Skip additional string length access in rb_mysql_client_escape and benchmark escaping "clean" strings as well

benchmark/escape.rb

@@ -7,31 +7,33 @@ require 'mysql'
 require 'mysql2'
 require 'do_mysql'
 
-number_of = 1000
-str = "abc'def\"ghi\0jkl%mno"
+def run_escape_benchmarks(str, number_of = 1000)
+  Benchmark.bmbm do |x|
+    mysql = Mysql.new("localhost", "root")
+    x.report do
+      puts "Mysql #{str.inspect}"
+      number_of.times do
+        mysql.quote str
+      end
+    end
 
-Benchmark.bmbm do |x|
-  mysql = Mysql.new("localhost", "root")
-  x.report do
-    puts "Mysql"
-    number_of.times do
-      mysql.quote str
+    mysql2 = Mysql2::Client.new(:host => "localhost", :username => "root")
+    x.report do
+      puts "Mysql2 #{str.inspect}"
+      number_of.times do
+        mysql2.escape str
+      end
+    end
+
+    do_mysql = DataObjects::Connection.new("mysql://localhost/test")
+    x.report do
+      puts "do_mysql #{str.inspect}"
+      number_of.times do
+        do_mysql.quote_string str
+      end
     end
   end
+end
 
-  mysql2 = Mysql2::Client.new(:host => "localhost", :username => "root")
-  x.report do
-    puts "Mysql2"
-    number_of.times do
-      mysql2.escape str
-    end
-  end
-
-  do_mysql = DataObjects::Connection.new("mysql://localhost/test")
-  x.report do
-    puts "do_mysql"
-    number_of.times do
-      do_mysql.quote_string str
-    end
-  end
-end
+run_escape_benchmarks "abc'def\"ghi\0jkl%mno"
+run_escape_benchmarks "clean string"

ext/mysql2/client.c

@@ -335,7 +335,7 @@ static VALUE rb_mysql_client_escape(VALUE self, VALUE str) {
   Data_Get_Struct(self, MYSQL, client);
 
   REQUIRE_OPEN_DB(client);
-  newLen = mysql_real_escape_string(client, escaped, StringValuePtr(str), RSTRING_LEN(str));
+  newLen = mysql_real_escape_string(client, escaped, StringValuePtr(str), oldLen);
   if (newLen == oldLen) {
     // no need to return a new ruby string if nothing changed
     return str;