The EventBufferEvent class

Intro

Represents Libevent's buffer event.

Usually an application wants to perform some amount of data buffering in addition to just responding to events. When we want to write data, for example, the usual pattern looks like:

1. Decide that we want to write some data to a connection; put that data in a buffer.
2. Wait for the connection to become writable
3. Write as much of the data as we can
4. Remember how much we wrote, and if we still have more data to write, wait for the connection to become writable again.

This buffered I/O pattern is common enough that Libevent provides a generic mechanism for it. A "buffer event" consists of an underlying transport (like a socket), a read buffer, and a write buffer. Instead of regular events, which give callbacks when the underlying transport is ready to be read or written, a buffer event invokes its user-supplied callbacks when it has read or written enough data.

Class synopsis

Properties

fd

Numeric file descriptor associated with the buffer event. Normally represents a bound socket. Equals to null, if there is no file descriptor(socket) associated with the buffer event.

priority

The priority of the events used to implement the buffer event.

input

Underlying input buffer object( EventBuffer)

output

Underlying output buffer object( EventBuffer)

Predefined Constants

EventBufferEvent::READING

An event occurred during a read operation on the bufferevent. See the other flags for which event it was.

EventBufferEvent::WRITING

An event occurred during a write operation on the bufferevent. See the other flags for which event it was.

EventBufferEvent::EOF

Got an end-of-file indication on the buffer event.

EventBufferEvent::ERROR

An error occurred during a bufferevent operation. For more information on what the error was, call EventUtil::getLastSocketErrno and/or EventUtil::getLastSocketError.

EventBufferEvent::TIMEOUT

EventBufferEvent::CONNECTED

Finished a requested connection on the bufferevent.

EventBufferEvent::OPT_CLOSE_ON_FREE

When the buffer event is freed, close the underlying transport. This will close an underlying socket, free an underlying buffer event, etc.

EventBufferEvent::OPT_THREADSAFE

Automatically allocate locks for the bufferevent, so that it’s safe to use from multiple threads.

EventBufferEvent::OPT_DEFER_CALLBACKS

When this flag is set, the bufferevent defers all of its callbacks. See Fast portable non-blocking network programming with Libevent, Deferred callbacks.

EventBufferEvent::OPT_UNLOCK_CALLBACKS

By default, when the bufferevent is set up to be threadsafe, the buffer event’s locks are held whenever the any user-provided callback is invoked. Setting this option makes Libevent release the buffer event’s lock when it’s invoking the callbacks.

EventBufferEvent::SSL_OPEN

The SSL handshake is done

EventBufferEvent::SSL_CONNECTING

SSL is currently performing negotiation as a client

EventBufferEvent::SSL_ACCEPTING

SSL is currently performing negotiation as a server

Eventbufferevent