The libpmemblk library
libpmemblk implements a pmem-resident array of blocks,
all the same size, where a block is updated atomically with
respect to power failure or program interruption (no torn
blocks).
This library is provided for cases requiring large arrays
of objects at least 512 bytes each. Most
developers will find higher level libraries like
libpmemobj to be more generally useful.
Man pages that contains a list of the Linux interfaces provided:
Man pages that contains a list of the Windows interfaces provided:
libpmemblk Examples
More Detail Coming Soon
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| #include <stdio.h>
#include <fcntl.h>
#include <errno.h>
#include <stdlib.h>
#include <unistd.h>
#include <string.h>
#include <libpmemblk.h>
/* size of the pmemblk pool -- 1 GB */
#define POOL_SIZE ((off_t)(1 << 30))
/* size of each element in the pmem pool */
#define ELEMENT_SIZE 1024
int
main(int argc, char *argv[])
{
const char path[] = "/pmem-fs/myfile";
PMEMblkpool *pbp;
size_t nelements;
char buf[ELEMENT_SIZE];
/* create the pmemblk pool or open it if it already exists */
pbp = pmemblk_create(path, ELEMENT_SIZE, POOL_SIZE, 0666);
if (pbp == NULL)
pbp = pmemblk_open(path, ELEMENT_SIZE);
if (pbp == NULL) {
perror(path);
exit(1);
}
/* how many elements fit into the file? */
nelements = pmemblk_nblock(pbp);
printf("file holds %zu elements\n", nelements);
/* store a block at index 5 */
strcpy(buf, "hello, world");
if (pmemblk_write(pbp, buf, 5) < 0) {
perror("pmemblk_write");
exit(1);
}
/* read the block at index 10 (reads as zeros initially) */
if (pmemblk_read(pbp, buf, 10) < 0) {
perror("pmemblk_read");
exit(1);
}
/* zero out the block at index 5 */
if (pmemblk_set_zero(pbp, 5) < 0) {
perror("pmemblk_set_zero");
exit(1);
}
/* ... */
pmemblk_close(pbp);
}
|
