17 the timer callback runs as soon as possible.
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18
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19 Data types
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20 ----------
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21
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22 .. c:type:: uv_timer_t
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23
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24 Timer handle type.
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25
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26 .. c:type:: void (*uv_timer_cb)(uv_timer_t* handle)
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27
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28 Type definition for callback passed to :c:func:`uv_timer_start`.
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29
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30
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31 Public members
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32 ^^^^^^^^^^^^^^
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33
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34 N/A
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35
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36 .. seealso:: The :c:type:`uv_handle_t` members also apply.
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37
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38
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39 API
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40 ---
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41
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42 .. c:function:: int uv_timer_init(uv_loop_t* loop, uv_timer_t* handle)
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43
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44 Initialize the handle.
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45
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46 .. c:function:: int uv_timer_start(uv_timer_t* handle, uv_timer_cb cb, uint64_t timeout, uint64_t repeat)
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47
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48 Start the timer. `timeout` and `repeat` are in milliseconds.
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49
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50 If `timeout` is zero, the callback fires on the next event loop iteration.
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51 If `repeat` is non-zero, the callback fires first after `timeout`
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52 milliseconds and then repeatedly after `repeat` milliseconds.
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53
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54 .. note::
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55 Does not update the event loop's concept of "now". See :c:func:`uv_update_time` for more information.
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56
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57 If the timer is already active, it is simply updated.
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58
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59 .. c:function:: int uv_timer_stop(uv_timer_t* handle)
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60
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61 Stop the timer, the callback will not be called anymore.
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62
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63 .. c:function:: int uv_timer_again(uv_timer_t* handle)
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64
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65 Stop the timer, and if it is repeating restart it using the repeat value
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66 as the timeout. If the timer has never been started before it returns
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67 UV_EINVAL.
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68
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69 .. c:function:: void uv_timer_set_repeat(uv_timer_t* handle, uint64_t repeat)
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70
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71 Set the repeat interval value in milliseconds. The timer will be scheduled
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72 to run on the given interval, regardless of the callback execution
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73 duration, and will follow normal timer semantics in the case of a
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74 time-slice overrun.
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75
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76 .. note::
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77 If the repeat value is set from a timer callback it does not immediately take effect.
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78 If the timer was non-repeating before, it will have been stopped. If it was repeating,
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79 then the old repeat value will have been used to schedule the next timeout.
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80
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81 .. c:function:: uint64_t uv_timer_get_repeat(const uv_timer_t* handle)
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82
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83 Get the timer repeat value.
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84
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85 .. c:function:: uint64_t uv_timer_get_due_in(const uv_timer_t* handle)
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86
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87 Get the timer due value or 0 if it has expired. The time is relative to
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88 :c:func:`uv_now()`.
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89
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90 .. versionadded:: 1.40.0
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91
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92 .. seealso:: The :c:type:`uv_handle_t` API functions also apply.
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