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DC_PLUG_READ(2)			   distcache		       DC_PLUG_READ(2)

NAME
       DC_PLUG_read, DC_PLUG_consume, DC_PLUG_write, DC_PLUG_write_more,
       DC_PLUG_commit, DC_PLUG_rollback	- DC_PLUG read/write functions

SYNOPSIS
	#include <distcache/dc_plug.h>

	int DC_PLUG_read(DC_PLUG *plug,	int resume, unsigned long *request_uid,
			 DC_CMD	*cmd, const unsigned char **payload_data,
			 unsigned int *payload_len);
	int DC_PLUG_consume(DC_PLUG *plug);
	int DC_PLUG_write(DC_PLUG *plug, int resume, unsigned long request_uid,
			  DC_CMD cmd, const unsigned char *payload_data,
			  unsigned int payload_len);
	int DC_PLUG_write_more(DC_PLUG *plug, const unsigned char *data,
			       unsigned	int data_len);
	int DC_PLUG_commit(DC_PLUG *plug);
	int DC_PLUG_rollback(DC_PLUG *plug);

	typedef	enum {
		DC_CMD_ERROR,
		DC_CMD_ADD,
		DC_CMD_GET,
		DC_CMD_REMOVE,
		DC_CMD_HAVE
	} DC_CMD;

DESCRIPTION
       DC_PLUG_read() will attempt to open the next distcache message received
       by plug for reading. This message will block the	reading	of any other
       received	messages remain	until DC_PLUG_consume()	is called. If a	mes-
       sage has	already	been opened for	reading	inside plug, then
       DC_PLUG_read() will fail	unless resume is set to	non-zero in which case
       it will simply re-open the message that was already being read. If
       DC_PLUG_read() succeeds,	request_uid, cmd, payload_data and payload_len
       are populated with the message's	data. Note that	payload_data points to
       the original data stored	inside plug and	this pointer is	only valid un-
       til the next call to DC_PLUG_consume().

       DC_PLUG_consume() will close the	message	currently opened for reading
       in plug,	and will allow a future	call to	DC_PLUG_read() to succeed if
       there any subsequent (complete) messages	received from the plug ob-
       ject's connection.

       DC_PLUG_write() will attempt to open a distcache	message	for writing in
       plug. If	successful, this message will block the	writing	of any other
       messages	until the message is committed with DC_PLUG_commit() or	dis-
       carded with DC_PLUG_rollback(). If a message has	already	been opened
       for writing, DC_PLUG_write() will fail unless resume is non-zero	in
       which case the message will be re-opened	and will overwrite the set-
       tings from the previous DC_PLUG_write() call. This is equivalent	to
       DC_PLUG_rollback() followed immediately by DC_PLUG_write() with a zero
       resume value. Note that payload_len can be zero (and thus payload_data
       can be NULL) even if the	message	will eventually	have payload data -
       this can	be supplemented	afterwards using the DC_PLUG_write_more()
       function. request_uid and cmd, on the other hand, must be specified at
       once in DC_PLUG_write().

       DC_PLUG_write_more() will attempt to add	more payload data to the mes-
       sage currently opened for writing in plug. This data will be concate-
       nated to	the end	of any payload data already provided in	prior calls to
       DC_PLUG_write() or DC_PLUG_write_more().

       DC_PLUG_commit()	will close the message currently opened	for writing,
       and queue it for	serialisation out on the plug object's connection.

       DC_PLUG_rollback() will discard the message currently opened for	writ-
       ing.

RETURN VALUES
       All these DC_PLUG functions return zero on failure, otherwise non-zero.

SEE ALSO
       DC_PLUG_new(2) -	Basic DC_PLUG functions.

       distcache(8) - Overview of the distcache	architecture.

       http://www.distcache.org/ - Distcache home page.

AUTHOR
       This toolkit was	designed and implemented by Geoff Thorpe for Crypto-
       graphic Appliances Incorporated.	Since the project was released into
       open source, it has a home page and a project environment where devel-
       opment, mailing lists, and releases are organised. For problems with
       the software or this man	page please check for new releases at the
       project web-site	below, mail the	users mailing list described there, or
       contact the author at geoff@geoffthorpe.net.

       Home Page: http://www.distcache.org

1.4.5				  2004.03.23		       DC_PLUG_READ(2)

NAME | SYNOPSIS | DESCRIPTION | RETURN VALUES | SEE ALSO | AUTHOR

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