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<div class="titlepage"><div><div><h3 class="title">
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<a name="asio.reference.Executor1"></a><a class="link" href="Executor1.html" title="Executor requirements">Executor requirements</a>
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</h3></div></div></div>
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<h5>
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<a name="asio.reference.Executor1.h0"></a>
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<span><a name="asio.reference.Executor1.standard_executors"></a></span><a class="link" href="Executor1.html#asio.reference.Executor1.standard_executors">Standard
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executors</a>
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</h5>
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<p>
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Let <code class="computeroutput"><span class="identifier">executor</span><span class="special">-</span><span class="identifier">of</span><span class="special">-</span><span class="identifier">impl</span></code>
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be the exposition-only concept
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</p>
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<pre class="programlisting"><span class="keyword">template</span><span class="special"><</span><span class="keyword">class</span> <span class="identifier">E</span><span class="special">,</span> <span class="keyword">class</span> <span class="identifier">F</span><span class="special">></span>
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<span class="identifier">concept</span> <span class="identifier">executor</span><span class="special">-</span><span class="identifier">of</span><span class="special">-</span><span class="identifier">impl</span> <span class="special">=</span>
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<span class="identifier">invocable</span><span class="special"><</span><span class="identifier">decay_t</span><span class="special"><</span><span class="identifier">F</span><span class="special">>&></span> <span class="special">&&</span>
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<span class="identifier">constructible_from</span><span class="special"><</span><span class="identifier">decay_t</span><span class="special"><</span><span class="identifier">F</span><span class="special">>,</span> <span class="identifier">F</span><span class="special">></span> <span class="special">&&</span>
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<span class="identifier">move_constructible</span><span class="special"><</span><span class="identifier">decay_t</span><span class="special"><</span><span class="identifier">F</span><span class="special">>></span> <span class="special">&&</span>
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<span class="identifier">copy_constructible</span><span class="special"><</span><span class="identifier">E</span><span class="special">></span> <span class="special">&&</span>
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<span class="identifier">is_nothrow_copy_constructible_v</span><span class="special"><</span><span class="identifier">E</span><span class="special">></span> <span class="special">&&</span>
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<span class="identifier">equality_comparable</span><span class="special"><</span><span class="identifier">E</span><span class="special">></span> <span class="comment">/* nothrow */</span> <span class="special">&&</span>
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<span class="identifier">requires</span><span class="special">(</span><span class="keyword">const</span> <span class="identifier">E</span><span class="special">&</span> <span class="identifier">e</span><span class="special">,</span> <span class="identifier">F</span><span class="special">&&</span> <span class="identifier">f</span><span class="special">)</span> <span class="special">{</span>
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<span class="identifier">e</span><span class="special">.</span><span class="identifier">execute</span><span class="special">((</span><span class="identifier">F</span><span class="special">&&)</span><span class="identifier">f</span><span class="special">);</span>
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<span class="special">};</span>
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</pre>
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<p>
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Then the <code class="computeroutput"><span class="identifier">executor</span></code> and <code class="computeroutput"><span class="identifier">executor_of</span></code> concepts are defined as follows:
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</p>
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<pre class="programlisting"><span class="keyword">template</span><span class="special"><</span><span class="keyword">class</span> <span class="identifier">E</span><span class="special">></span>
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<span class="identifier">concept</span> <span class="identifier">executor</span> <span class="special">=</span>
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<span class="identifier">executor</span><span class="special">-</span><span class="identifier">of</span><span class="special">-</span><span class="identifier">impl</span><span class="special"><</span><span class="identifier">E</span><span class="special">,</span> <span class="identifier">execution</span><span class="special">::</span><span class="identifier">invocable_archetype</span><span class="special">>;</span>
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<span class="keyword">template</span><span class="special"><</span><span class="keyword">class</span> <span class="identifier">E</span><span class="special">,</span> <span class="keyword">class</span> <span class="identifier">F</span><span class="special">></span>
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<span class="identifier">concept</span> <span class="identifier">executor_of</span> <span class="special">=</span>
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<span class="identifier">executor</span><span class="special"><</span><span class="identifier">E</span><span class="special">></span> <span class="special">&&</span>
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<span class="identifier">executor</span><span class="special">-</span><span class="identifier">of</span><span class="special">-</span><span class="identifier">impl</span><span class="special"><</span><span class="identifier">E</span><span class="special">,</span> <span class="identifier">F</span><span class="special">>;</span>
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</pre>
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<p>
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Neither an executor's equality comparison nor <code class="computeroutput"><span class="identifier">swap</span></code>
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operation shall exit via an exception.
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</p>
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<p>
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None of an executor type's copy constructor, destructor, equality comparison,
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<code class="computeroutput"><span class="identifier">swap</span></code> function, <code class="computeroutput"><span class="identifier">execute</span></code> function, or associated <code class="computeroutput"><span class="identifier">query</span></code> functions shall introduce data races
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as a result of concurrent invocations of those functions from different threads.
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</p>
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<p>
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For any two (possibly const) values <code class="computeroutput"><span class="identifier">x1</span></code>
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and <code class="computeroutput"><span class="identifier">x2</span></code> of some executor type
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<code class="computeroutput"><span class="identifier">X</span></code>, <code class="computeroutput"><span class="identifier">x1</span>
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<span class="special">==</span> <span class="identifier">x2</span></code>
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shall return <code class="computeroutput"><span class="keyword">true</span></code> only if <code class="computeroutput"><span class="identifier">asio</span><span class="special">::</span><span class="identifier">query</span><span class="special">(</span><span class="identifier">x1</span><span class="special">,</span><span class="identifier">p</span><span class="special">)</span> <span class="special">==</span> <span class="identifier">asio</span><span class="special">::</span><span class="identifier">query</span><span class="special">(</span><span class="identifier">x2</span><span class="special">,</span><span class="identifier">p</span><span class="special">)</span></code> for
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every property <code class="computeroutput"><span class="identifier">p</span></code> where both
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<code class="computeroutput"><span class="identifier">asio</span><span class="special">::</span><span class="identifier">query</span><span class="special">(</span><span class="identifier">x1</span><span class="special">,</span><span class="identifier">p</span><span class="special">)</span></code> and <code class="computeroutput"><span class="identifier">asio</span><span class="special">::</span><span class="identifier">query</span><span class="special">(</span><span class="identifier">x2</span><span class="special">,</span><span class="identifier">p</span><span class="special">)</span></code> are
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well-formed and result in a non-void type that is <code class="computeroutput"><span class="identifier">equality_comparable</span></code>
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(C++Std [equalitycomparable]). [<span class="emphasis"><em>Note:</em></span> The above requirements
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imply that <code class="computeroutput"><span class="identifier">x1</span> <span class="special">==</span>
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<span class="identifier">x2</span></code> returns <code class="computeroutput"><span class="keyword">true</span></code>
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if <code class="computeroutput"><span class="identifier">x1</span></code> and <code class="computeroutput"><span class="identifier">x2</span></code>
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can be interchanged with identical effects. An executor may conceptually
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contain additional properties which are not exposed by a named property type
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that can be observed via <code class="computeroutput"><span class="identifier">asio</span><span class="special">::</span><span class="identifier">query</span></code>;
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in this case, it is up to the concrete executor implementation to decide
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if these properties affect equality. Returning <code class="computeroutput"><span class="keyword">false</span></code>
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does not necessarily imply that the effects are not identical. —<span class="emphasis"><em>end
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||
note</em></span>]
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</p>
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<p>
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An executor type's destructor shall not block pending completion of the submitted
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function objects. [<span class="emphasis"><em>Note:</em></span> The ability to wait for completion
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of submitted function objects may be provided by the associated execution
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context. —<span class="emphasis"><em>end note</em></span>]
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</p>
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<p>
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In addition to the above requirements, types <code class="computeroutput"><span class="identifier">E</span></code>
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and <code class="computeroutput"><span class="identifier">F</span></code> model <code class="computeroutput"><span class="identifier">executor_of</span></code> only if they satisfy the requirements
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of the Table below.
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</p>
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<p>
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Let:
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</p>
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<div class="itemizedlist"><ul class="itemizedlist" type="disc">
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<li class="listitem">
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<code class="computeroutput"><span class="identifier">e</span></code> denotes a (possibly
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const) executor object of type <code class="computeroutput"><span class="identifier">E</span></code>,
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</li>
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<li class="listitem">
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<code class="computeroutput"><span class="identifier">cf</span></code> denotes the function
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object <code class="computeroutput"><span class="identifier">DECAY_COPY</span><span class="special">(</span><span class="identifier">std</span><span class="special">::</span><span class="identifier">forward</span><span class="special"><</span><span class="identifier">F</span><span class="special">>(</span><span class="identifier">f</span><span class="special">))</span></code>
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</li>
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<li class="listitem">
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<code class="computeroutput"><span class="identifier">f</span></code> denotes a function
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of type <code class="computeroutput"><span class="identifier">F</span><span class="special">&&</span></code>
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invocable as <code class="computeroutput"><span class="identifier">cf</span><span class="special">()</span></code>
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and where <code class="computeroutput"><span class="identifier">decay_t</span><span class="special"><</span><span class="identifier">F</span><span class="special">></span></code>
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models <code class="computeroutput"><span class="identifier">move_constructible</span></code>.
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</li>
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</ul></div>
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<p>
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The expression <code class="computeroutput"><span class="identifier">e</span><span class="special">.</span><span class="identifier">execute</span><span class="special">(</span><span class="identifier">f</span><span class="special">)</span></code>:
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</p>
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<div class="itemizedlist"><ul class="itemizedlist" type="disc">
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<li class="listitem">
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Evaluates <code class="computeroutput"><span class="identifier">DECAY_COPY</span><span class="special">(</span><span class="identifier">std</span><span class="special">::</span><span class="identifier">forward</span><span class="special"><</span><span class="identifier">F</span><span class="special">>(</span><span class="identifier">f</span><span class="special">))</span></code> on the calling thread to create <code class="computeroutput"><span class="identifier">cf</span></code> that will be invoked at most once
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by an execution agent.
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</li>
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<li class="listitem">
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May block pending completion of this invocation. Synchronizes with [intro.multithread]
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the invocation of <code class="computeroutput"><span class="identifier">f</span></code>.
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</li>
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<li class="listitem">
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Shall not propagate any exception thrown by the function object or any
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other function submitted to the executor.
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</li>
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</ul></div>
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<p>
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[<span class="emphasis"><em>Note:</em></span> The treatment of exceptions thrown by one-way
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submitted functions is implementation-defined. The forward progress guarantee
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of the associated execution agent(s) is implementation-defined. —<span class="emphasis"><em>end
|
||
note</em></span>]
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</p>
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<h5>
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<a name="asio.reference.Executor1.h1"></a>
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<span><a name="asio.reference.Executor1.networking_ts_style_executors"></a></span><a class="link" href="Executor1.html#asio.reference.Executor1.networking_ts_style_executors">Networking
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TS-style executors</a>
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</h5>
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<p>
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The library describes a standard set of requirements for <span class="emphasis"><em>executors</em></span>.
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A type meeting the <code class="computeroutput"><span class="identifier">Executor</span></code>
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requirements embodies a set of rules for determining how submitted function
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objects are to be executed.
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</p>
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<p>
|
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A type <code class="computeroutput"><span class="identifier">X</span></code> meets the <code class="computeroutput"><span class="identifier">Executor</span></code> requirements if it satisfies the
|
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requirements of <code class="computeroutput"><span class="identifier">CopyConstructible</span></code>
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(C++Std [copyconstructible]) and <code class="computeroutput"><span class="identifier">Destructible</span></code>
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(C++Std [destructible]), as well as the additional requirements listed below.
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||
</p>
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<p>
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No constructor, comparison operator, copy operation, move operation, swap
|
||
operation, or member functions <code class="computeroutput"><span class="identifier">context</span></code>,
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||
<code class="computeroutput"><span class="identifier">on_work_started</span></code>, and <code class="computeroutput"><span class="identifier">on_work_finished</span></code> on these types shall exit
|
||
via an exception.
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</p>
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<p>
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The executor copy constructor, comparison operators, and other member functions
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defined in these requirements shall not introduce data races as a result
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of concurrent calls to those functions from different threads.
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</p>
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<p>
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Let <code class="computeroutput"><span class="identifier">ctx</span></code> be the execution
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context returned by the executor's <code class="computeroutput"><span class="identifier">context</span><span class="special">()</span></code> member function. An executor becomes <span class="emphasis"><em>invalid</em></span>
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when the first call to <code class="computeroutput"><span class="identifier">ctx</span><span class="special">.</span><span class="identifier">shutdown</span><span class="special">()</span></code> returns. The effect of calling <code class="computeroutput"><span class="identifier">on_work_started</span></code>, <code class="computeroutput"><span class="identifier">on_work_finished</span></code>,
|
||
<code class="computeroutput"><span class="identifier">dispatch</span></code>, <code class="computeroutput"><span class="identifier">post</span></code>,
|
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or <code class="computeroutput"><span class="identifier">defer</span></code> on an invalid executor
|
||
is undefined. [<span class="emphasis"><em>Note:</em></span> The copy constructor, comparison
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||
operators, and <code class="computeroutput"><span class="identifier">context</span><span class="special">()</span></code>
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member function continue to remain valid until <code class="computeroutput"><span class="identifier">ctx</span></code>
|
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is destroyed. —<span class="emphasis"><em>end note</em></span>]
|
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</p>
|
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<p>
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In the table below, <code class="computeroutput"><span class="identifier">x1</span></code> and
|
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<code class="computeroutput"><span class="identifier">x2</span></code> denote (possibly const)
|
||
values of type <code class="computeroutput"><span class="identifier">X</span></code>, <code class="computeroutput"><span class="identifier">mx1</span></code> denotes an xvalue of type <code class="computeroutput"><span class="identifier">X</span></code>, <code class="computeroutput"><span class="identifier">f</span></code>
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denotes a <code class="computeroutput"><span class="identifier">MoveConstructible</span></code>
|
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(C++Std [moveconstructible]) function object callable with zero arguments,
|
||
<code class="computeroutput"><span class="identifier">a</span></code> denotes a (possibly const)
|
||
value of type <code class="computeroutput"><span class="identifier">A</span></code> meeting the
|
||
<code class="computeroutput"><span class="identifier">Allocator</span></code> requirements (C++Std
|
||
[allocator.requirements]), and <code class="computeroutput"><span class="identifier">u</span></code>
|
||
denotes an identifier.
|
||
</p>
|
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<div class="table">
|
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<a name="asio.reference.Executor1.t0"></a><p class="title"><b>Table 18. Executor requirements</b></p>
|
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<div class="table-contents"><table class="table" summary="Executor requirements">
|
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<colgroup>
|
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<col>
|
||
<col>
|
||
<col>
|
||
</colgroup>
|
||
<thead><tr>
|
||
<th>
|
||
<p>
|
||
expression
|
||
</p>
|
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</th>
|
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<th>
|
||
<p>
|
||
type
|
||
</p>
|
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</th>
|
||
<th>
|
||
<p>
|
||
assertion/note<br> pre/post-conditions
|
||
</p>
|
||
</th>
|
||
</tr></thead>
|
||
<tbody>
|
||
<tr>
|
||
<td>
|
||
<p>
|
||
<code class="computeroutput"><span class="identifier">X</span> <span class="identifier">u</span><span class="special">(</span><span class="identifier">x1</span><span class="special">);</span></code>
|
||
</p>
|
||
</td>
|
||
<td>
|
||
</td>
|
||
<td>
|
||
<p>
|
||
Shall not exit via an exception.<br> <br> post: <code class="computeroutput"><span class="identifier">u</span> <span class="special">==</span>
|
||
<span class="identifier">x1</span></code> and <code class="computeroutput"><span class="identifier">std</span><span class="special">::</span><span class="identifier">addressof</span><span class="special">(</span><span class="identifier">u</span><span class="special">.</span><span class="identifier">context</span><span class="special">())</span>
|
||
<span class="special">==</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">addressof</span><span class="special">(</span><span class="identifier">x1</span><span class="special">.</span><span class="identifier">context</span><span class="special">()).</span></code>
|
||
</p>
|
||
</td>
|
||
</tr>
|
||
<tr>
|
||
<td>
|
||
<p>
|
||
<code class="computeroutput"><span class="identifier">X</span> <span class="identifier">u</span><span class="special">(</span><span class="identifier">mx1</span><span class="special">);</span></code>
|
||
</p>
|
||
</td>
|
||
<td>
|
||
</td>
|
||
<td>
|
||
<p>
|
||
Shall not exit via an exception.<br> <br> post: <code class="computeroutput"><span class="identifier">u</span></code> equals the prior value of
|
||
<code class="computeroutput"><span class="identifier">mx1</span></code> and <code class="computeroutput"><span class="identifier">std</span><span class="special">::</span><span class="identifier">addressof</span><span class="special">(</span><span class="identifier">u</span><span class="special">.</span><span class="identifier">context</span><span class="special">())</span></code>
|
||
equals the prior value of <code class="computeroutput"><span class="identifier">std</span><span class="special">::</span><span class="identifier">addressof</span><span class="special">(</span><span class="identifier">mx1</span><span class="special">.</span><span class="identifier">context</span><span class="special">())</span></code>.
|
||
</p>
|
||
</td>
|
||
</tr>
|
||
<tr>
|
||
<td>
|
||
<p>
|
||
<code class="computeroutput"><span class="identifier">x1</span> <span class="special">==</span>
|
||
<span class="identifier">x2</span></code>
|
||
</p>
|
||
</td>
|
||
<td>
|
||
<p>
|
||
<code class="computeroutput"><span class="keyword">bool</span></code>
|
||
</p>
|
||
</td>
|
||
<td>
|
||
<p>
|
||
Returns <code class="computeroutput"><span class="keyword">true</span></code> only
|
||
if <code class="computeroutput"><span class="identifier">x1</span></code> and <code class="computeroutput"><span class="identifier">x2</span></code> can be interchanged with identical
|
||
effects in any of the expressions defined in these type requirements.
|
||
[<span class="emphasis"><em>Note:</em></span> Returning <code class="computeroutput"><span class="keyword">false</span></code>
|
||
does not necessarily imply that the effects are not identical.
|
||
—<span class="emphasis"><em>end note</em></span>] <br> <br> <code class="computeroutput"><span class="keyword">operator</span><span class="special">==</span></code> shall be reflexive, symmetric,
|
||
and transitive, and shall not exit via an exception.
|
||
</p>
|
||
</td>
|
||
</tr>
|
||
<tr>
|
||
<td>
|
||
<p>
|
||
<code class="computeroutput"><span class="identifier">x1</span> <span class="special">!=</span>
|
||
<span class="identifier">x2</span></code>
|
||
</p>
|
||
</td>
|
||
<td>
|
||
<p>
|
||
<code class="computeroutput"><span class="keyword">bool</span></code>
|
||
</p>
|
||
</td>
|
||
<td>
|
||
<p>
|
||
Same as <code class="computeroutput"><span class="special">!(</span><span class="identifier">x1</span>
|
||
<span class="special">==</span> <span class="identifier">x2</span><span class="special">)</span></code>.
|
||
</p>
|
||
</td>
|
||
</tr>
|
||
<tr>
|
||
<td>
|
||
<p>
|
||
<code class="computeroutput"><span class="identifier">x1</span><span class="special">.</span><span class="identifier">context</span><span class="special">()</span></code>
|
||
</p>
|
||
</td>
|
||
<td>
|
||
<p>
|
||
<code class="computeroutput"><span class="identifier">execution_context</span><span class="special">&</span></code>, or <code class="computeroutput"><span class="identifier">E</span><span class="special">&</span></code> where <code class="computeroutput"><span class="identifier">E</span></code>
|
||
is a type that satifisfies the <a class="link" href="ExecutionContext.html" title="Execution context requirements"><code class="computeroutput"><span class="identifier">ExecutionContext</span></code></a> requirements.
|
||
</p>
|
||
</td>
|
||
<td>
|
||
<p>
|
||
Shall not exit via an exception.<br> <br> The comparison operators
|
||
and member functions defined in these requirements shall not alter
|
||
the reference returned by this function.
|
||
</p>
|
||
</td>
|
||
</tr>
|
||
<tr>
|
||
<td>
|
||
<p>
|
||
<code class="computeroutput"><span class="identifier">x1</span><span class="special">.</span><span class="identifier">on_work_started</span><span class="special">()</span></code>
|
||
</p>
|
||
</td>
|
||
<td>
|
||
</td>
|
||
<td>
|
||
<p>
|
||
Shall not exit via an exception.
|
||
</p>
|
||
</td>
|
||
</tr>
|
||
<tr>
|
||
<td>
|
||
<p>
|
||
<code class="computeroutput"><span class="identifier">x1</span><span class="special">.</span><span class="identifier">on_work_finished</span><span class="special">()</span></code>
|
||
</p>
|
||
</td>
|
||
<td>
|
||
</td>
|
||
<td>
|
||
<p>
|
||
Shall not exit via an exception.<br> <br> Precondition: A preceding
|
||
call <code class="computeroutput"><span class="identifier">x2</span><span class="special">.</span><span class="identifier">on_work_started</span><span class="special">()</span></code>
|
||
where <code class="computeroutput"><span class="identifier">x1</span> <span class="special">==</span>
|
||
<span class="identifier">x2</span></code>.
|
||
</p>
|
||
</td>
|
||
</tr>
|
||
<tr>
|
||
<td>
|
||
<p>
|
||
<code class="computeroutput"><span class="identifier">x1</span><span class="special">.</span><span class="identifier">dispatch</span><span class="special">(</span><span class="identifier">std</span><span class="special">::</span><span class="identifier">move</span><span class="special">(</span><span class="identifier">f</span><span class="special">),</span><span class="identifier">a</span><span class="special">)</span></code>
|
||
</p>
|
||
</td>
|
||
<td>
|
||
</td>
|
||
<td>
|
||
<p>
|
||
Effects: Creates an object <code class="computeroutput"><span class="identifier">f1</span></code>
|
||
initialized with <code class="literal"><span class="emphasis"><em>DECAY_COPY</em></span></code><code class="computeroutput"><span class="special">(</span><span class="identifier">forward</span><span class="special"><</span><span class="identifier">Func</span><span class="special">>(</span><span class="identifier">f</span><span class="special">))</span></code> (C++Std [thread.decaycopy]) in
|
||
the current thread of execution . Calls <code class="computeroutput"><span class="identifier">f1</span><span class="special">()</span></code> at most once. The executor may
|
||
block forward progress of the caller until <code class="computeroutput"><span class="identifier">f1</span><span class="special">()</span></code> finishes execution.<br> <br>
|
||
Executor implementations should use the supplied allocator to allocate
|
||
any memory required to store the function object. Prior to invoking
|
||
the function object, the executor shall deallocate any memory allocated.
|
||
[<span class="emphasis"><em>Note:</em></span> Executors defined in this Technical
|
||
Specification always use the supplied allocator unless otherwise
|
||
specified. —<span class="emphasis"><em>end note</em></span>] <br> <br> Synchronization:
|
||
The invocation of <code class="computeroutput"><span class="identifier">dispatch</span></code>
|
||
synchronizes with (C++Std [intro.multithread]) the invocation of
|
||
<code class="computeroutput"><span class="identifier">f1</span></code>.
|
||
</p>
|
||
</td>
|
||
</tr>
|
||
<tr>
|
||
<td>
|
||
<p>
|
||
<code class="computeroutput"><span class="identifier">x1</span><span class="special">.</span><span class="identifier">post</span><span class="special">(</span><span class="identifier">std</span><span class="special">::</span><span class="identifier">move</span><span class="special">(</span><span class="identifier">f</span><span class="special">),</span><span class="identifier">a</span><span class="special">)</span></code><br>
|
||
<code class="computeroutput"><span class="identifier">x1</span><span class="special">.</span><span class="identifier">defer</span><span class="special">(</span><span class="identifier">std</span><span class="special">::</span><span class="identifier">move</span><span class="special">(</span><span class="identifier">f</span><span class="special">),</span><span class="identifier">a</span><span class="special">)</span></code>
|
||
</p>
|
||
</td>
|
||
<td>
|
||
</td>
|
||
<td>
|
||
<p>
|
||
Effects: Creates an object <code class="computeroutput"><span class="identifier">f1</span></code>
|
||
initialized with <code class="literal"><span class="emphasis"><em>DECAY_COPY</em></span></code><code class="computeroutput"><span class="special">(</span><span class="identifier">forward</span><span class="special"><</span><span class="identifier">Func</span><span class="special">>(</span><span class="identifier">f</span><span class="special">))</span></code> in the current thread of execution.
|
||
Calls <code class="computeroutput"><span class="identifier">f1</span><span class="special">()</span></code>
|
||
at most once. The executor shall not block forward progress of
|
||
the caller pending completion of <code class="computeroutput"><span class="identifier">f1</span><span class="special">()</span></code>.<br> <br> Executor implementations
|
||
should use the supplied allocator to allocate any memory required
|
||
to store the function object. Prior to invoking the function object,
|
||
the executor shall deallocate any memory allocated. [<span class="emphasis"><em>Note:</em></span>
|
||
Executors defined in this Technical Specification always use the
|
||
supplied allocator unless otherwise specified. —<span class="emphasis"><em>end note</em></span>]
|
||
<br> <br> Synchronization: The invocation of <code class="computeroutput"><span class="identifier">post</span></code> or <code class="computeroutput"><span class="identifier">defer</span></code>
|
||
synchronizes with (C++Std [intro.multithread]) the invocation of
|
||
<code class="computeroutput"><span class="identifier">f1</span></code>.<br> <br>
|
||
[<span class="emphasis"><em>Note:</em></span> Although the requirements placed on
|
||
<code class="computeroutput"><span class="identifier">defer</span></code> are identical
|
||
to <code class="computeroutput"><span class="identifier">post</span></code>, the use
|
||
of <code class="computeroutput"><span class="identifier">post</span></code> conveys
|
||
a preference that the caller <span class="emphasis"><em>does not</em></span> block
|
||
the first step of <code class="literal">f1</code>'s progress, whereas <code class="computeroutput"><span class="identifier">defer</span></code> conveys a preference that
|
||
the caller <span class="emphasis"><em>does</em></span> block the first step of <code class="literal">f1</code>.
|
||
One use of <code class="computeroutput"><span class="identifier">defer</span></code>
|
||
is to convey the intention of the caller that <code class="literal">f1</code>
|
||
is a continuation of the current call context. The executor may
|
||
use this information to optimize or otherwise adjust the way in
|
||
which <code class="computeroutput"><span class="identifier">f1</span></code> is invoked.
|
||
—<span class="emphasis"><em>end note</em></span>]
|
||
</p>
|
||
</td>
|
||
</tr>
|
||
</tbody>
|
||
</table></div>
|
||
</div>
|
||
<br class="table-break">
|
||
</div>
|
||
<div class="copyright-footer">Copyright © 2003-2023 Christopher M. Kohlhoff<p>
|
||
Distributed under the Boost Software License, Version 1.0. (See accompanying
|
||
file LICENSE_1_0.txt or copy at <a href="http://www.boost.org/LICENSE_1_0.txt" target="_top">http://www.boost.org/LICENSE_1_0.txt</a>)
|
||
</p>
|
||
</div>
|
||
<hr>
|
||
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|
||
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|
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|
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