Difference between revisions of "cpp/named req/SharedLockable"
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| − | {{cpp/named req/title|SharedLockable}} | + | {{cpp/named req/title|SharedLockable|notes={{mark since c++14}}}} |
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{|table class=wikitable | {|table class=wikitable | ||
|- | |- | ||
| − | !Expression | + | !Expression||Preconditions||Effects||Return value |
|- | |- | ||
|{{c|m.lock_shared()}} | |{{c|m.lock_shared()}} | ||
| − | |||
| | | | ||
|Blocks until a lock can be obtained for the current execution agent (thread, process, task). If an exception is thrown, no lock is obtained. | |Blocks until a lock can be obtained for the current execution agent (thread, process, task). If an exception is thrown, no lock is obtained. | ||
| + | | | ||
|- | |- | ||
|{{c|m.try_lock_shared()}} | |{{c|m.try_lock_shared()}} | ||
| − | |||
| | | | ||
| − | |Attempts to | + | |Attempts to obtain a lock for the current execution agent (thread, process, task) without blocking. If an exception is thrown, no lock is obtained. |
| − | + | |{{c|true}} if the lock was obtained, {{c|false}} otherwise | |
| − | + | ||
|- | |- | ||
|{{c|m.unlock_shared()}} | |{{c|m.unlock_shared()}} | ||
| − | |||
|The current execution agent holds a shared lock on {{tt|m}}. | |The current execution agent holds a shared lock on {{tt|m}}. | ||
|Releases the shared lock held by the execution agent. | |Releases the shared lock held by the execution agent. | ||
Throws no exceptions. | Throws no exceptions. | ||
| + | | | ||
|} | |} | ||
| + | |||
| + | ====Shared locks==== | ||
| + | A lock on an object is said to be ''shared lock'' if it is acquired by a call to {{tt|lock_shared}}, {{tt|try_lock_shared}}, {{tt|try_lock_shared_for}}, or {{tt|try_lock_shared_until}} member function. | ||
===See also=== | ===See also=== | ||
* [[cpp/thread|Thread support library]] | * [[cpp/thread|Thread support library]] | ||
* {{named req|SharedTimedLockable}} | * {{named req|SharedTimedLockable}} | ||
| + | * {{named req|SharedMutex}} | ||
{{langlinks|de|es|fr|it|ja|pt|ru|zh}} | {{langlinks|de|es|fr|it|ja|pt|ru|zh}} | ||
Latest revision as of 12:22, 8 November 2022
The SharedLockable requirements describe the minimal characteristics of types that provide shared blocking semantics for execution agents (i.e. threads).
[edit] Requirements
For type L to be SharedLockable, the following conditions have to be satisfied for an object m of type L:
| Expression | Preconditions | Effects | Return value |
|---|---|---|---|
| m.lock_shared() | Blocks until a lock can be obtained for the current execution agent (thread, process, task). If an exception is thrown, no lock is obtained. | ||
| m.try_lock_shared() | Attempts to obtain a lock for the current execution agent (thread, process, task) without blocking. If an exception is thrown, no lock is obtained. | true if the lock was obtained, false otherwise | |
| m.unlock_shared() | The current execution agent holds a shared lock on m.
|
Releases the shared lock held by the execution agent.
Throws no exceptions. |
[edit]
A lock on an object is said to be shared lock if it is acquired by a call to lock_shared, try_lock_shared, try_lock_shared_for, or try_lock_shared_until member function.
