Database information request
Requests database or server information.
Uses the [wireprotocol-requests-info] message with:
p_operation
|
|
p_info_object
|
Unused, always use |
p_info_items
|
Values of enum |
Cancellation
Protocol 12 and higher.
Cancels a running operation on the server.
Note
|
Operation |
Client
Int32
—p_operation
-
Operation code (
op_cancel
) Int32
—p_co_kind
-
Cancellation kind, one of:
fb_cancel_disable
—1
-
disable cancellation until
fb_cancel_enable
is sent fb_cancel_enable
—2
-
enable cancellation if it was disabled previously
fb_cancel_raise
—3
-
cancel current operation
fb_cancel_abort
—4
-
See note above, this kind should not be sent to the server.
As cancellation is generally performed asynchronously to be effective, the client implementation must take special care how the operation is sent.
For example, if you use a lock for socket operations, this operation will need to ignore it (running the risk of interfering/corrupting another send operation), or you need to split your locks in a lock for writing, and a lock for reading, or have some other way of detecting that another thread is not currently sending data.
Server
No formal response, cancellation is signalled as a [wireprotocol-responses-generic] with a failure for the cancelled operation.