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Re: [paho-dev] Blocking "wait" in the C async library

A deliberate choice.  Why have one blocking call in an asynchronous API which is designed for GUI use, amongst others?  This is an event-oriented API - use the deliveryComplete callback.  To receive messages with MQTTAsync, you have to use callbacks.  You have to use callbacks to determine the success of API calls. 

For a blocking, simpler to use API, with less use of callbacks, there is MQTTClient.


On 19/05/13 19:06, Frank Pagliughi wrote:
Well, while I'm throwing sand in the works, I might as well continue...

One thing that appears to be "missing" from the C async API is the ability to block a thread on a token while waiting for an action to complete. Something like:
int MQTTAsync_waitForCompletion(MQTTAsync handle, MQTTAsync_token token, int timeout);
This would prevent the app from wasting CPU cycles while spinning on a flag from a callback, and can simplify client apps that don't need the full power of a callback function by eliminating the need for them for basic synchronization. Plus it would allow the user to write more portable client apps, since the library would hide the OS-specific thread functionality.

It appears that the library already wraps condition variables in Linux. Maybe Windows could use a Manual Reset Event to do this?


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