,I+Berkeley DB: DbTxnMgr.unlink[P

DbTxnMgr.unlink





import com.sleepycat.db.*;

=public static void unlink(String dir, int force, DbEnv dbenv) throws DbException;





Description



_The DbTxnMgr.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.)

µIf there are processes that have called DbTxnMgr.open without calling DbTxnMgr.close](i.e., there are processes currently using the transaction region), DbTxnMgr.unlink will failSwithout further action, unless the force flag is set, in which case DbTxnMgr.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_FATALYflags to DbEnv.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 removingzall of the files in the directory specified to the DbTxnMgr.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 DbTxnMgr.unlinkHmethod throws an exception that encapsulates an errno on failure.



Errors

WIf a fatal error occurs in Berkeley DB, the DbTxnMgr.unlink method may fail and throw a}DbRunRecoveryException, at which point all subsequent database%calls will also fail in the same way.

The DbTxnMgr.unlink&method may fail and throw an exceptionKfor any of the errors specified for the following Berkeley DB and C library functions: abort(3), close(3),>DbEnv.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 DbTxnMgr.unlink&method may fail and throw an exceptionencapsulating errnofor the following conditions:

S

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




Class

9DbTxnMgr



See Also

@DbTxnMgr.begin,JDbTxnMgr.checkpoint,@DbTxnMgr.close,>DbTxnMgr.open,=DbTxnMgr.statandDbTxnMgr.unlink.
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