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:

Decide that we want to write some data to a connection; put that data in a buffer.
Wait for the connection to become writable
Write as much of the data as we can
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.

Обзор классов

final EventBufferEvent {

/* Constants */

const integer READING = 1 ;

const integer WRITING = 2 ;

const integer EOF = 16 ;

const integer ERROR = 32 ;

const integer TIMEOUT = 64 ;

const integer CONNECTED = 128 ;

const integer OPT_CLOSE_ON_FREE = 1 ;

const integer OPT_THREADSAFE = 2 ;

const integer OPT_DEFER_CALLBACKS = 4 ;

const integer OPT_UNLOCK_CALLBACKS = 8 ;

const integer SSL_OPEN = 0 ;

const integer SSL_CONNECTING = 1 ;

const integer SSL_ACCEPTING = 2 ;

/* Свойства */

public integer $fd ;

public integer $priority ;

public readonly EventBuffer $input ;

public readonly EventBuffer $output ;

/* Методы */

public void close ( void )

public bool connect ( string $addr )

public bool connectHost ( EventDnsBase $dns_base , string $hostname , int $port [, int $family = EventUtil::AF_UNSPEC ] )

public __construct ( EventBase $base [, mixed $socket = NULL [, int $options = 0 [, callable $readcb = NULL [, callable $writecb = NULL [, callable $eventcb = NULL ]]]]] )

public static array createPair ( EventBase $base [, int $options = 0 ] )

public bool disable ( int $events )

public bool enable ( int $events )

public void free ( void )

public string getDnsErrorString ( void )

public int getEnabled ( void )

public EventBuffer getInput ( void )

public EventBuffer getOutput ( void )

public string read ( int $size )

public bool readBuffer ( EventBuffer $buf )

public void setCallbacks ( callable $readcb , callable $writecb , callable $eventcb [, string $arg ] )

public bool setPriority ( int $priority )

public bool setTimeouts ( float $timeout_read , float $timeout_write )

public void setWatermark ( int $events , int $lowmark , int $highmark )

public string sslError ( void )

public static EventBufferEvent sslFilter ( EventBase $base , EventBufferEvent $underlying , EventSslContext $ctx , int $state [, int $options = 0 ] )

public string sslGetCipherInfo ( void )

public string sslGetCipherName ( void )

public string sslGetCipherVersion ( void )

public string sslGetProtocol ( void )

public void sslRenegotiate ( void )

public static EventBufferEvent sslSocket ( EventBase $base , mixed $socket , EventSslContext $ctx , int $state [, int $options ] )

public bool write ( string $data )

public bool writeBuffer ( EventBuffer $buf )

}

Свойства

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 )

Предопределенные константы

EventBufferEvent::READING: An event occured during a read operation on the bufferevent. See the other flags for which event it was.
EventBufferEvent::WRITING: An event occured 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

Содержание

EventBufferEvent::close — Closes file descriptor associated with the current buffer event
EventBufferEvent::connect — Connect buffer event's file descriptor to given address or UNIX socket
EventBufferEvent::connectHost — Connects to a hostname with optionally asyncronous DNS resolving
EventBufferEvent::__construct — Constructs EventBufferEvent object
EventBufferEvent::createPair — Creates two buffer events connected to each other
EventBufferEvent::disable — Disable events read, write, or both on a buffer event.
EventBufferEvent::enable — Enable events read, write, or both on a buffer event.
EventBufferEvent::free — Free a buffer event
EventBufferEvent::getDnsErrorString — Returns string describing the last failed DNS lookup attempt
EventBufferEvent::getEnabled — Returns bitmask of events currently enabled on the buffer event
EventBufferEvent::getInput — Returns underlying input buffer associated with current buffer event
EventBufferEvent::getOutput — Returns underlying output buffer associated with current buffer event
EventBufferEvent::read — Read buffer's data
EventBufferEvent::readBuffer — Drains the entire contents of the input buffer and places them into buf
EventBufferEvent::setCallbacks — Assigns read, write and event(status) callbacks
EventBufferEvent::setPriority — Assign a priority to a bufferevent
EventBufferEvent::setTimeouts — Set the read and write timeout for a buffer event
EventBufferEvent::setWatermark — Adjusts read and/or write watermarks
EventBufferEvent::sslError — Returns most recent OpenSSL error reported on the buffer event
EventBufferEvent::sslFilter — Create a new SSL buffer event to send its data over another buffer event
EventBufferEvent::sslGetCipherInfo — Returns a textual description of the cipher.
EventBufferEvent::sslGetCipherName — Returns the current cipher name of the SSL connection.
EventBufferEvent::sslGetCipherVersion — Returns version of cipher used by current SSL connection.
EventBufferEvent::sslGetProtocol — Returns the name of the protocol used for current SSL connection.
EventBufferEvent::sslRenegotiate — Tells a bufferevent to begin SSL renegotiation.
EventBufferEvent::sslSocket — Creates a new SSL buffer event to send its data over an SSL on a socket
EventBufferEvent::write — Adds data to a buffer event's output buffer
EventBufferEvent::writeBuffer — Adds contents of the entire buffer to a buffer event's output buffer

Вернуться к: Event