,I&Berkeley DB: txn_unlink[P

txn_unlink





#include <db.h>

int6txn_unlink(const char *dir, int force, DB_ENV *dbenv);





Description



ZThe txn_unlink function destroys the transaction region identified by the directoryHdir, removing all files used to implement the transaction region.*(The directory dir is not removed.)

¥If there are processes that have called txn_open without calling txn_closeX(i.e., there are processes currently using the transaction region), txn_unlink will failNwithout further action, unless the force flag is set, in which case txn_unlink_will attempt to remove the transaction region 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,Whowever processes attempting to join the transaction region 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 isWmaintained across failures, it is possible to clean up a transaction region by removingrall of the files in the directory specified to the txn_open function,Bas no transaction region 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 txn_unlinkHfunction returns the value of errno on failure, and 0 on success.



Errors

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

The txn_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 txn_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

5txn_abort,8txn_begin,Btxn_checkpoint,8txn_close,7txn_commit,/txn_id,6txn_open,9txn_prepare,5txn_statand txn_unlink.
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