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

benchmark/escape.rb

@@ -7,13 +7,11 @@ require 'mysql'
 require 'mysql2'
 require 'do_mysql'
 
-number_of = 1000
-str = "abc'def\"ghi\0jkl%mno"
-
-Benchmark.bmbm do |x|
+def run_escape_benchmarks(str, number_of = 1000)
+  Benchmark.bmbm do |x|
     mysql = Mysql.new("localhost", "root")
     x.report do
-    puts "Mysql"
+      puts "Mysql #{str.inspect}"
       number_of.times do
         mysql.quote str
       end
@@ -21,7 +19,7 @@ Benchmark.bmbm do |x|
 
     mysql2 = Mysql2::Client.new(:host => "localhost", :username => "root")
     x.report do
-    puts "Mysql2"
+      puts "Mysql2 #{str.inspect}"
       number_of.times do
         mysql2.escape str
       end
@@ -29,9 +27,13 @@ Benchmark.bmbm do |x|
 
     do_mysql = DataObjects::Connection.new("mysql://localhost/test")
     x.report do
-    puts "do_mysql"
+      puts "do_mysql #{str.inspect}"
       number_of.times do
         do_mysql.quote_string str
       end
     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;