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Code Issues 5 Pull Requests Releases Activity

Sleep forever waiting for lock. Previous method doesn't work well with

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a large number of clients accessing the cache at the same time, and
there is no simple way to add a timeout to the lock.


git-svn-id: svn://svn.h5l.se/heimdal/trunk/heimdal@13019 ec53bebd-3082-4978-b11e-865c3cabbd6b
This commit is contained in:
Johan Danielsson
2003-10-16 09:06:39 +00:00
parent 76e1e376c4
commit 8ad04cfa43
1 changed files with 12 additions and 18 deletions
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30
lib/krb5/fcache.c
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@@ -58,9 +58,6 @@ struct fcc_cursor {
#define FCC_CURSOR(C) ((struct fcc_cursor*)(C)) #define FCC_CURSOR(C) ((struct fcc_cursor*)(C))
#define KRB5_CC_LOCK_RETRY_COUNT 50
#define KRB5_CC_LOCK_RETRY 1
static const char* static const char*
fcc_get_name(krb5_context context, fcc_get_name(krb5_context context,
krb5_ccache id) krb5_ccache id)
@@ -71,16 +68,23 @@ fcc_get_name(krb5_context context,
static int static int
xlock(int fd, krb5_boolean exclusive) xlock(int fd, krb5_boolean exclusive)
{ {
int ret;
#ifdef HAVE_FCNTL #ifdef HAVE_FCNTL
struct flock l; struct flock l;
l.l_start = 0; l.l_start = 0;
l.l_len = 0; l.l_len = 0;
l.l_type = exclusive ? F_WRLCK : F_RDLCK; l.l_type = exclusive ? F_WRLCK : F_RDLCK;
l.l_whence = SEEK_SET; l.l_whence = SEEK_SET;
return fcntl(fd, F_SETLK, &l); ret = fcntl(fd, F_SETLKW, &l);
#else #else
return flock(fd, (exclusive ? LOCK_EX : LOCK_SH) | LOCK_NB); ret = flock(fd, exclusive ? LOCK_EX : LOCK_SH);
#endif #endif
if(ret < 0)
ret = errno;
if(ret == EACCES) /* fcntl can return EACCES instead of EAGAIN */
ret = EAGAIN;
return ret;
} }
static int static int
@@ -92,7 +96,7 @@ xunlock(int fd)
l.l_len = 0; l.l_len = 0;
l.l_type = F_UNLCK; l.l_type = F_UNLCK;
l.l_whence = SEEK_SET; l.l_whence = SEEK_SET;
return fcntl(fd, F_SETLK, &l); return fcntl(fd, F_SETLKW, &l);
#else #else
return flock(fd, LOCK_UN); return flock(fd, LOCK_UN);
#endif #endif
@@ -103,18 +107,8 @@ fcc_lock(krb5_context context, krb5_ccache id,
int fd, krb5_boolean exclusive) int fd, krb5_boolean exclusive)
{ {
krb5_error_code ret = 0; krb5_error_code ret = 0;
int i; ret = xlock(fd, exclusive);
for (i = 0; i < KRB5_CC_LOCK_RETRY_COUNT; i++) { if(ret == EAGAIN)
if (xlock(fd, exclusive) < 0) {
ret = errno;
if(ret == EAGAIN) {
sleep(KRB5_CC_LOCK_RETRY);
continue;
}
}
break;
}
if(ret == EAGAIN)
krb5_set_error_string(context, "timed out locking cache file %s", krb5_set_error_string(context, "timed out locking cache file %s",
fcc_get_name(context, id)); fcc_get_name(context, id));
else if(ret != 0) else if(ret != 0)