tmp/tmp84zo369j/{from.md → to.md}
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| 1 |
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#### General <a id="exec.run.loop.general">[[exec.run.loop.general]]</a>
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A `run_loop` is an execution resource on which work can be scheduled. It
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maintains a thread-safe first-in-first-out queue of work. Its `run`
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member function removes elements from the queue and executes them in a
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loop on the thread of execution that calls `run`.
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A `run_loop` instance has an associated *count* that corresponds to the
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number of work items that are in its queue. Additionally, a `run_loop`
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instance has an associated state that can be one of *starting*,
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*running*, *finishing*, or *finished*.
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Concurrent invocations of the member functions of `run_loop` other than
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`run` and its destructor do not introduce data races. The member
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functions *`pop-front`*, *`push-back`*, and `finish` execute atomically.
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*Recommended practice:* Implementations should use an intrusive queue of
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operation states to hold the work units to make scheduling
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allocation-free.
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``` cpp
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namespace std::execution {
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class run_loop {
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// [exec.run.loop.types], associated types
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class run-loop-scheduler; // exposition only
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class run-loop-sender; // exposition only
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struct run-loop-opstate-base { // exposition only
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virtual void execute() = 0; // exposition only
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run_loop* loop; // exposition only
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run-loop-opstate-base* next; // exposition only
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};
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template<class Rcvr>
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using run-loop-opstate = unspecified; // exposition only
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// [exec.run.loop.members], member functions
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run-loop-opstate-base* pop-front(); // exposition only
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void push-back(run-loop-opstate-base*); // exposition only
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public:
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// [exec.run.loop.ctor], constructor and destructor
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run_loop() noexcept;
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run_loop(run_loop&&) = delete;
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~run_loop();
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// [exec.run.loop.members], member functions
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run-loop-scheduler get_scheduler();
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void run();
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void finish();
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};
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}
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```
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