Package com.echothree.util.server.persistence.mutex

Class DatabasePostgresMutex

java.lang.Object

com.echothree.util.server.persistence.mutex.DatabasePostgresMutex

All Implemented Interfaces:

DatabaseMutex

@ApplicationScoped
public class DatabasePostgresMutex
extends Object
implements DatabaseMutex

Postgres session advisory locks keyed by the first 64 bits of SHA-256. Hash collisions cause otherwise distinct names to share a lock.

Field Summary

Fields inherited from interface com.echothree.util.server.persistence.mutex.DatabaseMutex

DEFAULT_TIMEOUT_SECONDS

Constructor Summary

Constructors

Constructor	Description
DatabasePostgresMutex()

Method Summary

Modifier and Type	Method	Description
boolean	acquireLock(String lockName, int timeoutSeconds)	Attempts to acquire the named lock within the specified timeout.
boolean	releaseLock(String lockName)	Releases one acquisition of the named lock on the session's connection.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Methods inherited from interface com.echothree.util.server.persistence.mutex.DatabaseMutex

acquireLock

Constructor Details

DatabasePostgresMutex

public DatabasePostgresMutex()

Method Details

acquireLock

public boolean acquireLock(String lockName,
 int timeoutSeconds)

Description copied from interface: DatabaseMutex

Attempts to acquire the named lock within the specified timeout.

Specified by:

acquireLock in interface DatabaseMutex

Parameters:

lockName - the name of the lock

timeoutSeconds - zero to try once, positive to wait up to that many seconds, or negative to wait indefinitely

Returns:

true only when the lock was acquired; false on timeout or a null database result. Postgres also returns false when interrupted, preserving the interrupt flag. SQL execution errors propagate to the caller.

releaseLock

public boolean releaseLock(String lockName)

Description copied from interface: DatabaseMutex

Releases one acquisition of the named lock on the session's connection.

Specified by:

releaseLock in interface DatabaseMutex

Parameters:

lockName - the name of the lock

Returns:

true only when the database confirms release; false when the lock is not owned by this session, does not exist, or the result is null. SQL execution errors propagate to the caller.