,I+Berkeley DB: DbMpool::unlink[P

DbMpool::unlink





#include <db_cxx.h>

static int5DbMpool::unlink(const char *dir, int force, DbEnv *);





Description



XThe DbMpool::unlink function destroys the memory pool identified by the directoryAdir, removing all files used to implement the memory pool.*(The directory dir is not removed.)

±If there are processes that have called DbMpool::open without calling DbMpool::closeV(i.e., there are processes currently using the memory pool), DbMpool::unlink will failSwithout further action, unless the force flag is set, in which case DbMpool::unlinkXwill attempt to remove the memory pool 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,Phowever processes attempting to join the memory pool 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 isPmaintained across failures, it is possible to clean up a memory pool by removingxall of the files in the directory specified to the DbMpool::open function,;as no memory pool 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 DbMpool::unlink>method either returns errno or throws an exception that:encapsulates an errno on failure, and 0 on success.



Errors

VIf a fatal error occurs in Berkeley DB, the DbMpool::unlink method may fail and eitherIreturn DB_RUNRECOVERY or throw an exception encapsulating DB_RUNRECOVERY,Gat which point all subsequent database calls will also fail in the sameFway. Methods marked as returning errno will, by default, throwHan exception that encapsulates the error information. The default error\behavior can be changed, see DbException.

The DbMpool::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 DbMpool::unlink&method may fail and throw an exceptionor return errnofor the following conditions:

S

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




Class

6DbMpool



See Also

>DbMpool::close,<DbMpool::open,JDbMpool::db_register,<DbMpool::stat,<DbMpool::sync,ADbMpool::trickleandDbMpool::unlink.
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