githubmo / mongo-lock

mongo-lock

#Mongo-Lock

This is a utility that prevents multiple instances of the same application to perform an operation at the same time. This can be useful of example when a REST api has to be called at a scheduled time. Without this utility every instance of the application would call the REST api.

The utility uses mongodb to create a lock

##Usage

1. Get access to mongodb

    val connection = {

          import play.api.Play.current
          ReactiveMongoPlugin.mongoConnector.db
   }
   val repo = LockMongoRepository(connection)

2. Create a LockKeeper. The forceLockRelease timeout allows other apps to release and get the lock if it was stuck for some reasons

    val lockKeeper = new LockKeeper {
    
        override def repo: LockRepository = repo //The repo created before
    
        override def lockId: String = "<something unique for the operation>"
    
        override val forceLockReleaseAfter: Duration = Duration.standardMinutes(5)
    }

3. Use the LockKeeper to execute the code

 lockKeeper.tryLock { 
    // This will be executed on one application only
 }

The function in LockKeeper accepts anything that returns a Future[T] tryLock will return the result in an Option. If it was not possible to acquire the lock, None is returned

def tryLock[T](body: => Future[T]): Future[Option[T]] 

Installing

Include the following dependency in your SBT build

resolvers += Resolver.bintrayRepo("hmrc", "releases")

libraryDependencies += "uk.gov.hmrc" %% "mongo-lock" % "x.x.x"

License

This code is open source software licensed under the Apache 2.0 License.