The Db::fd method
copies a file descriptor representative of the underlying database into
the memory to which fdp refers. A file descriptor referring to
the same file will be returned to all processes that call
Db::open with the same file argument. This file
descriptor may be safely used as an argument to the fcntl(2)
and flock(2) locking functions. The file descriptor is not
necessarily associated with any of the underlying files actually used
by the access method.
The Db::fd method only supports a coarse-grained form of locking.
Applications should use the lock manager where possible.
The Db::fd method either returns a non-zero error value or throws an exception that
encapsulates a non-zero error value on failure, and returns 0 on success.
The Db::fd method may fail and throw an exception or return a non-zero error for errors specified for other Berkeley DB and C library or system methods.
If a catastrophic error has occurred, the Db::fd method may fail and
either return DB_RUNRECOVERY or throw a
in which case all subsequent Berkeley DB calls will fail in the same way.
Databases and Related Methods
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