The io context determines the snapshot to read from, if any was set
by rados_ioctx_snap_set_read().
The return value of the completion will be number of bytes read on
success, negative error code on failure.
@note only the 'complete' callback of the completion will be called.
@param io the context in which to perform the read
@param oid the name of the object to read from
@param completion what to do when the read is complete
@param buf where to store the results
@param len the number of bytes to read
@param off the offset to start reading from in the object
@returns 0 on success, negative error code on failure
Asychronously read data from an object
The io context determines the snapshot to read from, if any was set by rados_ioctx_snap_set_read().
The return value of the completion will be number of bytes read on success, negative error code on failure.
@note only the 'complete' callback of the completion will be called.
@param io the context in which to perform the read @param oid the name of the object to read from @param completion what to do when the read is complete @param buf where to store the results @param len the number of bytes to read @param off the offset to start reading from in the object @returns 0 on success, negative error code on failure