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<h3>Parent</h3>
<p class="link"><a href="Object.html">Object</a>
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<h3>Methods</h3>
<ul class="link-list" role="directory">
<li ><a href="#method-c-new">::new</a>
<li ><a href="#method-i-3C-3C">#<<</a>
<li ><a href="#method-i-clear">#clear</a>
<li ><a href="#method-i-close">#close</a>
<li ><a href="#method-i-closed-3F">#closed?</a>
<li ><a href="#method-i-deq">#deq</a>
<li ><a href="#method-i-empty-3F">#empty?</a>
<li ><a href="#method-i-enq">#enq</a>
<li ><a href="#method-i-length">#length</a>
<li ><a href="#method-i-num_waiting">#num_waiting</a>
<li ><a href="#method-i-pop">#pop</a>
<li ><a href="#method-i-push">#push</a>
<li ><a href="#method-i-shift">#shift</a>
<li ><a href="#method-i-size">#size</a>
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<h1 id="class-Queue" class="class">
class Queue
</h1>
<section class="description">
<p>The <a href="Queue.html"><code>Queue</code></a> class implements multi-producer, multi-consumer queues. It is especially useful in threaded programming when information must be exchanged safely between multiple threads. The <a href="Queue.html"><code>Queue</code></a> class implements all the required locking semantics.</p>
<p>The class implements FIFO type of queue. In a FIFO queue, the first tasks added are the first retrieved.</p>
<p>Example:</p>
<pre class="ruby"><span class="ruby-identifier">queue</span> = <span class="ruby-constant">Queue</span>.<span class="ruby-identifier">new</span>
<span class="ruby-identifier">producer</span> = <span class="ruby-constant">Thread</span>.<span class="ruby-identifier">new</span> <span class="ruby-keyword">do</span>
<span class="ruby-value">5</span>.<span class="ruby-identifier">times</span> <span class="ruby-keyword">do</span> <span class="ruby-operator">|</span><span class="ruby-identifier">i</span><span class="ruby-operator">|</span>
<span class="ruby-identifier">sleep</span> <span class="ruby-identifier">rand</span>(<span class="ruby-identifier">i</span>) <span class="ruby-comment"># simulate expense</span>
<span class="ruby-identifier">queue</span> <span class="ruby-operator"><<</span> <span class="ruby-identifier">i</span>
<span class="ruby-identifier">puts</span> <span class="ruby-node">"#{i} produced"</span>
<span class="ruby-keyword">end</span>
<span class="ruby-keyword">end</span>
<span class="ruby-identifier">consumer</span> = <span class="ruby-constant">Thread</span>.<span class="ruby-identifier">new</span> <span class="ruby-keyword">do</span>
<span class="ruby-value">5</span>.<span class="ruby-identifier">times</span> <span class="ruby-keyword">do</span> <span class="ruby-operator">|</span><span class="ruby-identifier">i</span><span class="ruby-operator">|</span>
<span class="ruby-identifier">value</span> = <span class="ruby-identifier">queue</span>.<span class="ruby-identifier">pop</span>
<span class="ruby-identifier">sleep</span> <span class="ruby-identifier">rand</span>(<span class="ruby-identifier">i</span><span class="ruby-operator">/</span><span class="ruby-value">2</span>) <span class="ruby-comment"># simulate expense</span>
<span class="ruby-identifier">puts</span> <span class="ruby-node">"consumed #{value}"</span>
<span class="ruby-keyword">end</span>
<span class="ruby-keyword">end</span>
<span class="ruby-identifier">consumer</span>.<span class="ruby-identifier">join</span>
</pre>
</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">()</span>
<span class="method-click-advice">click to toggle source</span>
</div>
<div class="method-description">
<p>Creates a new queue instance.</p>
<div class="method-source-code" id="new-source">
<pre>static VALUE
rb_queue_initialize(VALUE self)
{
struct rb_queue *q = queue_ptr(self);
RB_OBJ_WRITE(self, &q->que, ary_buf_new());
list_head_init(queue_waitq(q));
return self;
}</pre>
</div>
</div>
</div>
</section>
<section id="public-instance-5Buntitled-5D-method-details" class="method-section">
<header>
<h3>Public Instance Methods</h3>
</header>
<div id="method-i-3C-3C" class="method-detail method-alias">
<div class="method-heading">
<span class="method-name"><<</span><span
class="method-args">(p1)</span>
</div>
<div class="method-description">
</div>
<div class="aliases">
Alias for: <a href="Queue.html#method-i-push">push</a>
</div>
</div>
<div id="method-i-clear" class="method-detail ">
<div class="method-heading">
<span class="method-name">clear</span><span
class="method-args">()</span>
<span class="method-click-advice">click to toggle source</span>
</div>
<div class="method-description">
<p>Removes all objects from the queue.</p>
<div class="method-source-code" id="clear-source">
<pre>static VALUE
rb_queue_clear(VALUE self)
{
struct rb_queue *q = queue_ptr(self);
rb_ary_clear(check_array(self, q->que));
return self;
}</pre>
</div>
</div>
</div>
<div id="method-i-close" class="method-detail ">
<div class="method-heading">
<span class="method-callseq">
close
</span>
<span class="method-click-advice">click to toggle source</span>
</div>
<div class="method-description">
<p>Closes the queue. A closed queue cannot be re-opened.</p>
<p>After the call to close completes, the following are true:</p>
<ul><li>
<p><code>closed?</code> will return true</p>
</li><li>
<p><code>close</code> will be ignored.</p>
</li><li>
<p>calling enq/push/<< will raise a <code>ClosedQueueError</code>.</p>
</li><li>
<p>when <code>empty?</code> is false, calling deq/pop/shift will return an object from the queue as usual.</p>
</li><li>
<p>when <code>empty?</code> is true, deq(false) will not suspend the thread and will return nil. deq(true) will raise a <code>ThreadError</code>.</p>
</li></ul>
<p><a href="ClosedQueueError.html"><code>ClosedQueueError</code></a> is inherited from <a href="StopIteration.html"><code>StopIteration</code></a>, so that you can break loop block.</p>
<pre>Example:
q = Queue.new
Thread.new{
while e = q.deq # wait for nil to break loop
# ...
end
}
q.close</pre>
<div class="method-source-code" id="close-source">
<pre>static VALUE
rb_queue_close(VALUE self)
{
struct rb_queue *q = queue_ptr(self);
if (!queue_closed_p(self)) {
FL_SET(self, QUEUE_CLOSED);
wakeup_all(queue_waitq(q));
}
return self;
}</pre>
</div>
</div>
</div>
<div id="method-i-closed-3F" class="method-detail ">
<div class="method-heading">
<span class="method-callseq">
closed?
</span>
<span class="method-click-advice">click to toggle source</span>
</div>
<div class="method-description">
<p>Returns <code>true</code> if the queue is closed.</p>
<div class="method-source-code" id="closed-3F-source">
<pre>static VALUE
rb_queue_closed_p(VALUE self)
{
return queue_closed_p(self) ? Qtrue : Qfalse;
}</pre>
</div>
</div>
</div>
<div id="method-i-deq" class="method-detail method-alias">
<div class="method-heading">
<span class="method-name">deq</span><span
class="method-args">(*args)</span>
</div>
<div class="method-description">
</div>
<div class="aliases">
Alias for: <a href="Queue.html#method-i-pop">pop</a>
</div>
</div>
<div id="method-i-empty-3F" class="method-detail ">
<div class="method-heading">
<span class="method-callseq">
empty?
</span>
<span class="method-click-advice">click to toggle source</span>
</div>
<div class="method-description">
<p>Returns <code>true</code> if the queue is empty.</p>
<div class="method-source-code" id="empty-3F-source">
<pre>static VALUE
rb_queue_empty_p(VALUE self)
{
return queue_length(self, queue_ptr(self)) == 0 ? Qtrue : Qfalse;
}</pre>
</div>
</div>
</div>
<div id="method-i-enq" class="method-detail method-alias">
<div class="method-heading">
<span class="method-name">enq</span><span
class="method-args">(p1)</span>
</div>
<div class="method-description">
</div>
<div class="aliases">
Alias for: <a href="Queue.html#method-i-push">push</a>
</div>
</div>
<div id="method-i-length" class="method-detail ">
<div class="method-heading">
<span class="method-callseq">
length
</span>
<span class="method-click-advice">click to toggle source</span>
</div>
<div class="method-heading">
<span class="method-callseq">
size
</span>
</div>
<div class="method-description">
<p>Returns the length of the queue.</p>
<div class="method-source-code" id="length-source">
<pre>static VALUE
rb_queue_length(VALUE self)
{
return LONG2NUM(queue_length(self, queue_ptr(self)));
}</pre>
</div>
</div>
<div class="aliases">
Also aliased as: <a href="Queue.html#method-i-size">size</a>
</div>
</div>
<div id="method-i-num_waiting" class="method-detail ">
<div class="method-heading">
<span class="method-name">num_waiting</span><span
class="method-args">()</span>
<span class="method-click-advice">click to toggle source</span>
</div>
<div class="method-description">
<p>Returns the number of threads waiting on the queue.</p>
<div class="method-source-code" id="num_waiting-source">
<pre>static VALUE
rb_queue_num_waiting(VALUE self)
{
struct rb_queue *q = queue_ptr(self);
return INT2NUM(q->num_waiting);
}</pre>
</div>
</div>
</div>
<div id="method-i-pop" class="method-detail ">
<div class="method-heading">
<span class="method-callseq">
pop(non_block=false)
</span>
<span class="method-click-advice">click to toggle source</span>
</div>
<div class="method-heading">
<span class="method-callseq">
deq(non_block=false)
</span>
</div>
<div class="method-heading">
<span class="method-callseq">
shift(non_block=false)
</span>
</div>
<div class="method-description">
<p>Retrieves data from the queue.</p>
<p>If the queue is empty, the calling thread is suspended until data is pushed onto the queue. If <code>non_block</code> is true, the thread isn't suspended, and <code>ThreadError</code> is raised.</p>
<div class="method-source-code" id="pop-source">
<pre>static VALUE
rb_queue_pop(int argc, VALUE *argv, VALUE self)
{
int should_block = queue_pop_should_block(argc, argv);
return queue_do_pop(self, queue_ptr(self), should_block);
}</pre>
</div>
</div>
<div class="aliases">
Also aliased as: <a href="Queue.html#method-i-deq">deq</a>, <a href="Queue.html#method-i-shift">shift</a>
</div>
</div>
<div id="method-i-push" class="method-detail ">
<div class="method-heading">
<span class="method-callseq">
push(object)
</span>
<span class="method-click-advice">click to toggle source</span>
</div>
<div class="method-heading">
<span class="method-callseq">
enq(object)
</span>
</div>
<div class="method-heading">
<span class="method-callseq">
<<(object)
</span>
</div>
<div class="method-description">
<p>Pushes the given <code>object</code> to the queue.</p>
<div class="method-source-code" id="push-source">
<pre>static VALUE
rb_queue_push(VALUE self, VALUE obj)
{
return queue_do_push(self, queue_ptr(self), obj);
}</pre>
</div>
</div>
<div class="aliases">
Also aliased as: <a href="Queue.html#method-i-enq">enq</a>, <a href="Queue.html#method-i-3C-3C"><<</a>
</div>
</div>
<div id="method-i-shift" class="method-detail method-alias">
<div class="method-heading">
<span class="method-name">shift</span><span
class="method-args">(*args)</span>
</div>
<div class="method-description">
</div>
<div class="aliases">
Alias for: <a href="Queue.html#method-i-pop">pop</a>
</div>
</div>
<div id="method-i-size" class="method-detail method-alias">
<div class="method-heading">
<span class="method-name">size</span><span
class="method-args">()</span>
</div>
<div class="method-description">
</div>
<div class="aliases">
Alias for: <a href="Queue.html#method-i-length">length</a>
</div>
</div>
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