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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 1.5.1 2004.10.19 DC_PLUG_READ(2)
NAME | SYNOPSIS | DESCRIPTION | RETURN VALUES | SEE ALSO | AUTHOR
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