C++ named requirements: SharedLockable (since C++14)
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The SharedLockable requirements describe the minimal characteristics of types that provide shared blocking semantics for execution agents (i.e. threads).
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
.
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Releases the shared lock held by the execution agent.
Throws no exceptions. |
Shared locks
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.
Standard library
The following standard library types satisfy SharedLockable requirements:
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(C++17)
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provides shared mutual exclusion facility
(class) |
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(C++14)
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provides shared mutual exclusion facility and implements locking with a timeout
(class) |