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esp_event: Clarify event handler un-registering

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Related to https://github.com/espressif/esp-idf/issues/10848
This commit is contained in:
Jakob Hasse 2023-03-21 18:45:34 +08:00
parent 0026f73dcb
commit 13a8ba8967
1 changed files with 22 additions and 0 deletions
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docs/en/api-reference/system/esp_event.rst
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@ -192,6 +192,28 @@ If the hypothetical event ``MY_EVENT_BASE``, ``MY_OTHER_EVENT_ID`` is posted, on
If the hypothetical event ``MY_OTHER_EVENT_BASE``, ``MY_OTHER_EVENT_ID`` is posted, only ``run_on_event_3`` would execute.
Handler Un-registering Itself
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
In general, an event handler run by an event loop is *not allowed to do any (un)registering activity on that event loop*. There is one exception, though: un-registering itself is allowed for the handler. E.g., it is possible to do the following:
.. code-block:: c
void run_on_event(void* handler_arg, esp_event_base_t base, int32_t id, void* event_data)
{
esp_event_loop_handle_t *loop_handle = (esp_event_loop_handle_t*) handler_arg;
esp_event_handler_unregister_with(*loop_handle, MY_EVENT_BASE, MY_EVENT_ID, run_on_event);
}
void app_main(void)
{
esp_event_loop_handle_t loop_handle;
esp_event_loop_create(&loop_args, &loop_handle);
esp_event_handler_register_with(loop_handle, MY_EVENT_BASE, MY_EVENT_ID, run_on_event, &loop_handle);
// ... post event MY_EVENT_BASE, MY_EVENT_ID and run loop at some point
}
Handler Registration and Handler Dispatch Order
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^