# OnQueueEvent

CFS generates events when the outgoing queue (for indexing) becomes full, becomes empty, or the queue size passes certain thresholds. This parameter specifies the name of the handler to use to handle the events.

- A `QueueFull` event occurs when the indexing queue becomes full.
- A `QueueFilling` event occurs when the queue size exceeds the value of QueueFillingThreshold and the last event was a `QueueEmpty` or `QueueEmptying` event.
- A `QueueEmptying` event occurs when the queue size falls below the value of QueueEmptyingThreshold and the last event was a `QueueFull` or `QueueFilling` event.
- A `QueueEmpty` event occurs when the indexing queue becomes empty.

The name that you specify must represent a section in the configuration file that contains the LibraryName parameter and any other settings for the event handler. For example:

    [Indexing]
    ...
    OnQueueEvent=MyHandler
    QueueFillingThreshold=0.7
    QueueEmptyingThreshold=0.4

    [MyHandler]
    LibraryName=LuaHandler
    LuaScript=./handle_queue_event.lua

In the example above, the Lua script might respond to the events by sending a notification to an administrator.

An event contains the following information:

`queueEventType` | The type of event, for example `QueueFull` or `QueueFilling`.
`maxQueueSize` | The maximum size of the queue.
`queueSize` | The current size of the queue (not present for `QueueEmpty` events).

Type: | String
Default: |
Required: | No
Configuration Section: | Indexing
Example: | `OnQueueEvent=MyEventHandler`
See Also: | QueueEmptyingThreshold QueueFillingThreshold

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