From bb089d8ab30bc3b210d41563872357e65ece0d8b Mon Sep 17 00:00:00 2001
From: navaneeth <navaneethpk@outlook.com>
Date: Fri, 14 May 2021 12:39:38 +0530
Subject: [PATCH] Feature: Purge cached connections on data source update

---
 app/services/concerns/datasource_utils.rb | 22 +++++++++++++++
 app/services/mysql_query_service.rb       | 27 +++++++++++--------
 app/services/postgresql_query_service.rb  | 33 +++++++++++++----------
 3 files changed, 57 insertions(+), 25 deletions(-)
 create mode 100644 app/services/concerns/datasource_utils.rb

diff --git a/app/services/concerns/datasource_utils.rb b/app/services/concerns/datasource_utils.rb
new file mode 100644
index 0000000000..1e7fd1ff4e
--- /dev/null
+++ b/app/services/concerns/datasource_utils.rb
@@ -0,0 +1,22 @@
+module DatasourceUtils
+  extend ActiveSupport::Concern
+
+  def get_cached_connection(data_source)
+
+    connection = nil
+    if $connections.include? data_source.id
+      data = $connections[data_source.id]
+      if data[:updated_at] === data_source.updated_at
+        connection = $connections[data_source.id][:connection]
+      end
+    end
+
+    connection            
+  end
+
+  def cache_connection(data_source, connection)
+    $connections[data_source.id] = { connection: connection, updated_at: data_source.updated_at }
+  end
+
+end
+  
\ No newline at end of file
diff --git a/app/services/mysql_query_service.rb b/app/services/mysql_query_service.rb
index 25a07ef281..981b54de60 100644
--- a/app/services/mysql_query_service.rb
+++ b/app/services/mysql_query_service.rb
@@ -1,4 +1,5 @@
 class MysqlQueryService
+  include DatasourceUtils
   attr_accessor :data_query, :data_source, :options, :source_options, :current_user
 
   def initialize(data_query, options, source_options, current_user)
@@ -20,9 +21,19 @@ class MysqlQueryService
   end
 
   def process
-    if $connections.include? data_source.id
-      connection = $connections[data_source.id][:connection]
-    else
+
+    connection = get_cached_connection(data_source)
+    connection = create_connection unless connection
+
+    query_text = options['query']
+
+    results = connection.query(query_text)
+
+    { status: 'success', data: results.to_a }
+  end
+
+  private
+    def create_connection
       connection = Mysql2::Client.new(
         host: source_options['host'],
         username: source_options['username'],
@@ -31,13 +42,7 @@ class MysqlQueryService
         database: source_options['database']
       )
 
-      $connections[data_source.id] = { connection: connection }
+      cache_connection(data_source, connection)
+      connection
     end
-
-    query_text = options['query']
-
-    results = connection.query(query_text)
-
-    { status: 'success', data: results.to_a }
-  end
 end
diff --git a/app/services/postgresql_query_service.rb b/app/services/postgresql_query_service.rb
index d04b2250ff..364356e27e 100644
--- a/app/services/postgresql_query_service.rb
+++ b/app/services/postgresql_query_service.rb
@@ -1,4 +1,5 @@
 class PostgresqlQueryService
+  include DatasourceUtils
   attr_accessor :data_query, :data_source, :options, :source_options, :current_user
 
   def initialize(data_query, options, source_options, current_user)
@@ -20,6 +21,10 @@ class PostgresqlQueryService
   end
 
   def process
+
+    connection = get_cached_connection(data_source)
+    connection = create_connection unless connection
+
     query_text = ''
     query_text = if options['mode'] === 'gui'
                    send("generate_#{options['operation']}_query", options)
@@ -27,20 +32,6 @@ class PostgresqlQueryService
                    options['query']
                  end
 
-    if $connections.include? data_source.id
-      connection = $connections[data_source.id][:connection]
-    else
-      connection = PG.connect(
-        dbname: source_options['database'],
-        user: source_options['username'],
-        password: source_options['password'],
-        host: source_options['host'],
-        port: source_options['port']
-      )
-
-      $connections[data_source.id] = { connection: connection }
-    end
-
     result = connection.exec(query_text)
     { status: 'success', data: result.to_a }
   end
@@ -67,4 +58,18 @@ class PostgresqlQueryService
 
     query_text
   end
+
+  def create_connection 
+    connection = PG.connect(
+      dbname: source_options['database'],
+      user: source_options['username'],
+      password: source_options['password'],
+      host: source_options['host'],
+      port: source_options['port']
+    )
+    
+    cache_connection(data_source, connection)
+
+    connection
+  end
 end