,I'Berkeley DB: lock_unlink[P

lock_unlink





#include <db.h>

int7lock_unlink(const char *dir, int force, DB_ENV *dbenv);





Description



SThe lock_unlink function destroys the lock table identified by the directory@dir, removing all files used to implement the lock table.*(The directory dir is not removed.)

©If there are processes that have called lock_open without calling lock_closeQ(i.e., there are processes currently using the lock table), lock_unlink will failOwithout further action, unless the force flag is set, in which case lock_unlinkWwill attempt to remove the lock table files regardless of any processes still using it.

FThe result of attempting to forcibly destroy the region when a process#has the region open is unspecified.GProcesses using a shared memory region maintain an open file descriptorfor it.2On UNIX systems, the region removal should succeedDand processes that have already joined the region should continue to!run in the region without change,Ohowever processes attempting to join the lock table will either fail or attemptto create a new region.FOn other systems (e.g., Windows/NT), where the unlink(2) systemKcall will fail if any process has an open file descriptor for the file, theregion removal will fail.

HIn the case of catastrophic or system failure, database recovery must benperformed (see db_recover), or the DB_RECOVER and DB_RECOVER_FATALSflags to db_appinit must be specified.GAlternatively, if recovery is not required because no database state isOmaintained across failures, it is possible to clean up a lock table by removingtall of the files in the directory specified to the lock_open function,:as no lock table files are created in any other directory.ENote, however, that this has the potential to remove files created byBthe other Berkeley DB subsystems in the same database environment.

The lock_unlinkHfunction returns the value of errno on failure, and 0 on success.



Errors

TIf a fatal error occurs in Berkeley DB, the lock_unlink function may fail and returnFDB_RUNRECOVERY, at which point all subsequent database calls will alsoreturn DB_RUNRECOVERY.

The lock_unlink)function may fail and return errnoKfor any of the errors specified for the following Berkeley DB and C library functions: abort(3), close(3),8db_version, fcntl(3), fflush(3), fprintf(3),free(3), fstat(3), fsync(3), getenv(3), getpid(3), getuid(3), isdigit(3), lseek(3), malloc(3), memcpy(3), memset(3),mmap(3), munmap(3),open(3),pstat_getdynamic(3),read(3), shmat(3), shmctl(3), shmdt(3),sigfillset(3),sigprocmask(3),stat(3), strerror(3), strlen(3), sysconf(3), unlink(3), vfprintf(3), vsnprintf(3),and write(3).

In addition, the lock_unlink)function may fail and return errnofor the following conditions:

S

EBUSY
The shared memory region was in use and the force flag was not set.




See Also

:lock_close,<lock_detect,6lock_get,4lock_id,8lock_open,3lock_put,8lock_stat, lock_unlinkand6lock_vec.
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