From Jason Turner

[thread.jthread.class]

C++20 → C++23 3.3 KB 37 lines
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Archived: C++20 | C++23
Markdown: C++20 | C++23
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C++ Weekly: Ep 207

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  1. tmp/tmpppzcmske/{from.md → to.md} +15 -17
tmp/tmpppzcmske/{from.md → to.md} RENAMED
@@ -1,7 +1,9 @@
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  ### Class `jthread` <a id="thread.jthread.class">[[thread.jthread.class]]</a>
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  The class `jthread` provides a mechanism to create a new thread of
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  execution. The functionality is the same as for class `thread`
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  [[thread.thread.class]] with the additional abilities to provide a
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  `stop_token` [[thread.stoptoken]] to the new thread of execution, make
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  stop requests, and automatically join.
@@ -67,34 +69,30 @@ template<class F, class... Args> explicit jthread(F&& f, Args&&... args);
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  *Constraints:* `remove_cvref_t<F>` is not the same type as `jthread`.
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  *Mandates:* The following are all `true`:
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  - `is_constructible_v<decay_t<F>, F>`,
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- - `(is_constructible_v<decay_t<Args>, Args> && ...)`,
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- - `is_move_constructible_v<decay_t<F>>`,
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- - `(is_move_constructible_v<decay_t<Args>> && ...)`, and
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  - `is_invocable_v<decay_t<F>, decay_t<Args>...> ||`
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  `is_invocable_v<decay_t<F>, stop_token, decay_t<Args>...>`.
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- *Preconditions:* `decay_t<F>` and each type in `decay_t<Args>` meet the
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- *Cpp17MoveConstructible* requirements.
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-
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  *Effects:* Initializes `ssource`. The new thread of execution executes
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  ``` cpp
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- invoke(decay-copy(std::forward<F>(f)), get_stop_token(),
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- decay-copy(std::forward<Args>(args))...)
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  ```
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  if that expression is well-formed, otherwise
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  ``` cpp
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- invoke(decay-copy(std::forward<F>(f)), decay-copy(std::forward<Args>(args))...)
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  ```
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- with the calls to *`decay-copy`* being evaluated in the constructing
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- thread. Any return value from this invocation is ignored.
 
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  [*Note 1*: This implies that any exceptions not thrown from the
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  invocation of the copy of `f` will be thrown in the constructing thread,
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  not the new thread. — *end note*]
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@@ -138,18 +136,18 @@ of `x.ssource` prior to the start of construction and
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  ``` cpp
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  jthread& operator=(jthread&& x) noexcept;
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  ```
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- *Effects:* If `joinable()` is `true`, calls `request_stop()` and then
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- `join()`. Assigns the state of `x` to `*this` and sets `x` to a default
 
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  constructed state.
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- *Ensures:* `x.get_id() == id()` and `get_id()` returns the value of
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- `x.get_id()` prior to the assignment. `ssource` has the value of
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- `x.ssource` prior to the assignment and `x.ssource.stop_possible()` is
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- `false`.
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  *Returns:* `*this`.
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  #### Members <a id="thread.jthread.mem">[[thread.jthread.mem]]</a>
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  ### Class `jthread` <a id="thread.jthread.class">[[thread.jthread.class]]</a>
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+ #### General <a id="thread.jthread.class.general">[[thread.jthread.class.general]]</a>
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+
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  The class `jthread` provides a mechanism to create a new thread of
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  execution. The functionality is the same as for class `thread`
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  [[thread.thread.class]] with the additional abilities to provide a
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  `stop_token` [[thread.stoptoken]] to the new thread of execution, make
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  stop requests, and automatically join.
 
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  *Constraints:* `remove_cvref_t<F>` is not the same type as `jthread`.
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  *Mandates:* The following are all `true`:
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  - `is_constructible_v<decay_t<F>, F>`,
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+ - `(is_constructible_v<decay_t<Args>, Args> && ...)`, and
 
 
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  - `is_invocable_v<decay_t<F>, decay_t<Args>...> ||`
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  `is_invocable_v<decay_t<F>, stop_token, decay_t<Args>...>`.
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  *Effects:* Initializes `ssource`. The new thread of execution executes
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  ``` cpp
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+ invoke(auto(std::forward<F>(f)), get_stop_token(), // for invoke, see [func.invoke]
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+ auto(std::forward<Args>(args))...)
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  ```
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  if that expression is well-formed, otherwise
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  ``` cpp
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+ invoke(auto(std::forward<F>(f)), auto(std::forward<Args>(args))...)
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  ```
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+ with the values produced by `auto` being materialized [[conv.rval]] in
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+ the constructing thread. Any return value from this invocation is
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+ ignored.
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  [*Note 1*: This implies that any exceptions not thrown from the
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  invocation of the copy of `f` will be thrown in the constructing thread,
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  not the new thread. — *end note*]
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  ``` cpp
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  jthread& operator=(jthread&& x) noexcept;
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  ```
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+ *Effects:* If `&x == this` is `true`, there are no effects. Otherwise,
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+ if `joinable()` is `true`, calls `request_stop()` and then `join()`,
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+ then assigns the state of `x` to `*this` and sets `x` to a default
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  constructed state.
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+ *Ensures:* `get_id()` returns the value of `x.get_id()` prior to the
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+ assignment. `ssource` has the value of `x.ssource` prior to the
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+ assignment.
 
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  *Returns:* `*this`.
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  #### Members <a id="thread.jthread.mem">[[thread.jthread.mem]]</a>
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