NAME Lock::Server - Light-weight socket based resource locking manager. DESCRIPTION This creates a child process socket server that takes lock and unlock requests. The lock requests only return once a lock is obtained or a timeout has occurred. A lock may only be locked for a specific amount of time before the lock is timed out. The protocol used is RESTFUL HTTP though the helper class wraps that. It uses the GET verb with the following paths : * CHECK/key - returns 1 if the key in question is currently locked returns 0 if not * LOCK/key/requester - returns lock expire time or 0 if there was an error * UNLOCK/key/requester - returns 1 if the unlock went as expected, 0 otherwise * VERIFY/key/requester - returns 1 if the key is locked to the requester and did not time out and 0 otherwise. * PING - returns 1 if the server is active This does not do deadlock detection, relying on the timeouts to prevent the system from getting in a hopelessly tangled state. Care should be taken, as with any resource locking system, with the use of Lock::Server. Adjust the timeouts for what makes sense with the system you are designing. The lock requests return with the time that the lock will expire. SYNPOSIS use Lock::Server; use Lock::Server::Client; my $lockServer = new Lock::Server( { lock_timeout => 10, #seconds. default is 3 lock_attempt_timeout => 12, #seconds. default is 4 port => 888, #default is 8004 host => 'localhost', #default 127.0.0.1 } ); if( my $childPid = $lockServer->start ) { print "Lock server started in child thread $childPid\n"; } my $lockClient_A = $lockServer->client( "CLIENT_A" ); my $lockClient_B = new Lock::Server::Client( "CLIENT_B", 'localhost', 888 ); if( $lockClient_A->lock( "KEYA" ) ) { print "Lock Successfull for locker A and KEYA\n"; } else { print "Could not obtain lock in 12 seconds.\n"; } # KEYA for LockerI times out after 10 seconds. # Lock Client B waits until it can obtain the lock if( $lockClient_B->lock( "KEYA" ) ) { print "Lock Successfull for Client B lock 'KEYA'\n"; } else { print "Could not obtain lock in 12 seconds.\n"; } # KEYA for LockerII is now freed. The next locker # attempting to lock KEYA will then obtain the lock. if( $lockClientB->unlock( "KEYA" ) ) { print "Unlock Successfull\n"; } if( $lockServer->stop ) { print "Lock server shut down.\n"; } METHODS Lock::Server::new( $args ) Creates a new lock server for the given optional arguments. Arguments are : * port - port to serve on. Defaults to 8004 * lock_timeout - low long should a lock last in seconds * lock_attempt_timeout - how long should a requester wait for a lock in seconds client( lockername ) Returns a client with the given name that can send lock and unlock requests for keys. stop Kills the lock server, breaking off any connections that are waiting for a lock. start Starts the lock server in a child process, opening up a tcpip socket and returning the child pid or 0 if there was an error. run Runs the lock server. Helper package NAME Lock::Server::Client - client for locking server. DESCRIPTION Sends request to a Lock::Server to lock, unlock and check locks. METHODS new( lockername, host, port ) Creates a client object with the given name for the host and port. isLocked( key ) Returns true if the key is locked by anyone. lockedByMe( key ) Returns true if the key is locked by this client or anyone with the name of this client. The name was given in the constructor. lock( key ) Attempt to get the lock for the given key. Returns true if the lock was obtained. unlock( key ) Attempt to get unlock the given key. Returns true if the key was locked to this client ( or someting with the same name ). AUTHOR Eric Wolf coyocanid@gmail.com COPYRIGHT AND LICENSE Copyright (c) 2015 Eric Wolf. All rights reserved. This program is free software; you can redistribute it and/or modify it under the same terms as Perl itself.