View source for QSharedMemory & QSystemSemaphore in Qt 7

[[Category:QtCS2023]]

==Session Summary==
What to do with QSharedMemory and QSystemSemaphore

==Session Owners==
Thiago Macieira

==Notes==
(Note: recreated from memory, note taker had a laptop trouble and the file wasn't saved)
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* Thiago proposed deprecating now and moving to Qt6CoreCompat in Qt 7
** No replacement class
** Fabian has volunteered to investigate a replacement API before Qt 6.10
* We'll add the deprecation markers now, with a trigger time in the future
** Markers can be disabled with a macro (opt-out)
** Current users shouldn't be affected &ndash; any issues that you have are ones you've always had
* We'll link to a doc page explaining how to replace QSharedMemory
** Use QFile::map for simple sharing of memory
** Update as we learn more about use-cases
** Ask for contact if use-case isn't taken into account
* Known uses:
** Biggest user of QSharedMemory is QtSingleApplication
*** Multiple different versions out there
*** Thiago volunteers to fix it
** Use D-Bus on Linux, figure out what to do elsewhere
** qtwayland has one use of QSharedMemory too
** Sharing of large data sets to avoid serialisation
** Shared images (qtdeclarative)
** Androidtestrunner (single-application exclusion)
* WINE implements Windows semantics on Unix; we could investigate
* memfd is the "correct" solution on Linux and FreeBSD
** similar enough to Windows semantics (disappears on last close)
** not portable elsewhere