twisted.internet.process.ProcessWriter : API documentation

(Internal) Helper class to write into a Process's input pipe.

I am a helper which describes a selectable asynchronous writer to a process's input pipe, including stdin.

Instance Variables enableReadHack A flag which determines how readability on this write descriptor will be handled. If True, then readability may indicate the reader for this write descriptor has been closed (ie, the connection has been lost). If False, then readability events are ignored.

Method	__init__	Initialize, specifying a Process instance to connect to.
Method	fileno	Return the fileno() of my process's stdin.
Method	writeSomeData	Write some data to the open process.
Method	write	Reliably write some data.
Method	doRead	The only way a write pipe can become "readable" is at EOF, because the child has closed it, and we're using a reactor which doesn't distinguish between readable and closed (such as the select reactor).
Method	connectionLost	See abstract.FileDescriptor.connectionLost.

Inherited from FileDescriptor:

Method	logPrefix	Returns the default log prefix
Method	doWrite	Called when data can be written.
Method	writeConnectionLost	Indicates write connection was lost.
Method	readConnectionLost	Indicates read connection was lost.
Method	writeSequence	Reliably write a sequence of data.
Method	loseConnection	Close the connection at the next available opportunity.
Method	loseWriteConnection	Undocumented
Method	stopReading	Stop waiting for read availability.
Method	stopWriting	Stop waiting for write availability.
Method	startReading	Start waiting for read availability.
Method	startWriting	Start waiting for write availability.
Method	stopConsuming	Stop consuming data.
Method	resumeProducing	Undocumented
Method	pauseProducing	Undocumented
Method	stopProducing	Stop producing data.
Method	_postLoseConnection	Called after a loseConnection(), when all data has been written.
Method	_closeWriteConnection	Undocumented

Inherited from _ConsumerMixin (via FileDescriptor):

Method	registerProducer	Register to receive data from a producer.
Method	unregisterProducer	Stop consuming data from a producer, without disconnecting.

def write(self, data): (source)

from twisted.internet.interfaces.IConsumer

overrides twisted.internet.abstract.FileDescriptor.write

Reliably write some data.

The data is buffered until the underlying file descriptor is ready for writing. If there is more than self.bufferSize data in the buffer and this descriptor has a registered streaming producer, its pauseProducing() method will be called.

def doRead(self): (source)

overrides twisted.internet.abstract.FileDescriptor.doRead

The only way a write pipe can become "readable" is at EOF, because the child has closed it, and we're using a reactor which doesn't distinguish between readable and closed (such as the select reactor).

Except that's not true on linux < 2.6.11. It has the following characteristics: write pipe is completely empty => POLLOUT (writable in select), write pipe is not completely empty => POLLIN (readable in select), write pipe's reader closed => POLLIN|POLLERR (readable and writable in select)

That's what this funky code is for. If linux was not broken, this function could be simply "return CONNECTION_LOST".

BUG: We call select no matter what the reactor. If the reactor is pollreactor, and the fd is > 1024, this will fail. (only occurs on broken versions of linux, though).

t.i.p.ProcessWriter(abstract.FileDescriptor) : class documentation