From bf2ff249b97b31822cb02c4850dae15966b70a6f Mon Sep 17 00:00:00 2001
From: Kevin Clark <kclark@apache.org>
Date: Tue, 8 Jul 2008 23:20:15 +0000
Subject: [PATCH] rb: Buffer the slice!s in MemoryBuffer for a significant
 performance increase [THRIFT-63]

Author: Kevin Ballard <kevin@rapleaf.com>

Currently it buffers up to 4kB before throwing away the data.
Tests with 1MB shows the exact same performance characteristics.


git-svn-id: https://svn.apache.org/repos/asf/incubator/thrift/trunk@675049 13f79535-47bb-0310-9956-ffa450edef68
---
 lib/rb/lib/thrift/transport.rb | 30 ++++++++++++++++++++----------
 lib/rb/spec/transport_spec.rb  |  3 ++-
 2 files changed, 22 insertions(+), 11 deletions(-)

diff --git a/lib/rb/lib/thrift/transport.rb b/lib/rb/lib/thrift/transport.rb
index d55adf0d..6b1152e3 100644
--- a/lib/rb/lib/thrift/transport.rb
+++ b/lib/rb/lib/thrift/transport.rb
@@ -217,12 +217,16 @@ module Thrift
   deprecate_class! :TFramedTransportFactory => FramedTransportFactory
 
   class MemoryBuffer < Transport
+    GARBAGE_BUFFER_SIZE = 4*(2**10) # 4kB
+
     # If you pass a string to this, you should #dup that string
     # unless you want it to be modified by #read and #write
     #--
-    # yes this behavior is intentional
+    # this behavior is no longer required. If you wish to change it
+    # go ahead, just make sure the specs pass
     def initialize(buffer = nil)
       @buf = buffer || ''
+      @index = 0
     end
 
     def open?
@@ -236,20 +240,28 @@ module Thrift
     end
 
     def peek
-      not @buf.empty?
+      @index < @buf.size
     end
 
     # this method does not use the passed object directly but copies it
     def reset_buffer(new_buf = '')
       @buf.replace new_buf
+      @index = 0
     end
 
     def available
-      @buf.length
+      @buf.length - @index
     end
 
     def read(len)
-      @buf.slice!(0, len)
+      data = @buf.slice(@index, len)
+      @index += len
+      @index = @buf.size if @index > @buf.size
+      if @index >= GARBAGE_BUFFER_SIZE
+        @buf = @buf.slice(@index..-1)
+        @index = 0
+      end
+      data
     end
 
     def write(wbuf)
@@ -262,19 +274,17 @@ module Thrift
     # For fast binary protocol access
     def borrow(size = nil)
       if size.nil?
-        @buf[0..-1]
+        @buf[@index..-1]
       else
-        if size > @buf.length
+        if size > available
           raise EOFError # Memory buffers only get one shot.
         else
-          @buf[0..size]
+          @buf[@index, size]
         end
       end
     end
 
-    def consume!(size)
-      @buf.slice!(0, size)
-    end
+    alias_method :consume!, :read
   end
   deprecate_class! :TMemoryBuffer => MemoryBuffer
 
diff --git a/lib/rb/spec/transport_spec.rb b/lib/rb/spec/transport_spec.rb
index 1fe8600f..972e9846 100644
--- a/lib/rb/spec/transport_spec.rb
+++ b/lib/rb/spec/transport_spec.rb
@@ -240,7 +240,8 @@ class ThriftTransportSpec < Spec::ExampleGroup
       s = "this is a test"
       @buffer = MemoryBuffer.new(s)
       @buffer.read(4).should == "this"
-      s.should == " is a test"
+      s.slice!(-4..-1)
+      @buffer.read(@buffer.available).should == " is a "
     end
 
     it "should always remain open" do
-- 
2.17.1