int DbMpoolFile::get(db_pgno_t *pgnoaddr, u_int32_t flags, void **pagep);
The DbMpoolFile::get method copies a pointer to the page with the page number specified by pgnoaddr, from the source file in the DbMpoolFile, into the memory location referenced by pagep. If the page does not exist or cannot be retrieved, DbMpoolFile::get will fail.
Page numbers begin at 0, i.e., the first page in the file is page number 0, not page number 1.
The returned page is size_t type aligned.
The flags argument is specified by logically OR'ing together one or more of the following values:
The DB_MPOOL_CREATE, DB_MPOOL_LAST and DB_MPOOL_NEW flags are mutually exclusive.
Created pages have all their bytes set to 0, unless otherwise specified when the file was opened.
All pages returned by DbMpoolFile::get will be retained (i.e. pinned in the pool until a subsequent call to DbMpoolFile::put.
The DbMpoolFile::get method either returns errno or throws an exception that encapsulates an errno on failure, and 0 on success.
The DbMpoolFile::get 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 DbMpoolFile::get method may fail and throw an exception or return errno for the following conditions:
The DB_MPOOL_NEW flag was set and the source file was not opened for writing.
The requested page does not exist and DB_MPOOL_CREATE was not set.
More than one of DB_MPOOL_CREATE, DB_MPOOL_LAST and DB_MPOOL_NEW was set.