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QSharedPointer: fix threadsafety docs

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Try and explain better the situation around QSharedPointer:
it's reentrant, not thread safe.

Change-Id: Ief9d28be8ea3fbaa6014cb6b999626db1bab52ca
Reviewed-by: Martin Smith <martin.smith@qt.io>
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>
This commit is contained in:
Giuseppe D'Angelo 2019-05-10 20:47:33 +02:00
parent 341c910688
commit 41aa78856e
1 changed files with 12 additions and 7 deletions
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19
src/corelib/tools/qsharedpointer.cpp
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@ -65,14 +65,19 @@
\section1 Thread-Safety
QSharedPointer and QWeakPointer are thread-safe and operate
atomically on the pointer value. Different threads can also access
the QSharedPointer or QWeakPointer pointing to the same object at
the same time without need for locking mechanisms.
QSharedPointer and QWeakPointer are reentrant classes. This means that, in
general, a given QSharedPointer or QWeakPointer object \b{cannot} be
accessed by multiple threads at the same time without synchronization.
It should be noted that, while the pointer value can be accessed
in this manner, QSharedPointer and QWeakPointer provide no
guarantee about the object being pointed to. Thread-safety and
Different QSharedPointer and QWeakPointer objects can safely be accessed
by multiple threads at the same time. This includes the case where they
hold pointers to the same object; the reference counting mechanism
is atomic, and no manual synchronization is required.
It should be noted that, while the pointer value can be accessed in this
manner (that is, by multiple threads at the same time, without
synchronization), QSharedPointer and QWeakPointer provide no guarantee
about the object being pointed to. The specific thread-safety and
reentrancy rules for that object still apply.
\section1 Other Pointer Classes