Merge pull request #40 from Sage/mutex

Use a mutex when checking out and checking in connections

Author: ianoxley

lib/mysql_framework/connector.rb

@@ -4,6 +4,7 @@ module MysqlFramework
   class Connector
     def initialize(options = {})
       @options = default_options.merge(options)
+      @mutex = Mutex.new
 
       Mysql2::Client.default_query_options.merge!(symbolize_keys: true, cast_booleans: true)
     end
@@ -25,7 +26,7 @@ def dispose
 
       until @connection_pool.empty?
         conn = @connection_pool.pop(true)
-        conn.close
+        conn&.close
       end
 
       @connection_pool = nil
@@ -38,31 +39,37 @@ def connections
 
     # This method is called to fetch a client from the connection pool.
     def check_out
-      return new_client unless connection_pool_enabled?
+      @mutex.synchronize do
+        begin
+          return new_client unless connection_pool_enabled?
 
-      client = @connection_pool.pop(true)
+          client = @connection_pool.pop(true)
 
-      client.ping if @options[:reconnect]
+          client.ping if @options[:reconnect]
 
-      client
-    rescue ThreadError
-      if @created_connections < max_pool_size
-        client = new_client
-        @created_connections += 1
-        return client
-      end
+          client
+        rescue ThreadError
+          if @created_connections < max_pool_size
+            client = new_client
+            @created_connections += 1
+            return client
+          end
 
-      MysqlFramework.logger.error { "[#{self.class}] - Database connection pool depleted." }
+          MysqlFramework.logger.error { "[#{self.class}] - Database connection pool depleted." }
 
-      raise 'Database connection pool depleted.'
+          raise 'Database connection pool depleted.'
+        end
+      end
     end
 
     # This method is called to check a client back in to the connection when no longer needed.
     def check_in(client)
-      return client&.close unless connection_pool_enabled?
+      @mutex.synchronize do
+        return client&.close unless connection_pool_enabled?
 
-      client = new_client if client.nil? || client.closed?
-      @connection_pool.push(client)
+        client = new_client if client&.closed?
+        @connection_pool.push(client)
+      end
     end
 
     # This method is called to use a client from the connection pool.

lib/mysql_framework/version.rb

@@ -1,5 +1,5 @@
 # frozen_string_literal: true
 
 module MysqlFramework
-  VERSION = '2.1.3'
+  VERSION = '2.1.4'
 end

spec/lib/mysql_framework/connector_spec.rb

@@ -118,6 +118,12 @@
   end
 
   describe '#check_out' do
+    it 'calls synchronize on the mutex' do
+      expect(subject.instance_variable_get(:@mutex)).to receive(:synchronize)
+
+      subject.check_out
+    end
+
     context 'when connection pooling is enabled' do
       context 'when there are available connections' do
         before do
@@ -203,6 +209,12 @@
   end
 
   describe '#check_in' do
+    it 'calls synchronize on the mutex' do
+      expect(subject.instance_variable_get(:@mutex)).to receive(:synchronize)
+
+      subject.check_out
+    end
+
     context 'when connection pooling is enabled' do
       it 'returns the provided client to the connection pool' do
         expect(subject.connections).to receive(:push).with(client)