event_buffer_watermark_set

Sets the watermarks for read and write events. Libevent does not invoke read callback unless there is at least lowmark bytes in the input buffer; if the read buffer is beyond the highmark, reading is stopped. On output, the write callback is invoked whenever the buffered data falls below the lowmark.

Valid buffered event resource.

Any combination of EV_READ and EV_WRITE.

Low watermark.

High watermark.