From 77b1804eefe78a288611ea0de6dd8dfef8599220 Mon Sep 17 00:00:00 2001
From: Shivam Mishra <scm.mymail@gmail.com>
Date: Mon, 21 Aug 2023 15:11:29 +0700
Subject: [PATCH] feat: create mutex application job

---
 app/jobs/mutex_application_job.rb | 35 +++++++++++++++++++++++++++++++
 1 file changed, 35 insertions(+)
 create mode 100644 app/jobs/mutex_application_job.rb

diff --git a/app/jobs/mutex_application_job.rb b/app/jobs/mutex_application_job.rb
new file mode 100644
index 000000000..16d681b34
--- /dev/null
+++ b/app/jobs/mutex_application_job.rb
@@ -0,0 +1,35 @@
+# MutexApplicationJob serves as a base class for jobs that require distributed locking mechanisms.
+# It abstracts the locking logic using Redis and ensures that a block of code can be executed with
+# mutual exclusion.
+#
+# The primary mechanism provided is the `with_lock` method, which accepts a key format and associated
+# arguments. This method attempts to acquire a lock using the generated key, and if successful, it
+# executes the provided block of code. If the lock cannot be acquired, it raises a LockAcquisitionError.
+#
+# To use this class, inherit from MutexApplicationJob and make use of the `with_lock` method in the
+# `perform` method of the derived job class.
+#
+# Also see, retry mechanism here: https://edgeapi.rubyonrails.org/classes/ActiveJob/Exceptions/ClassMethods.html#method-i-retry_on
+#
+class MutexApplicationJob < ApplicationJob
+  class LockAcquisitionError < StandardError; end
+
+  def with_lock(key_format, *args)
+    lock_key = format(key_format, *args)
+    lock_manager = Redis::LockManager.new
+
+    if lock_manager.locked?(lock_key)
+      Rails.logger.error "[#{self.class.name}] Failed to acquire lock on attempt #{executions + 1}: #{lock_key}"
+      raise LockAcquisitionError, "Failed to acquire lock for key: #{lock_key}"
+    end
+
+    begin
+      lock_manager.lock(lock_key)
+      Rails.logger.info "[#{self.class.name}] Acquired lock for: #{lock_key}"
+      yield
+    ensure
+      # Ensure that the lock is released even if there's an error in processing
+      lock_manager.unlock(lock_key)
+    end
+  end
+end