The nng_aio_begin() function is called by the I/O provider to indicate that
it is going to process the operation.
The function may return false, indicating that the aio has been closed
by the caller asynchronously.
In this case the provider should abandon the operation and do nothing else.
This operation should be called at the start of any I/O operation, and must be called not more than once for a given I/O operation on a given aio.
Once this function is called, if true is returned, then the provider MUST
guarantee that nng_aio_finish() is called for the aio
exactly once, when the operation is complete or canceled.
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Note
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This function is only for I/O providers (those actually performing the operation such as HTTP handler functions or transport providers); ordinary users of the aio should not call this function. |