Lock/Unlock

Detailed Description

Documents may be locked and unlocked on the server. While a document is locked, any attempt to modify it (or lock it again) will fail.

Note

Locks are not persistent across nodes (if a node fails over, the lock is not transferred to a replica).

The recommended way to manage access and concurrency control for documents in Couchbase is through the CAS (See lcb_CMDBASE::cas and lcb_RESPBASE::cas), which can also be considered a form of opportunistic locking.

Locking an item

There is no exclusive function to lock an item. Locking an item is done using lcb_get3(), by setting the lcb_CMDGET::lock option to true.

Functions
lcb_error_t	lcb_unlock3 (lcb_t instance, const void *cookie, const lcb_CMDUNLOCK *cmd)
	Unlock a previously locked item using lcb_CMDGET::lock. More...

Typedefs
typedef lcb_CMDBASE	lcb_CMDUNLOCK
	Command for lcb_unlock3() More...
typedef lcb_RESPBASE	lcb_RESPUNLOCK
	Response structure for an unlock command. More...

Function Documentation

lcb_error_t lcb_unlock3	(	lcb_t	instance,
		const void *	cookie,
		const lcb_CMDUNLOCK *	cmd
	)

Unlock a previously locked item using lcb_CMDGET::lock.

Stability

Committed:

Parameters

instance	the instance
cookie	the context pointer to associate with the command
cmd	the command containing the information about the locked key

Returns

LCB_SUCCESS if successful, an error code otherwise

See also

lcb_get3()

Request

void locked_callback(lcb_t, lcb_CALLBACKTYPE, const lcb_RESPBASE *resp) {
  lcb_CMDUNLOCK cmd = { 0 };
  LCB_CMD_SET_KEY(&cmd, resp->key, resp->nkey);
  cmd.cas = resp->cas;
  lcb_unlock3(instance, cookie, &cmd);
}

Typedef Documentation

typedef lcb_CMDBASE lcb_CMDUNLOCK

Command for lcb_unlock3()

Attention

lcb_CMDBASE::cas must be specified, or the operation will fail on the server

typedef lcb_RESPBASE lcb_RESPUNLOCK

Response structure for an unlock command.

Note

the lcb_RESPBASE::cas field does not contain the CAS of the item