File Locking And Block Execution

Examples using file locks and executing multiple operations within the context of a single open file

Lock

Perform an actions within a file lock

    import scalax.file.{FileOps, Path}

    val file: FileOps =  Path ("file")

    implicit val codec = scalax.io.Codec.UTF8

    // By default the entire file is locked with exclusive access
    val result: Option[String] = file.withLock() { s =>
      s.slurpString
    }

    // if the filesystem does not support locking then None will be returned
    result match {
      case None => file.slurpString // oh well this is the best I can do
      case Some(data) => data
    }

    def fail: Nothing = throw new AssertionError("Uh oh")

    // or perhaps we only lock part of the file
    val result2: Traversable[Byte] = file.withLock(10, 20) { s =>
      s.bytes slice (10,20)
    } getOrElse {fail}

Operation Block

when several operation need to be performed on a file it is often more performant to execute them within an function passed to the open method this is because the underlying filesystem has options for optimizing the use of the file channels for example a file could be mapped into memory for the duration of the function and all operations could be performed using the same channel object

    import scalax.file.{FileOps, Path}
    // see codec examples in scala io core for details on why there is an implicit codec here
    implicit val codec = scalax.io.Codec.UTF8

    val file: FileOps =  Path ("file")

    file.open()( f => {
      val s = f.slurpString
      file.write(s.replaceAll("l", "L"))
    })