mirror/labs-bird
1
0
Fork 0
mirror of https://gitlab.labs.nic.cz/labs/bird.git synced 2024-05-11 16:54:54 +00:00
Code Releases Activity

Logging: fixed size logfiles behaving as mmapped ringbuffers

Browse Source 
This variant of logging avoids calling write() for every log line,
allowing for waitless logging. This makes heavy logging less heavy
and more useful for race condition debugging.
This commit is contained in:
Maria Matejka
2023-08-24 17:00:54 +02:00
parent 75a5936924
commit 144ac4c1d3
4 changed files with 56 additions and 6 deletions
Download Patch File Download Diff File Expand all files Collapse all files

44
sysdep/unix/io.c
View File

@@ -16,6 +16,7 @@
#include <stdio.h>
#include <stdlib.h>
#include <time.h>
#include <sys/mman.h>
#include <sys/time.h>
#include <sys/types.h>
#include <sys/stat.h>
@@ -69,6 +70,7 @@ struct rfile {
int fd;
off_t limit;
_Atomic off_t pos;
void *mapping;
};
struct rfile rf_stderr = {
@@ -80,6 +82,9 @@ rf_free(resource *r)
{
struct rfile *a = (struct rfile *) r;
if (a->mapping)
munmap(a->mapping, a->limit);
close(a->fd);
}
@@ -112,6 +117,10 @@ rf_open_get_fd(const char *name, enum rf_mode mode)
flags = O_WRONLY | O_CREAT | O_APPEND;
break;
case RF_FIXED:
flags = O_RDWR | O_CREAT;
break;
default:
bug("rf_open() must have the mode set");
}
@@ -145,6 +154,18 @@ rf_open(pool *p, const char *name, enum rf_mode mode, off_t limit)
r->pos = S_ISREG(r->stat.st_mode) ? r->stat.st_size : 0;
break;
case RF_FIXED:
if ((ftruncate(fd, limit) < 0)
|| ((r->mapping = mmap(NULL, limit, PROT_WRITE, MAP_SHARED, fd, 0)) == MAP_FAILED))
{
int erf = errno;
r->mapping = NULL;
rfree(r);
errno = erf;
return NULL;
}
break;
default:
bug("rf_open() must have the mode set");
}
@@ -165,15 +186,34 @@ rf_same(struct rfile *a, struct rfile *b)
rf_stat(b);
return
(a->limit == b->limit) &&
(a->stat.st_mode == b->stat.st_mode) &&
(a->stat.st_dev == b->stat.st_dev) &&
(a->stat.st_ino == b->stat.st_ino);
}
int
rf_write(struct rfile *r, const void *buf, size_t count)
rf_write(struct rfile *r, const void *buf, size_t _count)
{
if (r->limit && (atomic_fetch_add_explicit(&r->pos, count, memory_order_relaxed) + (off_t) count > r->limit))
off_t count = _count;
if (r->mapping)
{
/* Update the pointer */
off_t target = atomic_fetch_add_explicit(&r->pos, count, memory_order_relaxed) % r->limit;
/* Take care of wrapping */
if (target + count > r->limit)
{
memcpy(r->mapping, buf + (r->limit - target), target + count - r->limit);
count = r->limit - target;
}
/* Write the line */
memcpy(r->mapping + target, buf, count);
return 1;
}
else if (r->limit && (atomic_fetch_add_explicit(&r->pos, count, memory_order_relaxed) + count > r->limit))
{
atomic_fetch_sub_explicit(&r->pos, count, memory_order_relaxed);
return 0;