The distributed lock is a configdb backed way of synchronizing system-wide tasks. More...
#include <distlock.h>
Public Member Functions | |
| DistributedLock (const ConnectionString &conn, const string &name, unsigned takeoverMinutes=15) | |
| The constructor does not connect to the configdb yet and constructing does not mean the lock was acquired. | |
| bool | lock_try (string why, BSONObj *other=0) |
| Attempts to aquire 'this' lock, checking if it could or should be stolen from the previous holder. | |
| void | unlock () |
| Releases a previously taken lock. | |
The distributed lock is a configdb backed way of synchronizing system-wide tasks.
A task must be identified by a unique name across the system (e.g., "balancer"). A lock is taken by writing a document in the configdb's locks collection with that name.
To be maintained, each taken lock needs to be revalidaded ("pinged") within a pre-established amount of time. This class does this maintenance automatically once a DistributedLock object was constructed.
| mongo::DistributedLock::DistributedLock | ( | const ConnectionString & | conn, | |
| const string & | name, | |||
| unsigned | takeoverMinutes = 15 | |||
| ) |
The constructor does not connect to the configdb yet and constructing does not mean the lock was acquired.
Construction does trigger a lock "pinging" mechanism, though.
| conn | address of config(s) server(s) | |
| name | identifier for the lock | |
| takeoverMinutes | how long can the log go "unpinged" before a new attempt to lock steals it (in minutes) |
| bool mongo::DistributedLock::lock_try | ( | string | why, | |
| BSONObj * | other = 0 | |||
| ) |
Attempts to aquire 'this' lock, checking if it could or should be stolen from the previous holder.
Please consider using the dist_lock_try construct to acquire this lock in an exception safe way.
| why | human readable description of why the lock is being taken (used to log) | |
| other | configdb's lock document that is currently holding the lock, if lock is taken |
1.6.3