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ScheduledTask.html
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ScheduledTask.html
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<!DOCTYPE html>
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Class: Concurrent::ScheduledTask
— Concurrent Ruby
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<div id="content"><h1>Class: Concurrent::ScheduledTask
</h1>
<div class="box_info">
<dl>
<dt>Inherits:</dt>
<dd>
<span class="inheritName"><span class='object_link'><a href="IVar.html" title="Concurrent::IVar (class)">IVar</a></span></span>
<ul class="fullTree">
<li>Object</li>
<li class="next"><span class='object_link'>Concurrent::Synchronization::LockableObject</span></li>
<li class="next"><span class='object_link'><a href="IVar.html" title="Concurrent::IVar (class)">IVar</a></span></li>
<li class="next">Concurrent::ScheduledTask</li>
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<dl>
<dt>Includes:</dt>
<dd>Comparable</dd>
</dl>
<dl>
<dt>Defined in:</dt>
<dd>lib/concurrent/scheduled_task.rb</dd>
</dl>
</div>
<h2>Overview</h2><div class="docstring">
<div class="discussion">
<div class="note notetag">
<strong>Note:</strong>
<div class='inline'><p>Time calculations on all platforms and languages are sensitive to
changes to the system clock. To alleviate the potential problems
associated with changing the system clock while an application is running,
most modern operating systems provide a monotonic clock that operates
independently of the system clock. A monotonic clock cannot be used to
determine human-friendly clock times. A monotonic clock is used exclusively
for calculating time intervals. Not all Ruby platforms provide access to an
operating system monotonic clock. On these platforms a pure-Ruby monotonic
clock will be used as a fallback. An operating system monotonic clock is both
faster and more reliable than the pure-Ruby implementation. The pure-Ruby
implementation should be fast and reliable enough for most non-realtime
operations. At this time the common Ruby platforms that provide access to an
operating system monotonic clock are MRI 2.1 and above and JRuby (all versions).</p>
</div>
</div>
<p><code>ScheduledTask</code> is a close relative of <code>Concurrent::Future</code> but with one
important difference: A <code>Future</code> is set to execute as soon as possible
whereas a <code>ScheduledTask</code> is set to execute after a specified delay. This
implementation is loosely based on Java's
<a href="http://docs.oracle.com/javase/7/docs/api/java/util/concurrent/ScheduledExecutorService.html">ScheduledExecutorService</a>.
It is a more feature-rich variant of timer.</p>
<p>The <em>intended</em> schedule time of task execution is set on object construction
with the <code>delay</code> argument. The delay is a numeric (floating point or integer)
representing a number of seconds in the future. Any other value or a numeric
equal to or less than zero will result in an exception. The <em>actual</em> schedule
time of task execution is set when the <code>execute</code> method is called.</p>
<p>The constructor can also be given zero or more processing options. Currently
the only supported options are those recognized by the
<a href="Dereferenceable">Dereferenceable</a> module.</p>
<p>The final constructor argument is a block representing the task to be performed.
If no block is given an <code>ArgumentError</code> will be raised.</p>
<p><strong>States</strong></p>
<p><code>ScheduledTask</code> mixes in the <a href="Obligation">Obligation</a> module thus giving it
"future" behavior. This includes the expected lifecycle states. <code>ScheduledTask</code>
has one additional state, however. While the task (block) is being executed the
state of the object will be <code>:processing</code>. This additional state is necessary
because it has implications for task cancellation.</p>
<p><strong>Cancellation</strong></p>
<p>A <code>:pending</code> task can be cancelled using the <code>#cancel</code> method. A task in any
other state, including <code>:processing</code>, cannot be cancelled. The <code>#cancel</code>
method returns a boolean indicating the success of the cancellation attempt.
A cancelled <code>ScheduledTask</code> cannot be restarted. It is immutable.</p>
<p><strong>Obligation and Observation</strong></p>
<p>The result of a <code>ScheduledTask</code> can be obtained either synchronously or
asynchronously. <code>ScheduledTask</code> mixes in both the <a href="Obligation">Obligation</a>
module and the
<a href="http://ruby-doc.org/stdlib-2.0/libdoc/observer/rdoc/Observable.html">Observable</a>
module from the Ruby standard library. With one exception <code>ScheduledTask</code>
behaves identically to <a href="Observable">Future</a> with regard to these modules.</p>
<h2>Copy Options</h2>
<p>Object references in Ruby are mutable. This can lead to serious
problems when the <span class='object_link'><a href="Concern/Obligation.html#value-instance_method" title="Concurrent::Concern::Obligation#value (method)">Concern::Obligation#value</a></span> of an object is a mutable reference. Which
is always the case unless the value is a <code>Fixnum</code>, <code>Symbol</code>, or similar
"primitive" data type. Each instance can be configured with a few
options that can help protect the program from potentially dangerous
operations. Each of these options can be optionally set when the object
instance is created:</p>
<ul>
<li><code>:dup_on_deref</code> When true the object will call the <code>#dup</code> method on
the <code>value</code> object every time the <code>#value</code> method is called
(default: false)</li>
<li><code>:freeze_on_deref</code> When true the object will call the <code>#freeze</code>
method on the <code>value</code> object every time the <code>#value</code> method is called
(default: false)</li>
<li><code>:copy_on_deref</code> When given a <code>Proc</code> object the <code>Proc</code> will be run
every time the <code>#value</code> method is called. The <code>Proc</code> will be given
the current <code>value</code> as its only argument and the result returned by
the block will be the return value of the <code>#value</code> call. When <code>nil</code>
this option will be ignored (default: nil)</li>
</ul>
<p>When multiple deref options are set the order of operations is strictly defined.
The order of deref operations is:</p>
<ul>
<li><code>:copy_on_deref</code></li>
<li><code>:dup_on_deref</code></li>
<li><code>:freeze_on_deref</code></li>
</ul>
<p>Because of this ordering there is no need to <code>#freeze</code> an object created by a
provided <code>:copy_on_deref</code> block. Simply set <code>:freeze_on_deref</code> to <code>true</code>.
Setting both <code>:dup_on_deref</code> to <code>true</code> and <code>:freeze_on_deref</code> to <code>true</code> is
as close to the behavior of a "pure" functional language (like Erlang, Clojure,
or Haskell) as we are likely to get in Ruby.</p>
</div>
</div>
<div class="tags">
<div class="examples">
<p class="tag_title">Examples:</p>
<p class="example_title"><div class='inline'><p>Basic usage</p>
</div></p>
<pre class="example code"><code>
<span class='id identifier rubyid_require'>require</span> <span class='tstring'><span class='tstring_beg'>'</span><span class='tstring_content'>concurrent</span><span class='tstring_end'>'</span></span>
<span class='id identifier rubyid_require'>require</span> <span class='tstring'><span class='tstring_beg'>'</span><span class='tstring_content'>thread</span><span class='tstring_end'>'</span></span> <span class='comment'># for Queue
</span><span class='id identifier rubyid_require'>require</span> <span class='tstring'><span class='tstring_beg'>'</span><span class='tstring_content'>open-uri</span><span class='tstring_end'>'</span></span> <span class='comment'># for open(uri)
</span>
<span class='kw'>class</span> <span class='const'>Ticker</span>
<span class='kw'>def</span> <span class='id identifier rubyid_get_year_end_closing'>get_year_end_closing</span><span class='lparen'>(</span><span class='id identifier rubyid_symbol'>symbol</span><span class='comma'>,</span> <span class='id identifier rubyid_year'>year</span><span class='rparen'>)</span>
<span class='id identifier rubyid_uri'>uri</span> <span class='op'>=</span> <span class='tstring'><span class='tstring_beg'>"</span><span class='tstring_content'>http://ichart.finance.yahoo.com/table.csv?s=</span><span class='embexpr_beg'>#{</span><span class='id identifier rubyid_symbol'>symbol</span><span class='embexpr_end'>}</span><span class='tstring_content'>&a=11&b=01&c=</span><span class='embexpr_beg'>#{</span><span class='id identifier rubyid_year'>year</span><span class='embexpr_end'>}</span><span class='tstring_content'>&d=11&e=31&f=</span><span class='embexpr_beg'>#{</span><span class='id identifier rubyid_year'>year</span><span class='embexpr_end'>}</span><span class='tstring_content'>&g=m</span><span class='tstring_end'>"</span></span>
<span class='id identifier rubyid_data'>data</span> <span class='op'>=</span> <span class='id identifier rubyid_open'>open</span><span class='lparen'>(</span><span class='id identifier rubyid_uri'>uri</span><span class='rparen'>)</span> <span class='lbrace'>{</span><span class='op'>|</span><span class='id identifier rubyid_f'>f</span><span class='op'>|</span> <span class='id identifier rubyid_f'>f</span><span class='period'>.</span><span class='id identifier rubyid_collect'>collect</span><span class='lbrace'>{</span><span class='op'>|</span><span class='id identifier rubyid_line'>line</span><span class='op'>|</span> <span class='id identifier rubyid_line'>line</span><span class='period'>.</span><span class='id identifier rubyid_strip'>strip</span> <span class='rbrace'>}</span> <span class='rbrace'>}</span>
<span class='id identifier rubyid_data'>data</span><span class='lbracket'>[</span><span class='int'>1</span><span class='rbracket'>]</span><span class='period'>.</span><span class='id identifier rubyid_split'>split</span><span class='lparen'>(</span><span class='tstring'><span class='tstring_beg'>'</span><span class='tstring_content'>,</span><span class='tstring_end'>'</span></span><span class='rparen'>)</span><span class='lbracket'>[</span><span class='int'>4</span><span class='rbracket'>]</span><span class='period'>.</span><span class='id identifier rubyid_to_f'>to_f</span>
<span class='kw'>end</span>
<span class='kw'>end</span>
<span class='comment'># Future
</span><span class='id identifier rubyid_price'>price</span> <span class='op'>=</span> <span class='const'><span class='object_link'><a href="../Concurrent.html" title="Concurrent (module)">Concurrent</a></span></span><span class='op'>::</span><span class='const'><span class='object_link'><a href="Future.html" title="Concurrent::Future (class)">Future</a></span></span><span class='period'>.</span><span class='id identifier rubyid_execute'><span class='object_link'><a href="Future.html#execute-class_method" title="Concurrent::Future.execute (method)">execute</a></span></span><span class='lbrace'>{</span> <span class='const'>Ticker</span><span class='period'>.</span><span class='id identifier rubyid_new'>new</span><span class='period'>.</span><span class='id identifier rubyid_get_year_end_closing'>get_year_end_closing</span><span class='lparen'>(</span><span class='tstring'><span class='tstring_beg'>'</span><span class='tstring_content'>TWTR</span><span class='tstring_end'>'</span></span><span class='comma'>,</span> <span class='int'>2013</span><span class='rparen'>)</span> <span class='rbrace'>}</span>
<span class='id identifier rubyid_price'>price</span><span class='period'>.</span><span class='id identifier rubyid_state'>state</span> <span class='comment'>#=> :pending
</span><span class='id identifier rubyid_sleep'>sleep</span><span class='lparen'>(</span><span class='int'>1</span><span class='rparen'>)</span> <span class='comment'># do other stuff
</span><span class='id identifier rubyid_price'>price</span><span class='period'>.</span><span class='id identifier rubyid_value'>value</span> <span class='comment'>#=> 63.65
</span><span class='id identifier rubyid_price'>price</span><span class='period'>.</span><span class='id identifier rubyid_state'>state</span> <span class='comment'>#=> :fulfilled
</span>
<span class='comment'># ScheduledTask
</span><span class='id identifier rubyid_task'>task</span> <span class='op'>=</span> <span class='const'><span class='object_link'><a href="../Concurrent.html" title="Concurrent (module)">Concurrent</a></span></span><span class='op'>::</span><span class='const'>ScheduledTask</span><span class='period'>.</span><span class='id identifier rubyid_execute'><span class='object_link'><a href="#execute-class_method" title="Concurrent::ScheduledTask.execute (method)">execute</a></span></span><span class='lparen'>(</span><span class='int'>2</span><span class='rparen'>)</span><span class='lbrace'>{</span> <span class='const'>Ticker</span><span class='period'>.</span><span class='id identifier rubyid_new'>new</span><span class='period'>.</span><span class='id identifier rubyid_get_year_end_closing'>get_year_end_closing</span><span class='lparen'>(</span><span class='tstring'><span class='tstring_beg'>'</span><span class='tstring_content'>INTC</span><span class='tstring_end'>'</span></span><span class='comma'>,</span> <span class='int'>2013</span><span class='rparen'>)</span> <span class='rbrace'>}</span>
<span class='id identifier rubyid_task'>task</span><span class='period'>.</span><span class='id identifier rubyid_state'>state</span> <span class='comment'>#=> :pending
</span><span class='id identifier rubyid_sleep'>sleep</span><span class='lparen'>(</span><span class='int'>3</span><span class='rparen'>)</span> <span class='comment'># do other stuff
</span><span class='id identifier rubyid_task'>task</span><span class='period'>.</span><span class='id identifier rubyid_value'>value</span> <span class='comment'>#=> 25.96</span></code></pre>
<p class="example_title"><div class='inline'><p>Successful task execution</p>
</div></p>
<pre class="example code"><code>
<span class='id identifier rubyid_task'>task</span> <span class='op'>=</span> <span class='const'><span class='object_link'><a href="../Concurrent.html" title="Concurrent (module)">Concurrent</a></span></span><span class='op'>::</span><span class='const'>ScheduledTask</span><span class='period'>.</span><span class='id identifier rubyid_new'><span class='object_link'><a href="#initialize-instance_method" title="Concurrent::ScheduledTask#initialize (method)">new</a></span></span><span class='lparen'>(</span><span class='int'>2</span><span class='rparen'>)</span><span class='lbrace'>{</span> <span class='tstring'><span class='tstring_beg'>'</span><span class='tstring_content'>What does the fox say?</span><span class='tstring_end'>'</span></span> <span class='rbrace'>}</span>
<span class='id identifier rubyid_task'>task</span><span class='period'>.</span><span class='id identifier rubyid_state'>state</span> <span class='comment'>#=> :unscheduled
</span><span class='id identifier rubyid_task'>task</span><span class='period'>.</span><span class='id identifier rubyid_execute'>execute</span>
<span class='id identifier rubyid_task'>task</span><span class='period'>.</span><span class='id identifier rubyid_state'>state</span> <span class='comment'>#=> pending
</span>
<span class='comment'># wait for it...
</span><span class='id identifier rubyid_sleep'>sleep</span><span class='lparen'>(</span><span class='int'>3</span><span class='rparen'>)</span>
<span class='id identifier rubyid_task'>task</span><span class='period'>.</span><span class='id identifier rubyid_unscheduled?'>unscheduled?</span> <span class='comment'>#=> false
</span><span class='id identifier rubyid_task'>task</span><span class='period'>.</span><span class='id identifier rubyid_pending?'>pending?</span> <span class='comment'>#=> false
</span><span class='id identifier rubyid_task'>task</span><span class='period'>.</span><span class='id identifier rubyid_fulfilled?'>fulfilled?</span> <span class='comment'>#=> true
</span><span class='id identifier rubyid_task'>task</span><span class='period'>.</span><span class='id identifier rubyid_rejected?'>rejected?</span> <span class='comment'>#=> false
</span><span class='id identifier rubyid_task'>task</span><span class='period'>.</span><span class='id identifier rubyid_value'>value</span> <span class='comment'>#=> 'What does the fox say?'</span></code></pre>
<p class="example_title"><div class='inline'><p>One line creation and execution</p>
</div></p>
<pre class="example code"><code>
<span class='id identifier rubyid_task'>task</span> <span class='op'>=</span> <span class='const'><span class='object_link'><a href="../Concurrent.html" title="Concurrent (module)">Concurrent</a></span></span><span class='op'>::</span><span class='const'>ScheduledTask</span><span class='period'>.</span><span class='id identifier rubyid_new'><span class='object_link'><a href="#initialize-instance_method" title="Concurrent::ScheduledTask#initialize (method)">new</a></span></span><span class='lparen'>(</span><span class='int'>2</span><span class='rparen'>)</span><span class='lbrace'>{</span> <span class='tstring'><span class='tstring_beg'>'</span><span class='tstring_content'>What does the fox say?</span><span class='tstring_end'>'</span></span> <span class='rbrace'>}</span><span class='period'>.</span><span class='id identifier rubyid_execute'>execute</span>
<span class='id identifier rubyid_task'>task</span><span class='period'>.</span><span class='id identifier rubyid_state'>state</span> <span class='comment'>#=> pending
</span>
<span class='id identifier rubyid_task'>task</span> <span class='op'>=</span> <span class='const'><span class='object_link'><a href="../Concurrent.html" title="Concurrent (module)">Concurrent</a></span></span><span class='op'>::</span><span class='const'>ScheduledTask</span><span class='period'>.</span><span class='id identifier rubyid_execute'><span class='object_link'><a href="#execute-class_method" title="Concurrent::ScheduledTask.execute (method)">execute</a></span></span><span class='lparen'>(</span><span class='int'>2</span><span class='rparen'>)</span><span class='lbrace'>{</span> <span class='tstring'><span class='tstring_beg'>'</span><span class='tstring_content'>What do you get when you multiply 6 by 9?</span><span class='tstring_end'>'</span></span> <span class='rbrace'>}</span>
<span class='id identifier rubyid_task'>task</span><span class='period'>.</span><span class='id identifier rubyid_state'>state</span> <span class='comment'>#=> pending</span></code></pre>
<p class="example_title"><div class='inline'><p>Failed task execution</p>
</div></p>
<pre class="example code"><code>
<span class='id identifier rubyid_task'>task</span> <span class='op'>=</span> <span class='const'><span class='object_link'><a href="../Concurrent.html" title="Concurrent (module)">Concurrent</a></span></span><span class='op'>::</span><span class='const'>ScheduledTask</span><span class='period'>.</span><span class='id identifier rubyid_execute'><span class='object_link'><a href="#execute-class_method" title="Concurrent::ScheduledTask.execute (method)">execute</a></span></span><span class='lparen'>(</span><span class='int'>2</span><span class='rparen'>)</span><span class='lbrace'>{</span> <span class='id identifier rubyid_raise'>raise</span> <span class='const'>StandardError</span><span class='period'>.</span><span class='id identifier rubyid_new'>new</span><span class='lparen'>(</span><span class='tstring'><span class='tstring_beg'>'</span><span class='tstring_content'>Call me maybe?</span><span class='tstring_end'>'</span></span><span class='rparen'>)</span> <span class='rbrace'>}</span>
<span class='id identifier rubyid_task'>task</span><span class='period'>.</span><span class='id identifier rubyid_pending?'>pending?</span> <span class='comment'>#=> true
</span>
<span class='comment'># wait for it...
</span><span class='id identifier rubyid_sleep'>sleep</span><span class='lparen'>(</span><span class='int'>3</span><span class='rparen'>)</span>
<span class='id identifier rubyid_task'>task</span><span class='period'>.</span><span class='id identifier rubyid_unscheduled?'>unscheduled?</span> <span class='comment'>#=> false
</span><span class='id identifier rubyid_task'>task</span><span class='period'>.</span><span class='id identifier rubyid_pending?'>pending?</span> <span class='comment'>#=> false
</span><span class='id identifier rubyid_task'>task</span><span class='period'>.</span><span class='id identifier rubyid_fulfilled?'>fulfilled?</span> <span class='comment'>#=> false
</span><span class='id identifier rubyid_task'>task</span><span class='period'>.</span><span class='id identifier rubyid_rejected?'>rejected?</span> <span class='comment'>#=> true
</span><span class='id identifier rubyid_task'>task</span><span class='period'>.</span><span class='id identifier rubyid_value'>value</span> <span class='comment'>#=> nil
</span><span class='id identifier rubyid_task'>task</span><span class='period'>.</span><span class='id identifier rubyid_reason'>reason</span> <span class='comment'>#=> #<StandardError: Call me maybe?></span></code></pre>
<p class="example_title"><div class='inline'><p>Task execution with observation</p>
</div></p>
<pre class="example code"><code>
<span class='id identifier rubyid_observer'>observer</span> <span class='op'>=</span> <span class='const'>Class</span><span class='period'>.</span><span class='id identifier rubyid_new'>new</span><span class='lbrace'>{</span>
<span class='kw'>def</span> <span class='id identifier rubyid_update'>update</span><span class='lparen'>(</span><span class='id identifier rubyid_time'>time</span><span class='comma'>,</span> <span class='id identifier rubyid_value'>value</span><span class='comma'>,</span> <span class='id identifier rubyid_reason'>reason</span><span class='rparen'>)</span>
<span class='id identifier rubyid_puts'>puts</span> <span class='tstring'><span class='tstring_beg'>"</span><span class='tstring_content'>The task completed at </span><span class='embexpr_beg'>#{</span><span class='id identifier rubyid_time'>time</span><span class='embexpr_end'>}</span><span class='tstring_content'> with value '</span><span class='embexpr_beg'>#{</span><span class='id identifier rubyid_value'>value</span><span class='embexpr_end'>}</span><span class='tstring_content'>'</span><span class='tstring_end'>"</span></span>
<span class='kw'>end</span>
<span class='rbrace'>}</span><span class='period'>.</span><span class='id identifier rubyid_new'>new</span>
<span class='id identifier rubyid_task'>task</span> <span class='op'>=</span> <span class='const'><span class='object_link'><a href="../Concurrent.html" title="Concurrent (module)">Concurrent</a></span></span><span class='op'>::</span><span class='const'>ScheduledTask</span><span class='period'>.</span><span class='id identifier rubyid_new'><span class='object_link'><a href="#initialize-instance_method" title="Concurrent::ScheduledTask#initialize (method)">new</a></span></span><span class='lparen'>(</span><span class='int'>2</span><span class='rparen'>)</span><span class='lbrace'>{</span> <span class='tstring'><span class='tstring_beg'>'</span><span class='tstring_content'>What does the fox say?</span><span class='tstring_end'>'</span></span> <span class='rbrace'>}</span>
<span class='id identifier rubyid_task'>task</span><span class='period'>.</span><span class='id identifier rubyid_add_observer'>add_observer</span><span class='lparen'>(</span><span class='id identifier rubyid_observer'>observer</span><span class='rparen'>)</span>
<span class='id identifier rubyid_task'>task</span><span class='period'>.</span><span class='id identifier rubyid_execute'>execute</span>
<span class='id identifier rubyid_task'>task</span><span class='period'>.</span><span class='id identifier rubyid_pending?'>pending?</span> <span class='comment'>#=> true
</span>
<span class='comment'># wait for it...
</span><span class='id identifier rubyid_sleep'>sleep</span><span class='lparen'>(</span><span class='int'>3</span><span class='rparen'>)</span>
<span class='comment'>#>> The task completed at 2013-11-07 12:26:09 -0500 with value 'What does the fox say?'</span></code></pre>
</div>
<p class="tag_title">See Also:</p>
<ul class="see">
<li><a href="http://linux.die.net/man/3/clock_gettime" target="_parent" title="Linux clock_gettime(3)">Linux clock_gettime(3)</a></li>
<li>timer</li>
</ul>
</div>
<h2>
Class Method Summary
<small><a href="#" class="summary_toggle">collapse</a></small>
</h2>
<ul class="summary">
<li class="public ">
<span class="summary_signature">
<a href="#execute-class_method" title="execute (class method)">.<strong>execute</strong>(delay, opts = {}, &task) ⇒ ScheduledTask </a>
</span>
<span class="summary_desc"><div class='inline'><p>Create a new <code>ScheduledTask</code> object with the given block, execute it, and return the <code>:pending</code> object.</p>
</div></span>
</li>
</ul>
<h2>
Instance Method Summary
<small><a href="#" class="summary_toggle">collapse</a></small>
</h2>
<ul class="summary">
<li class="public ">
<span class="summary_signature">
<a href="#cancel-instance_method" title="#cancel (instance method)">#<strong>cancel</strong> ⇒ Boolean </a>
</span>
<span class="summary_desc"><div class='inline'><p>Cancel this task and prevent it from executing.</p>
</div></span>
</li>
<li class="public ">
<span class="summary_signature">
<a href="#cancelled%3F-instance_method" title="#cancelled? (instance method)">#<strong>cancelled?</strong> ⇒ Boolean </a>
</span>
<span class="summary_desc"><div class='inline'><p>Has the task been cancelled?.</p>
</div></span>
</li>
<li class="public ">
<span class="summary_signature">
<a href="#execute-instance_method" title="#execute (instance method)">#<strong>execute</strong> ⇒ ScheduledTask </a>
</span>
<span class="summary_desc"><div class='inline'><p>Execute an <code>:unscheduled</code> <code>ScheduledTask</code>.</p>
</div></span>
</li>
<li class="public ">
<span class="summary_signature">
<a href="#initial_delay-instance_method" title="#initial_delay (instance method)">#<strong>initial_delay</strong> ⇒ Float </a>
</span>
<span class="summary_desc"><div class='inline'><p>The <code>delay</code> value given at instanciation.</p>
</div></span>
</li>
<li class="public ">
<span class="summary_signature">
<a href="#initialize-instance_method" title="#initialize (instance method)">#<strong>initialize</strong>(delay, opts = {}) { ... } ⇒ ScheduledTask </a>
</span>
<span class="note title constructor">constructor</span>
<span class="summary_desc"><div class='inline'><p>Schedule a task for execution at a specified future time.</p>
</div></span>
</li>
<li class="public ">
<span class="summary_signature">
<a href="#processing%3F-instance_method" title="#processing? (instance method)">#<strong>processing?</strong> ⇒ Boolean </a>
</span>
<span class="summary_desc"><div class='inline'><p>In the task execution in progress?.</p>
</div></span>
</li>
<li class="public ">
<span class="summary_signature">
<a href="#reschedule-instance_method" title="#reschedule (instance method)">#<strong>reschedule</strong>(delay) ⇒ Boolean </a>
</span>
<span class="summary_desc"><div class='inline'><p>Reschedule the task using the given delay and the current time.</p>
</div></span>
</li>
<li class="public ">
<span class="summary_signature">
<a href="#reset-instance_method" title="#reset (instance method)">#<strong>reset</strong> ⇒ Boolean </a>
</span>
<span class="summary_desc"><div class='inline'><p>Reschedule the task using the original delay and the current time.</p>
</div></span>
</li>
<li class="public ">
<span class="summary_signature">
<a href="#schedule_time-instance_method" title="#schedule_time (instance method)">#<strong>schedule_time</strong> ⇒ Float </a>
</span>
<span class="summary_desc"><div class='inline'><p>The monotonic time at which the the task is scheduled to be executed.</p>
</div></span>
</li>
</ul>
<div id="constructor_details" class="method_details_list">
<h2>Constructor Details</h2>
<div class="method_details first">
<h3 class="signature first" id="initialize-instance_method">
#<strong>initialize</strong>(delay, opts = {}) { ... } ⇒ <tt><span class='object_link'><a href="" title="Concurrent::ScheduledTask (class)">ScheduledTask</a></span></tt>
</h3><div class="docstring">
<div class="discussion">
<p>Schedule a task for execution at a specified future time.</p>
</div>
</div>
<div class="tags">
<p class="tag_title">Parameters:</p>
<ul class="param">
<li>
<span class='name'>delay</span>
<span class='type'>(<tt>Float</tt>)</span>
—
<div class='inline'><p>the number of seconds to wait for before executing the task</p>
</div>
</li>
<li>
<span class='name'>opts</span>
<span class='type'>(<tt><span class='object_link'><a href="Hash.html" title="Concurrent::Hash (class)">Hash</a></span></tt>)</span>
<em class="default">(defaults to: <tt>{}</tt>)</em>
—
<div class='inline'><p>the options used to define the behavior at update and deref
and to specify the executor on which to perform actions</p>
</div>
</li>
</ul>
<p class="tag_title">Options Hash (<tt>opts</tt>):</p>
<ul class="option">
<li>
<span class="name">:executor</span>
<span class="type">(<tt>Executor</tt>)</span>
<span class="default">
</span>
— <div class='inline'><p>when set use the given <code>Executor</code> instance.
Three special values are also supported: <code>:io</code> returns the global pool for
long, blocking (IO) tasks, <code>:fast</code> returns the global pool for short, fast
operations, and <code>:immediate</code> returns the global <code>ImmediateExecutor</code> object.</p>
</div>
</li>
<li>
<span class="name">:dup_on_deref</span>
<span class="type">(<tt>Boolean</tt>)</span>
<span class="default">
— default:
<tt>false</tt>
</span>
— <div class='inline'><p>Call <code>#dup</code> before
returning the data from <span class='object_link'><a href="Concern/Obligation.html#value-instance_method" title="Concurrent::Concern::Obligation#value (method)">Concern::Obligation#value</a></span></p>
</div>
</li>
<li>
<span class="name">:freeze_on_deref</span>
<span class="type">(<tt>Boolean</tt>)</span>
<span class="default">
— default:
<tt>false</tt>
</span>
— <div class='inline'><p>Call <code>#freeze</code> before
returning the data from <span class='object_link'><a href="Concern/Obligation.html#value-instance_method" title="Concurrent::Concern::Obligation#value (method)">Concern::Obligation#value</a></span></p>
</div>
</li>
<li>
<span class="name">:copy_on_deref</span>
<span class="type">(<tt>Proc</tt>)</span>
<span class="default">
— default:
<tt>nil</tt>
</span>
— <div class='inline'><p>When calling the <span class='object_link'><a href="Concern/Obligation.html#value-instance_method" title="Concurrent::Concern::Obligation#value (method)">Concern::Obligation#value</a></span>
method, call the given proc passing the internal value as the sole
argument then return the new value returned from the proc.</p>
</div>
</li>
<li>
<span class="name">:args</span>
<span class="type">(<tt>object</tt>, <tt><span class='object_link'><a href="Array.html" title="Concurrent::Array (class)">Array</a></span></tt>)</span>
<span class="default">
</span>
— <div class='inline'><p>zero or more arguments to be passed the task
block on execution</p>
</div>
</li>
</ul>
<p class="tag_title">Yields:</p>
<ul class="yield">
<li>
<span class='type'></span>
<div class='inline'><p>the task to be performed</p>
</div>
</li>
</ul>
<p class="tag_title">Raises:</p>
<ul class="raise">
<li>
<span class='type'>(<tt>ArgumentError</tt>)</span>
—
<div class='inline'><p>When no block is given</p>
</div>
</li>
<li>
<span class='type'>(<tt>ArgumentError</tt>)</span>
—
<div class='inline'><p>When given a time that is in the past</p>
</div>
</li>
</ul>
</div><table class="source_code">
<tr>
<td>
<pre class="lines">
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</td>
<td>
<pre class="code"><span class="info file"># File 'lib/concurrent/scheduled_task.rb', line 165</span>
<span class='kw'>def</span> <span class='id identifier rubyid_initialize'>initialize</span><span class='lparen'>(</span><span class='id identifier rubyid_delay'>delay</span><span class='comma'>,</span> <span class='id identifier rubyid_opts'>opts</span> <span class='op'>=</span> <span class='lbrace'>{</span><span class='rbrace'>}</span><span class='comma'>,</span> <span class='op'>&</span><span class='id identifier rubyid_task'>task</span><span class='rparen'>)</span>
<span class='id identifier rubyid_raise'>raise</span> <span class='const'>ArgumentError</span><span class='period'>.</span><span class='id identifier rubyid_new'>new</span><span class='lparen'>(</span><span class='tstring'><span class='tstring_beg'>'</span><span class='tstring_content'>no block given</span><span class='tstring_end'>'</span></span><span class='rparen'>)</span> <span class='kw'>unless</span> <span class='id identifier rubyid_block_given?'>block_given?</span>
<span class='id identifier rubyid_raise'>raise</span> <span class='const'>ArgumentError</span><span class='period'>.</span><span class='id identifier rubyid_new'>new</span><span class='lparen'>(</span><span class='tstring'><span class='tstring_beg'>'</span><span class='tstring_content'>seconds must be greater than zero</span><span class='tstring_end'>'</span></span><span class='rparen'>)</span> <span class='kw'>if</span> <span class='id identifier rubyid_delay'>delay</span><span class='period'>.</span><span class='id identifier rubyid_to_f'>to_f</span> <span class='op'><</span> <span class='float'>0.0</span>
<span class='kw'>super</span><span class='lparen'>(</span><span class='const'>NULL</span><span class='comma'>,</span> <span class='id identifier rubyid_opts'>opts</span><span class='comma'>,</span> <span class='op'>&</span><span class='kw'>nil</span><span class='rparen'>)</span>
<span class='id identifier rubyid_synchronize'>synchronize</span> <span class='kw'>do</span>
<span class='id identifier rubyid_ns_set_state'>ns_set_state</span><span class='lparen'>(</span><span class='symbol'>:unscheduled</span><span class='rparen'>)</span>
<span class='ivar'>@parent</span> <span class='op'>=</span> <span class='id identifier rubyid_opts'>opts</span><span class='period'>.</span><span class='id identifier rubyid_fetch'>fetch</span><span class='lparen'>(</span><span class='symbol'>:timer_set</span><span class='comma'>,</span> <span class='const'><span class='object_link'><a href="../Concurrent.html" title="Concurrent (module)">Concurrent</a></span></span><span class='period'>.</span><span class='id identifier rubyid_global_timer_set'><span class='object_link'><a href="../Concurrent.html#global_timer_set-class_method" title="Concurrent.global_timer_set (method)">global_timer_set</a></span></span><span class='rparen'>)</span>
<span class='ivar'>@args</span> <span class='op'>=</span> <span class='id identifier rubyid_get_arguments_from'>get_arguments_from</span><span class='lparen'>(</span><span class='id identifier rubyid_opts'>opts</span><span class='rparen'>)</span>
<span class='ivar'>@delay</span> <span class='op'>=</span> <span class='id identifier rubyid_delay'>delay</span><span class='period'>.</span><span class='id identifier rubyid_to_f'>to_f</span>
<span class='ivar'>@task</span> <span class='op'>=</span> <span class='id identifier rubyid_task'>task</span>
<span class='ivar'>@time</span> <span class='op'>=</span> <span class='kw'>nil</span>
<span class='ivar'>@executor</span> <span class='op'>=</span> <span class='const'>Options</span><span class='period'>.</span><span class='id identifier rubyid_executor_from_options'>executor_from_options</span><span class='lparen'>(</span><span class='id identifier rubyid_opts'>opts</span><span class='rparen'>)</span> <span class='op'>||</span> <span class='const'><span class='object_link'><a href="../Concurrent.html" title="Concurrent (module)">Concurrent</a></span></span><span class='period'>.</span><span class='id identifier rubyid_global_io_executor'><span class='object_link'><a href="../Concurrent.html#global_io_executor-class_method" title="Concurrent.global_io_executor (method)">global_io_executor</a></span></span>
<span class='kw'>self</span><span class='period'>.</span><span class='id identifier rubyid_observers'>observers</span> <span class='op'>=</span> <span class='const'>Collection</span><span class='op'>::</span><span class='const'><span class='object_link'><a href="Collection/CopyOnNotifyObserverSet.html" title="Concurrent::Collection::CopyOnNotifyObserverSet (class)">CopyOnNotifyObserverSet</a></span></span><span class='period'>.</span><span class='id identifier rubyid_new'><span class='object_link'><a href="Collection/CopyOnNotifyObserverSet.html#initialize-instance_method" title="Concurrent::Collection::CopyOnNotifyObserverSet#initialize (method)">new</a></span></span>
<span class='kw'>end</span>
<span class='kw'>end</span></pre>
</td>
</tr>
</table>
</div>
</div>
<div id="class_method_details" class="method_details_list">
<h2>Class Method Details</h2>
<div class="method_details first">
<h3 class="signature first" id="execute-class_method">
.<strong>execute</strong>(delay, opts = {}, &task) ⇒ <tt><span class='object_link'><a href="" title="Concurrent::ScheduledTask (class)">ScheduledTask</a></span></tt>
</h3><div class="docstring">
<div class="discussion">
<p>Create a new <code>ScheduledTask</code> object with the given block, execute it, and return the
<code>:pending</code> object.</p>
</div>
</div>
<div class="tags">
<p class="tag_title">Parameters:</p>
<ul class="param">
<li>
<span class='name'>delay</span>
<span class='type'>(<tt>Float</tt>)</span>
—
<div class='inline'><p>the number of seconds to wait for before executing the task</p>
</div>
</li>
<li>
<span class='name'>opts</span>
<span class='type'>(<tt><span class='object_link'><a href="Hash.html" title="Concurrent::Hash (class)">Hash</a></span></tt>)</span>
<em class="default">(defaults to: <tt>{}</tt>)</em>
—
<div class='inline'><p>the options used to define the behavior at update and deref
and to specify the executor on which to perform actions</p>
</div>
</li>
</ul>
<p class="tag_title">Options Hash (<tt>opts</tt>):</p>
<ul class="option">
<li>
<span class="name">:executor</span>
<span class="type">(<tt>Executor</tt>)</span>
<span class="default">
</span>
— <div class='inline'><p>when set use the given <code>Executor</code> instance.
Three special values are also supported: <code>:io</code> returns the global pool for
long, blocking (IO) tasks, <code>:fast</code> returns the global pool for short, fast
operations, and <code>:immediate</code> returns the global <code>ImmediateExecutor</code> object.</p>
</div>
</li>
<li>
<span class="name">:dup_on_deref</span>
<span class="type">(<tt>Boolean</tt>)</span>
<span class="default">
— default:
<tt>false</tt>
</span>
— <div class='inline'><p>Call <code>#dup</code> before
returning the data from <span class='object_link'><a href="Concern/Obligation.html#value-instance_method" title="Concurrent::Concern::Obligation#value (method)">Concern::Obligation#value</a></span></p>
</div>
</li>
<li>
<span class="name">:freeze_on_deref</span>
<span class="type">(<tt>Boolean</tt>)</span>
<span class="default">
— default:
<tt>false</tt>
</span>
— <div class='inline'><p>Call <code>#freeze</code> before
returning the data from <span class='object_link'><a href="Concern/Obligation.html#value-instance_method" title="Concurrent::Concern::Obligation#value (method)">Concern::Obligation#value</a></span></p>
</div>
</li>
<li>
<span class="name">:copy_on_deref</span>
<span class="type">(<tt>Proc</tt>)</span>
<span class="default">
— default:
<tt>nil</tt>
</span>
— <div class='inline'><p>When calling the <span class='object_link'><a href="Concern/Obligation.html#value-instance_method" title="Concurrent::Concern::Obligation#value (method)">Concern::Obligation#value</a></span>
method, call the given proc passing the internal value as the sole
argument then return the new value returned from the proc.</p>
</div>
</li>
</ul>
<p class="tag_title">Returns:</p>
<ul class="return">
<li>
<span class='type'>(<tt><span class='object_link'><a href="" title="Concurrent::ScheduledTask (class)">ScheduledTask</a></span></tt>)</span>
—
<div class='inline'><p>the newly created <code>ScheduledTask</code> in the <code>:pending</code> state</p>
</div>