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<title>class Rack::Deflater - rack-2.2.10 Documentation</title>
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<li ><a href="#method-c-new">::new</a>
<li ><a href="#method-i-call">#call</a>
<li ><a href="#method-i-should_deflate-3F">#should_deflate?</a>
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<h1 id="class-Rack::Deflater" class="class">
class Rack::Deflater
</h1>
<section class="description">
<p>This middleware enables content encoding of http responses, usually for purposes of compression.</p>
<p>Currently supported encodings:</p>
<ul><li>
<p>gzip</p>
</li><li>
<p>identity (no transformation)</p>
</li></ul>
<p>This middleware automatically detects when encoding is supported and allowed. For example no encoding is made when a cache directive of 'no-transform' is present, when the response status code is one that doesn't allow an entity body, or when the body is empty.</p>
<p>Note that despite the name, <a href="Deflater.html"><code>Deflater</code></a> does not support the <code>deflate</code> encoding.</p>
</section>
<section id="5Buntitled-5D" class="documentation-section">
<section id="public-class-5Buntitled-5D-method-details" class="method-section">
<header>
<h3>Public Class Methods</h3>
</header>
<div id="method-c-new" class="method-detail ">
<div class="method-heading">
<span class="method-name">new</span><span
class="method-args">(app, options = {})</span>
<span class="method-click-advice">click to toggle source</span>
</div>
<div class="method-description">
<p>Creates <a href="Deflater.html"><code>Rack::Deflater</code></a> middleware. Options:</p>
<dl class="rdoc-list note-list"><dt>:if
<dd>
<p>a lambda enabling / disabling deflation based on returned boolean value (e.g <code>use Rack::Deflater, :if => lambda { |*, body| sum=0; body.each { |i| sum += i.length }; sum > 512 }</code>). However, be aware that calling `body.each` inside the block will break cases where `body.each` is not idempotent, such as when it is an <code>IO</code> instance.</p>
</dd><dt>:include
<dd>
<p>a list of content types that should be compressed. By default, all content types are compressed.</p>
</dd><dt>:sync
<dd>
<p>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 <code>true</code>.</p>
</dd></dl>
<div class="method-source-code" id="new-source">
<pre><span class="ruby-comment"># File lib/rack/deflater.rb, line 36</span>
<span class="ruby-keyword">def</span> <span class="ruby-identifier ruby-title">initialize</span>(<span class="ruby-identifier">app</span>, <span class="ruby-identifier">options</span> = {})
<span class="ruby-ivar">@app</span> = <span class="ruby-identifier">app</span>
<span class="ruby-ivar">@condition</span> = <span class="ruby-identifier">options</span>[<span class="ruby-value">:if</span>]
<span class="ruby-ivar">@compressible_types</span> = <span class="ruby-identifier">options</span>[<span class="ruby-value">:include</span>]
<span class="ruby-ivar">@sync</span> = <span class="ruby-identifier">options</span>.<span class="ruby-identifier">fetch</span>(<span class="ruby-value">:sync</span>, <span class="ruby-keyword">true</span>)
<span class="ruby-keyword">end</span></pre>
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</section>
<section id="public-instance-5Buntitled-5D-method-details" class="method-section">
<header>
<h3>Public Instance Methods</h3>
</header>
<div id="method-i-call" class="method-detail ">
<div class="method-heading">
<span class="method-name">call</span><span
class="method-args">(env)</span>
<span class="method-click-advice">click to toggle source</span>
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<div class="method-description">
<div class="method-source-code" id="call-source">
<pre><span class="ruby-comment"># File lib/rack/deflater.rb, line 43</span>
<span class="ruby-keyword">def</span> <span class="ruby-identifier ruby-title">call</span>(<span class="ruby-identifier">env</span>)
<span class="ruby-identifier">status</span>, <span class="ruby-identifier">headers</span>, <span class="ruby-identifier">body</span> = <span class="ruby-ivar">@app</span>.<span class="ruby-identifier">call</span>(<span class="ruby-identifier">env</span>)
<span class="ruby-identifier">headers</span> = <span class="ruby-constant">Utils</span><span class="ruby-operator">::</span><span class="ruby-constant">HeaderHash</span>[<span class="ruby-identifier">headers</span>]
<span class="ruby-keyword">unless</span> <span class="ruby-identifier">should_deflate?</span>(<span class="ruby-identifier">env</span>, <span class="ruby-identifier">status</span>, <span class="ruby-identifier">headers</span>, <span class="ruby-identifier">body</span>)
<span class="ruby-keyword">return</span> [<span class="ruby-identifier">status</span>, <span class="ruby-identifier">headers</span>, <span class="ruby-identifier">body</span>]
<span class="ruby-keyword">end</span>
<span class="ruby-identifier">request</span> = <span class="ruby-constant">Request</span>.<span class="ruby-identifier">new</span>(<span class="ruby-identifier">env</span>)
<span class="ruby-identifier">encoding</span> = <span class="ruby-constant">Utils</span>.<span class="ruby-identifier">select_best_encoding</span>(<span class="ruby-node">%w(gzip identity)</span>,
<span class="ruby-identifier">request</span>.<span class="ruby-identifier">accept_encoding</span>)
<span class="ruby-comment"># Set the Vary HTTP header.</span>
<span class="ruby-identifier">vary</span> = <span class="ruby-identifier">headers</span>[<span class="ruby-string">"Vary"</span>].<span class="ruby-identifier">to_s</span>.<span class="ruby-identifier">split</span>(<span class="ruby-string">","</span>).<span class="ruby-identifier">map</span>(<span class="ruby-operator">&</span><span class="ruby-value">:strip</span>)
<span class="ruby-keyword">unless</span> <span class="ruby-identifier">vary</span>.<span class="ruby-identifier">include?</span>(<span class="ruby-string">"*"</span>) <span class="ruby-operator">||</span> <span class="ruby-identifier">vary</span>.<span class="ruby-identifier">include?</span>(<span class="ruby-string">"Accept-Encoding"</span>)
<span class="ruby-identifier">headers</span>[<span class="ruby-string">"Vary"</span>] = <span class="ruby-identifier">vary</span>.<span class="ruby-identifier">push</span>(<span class="ruby-string">"Accept-Encoding"</span>).<span class="ruby-identifier">join</span>(<span class="ruby-string">","</span>)
<span class="ruby-keyword">end</span>
<span class="ruby-keyword">case</span> <span class="ruby-identifier">encoding</span>
<span class="ruby-keyword">when</span> <span class="ruby-string">"gzip"</span>
<span class="ruby-identifier">headers</span>[<span class="ruby-string">'Content-Encoding'</span>] = <span class="ruby-string">"gzip"</span>
<span class="ruby-identifier">headers</span>.<span class="ruby-identifier">delete</span>(<span class="ruby-constant">CONTENT_LENGTH</span>)
<span class="ruby-identifier">mtime</span> = <span class="ruby-identifier">headers</span>[<span class="ruby-string">"Last-Modified"</span>]
<span class="ruby-identifier">mtime</span> = <span class="ruby-constant">Time</span>.<span class="ruby-identifier">httpdate</span>(<span class="ruby-identifier">mtime</span>).<span class="ruby-identifier">to_i</span> <span class="ruby-keyword">if</span> <span class="ruby-identifier">mtime</span>
[<span class="ruby-identifier">status</span>, <span class="ruby-identifier">headers</span>, <span class="ruby-constant">GzipStream</span>.<span class="ruby-identifier">new</span>(<span class="ruby-identifier">body</span>, <span class="ruby-identifier">mtime</span>, <span class="ruby-ivar">@sync</span>)]
<span class="ruby-keyword">when</span> <span class="ruby-string">"identity"</span>
[<span class="ruby-identifier">status</span>, <span class="ruby-identifier">headers</span>, <span class="ruby-identifier">body</span>]
<span class="ruby-keyword">when</span> <span class="ruby-keyword">nil</span>
<span class="ruby-identifier">message</span> = <span class="ruby-node">"An acceptable encoding for the requested resource #{request.fullpath} could not be found."</span>
<span class="ruby-identifier">bp</span> = <span class="ruby-constant">Rack</span><span class="ruby-operator">::</span><span class="ruby-constant">BodyProxy</span>.<span class="ruby-identifier">new</span>([<span class="ruby-identifier">message</span>]) { <span class="ruby-identifier">body</span>.<span class="ruby-identifier">close</span> <span class="ruby-keyword">if</span> <span class="ruby-identifier">body</span>.<span class="ruby-identifier">respond_to?</span>(<span class="ruby-value">:close</span>) }
[<span class="ruby-value">406</span>, { <span class="ruby-constant">CONTENT_TYPE</span> <span class="ruby-operator">=></span> <span class="ruby-string">"text/plain"</span>, <span class="ruby-constant">CONTENT_LENGTH</span> <span class="ruby-operator">=></span> <span class="ruby-identifier">message</span>.<span class="ruby-identifier">length</span>.<span class="ruby-identifier">to_s</span> }, <span class="ruby-identifier">bp</span>]
<span class="ruby-keyword">end</span>
<span class="ruby-keyword">end</span></pre>
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</section>
<section id="private-instance-5Buntitled-5D-method-details" class="method-section">
<header>
<h3>Private Instance Methods</h3>
</header>
<div id="method-i-should_deflate-3F" class="method-detail ">
<div class="method-heading">
<span class="method-name">should_deflate?</span><span
class="method-args">(env, status, headers, body)</span>
<span class="method-click-advice">click to toggle source</span>
</div>
<div class="method-description">
<p>Whether the body should be compressed.</p>
<div class="method-source-code" id="should_deflate-3F-source">
<pre><span class="ruby-comment"># File lib/rack/deflater.rb, line 122</span>
<span class="ruby-keyword">def</span> <span class="ruby-identifier ruby-title">should_deflate?</span>(<span class="ruby-identifier">env</span>, <span class="ruby-identifier">status</span>, <span class="ruby-identifier">headers</span>, <span class="ruby-identifier">body</span>)
<span class="ruby-comment"># Skip compressing empty entity body responses and responses with</span>
<span class="ruby-comment"># no-transform set.</span>
<span class="ruby-keyword">if</span> <span class="ruby-constant">Utils</span><span class="ruby-operator">::</span><span class="ruby-constant">STATUS_WITH_NO_ENTITY_BODY</span>.<span class="ruby-identifier">key?</span>(<span class="ruby-identifier">status</span>.<span class="ruby-identifier">to_i</span>) <span class="ruby-operator">||</span>
<span class="ruby-regexp">/\bno-transform\b/</span>.<span class="ruby-identifier">match?</span>(<span class="ruby-identifier">headers</span>[<span class="ruby-string">'Cache-Control'</span>].<span class="ruby-identifier">to_s</span>) <span class="ruby-operator">||</span>
<span class="ruby-identifier">headers</span>[<span class="ruby-string">'Content-Encoding'</span>]&.<span class="ruby-identifier">!~</span>(<span class="ruby-regexp">/\bidentity\b/</span>)
<span class="ruby-keyword">return</span> <span class="ruby-keyword">false</span>
<span class="ruby-keyword">end</span>
<span class="ruby-comment"># Skip if @compressible_types are given and does not include request's content type</span>
<span class="ruby-keyword">return</span> <span class="ruby-keyword">false</span> <span class="ruby-keyword">if</span> <span class="ruby-ivar">@compressible_types</span> <span class="ruby-operator">&&</span> <span class="ruby-operator">!</span>(<span class="ruby-identifier">headers</span>.<span class="ruby-identifier">has_key?</span>(<span class="ruby-string">'Content-Type'</span>) <span class="ruby-operator">&&</span> <span class="ruby-ivar">@compressible_types</span>.<span class="ruby-identifier">include?</span>(<span class="ruby-identifier">headers</span>[<span class="ruby-string">'Content-Type'</span>][<span class="ruby-regexp">/[^;]*/</span>]))
<span class="ruby-comment"># Skip if @condition lambda is given and evaluates to false</span>
<span class="ruby-keyword">return</span> <span class="ruby-keyword">false</span> <span class="ruby-keyword">if</span> <span class="ruby-ivar">@condition</span> <span class="ruby-operator">&&</span> <span class="ruby-operator">!</span><span class="ruby-ivar">@condition</span>.<span class="ruby-identifier">call</span>(<span class="ruby-identifier">env</span>, <span class="ruby-identifier">status</span>, <span class="ruby-identifier">headers</span>, <span class="ruby-identifier">body</span>)
<span class="ruby-comment"># No point in compressing empty body, also handles usage with</span>
<span class="ruby-comment"># Rack::Sendfile.</span>
<span class="ruby-keyword">return</span> <span class="ruby-keyword">false</span> <span class="ruby-keyword">if</span> <span class="ruby-identifier">headers</span>[<span class="ruby-constant">CONTENT_LENGTH</span>] <span class="ruby-operator">==</span> <span class="ruby-string">'0'</span>
<span class="ruby-keyword">true</span>
<span class="ruby-keyword">end</span></pre>
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