11 lines
1.0 KiB
Groff
11 lines
1.0 KiB
Groff
.TH "callbacks" 3 "Sat Aug 16 2025 14:15:23" "Paho Asynchronous MQTT C Client Library" \" -*- nroff -*-
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.ad l
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.nh
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.SH NAME
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callbacks \- Callbacks
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.PP
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Any function from this API may be used within a callback\&. It is not advisable to use \fBMQTTAsync_waitForCompletion\fP within a callback, however, as it is the only API call that may take some time to complete, which may cause unpredictable behaviour\&. All the other API calls are intended to complete quickly, starting a request in the background, with success or failure notified by other callbacks\&.
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.PP
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If no callbacks are assigned, this will include the message arrived callback\&. This could be done if the application is a pure publisher, and does not subscribe to any topics\&. If however messages are received, and no message arrived callback is set, then those messages will accumulate and take up memory, as there is no place for them to be delivered\&. A log message will be written to highlight the issue, but it is up to the application to protect against this situation\&.
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