Berkeley DB: DbMpool::trickle
Полезная информация


#include <db_cxx.h>

int DbMpool::trickle(int pct, int *nwrotep);


The DbMpool::trickle method ensures that at least pct percent of the pages in the shared memory pool are clean by writing dirty pages to their backing files. If the nwrotep argument is non-NULL, the number of pages that were written to reach the correct percentage is returned in the memory location it references.

The purpose of the DbMpool::trickle function is to enable a memory pool manager to ensure that a page is always available for reading in new information without having to wait for a write.

The DbMpool::trickle method either returns errno or throws an exception that encapsulates an errno on failure, and 0 on success.


If a fatal error occurs in Berkeley DB, the DbMpool::trickle method may fail and either return DB_RUNRECOVERY or throw an exception encapsulating DB_RUNRECOVERY, at which point all subsequent database calls will also fail in the same way. Methods marked as returning errno will, by default, throw an exception that encapsulates the error information. The default error behavior can be changed, see DbException.

The DbMpool::trickle method may fail and throw an exception for any of the errors specified for the following Berkeley DB and C library functions: DBmemp->pgin(3), DBmemp->pgout(3), abort(3), close(3), dbenv->db_paniccall(3), fcntl(3), fflush(3), fprintf(3), free(3), fstat(3), fsync(3), getenv(3), getpid(3), getuid(3), isdigit(3), DbLog::compare, DbLog::flush, lseek(3), malloc(3), memcmp(3), memcpy(3), memset(3), mmap(3), open(3), pread(3), pstat_getdynamic(3), pwrite(3), read(3), sigfillset(3), sigprocmask(3), stat(3), strerror(3), strlen(3), sysconf(3), time(3), unlink(3), vfprintf(3), vsnprintf(3), and write(3).

In addition, the DbMpool::trickle method may fail and throw an exception or return errno for the following conditions:

An invalid flag value or parameter was specified.



See Also

DbMpool::close, DbMpool::open, DbMpool::db_register, DbMpool::stat, DbMpool::sync, DbMpool::trickle and DbMpool::unlink.