📂 Add option for gzip_compression_level for Rack::Deflater.

`:gzip_compression_level ::` An integer from 0 to 9 controlling the
level of compression; 1 is fastest and produces the least compression,
and 9 is slowest and produces the most compression. 0 is no compression.
The default is 6. This is only needed for the `gzip` type encoding.

CHANGELOG.md

@@ -11,6 +11,7 @@ All notable changes to this project will be documented in this file. For info on
 ### Added
 
 - `Rack::RewindableInput` supports size. ([@ahorek](https://github.com/ahorek))
+- `Rack::Deflater` supports `gzip_compression_level`. ([@bayleedev](https://github.com/bayleedev))
 
 ### Changed
 

lib/rack/deflater.rb

@@ -33,11 +33,18 @@ class Deflater
     # :sync :: determines if the stream is going to be flushed after every chunk.  Flushing after every chunk reduces
     #          latency for time-sensitive streaming applications, but hurts compression and throughput.
     #          Defaults to +true+.
+    # :gzip_compression_level ::  An integer from 0 to 9 controlling the level of
+    #                          compression; 1 is fastest and produces the least
+    #                          compression, and 9 is slowest and produces the
+    #                          most compression. 0 is no compression. The
+    #                          default is 6. This is only needed for the `gzip`
+    #                          type encoding.
     def initialize(app, options = {})
       @app = app
       @condition = options[:if]
       @compressible_types = options[:include]
       @sync = options.fetch(:sync, true)
+      @gzip_compression_level = options.fetch(:gzip_compression_level, 6)
     end
 
     def call(env)
@@ -65,7 +72,7 @@ def call(env)
         headers.delete(CONTENT_LENGTH)
         mtime = headers["Last-Modified"]
         mtime = Time.httpdate(mtime).to_i if mtime
-        [status, headers, GzipStream.new(body, mtime, @sync)]
+        [status, headers, GzipStream.new(body, mtime, @sync, @gzip_compression_level)]
       when "identity"
         [status, headers, body]
       when nil
@@ -82,16 +89,18 @@ class GzipStream
       # mtime :: The modification time of the body, used to set the
       #          modification time in the gzip header.
       # sync :: Whether to flush each gzip chunk as soon as it is ready.
-      def initialize(body, mtime, sync)
+      # gzip_compression_level :: The compression value for gzip.
+      def initialize(body, mtime, sync, gzip_compression_level)
         @body = body
         @mtime = mtime
         @sync = sync
+        @gzip_compression_level = gzip_compression_level
       end
 
       # Yield gzip compressed strings to the given block.
       def each(&block)
         @writer = block
-        gzip = ::Zlib::GzipWriter.new(self)
+        gzip = ::Zlib::GzipWriter.new(self, @gzip_compression_level)
         gzip.mtime = @mtime if @mtime
         @body.each { |part|
           # Skip empty strings, as they would result in no output,

test/spec_deflater.rb

@@ -402,6 +402,31 @@ class << app_body; def each; yield('foo'); yield('bar'); end; end
     verify(200, response, 'gzip', options)
   end
 
+  it 'will change gzip level' do
+    response = 'Hello World!' * 1000
+    small_options = {
+      'deflater_options' => { gzip_compression_level: 9 },
+      'skip_body_verify' => true,
+    }
+    fast_options = {
+      'deflater_options' => { gzip_compression_level: 1 },
+      'skip_body_verify' => true,
+    }
+    verify(200, response, 'gzip', small_options) do |_, _, body_small|
+      verify(200, response, 'gzip', fast_options) do |_, _, body_fast|
+        small_bytes = 0
+        body_small.each do |part|
+          small_bytes += part.bytesize
+        end
+        fast_bytes = 0
+        body_fast.each do |part|
+          fast_bytes += part.bytesize
+        end
+        assert small_bytes < fast_bytes
+      end
+    end
+  end
+
   it 'will honor sync: false to avoid unnecessary flushing' do
     app_body = Object.new
     class << app_body