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Keyway

A simple lock file library.

Features

• Provides mutual exclusion for scripts that require the same resource.
• Requires three additional lines of code in your script, including sourcing the library.
• Scripts using Keyway can be configured to either terminate or busy-wait if a resource is blocked.
• Keyway will report when an external error was caught and there are lock files in the lock directory.

Usage:

• acquire_lock_for "your_task_name"
  • If the resource is not locked, your task will execute, otherwise it will terminate.
• acquire_spinlock_for "your_task_name"
  • If the resource is locked, your task will wait until the lock has been released before acquiring its own lock and executing.

Return Code Explanations:

1. Your application was not able to acquire lock.
2. There was some other problem:
   • Keyway could not create the lock directory.
   • Keyway could not create or remove a lock.
3. An error was caught and there are lock files in the lock directory.

An example:

#!/bin/bash
source keyway_lib.sh

# optionally override the lock file directory
LOCK_DIR="alt-lock-dir"

# attempt to lock the shared resource
acquire_lock_for "your_task_name"

# if the lock was successful, execute the task
echo "executing critical section"

# release the lock when the task is done
release_lock_for "your_task_name"