src/ach.c File Reference

#include <time.h>
#include <stdlib.h>
#include <errno.h>
#include <sys/mman.h>
#include <fcntl.h>
#include <assert.h>
#include <string.h>
#include <stdio.h>
#include <pthread.h>
#include <unistd.h>
#include <ctype.h>
#include <stdbool.h>
#include <sys/stat.h>
#include <inttypes.h>
#include "ach.h"

Defines
#define	DEBUGF(fmt, a...)   fprintf(stderr, (fmt), ## a )
	macro to print debug messages
#define	DEBUG_PERROR(a)   perror(a)
	Call perror() when debugging.
#define	IFDEBUG(x)   (x)
	macro to do things when debugging
Functions
const char *	ach_result_to_string (ach_status_t result)
	Converts return code from ach call to a human readable string;.
void	ach_create_attr_init (ach_create_attr_t *attr)
	Initialize attributes for creating channels.
enum ach_status	ach_create (const char *channel_name, size_t frame_cnt, size_t frame_size, ach_create_attr_t *attr)
	Creates a new channel.
enum ach_status	ach_open (ach_channel_t *chan, const char *channel_name, ach_attr_t *attr)
	Opens a handle to channel.
enum ach_status	ach_get (ach_channel_t *chan, void *buf, size_t size, size_t *frame_size, const struct timespec *ACH_RESTRICT abstime, int options)
	Pulls a message from the channel.
enum ach_status	ach_flush (ach_channel_t *chan)
	Discards all previously received messages for this handle.
enum ach_status	ach_put (ach_channel_t *chan, void *buf, size_t len)
	Writes a new message in the channel.
enum ach_status	ach_close (ach_channel_t *chan)
	Closes the shared memory block.
void	ach_dump (ach_header_t *shm)
	Prints information about the channel shm to stderr.
void	ach_attr_init (ach_attr_t *attr)
	Initialize attributes for opening channels.
enum ach_status	ach_chmod (ach_channel_t *chan, mode_t mode)
	Sets permissions of chan to specified mode.
enum ach_status	ach_unlink (const char *name)
	Delete an ach channel.
Variables
size_t	ach_channel_size = sizeof(ach_channel_t)
	Size of ach_channel_t.
size_t	ach_attr_size = sizeof(ach_attr_t)
	Size of ach_attr_t.

---

Detailed Description

Author:

Neil T. Dantam

---

Function Documentation

void ach_attr_init

(

ach_attr_t *

attr

)

Initialize attributes for opening channels.

enum ach_status ach_close

(

ach_channel_t *

chan

)

Closes the shared memory block.

Precondition:

chan is an initialized ach channel with open shared memory area

Postcondition:

the shared memory file for chan is closed

enum ach_status ach_create	(	const char *	channel_name,
		size_t	frame_cnt,
		size_t	frame_size,
		ach_create_attr_t *	attr
	)

Creates a new channel.

Parameters:

	channel_name	Name of the channel
	frame_cnt	number of frames to hold in circular buffer
	frame_size	nominal size of each frame
	attr	options

void ach_create_attr_init

(

ach_create_attr_t *

attr

)

Initialize attributes for creating channels.

void ach_dump

(

ach_header_t *

shm

)

Prints information about the channel shm to stderr.

This function is mostly for internal debugging.

enum ach_status ach_flush

(

ach_channel_t *

chan

)

Discards all previously received messages for this handle.

Does not change the actual channel, just resets the sequence number in the handle.

enum ach_status ach_get	(	ach_channel_t *	chan,
		void *	buf,
		size_t	size,
		size_t *	frame_size,
		const struct timespec *ACH_RESTRICT	abstime,
		int	options
	)

Pulls a message from the channel.

Precondition:

chan has been opened with ach_open()

Postcondition:

If buf is big enough to hold the next frame, buf contains the data for the last frame and chan.seq_num is set to the last frame. If buf is too small to hold the next frame, no side effects occur. The seq_num field of chan will be set to the latest sequence number (that of the gotten frame).

Parameters:

	chan	The previously opened channel handle
	buf	Buffer to store data
	size	Length of buffer in bytes
	frame_size	The number of bytes copied to buf, or the size of the desired frame if buf is too small.
	abstime	An absolute timeout if ACH_O_WAIT is specified. Take care that abstime is given in the correct clock. The default is defined by ACH_DEFAULT_CLOCK.
	options	Option flags

enum ach_status ach_put	(	ach_channel_t *	chan,
		void *	buf,
		size_t	len
	)

Writes a new message in the channel.

Precondition:

chan has been opened with ach_open()

Postcondition:

The contents of buf are copied into the channel and the sequence number of the channel is incremented.

Parameters:

	chan	(action) The channel to write to
	buf	The buffer containing the data to copy into the channel
	len	number of bytes in buf to copy, len > 0

Returns:

ACH_OK on success.