lockable.rb in good_job-0.3.0

- old
+ new
@@ -13,90 +13,81 @@
             AND pg_locks.objid = (('x'||substr(md5(good_jobs.id::text), 1, 16))::bit(64) << 32)::bit(32)::int
         SQL
       end)
 
       scope :advisory_unlocked, -> { joins_advisory_locks.where(pg_locks: { locktype: nil }) }
-      scope :with_advisory_lock, (lambda do
-        where(<<~SQL)
-          pg_try_advisory_lock(('x'||substr(md5(id::text), 1, 16))::bit(64)::bigint)
-        SQL
-      end)
 
-      def self.first_advisory_locked_row(query)
-        find_by_sql(<<~SQL)
+      attr_accessor :create_with_advisory_lock
+
+      after_create -> { advisory_lock }, if: :create_with_advisory_lock
+    end
+
+    class_methods do
+      def first_advisory_locked_row(query)
+        find_by_sql(<<~SQL).first
           WITH rows AS (#{query.to_sql})
-          SELECT rows.id
+          SELECT rows.*
           FROM rows
           WHERE pg_try_advisory_lock(('x'||substr(md5(id::text), 1, 16))::bit(64)::bigint)
+          LIMIT 1
         SQL
       end
-      # private_class_method :first_advisory_locked_row
+    end
 
-      # https://www.postgresql.org/docs/9.6/view-pg-locks.html
-      # Advisory locks can be acquired on keys consisting of either a single bigint value or two integer values.
-      # A bigint key is displayed with its high-order half in the classid column, its low-order half in the objid column, and objsubid equal to 1.
-      # The original bigint value can be reassembled with the expression (classid::bigint << 32) | objid::bigint.
-      # Integer keys are displayed with the first key in the classid column, the second key in the objid column, and objsubid equal to 2.
-      # The actual meaning of the keys is up to the user. Advisory locks are local to each database, so the database column is meaningful for an advisory lock.
-      def self.advisory_lock_details
-        connection.select("SELECT * FROM pg_locks WHERE locktype = 'advisory' AND objsubid = 1")
-      end
+    def advisory_lock
+      self.class.connection.execute(sanitize_sql_for_conditions(["SELECT 1 as one WHERE pg_try_advisory_lock(('x'||substr(md5(?), 1, 16))::bit(64)::bigint)", id])).ntuples.positive?
+    end
 
-      def advisory_lock
-        self.class.connection.execute(sanitize_sql_for_conditions(["SELECT 1 as one WHERE pg_try_advisory_lock(('x'||substr(md5(?), 1, 16))::bit(64)::bigint)", id])).ntuples.positive?
-      end
+    def advisory_lock!
+      result = advisory_lock
+      result || raise(RecordAlreadyAdvisoryLockedError)
+    end
 
-      def advisory_lock!
-        result = advisory_lock
-        result || raise(RecordAlreadyAdvisoryLockedError)
-      end
+    def with_advisory_lock
+      advisory_lock!
+      yield
+    rescue StandardError => e
+      advisory_unlock unless e.is_a? RecordAlreadyAdvisoryLockedError
+      raise
+    end
 
-      def with_advisory_lock
-        advisory_lock!
-        yield
-      rescue StandardError => e
-        advisory_unlock unless e.is_a? RecordAlreadyAdvisoryLockedError
-        raise
-      end
+    def advisory_locked?
+      self.class.connection.execute(<<~SQL).ntuples.positive?
+        SELECT 1 as one
+        FROM pg_locks
+        WHERE
+          locktype = 'advisory'
+          AND objsubid = 1
+          AND classid = ('x'||substr(md5('#{id}'), 1, 16))::bit(32)::int
+          AND objid = (('x'||substr(md5('#{id}'), 1, 16))::bit(64) << 32)::bit(32)::int
+      SQL
+    end
 
-      def advisory_locked?
-        self.class.connection.execute(<<~SQL).ntuples.positive?
-          SELECT 1 as one
-          FROM pg_locks
-          WHERE
-            locktype = 'advisory'
-            AND objsubid = 1
-            AND classid = ('x'||substr(md5('#{id}'), 1, 16))::bit(32)::int
-            AND objid = (('x'||substr(md5('#{id}'), 1, 16))::bit(64) << 32)::bit(32)::int
-        SQL
-      end
+    def owns_advisory_lock?
+      self.class.connection.execute(<<~SQL).ntuples.positive?
+        SELECT 1 as one
+        FROM pg_locks
+        WHERE
+          locktype = 'advisory'
+          AND objsubid = 1
+          AND classid = ('x'||substr(md5('#{id}'), 1, 16))::bit(32)::int
+          AND objid = (('x'||substr(md5('#{id}'), 1, 16))::bit(64) << 32)::bit(32)::int
+          AND pid = pg_backend_pid()
+      SQL
+    end
 
-      def owns_advisory_lock?
-        self.class.connection.execute(<<~SQL).ntuples.positive?
-          SELECT 1 as one
-          FROM pg_locks
-          WHERE
-            locktype = 'advisory'
-            AND objsubid = 1
-            AND classid = ('x'||substr(md5('#{id}'), 1, 16))::bit(32)::int
-            AND objid = (('x'||substr(md5('#{id}'), 1, 16))::bit(64) << 32)::bit(32)::int
-            AND pid = pg_backend_pid()
-        SQL
-      end
+    def advisory_unlock
+      self.class.connection.execute("SELECT pg_advisory_unlock(('x'||substr(md5('#{id}'), 1, 16))::bit(64)::bigint)").first["pg_advisory_unlock"]
+    end
 
-      def advisory_unlock
-        self.class.connection.execute("SELECT pg_advisory_unlock(('x'||substr(md5('#{id}'), 1, 16))::bit(64)::bigint)").first["pg_advisory_unlock"]
-      end
+    def advisory_unlock!
+      advisory_unlock while advisory_locked?
+    end
 
-      def advisory_unlock!
-        advisory_unlock while advisory_locked?
-      end
+    private
 
-      private
-
-      def sanitize_sql_for_conditions(*args)
-        # Made public in Rails 5.2
-        self.class.send(:sanitize_sql_for_conditions, *args)
-      end
+    def sanitize_sql_for_conditions(*args)
+      # Made public in Rails 5.2
+      self.class.send(:sanitize_sql_for_conditions, *args)
     end
   end
 end