tmp/tmp_t6a0bdi/{from.md → to.md}
RENAMED
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@@ -19,17 +19,31 @@ The standard library templates `unique_lock` [[thread.lock.unique]],
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`shared_lock` [[thread.lock.shared]], `scoped_lock`
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[[thread.lock.scoped]], `lock_guard` [[thread.lock.guard]], `lock`,
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`try_lock` [[thread.lock.algorithm]], and `condition_variable_any`
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[[thread.condition.condvarany]] all operate on user-supplied lockable
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objects. The *Cpp17BasicLockable* requirements, the *Cpp17Lockable*
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requirements,
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requirements
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-
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[*Note 3*: The nature of any lock ownership and any synchronization it
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entails are not part of these requirements. — *end note*]
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#### *Cpp17BasicLockable* requirements <a id="thread.req.lockable.basic">[[thread.req.lockable.basic]]</a>
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A type `L` meets the *Cpp17BasicLockable* requirements if the following
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expressions are well-formed and have the specified semantics (`m`
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denotes a value of type `L`).
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@@ -44,13 +58,15 @@ acquired for the current execution agent.
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``` cpp
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m.unlock()
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```
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*Preconditions:* The current execution agent holds a lock on
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*Effects:* Releases a lock on `m` held by the current
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*Throws:* Nothing.
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#### *Cpp17Lockable* requirements <a id="thread.req.lockable.req">[[thread.req.lockable.req]]</a>
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@@ -67,11 +83,11 @@ m.try_lock()
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without blocking. If an exception is thrown then a lock shall not have
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been acquired for the current execution agent.
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*Return type:* `bool`.
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*Returns:* `true` if the lock was acquired, `false`
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#### *Cpp17TimedLockable* requirements <a id="thread.req.lockable.timed">[[thread.req.lockable.timed]]</a>
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A type `L` meets the *Cpp17TimedLockable* requirements if it meets the
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*Cpp17Lockable* requirements and the following expressions are
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@@ -91,11 +107,11 @@ within the relative timeout [[thread.req.timing]] specified by
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execution agent. If an exception is thrown then a lock has not been
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acquired for the current execution agent.
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*Return type:* `bool`.
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*Returns:* `true` if the lock was acquired, `false`
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``` cpp
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m.try_lock_until(abs_time)
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```
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@@ -106,7 +122,78 @@ before the absolute timeout [[thread.req.timing]] specified by
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execution agent. If an exception is thrown then a lock has not been
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acquired for the current execution agent.
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*Return type:* `bool`.
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*Returns:* `true` if the lock was acquired, `false` otherwise.
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`shared_lock` [[thread.lock.shared]], `scoped_lock`
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[[thread.lock.scoped]], `lock_guard` [[thread.lock.guard]], `lock`,
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`try_lock` [[thread.lock.algorithm]], and `condition_variable_any`
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[[thread.condition.condvarany]] all operate on user-supplied lockable
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objects. The *Cpp17BasicLockable* requirements, the *Cpp17Lockable*
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+
requirements, the *Cpp17TimedLockable* requirements, the
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+
*Cpp17SharedLockable* requirements, and the *Cpp17SharedTimedLockable*
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+
requirements list the requirements imposed by these library types in
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order to acquire or release ownership of a `lock` by a given execution
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+
agent.
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[*Note 3*: The nature of any lock ownership and any synchronization it
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entails are not part of these requirements. — *end note*]
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+
A lock on an object `m` is said to be
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+
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- a *non-shared lock* if it is acquired by a call to `lock`, `try_lock`,
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`try_lock_for`, or `try_lock_until` on `m`, or
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- a *shared lock* if it is acquired by a call to `lock_shared`,
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`try_lock_shared`, `try_lock_shared_for`, or `try_lock_shared_until`
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on `m`.
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+
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[*Note 4*: Only the method of lock acquisition is considered; the
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nature of any lock ownership is not part of these
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definitions. — *end note*]
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+
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#### *Cpp17BasicLockable* requirements <a id="thread.req.lockable.basic">[[thread.req.lockable.basic]]</a>
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A type `L` meets the *Cpp17BasicLockable* requirements if the following
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expressions are well-formed and have the specified semantics (`m`
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denotes a value of type `L`).
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``` cpp
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m.unlock()
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```
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+
*Preconditions:* The current execution agent holds a non-shared lock on
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`m`.
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*Effects:* Releases a non-shared lock on `m` held by the current
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execution agent.
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*Throws:* Nothing.
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#### *Cpp17Lockable* requirements <a id="thread.req.lockable.req">[[thread.req.lockable.req]]</a>
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without blocking. If an exception is thrown then a lock shall not have
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been acquired for the current execution agent.
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*Return type:* `bool`.
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+
*Returns:* `true` if the lock was acquired, otherwise `false`.
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#### *Cpp17TimedLockable* requirements <a id="thread.req.lockable.timed">[[thread.req.lockable.timed]]</a>
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A type `L` meets the *Cpp17TimedLockable* requirements if it meets the
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*Cpp17Lockable* requirements and the following expressions are
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execution agent. If an exception is thrown then a lock has not been
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acquired for the current execution agent.
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*Return type:* `bool`.
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+
*Returns:* `true` if the lock was acquired, otherwise `false`.
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``` cpp
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m.try_lock_until(abs_time)
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```
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execution agent. If an exception is thrown then a lock has not been
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acquired for the current execution agent.
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*Return type:* `bool`.
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+
*Returns:* `true` if the lock was acquired, otherwise `false`.
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+
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+
#### *Cpp17SharedLockable* requirements <a id="thread.req.lockable.shared">[[thread.req.lockable.shared]]</a>
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+
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+
A type `L` meets the *Cpp17SharedLockable* requirements if the following
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expressions are well-formed, have the specified semantics, and the
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expression `m.try_lock_shared()` has type `bool` (`m` denotes a value of
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type `L`):
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+
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``` cpp
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m.lock_shared()
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```
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+
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*Effects:* Blocks until a lock can be acquired for the current execution
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agent. If an exception is thrown then a lock shall not have been
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acquired for the current execution agent.
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+
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``` cpp
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m.try_lock_shared()
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```
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+
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*Effects:* Attempts to acquire a lock for the current execution agent
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without blocking. If an exception is thrown then a lock shall not have
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been acquired for the current execution agent.
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+
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*Returns:* `true` if the lock was acquired, `false` otherwise.
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+
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``` cpp
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m.unlock_shared()
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```
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+
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+
*Preconditions:* The current execution agent holds a shared lock on `m`.
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+
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*Effects:* Releases a shared lock on `m` held by the current execution
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agent.
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+
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*Throws:* Nothing.
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+
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+
#### *Cpp17SharedTimedLockable* requirements <a id="thread.req.lockable.shared.timed">[[thread.req.lockable.shared.timed]]</a>
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+
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+
A type `L` meets the *Cpp17SharedTimedLockable* requirements if it meets
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+
the *Cpp17SharedLockable* requirements, and the following expressions
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+
are well-formed, have type `bool`, and have the specified semantics (`m`
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+
denotes a value of type `L`, `rel_time` denotes a value of a
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+
specialization of `chrono::duration`, and `abs_time` denotes a value of
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a specialization of `chrono::time_point`).
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+
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``` cpp
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m.try_lock_shared_for(rel_time)
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```
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+
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+
*Effects:* Attempts to acquire a lock for the current execution agent
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within the relative timeout [[thread.req.timing]] specified by
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`rel_time`. The function will not return within the timeout specified by
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`rel_time` unless it has obtained a lock on `m` for the current
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execution agent. If an exception is thrown then a lock has not been
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acquired for the current execution agent.
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+
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*Returns:* `true` if the lock was acquired, `false` otherwise.
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+
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+
``` cpp
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m.try_lock_shared_until(abs_time)
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```
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+
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*Effects:* Attempts to acquire a lock for the current execution agent
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before the absolute timeout [[thread.req.timing]] specified by
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`abs_time`. The function will not return before the timeout specified by
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`abs_time` unless it has obtained a lock on `m` for the current
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execution agent. If an exception is thrown then a lock has not been
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acquired for the current execution agent.
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+
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*Returns:* `true` if the lock was acquired, `false` otherwise.
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