Add optional automatic response body compression

This behavior can be enabled with the `compress` protocol option.
See the `compress_response` example for more details.

All tests are now ran with and without compression for both HTTP
and HTTPS.

examples/compress_response/README.md

@@ -0,0 +1,62 @@
+Cowboy Compress Response
+========================
+
+To compile this example you need rebar in your PATH.
+
+Type the following command:
+```
+$ rebar get-deps compile
+```
+
+You can then start the Erlang node with the following command:
+```
+./start.sh
+```
+
+Then point your browser to the indicated URL.
+
+Example
+-------
+
+``` bash
+$ curl -i http://localhost:8080
+HTTP/1.1 200 OK
+connection: keep-alive
+server: Cowboy
+date: Mon, 07 Jan 2013 18:42:29 GMT
+content-length: 909
+
+A cowboy is an animal herder who tends cattle on ranches in North America,
+traditionally on horseback, and often performs a multitude of other ranch-
+related tasks. The historic American cowboy of the late 19th century arose
+from the vaquero traditions of northern Mexico and became a figure of special
+significance and legend. A subtype, called a wrangler, specifically tends the
+horses used to work cattle. In addition to ranch work, some cowboys work for
+or participate in rodeos. Cowgirls, first defined as such in the late 19th
+century, had a less-well documented historical role, but in the modern world
+have established the ability to work at virtually identical tasks and obtained
+considerable respect for their achievements. There are also cattle handlers
+in many other parts of the world, particularly South America and Australia,
+who perform work similar to the cowboy in their respective nations.
+
+$ curl -i --compressed http://localhost:8080
+HTTP/1.1 200 OK
+connection: keep-alive
+server: Cowboy
+date: Mon, 07 Jan 2013 18:42:30 GMT
+content-encoding: gzip
+content-length: 510
+
+A cowboy is an animal herder who tends cattle on ranches in North America,
+traditionally on horseback, and often performs a multitude of other ranch-
+related tasks. The historic American cowboy of the late 19th century arose
+from the vaquero traditions of northern Mexico and became a figure of special
+significance and legend. A subtype, called a wrangler, specifically tends the
+horses used to work cattle. In addition to ranch work, some cowboys work for
+or participate in rodeos. Cowgirls, first defined as such in the late 19th
+century, had a less-well documented historical role, but in the modern world
+have established the ability to work at virtually identical tasks and obtained
+considerable respect for their achievements. There are also cattle handlers
+in many other parts of the world, particularly South America and Australia,
+who perform work similar to the cowboy in their respective nations.
+```

examples/compress_response/rebar.config

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+{deps, [
+	{cowboy, ".*",
+		{git, "git://github.com/extend/cowboy.git", "master"}}
+]}.

examples/compress_response/src/compress_response.app.src

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+%% Feel free to use, reuse and abuse the code in this file.
+
+{application, compress_response, [
+	{description, "Cowboy Compress Response example."},
+	{vsn, "1"},
+	{modules, []},
+	{registered, []},
+	{applications, [
+		kernel,
+		stdlib,
+		cowboy
+	]},
+	{mod, {compress_response_app, []}},
+	{env, []}
+]}.

examples/compress_response/src/compress_response.erl

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+%% Feel free to use, reuse and abuse the code in this file.
+
+-module(compress_response).
+
+%% API.
+-export([start/0]).
+
+%% API.
+
+start() ->
+	ok = application:start(crypto),
+	ok = application:start(ranch),
+	ok = application:start(cowboy),
+	ok = application:start(compress_response).

examples/compress_response/src/compress_response_app.erl

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+%% Feel free to use, reuse and abuse the code in this file.
+
+%% @private
+-module(compress_response_app).
+-behaviour(application).
+
+%% API.
+-export([start/2]).
+-export([stop/1]).
+
+%% API.
+
+start(_Type, _Args) ->
+	Dispatch = [
+		{'_', [
+			{[], toppage_handler, []}
+		]}
+	],
+	{ok, _} = cowboy:start_http(http, 100, [{port, 8080}], [
+		{compress, true},
+		{env, [{dispatch, Dispatch}]}
+	]),
+	compress_response_sup:start_link().
+
+stop(_State) ->
+	ok.

examples/compress_response/src/compress_response_sup.erl

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+%% Feel free to use, reuse and abuse the code in this file.
+
+%% @private
+-module(compress_response_sup).
+-behaviour(supervisor).
+
+%% API.
+-export([start_link/0]).
+
+%% supervisor.
+-export([init/1]).
+
+%% API.
+
+-spec start_link() -> {ok, pid()}.
+start_link() ->
+	supervisor:start_link({local, ?MODULE}, ?MODULE, []).
+
+%% supervisor.
+
+init([]) ->
+	Procs = [],
+	{ok, {{one_for_one, 10, 10}, Procs}}.

examples/compress_response/src/toppage_handler.erl

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+%% Feel free to use, reuse and abuse the code in this file.
+
+%% @doc Compress response handler.
+-module(toppage_handler).
+
+-export([init/3]).
+-export([handle/2]).
+-export([terminate/2]).
+
+init(_Transport, Req, []) ->
+	{ok, Req, undefined}.
+
+handle(Req, State) ->
+	BigBody =
+<<"A cowboy is an animal herder who tends cattle on ranches in North America,
+traditionally on horseback, and often performs a multitude of other ranch-
+related tasks. The historic American cowboy of the late 19th century arose
+from the vaquero traditions of northern Mexico and became a figure of special
+significance and legend. A subtype, called a wrangler, specifically tends the
+horses used to work cattle. In addition to ranch work, some cowboys work for
+or participate in rodeos. Cowgirls, first defined as such in the late 19th
+century, had a less-well documented historical role, but in the modern world
+have established the ability to work at virtually identical tasks and obtained
+considerable respect for their achievements. There are also cattle handlers
+in many other parts of the world, particularly South America and Australia,
+who perform work similar to the cowboy in their respective nations.\n">>,
+	{ok, Req2} = cowboy_req:reply(200, [], BigBody, Req),
+	{ok, Req2, State}.
+
+terminate(_Req, _State) ->
+	ok.

examples/compress_response/start.sh

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+#!/bin/sh
+erl -pa ebin deps/*/ebin -s compress_response \
+	-eval "io:format(\"Point your browser at http://localhost:8080~n\")."