Initial commit

app/workers/daemons/base.rb

@@ -0,0 +1,66 @@
+# encoding: UTF-8
+# frozen_string_literal: true
+
+module Workers
+  module Daemons
+    class Base
+      class GetLockError < StandardError; end
+      class << self; attr_accessor :sleep_time end
+
+      attr_accessor :running
+      attr_reader :logger
+
+      def initialize
+        @running = true
+        @logger = Rails.logger
+      end
+
+      def stop
+        @running = false
+      end
+
+      def run
+        while running
+          begin
+            process
+          rescue ScriptError => e
+            raise e if is_db_connection_error?(e)
+
+            report_exception(e)
+          end
+          wait
+        end
+      end
+
+      def process
+        method_not_implemented
+      end
+
+      def wait
+        Kernel.sleep self.class.sleep_time
+      end
+
+      def is_db_connection_error?(exception)
+        exception.is_a?(Mysql2::Error::ConnectionError) || exception.cause.is_a?(Mysql2::Error)
+      end
+
+      def lock(klass, timeout)
+        res = ActiveRecord::Base.connection.exec_query("SELECT GET_LOCK('Peatio_#{klass}',#{timeout})")
+
+        # response from this query will look like this [{"GET_LOCK(id,10)"=>1}]
+        # returns 1 if the lock was obtained successfully, 0 if the attempt timed out
+        if res.to_a[0].values[0] == 1
+          begin
+            yield
+          rescue StandardError => e
+            report_exception(e)
+          ensure
+            ActiveRecord::Base.connection.exec_query("SELECT RELEASE_LOCK('Peatio_#{klass}')")
+          end
+        else
+          raise GetLockError, "Peatio_#{klass} is already running"
+        end
+      end
+    end
+  end
+end