From 27eb2d7ebd29239a5043a528c97c6dd218d03217 Mon Sep 17 00:00:00 2001
From: Eric Wong <normalperson@yhbt.net>
Date: Tue, 30 Nov 2010 16:26:20 -0800
Subject: support pass-through :encoding for deflate and gzip

These allow serving pre-compressed data off disk and
on-the-fly uncompressing for the few clients that do
not accept compressed responses.
---
 lib/metropolis.rb               |  3 +++
 lib/metropolis/common.rb        |  9 +++++++++
 lib/metropolis/deflate.rb       | 45 +++++++++++++++++++++++++++++++++++++++++
 lib/metropolis/gzip.rb          | 38 ++++++++++++++++++++++++++++++++++
 lib/metropolis/input_wrapper.rb | 21 +++++++++++++++++++
 5 files changed, 116 insertions(+)
 create mode 100644 lib/metropolis/deflate.rb
 create mode 100644 lib/metropolis/gzip.rb
 create mode 100644 lib/metropolis/input_wrapper.rb

(limited to 'lib')

diff --git a/lib/metropolis.rb b/lib/metropolis.rb
index a7cfc47..3afc3ec 100644
--- a/lib/metropolis.rb
+++ b/lib/metropolis.rb
@@ -3,6 +3,9 @@ require 'rack'
 require 'uri'
 
 module Metropolis
+  autoload :InputWrapper, 'metropolis/input_wrapper'
+  autoload :Deflate, 'metropolis/deflate'
+  autoload :Gzip, 'metropolis/gzip'
   autoload :TC, 'metropolis/tc'
   autoload :Hash, 'metropolis/hash'
 
diff --git a/lib/metropolis/common.rb b/lib/metropolis/common.rb
index 273a1b3..971accd 100644
--- a/lib/metropolis/common.rb
+++ b/lib/metropolis/common.rb
@@ -13,6 +13,15 @@ module Metropolis::Common
     if @readonly && @exclusive
       raise ArgumentError, ":readonly and :exclusive may not be used together"
     end
+    case @encoding = opts[:encoding]
+    when nil
+    when :deflate
+      extend(Metropolis::Deflate)
+    when :gzip
+      extend(Metropolis::Gzip)
+    else
+      raise ArgumentError, "unsupported encoding"
+    end
   end
 
   def r(code, body = nil)
diff --git a/lib/metropolis/deflate.rb b/lib/metropolis/deflate.rb
new file mode 100644
index 0000000..d585b43
--- /dev/null
+++ b/lib/metropolis/deflate.rb
@@ -0,0 +1,45 @@
+# -*- encoding: binary -*-
+require "zlib"
+
+# allows storing pre-deflated data on disk and serving it
+# as-is for clients that accept that deflate encoding
+module Metropolis::Deflate
+  def get(key, env)
+    status, headers, body = r = super
+    if 200 == status && /\bdeflate\b/ !~ env['HTTP_ACCEPT_ENCODING']
+      inflater = Zlib::Inflate.new(-Zlib::MAX_WBITS)
+      body[0] = "#{inflater.inflate(body[0])}#{inflater.finish}"
+      inflater.end
+      headers['Content-Length'] = body[0].size.to_s
+      headers.delete('Content-Encoding')
+      headers.delete('Vary')
+    end
+    r
+  end
+
+  def put(key, env)
+    Wrapper.new(env)
+    super(key, env)
+  end
+
+  def self.extended(obj)
+    obj.instance_eval do
+      @headers['Content-Encoding'] = 'deflate'
+      @headers['Vary'] = 'Accept-Encoding'
+    end
+  end
+
+  class Wrapper < Metropolis::InputWrapper
+
+    def read_all
+      deflater = Zlib::Deflate.new(
+        Zlib::DEFAULT_COMPRESSION,
+        # drop the zlib header which causes both Safari and IE to choke
+        -Zlib::MAX_WBITS,
+        Zlib::DEF_MEM_LEVEL,
+        Zlib::DEFAULT_STRATEGY
+      )
+      "#{deflater.deflate(@input.read)}#{deflater.finish}"
+    end
+  end
+end
diff --git a/lib/metropolis/gzip.rb b/lib/metropolis/gzip.rb
new file mode 100644
index 0000000..50d71ef
--- /dev/null
+++ b/lib/metropolis/gzip.rb
@@ -0,0 +1,38 @@
+# -*- encoding: binary -*-
+require "zlib"
+
+# allows storing pre-gzipped data on disk and serving it
+# as-is for clients that accept that gzip encoding
+module Metropolis::Gzip
+  def get(key, env)
+    status, headers, body = r = super
+    if 200 == status && /\bgzip\b/ !~ env['HTTP_ACCEPT_ENCODING']
+      body[0] = Zlib::GzipReader.new(StringIO.new(body[0])).read
+      headers['Content-Length'] = body[0].size.to_s
+      headers.delete('Content-Encoding')
+      headers.delete('Vary')
+    end
+    r
+  end
+
+  def put(key, env)
+    Wrapper.new(env)
+    super(key, env)
+  end
+
+  def self.extended(obj)
+    obj.instance_eval do
+      @headers['Content-Encoding'] = 'gzip'
+      @headers['Vary'] = 'Accept-Encoding'
+    end
+  end
+
+  class Wrapper < Metropolis::InputWrapper
+
+    def read_all
+      zipped = StringIO.new("")
+      Zlib::GzipWriter.wrap(zipped) { |io| io.write(@input.read) }
+      zipped.string
+    end
+  end
+end
diff --git a/lib/metropolis/input_wrapper.rb b/lib/metropolis/input_wrapper.rb
new file mode 100644
index 0000000..12a1bcc
--- /dev/null
+++ b/lib/metropolis/input_wrapper.rb
@@ -0,0 +1,21 @@
+# -*- encoding: binary -*-
+
+class Metropolis::InputWrapper
+  def initialize(env)
+    @input = env["rack.input"]
+    env["rack.input"] = self
+  end
+
+  def read(*args)
+    args.empty? and return read_all
+    ni
+  end
+
+  def ni(*args)
+    raise NotImplementedError
+  end
+
+  alias gets ni
+  alias each ni
+  alias rewind ni
+end
-- 
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