From 38746d085b2c3344f6d26d38d48afb3a356a3e40 Mon Sep 17 00:00:00 2001
From: Ryuta Kamizono <kamipo@gmail.com>
Date: Wed, 16 Sep 2015 13:37:04 +0900
Subject: Add prepared statements support for `Mysql2Adapter`

---
 .../connection_adapters/mysql2_adapter.rb          | 77 +++++++++++++++-------
 1 file changed, 52 insertions(+), 25 deletions(-)

(limited to 'activerecord/lib/active_record/connection_adapters/mysql2_adapter.rb')

diff --git a/activerecord/lib/active_record/connection_adapters/mysql2_adapter.rb b/activerecord/lib/active_record/connection_adapters/mysql2_adapter.rb
index 3944698910..273a9ee5fa 100644
--- a/activerecord/lib/active_record/connection_adapters/mysql2_adapter.rb
+++ b/activerecord/lib/active_record/connection_adapters/mysql2_adapter.rb
@@ -1,6 +1,6 @@
 require 'active_record/connection_adapters/abstract_mysql_adapter'
 
-gem 'mysql2', '>= 0.3.18', '< 0.5'
+gem 'mysql2', '>= 0.4.2', '< 0.5'
 require 'mysql2'
 
 module ActiveRecord
@@ -33,7 +33,6 @@ module ActiveRecord
 
       def initialize(connection, logger, connection_options, config)
         super
-        @prepared_statements = false
         configure_connection
       end
 
@@ -126,9 +125,13 @@ module ActiveRecord
       # Returns an array of arrays containing the field values.
       # Order is the same as that returned by +columns+.
       def select_rows(sql, name = nil, binds = [])
-        result = execute(sql, name)
+        rows = if without_prepared_statement?(binds)
+          execute_and_free(sql, name) { |result| result.to_a }
+        else
+          exec_stmt_and_free(sql, name, binds) { |stmt, result| result.to_a }
+        end
         @connection.next_result while @connection.more_results?
-        result.to_a
+        rows
       end
 
       # Executes the SQL statement in the context of this connection.
@@ -143,34 +146,58 @@ module ActiveRecord
       end
 
       def exec_query(sql, name = 'SQL', binds = [], prepare: false)
-        result = execute(sql, name)
-        @connection.next_result while @connection.more_results?
-        ActiveRecord::Result.new(result.fields, result.to_a)
+        if without_prepared_statement?(binds)
+          execute_and_free(sql, name) do |result|
+            ActiveRecord::Result.new(result.fields, result.to_a) if result
+          end
+        else
+          exec_stmt_and_free(sql, name, binds, cache_stmt: prepare) do |stmt, result|
+            ActiveRecord::Result.new(result.fields, result.to_a) if result
+          end
+        end
       end
 
-      alias exec_without_stmt exec_query
-
-      def insert_sql(sql, name = nil, pk = nil, id_value = nil, sequence_name = nil)
-        super
-        id_value || @connection.last_id
+      def last_inserted_id(result = nil)
+        @connection.last_id
       end
-      alias :create :insert_sql
 
-      def exec_insert(sql, name, binds, pk = nil, sequence_name = nil)
-        execute to_sql(sql, binds), name
-      end
+      private
 
-      def exec_delete(sql, name, binds)
-        execute to_sql(sql, binds), name
-        @connection.affected_rows
-      end
-      alias :exec_update :exec_delete
+      def exec_stmt_and_free(sql, name, binds, cache_stmt: false)
+        if @connection
+          # make sure we carry over any changes to ActiveRecord::Base.default_timezone that have been
+          # made since we established the connection
+          @connection.query_options[:database_timezone] = ActiveRecord::Base.default_timezone
+        end
 
-      def last_inserted_id(result)
-        @connection.last_id
-      end
+        type_casted_binds = binds.map { |attr| type_cast(attr.value_for_database) }
 
-      private
+        log(sql, name, binds) do
+          if !cache_stmt
+            stmt = @connection.prepare(sql)
+          else
+            cache = @statements[sql] ||= {
+              stmt: @connection.prepare(sql)
+            }
+            stmt = cache[:stmt]
+          end
+
+          begin
+            result = stmt.execute(*type_casted_binds)
+          rescue Mysql2::Error => e
+            if !cache_stmt
+              stmt.close
+            else
+              @statements.delete(sql)
+            end
+            raise e
+          end
+
+          ret = yield stmt, result
+          stmt.close if !cache_stmt
+          ret
+        end
+      end
 
       def connect
         @connection = Mysql2::Client.new(@config)
-- 
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