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* Long live futexes for Darwin!Thiago Macieira2023-06-181-1/+3
| | | | | | | | | | | | | | | | | | | | | | | | | | | Like commit 91f6460aff0a6ab5142f16d5f4fc1f559ca1c325 which added support for Windows, this commit does the same for our final major OS. The Darwin kernel exposes a set of __ulock_{wait,wait2,wake} APIs [1], but these APIs are marked as private, so we cannot rely on them being stable, nor we can use these APIs in builds of Qt intended for the Apple App Store. By wholesale disabling the use of the APIs in App Store compliant builds, and runtime checking availability of the APIs when we do build them in, we should be safe, unless the semantics of the APIs change in ways we haven't accounted for, but that's a risk we're willing to take. Note that libc++ uses these private APIs to implement P1135R5 (the C++20 synchronization library) [2], but that use is under a "special permission" from the Darwin team, and meant only for use in the Apple vendored version of libc++ shipped with their operating systems, where they control both the kernel and the standard library. [1] https://github.com/apple-oss-distributions/xnu/blob/xnu-8792.81.2/bsd/sys/ulock.h [2] https://reviews.llvm.org/D68480. Change-Id: Ib709fc1585f647a98d54fffd16663b4965458404 Reviewed-by: Tor Arne Vestbø <tor.arne.vestbo@qt.io>
* Long live futexes for FreeBSD!Thiago Macieira2023-06-151-2/+3
| | | | | | | | | | | | | | Like commit 91f6460aff0a6ab5142f16d5f4fc1f559ca1c325 which added support for Windows. This API is documented and has apparently been present in FreeBSD for a long while. The DragonflyBSD API is very similar, but I don't have one to confirm that I've coded correctly. OpenBSD and NetBSD may have similar APIs, but I haven't even researched them. We're open to contributions, though. Change-Id: I63b988479db546dabffcfffd1766bc431fed614b Reviewed-by: Mårten Nordheim <marten.nordheim@qt.io> Reviewed-by: Fabian Kosmale <fabian.kosmale@qt.io>
* Switch futex support to QDeadlineTimerThiago Macieira2023-06-151-3/+2
| | | | | | | | | | This allows us to use absolute times on Linux (today) and FreeBSD (soon), plus simplifies both QMutex and QSemaphore. Change-Id: I63b988479db546dabffcfffd17675a182aa528fa Reviewed-by: Ahmad Samir <a.samirh78@gmail.com> Reviewed-by: Qt CI Bot <qt_ci_bot@qt-project.org> Reviewed-by: Mårten Nordheim <marten.nordheim@qt.io>
* Split qfutex_p.h per OSThiago Macieira2023-06-151-107/+2
| | | | | | | | | Makes it cleaner when I add more OSes. Change-Id: I63b988479db546dabffcfffd1766bee2e6370b94 Reviewed-by: Mårten Nordheim <marten.nordheim@qt.io> Reviewed-by: Ahmad Samir <a.samirh78@gmail.com> Reviewed-by: Fabian Kosmale <fabian.kosmale@qt.io>
* QtLinuxFutex, QBasicMutex, QSemaphore: use chrono for time arithmeticAhmad Samir2023-06-091-7/+11
| | | | | | Done-With: Thiago Macieira <thiago.macieira@intel.com> Change-Id: I7c696d58ee596254f91bcd131fe884b6e6ef0852 Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>
* Long live Q_UNREACHABLE_RETURN()!Marc Mutz2022-10-151-1/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | This is a combination of Q_UNREACHABLE() with a return statement. ATM, the return statement is unconditionally included. If we notice that some compilers warn about return after __builtin_unreachable(), then we can map Q_UNREACHABLE_RETURN(...) to Q_UNREACHABLE() without having to touch all the code that uses explicit Q_UNREACHABLE() + return. The fact that Boost has BOOST_UNREACHABLE_RETURN() indicates that there are compilers that complain about a lack of return after Q_UNREACHABLE (we know that MSVC, ICC, and GHS are among them), as well as compilers that complained about a return being present (Coverity). Take this opportunity to properly adapt to Coverity, by leaving out the return statement on this compiler. Apply the macro around the code base, using a clang-tidy transformer rule: const std::string unr = "unr", val = "val", ret = "ret"; auto makeUnreachableReturn = cat("Q_UNREACHABLE_RETURN(", ifBound(val, cat(node(val)), cat("")), ")"); auto ignoringSwitchCases = [](auto stmt) { return anyOf(stmt, switchCase(subStmt(stmt))); }; makeRule( stmt(ignoringSwitchCases(stmt(isExpandedFromMacro("Q_UNREACHABLE")).bind(unr)), nextStmt(returnStmt(optionally(hasReturnValue(expr().bind(val)))).bind(ret))), {changeTo(node(unr), cat(makeUnreachableReturn, ";")), // TODO: why is the ; lost w/o this? changeTo(node(ret), cat(""))}, cat("use ", makeUnreachableReturn)) ); where nextStmt() is copied from some upstream clang-tidy check's private implementation and subStmt() is a private matcher that gives access to SwitchCase's SubStmt. A.k.a. qt-use-unreachable-return. There were some false positives, suppressed them with NOLINTNEXTLINE. They're not really false positiives, it's just that Clang sees the world in one way and if conditonal compilation (#if) differs for other compilers, Clang doesn't know better. This is an artifact of matching two consecutive statements. I haven't figured out how to remove the empty line left by the deletion of the return statement, if it, indeed, was on a separate line, so post-processed the patch to remove all the lines matching ^\+ *$ from the diff: git commit -am meep git reset --hard HEAD^ git diff HEAD..HEAD@{1} | sed '/^\+ *$/d' | recountdiff - | patch -p1 [ChangeLog][QtCore][QtAssert] Added Q_UNREACHABLE_RETURN() macro. Change-Id: I9782939f16091c964f25b7826e1c0dbd13a71305 Reviewed-by: Marc Mutz <marc.mutz@qt.io> Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>
* Use SPDX license identifiersLucie Gérard2022-05-161-38/+2
| | | | | | | | | | | | | Replace the current license disclaimer in files by a SPDX-License-Identifier. Files that have to be modified by hand are modified. License files are organized under LICENSES directory. Task-number: QTBUG-67283 Change-Id: Id880c92784c40f3bbde861c0d93f58151c18b9f1 Reviewed-by: Qt CI Bot <qt_ci_bot@qt-project.org> Reviewed-by: Lars Knoll <lars.knoll@qt.io> Reviewed-by: Jörg Bornemann <joerg.bornemann@qt.io>
* Annotate QMutex with TSAN annotationsGiuseppe D'Angelo2022-04-111-26/+5
| | | | | | | | | | | | | | | | The Q(Basic)Mutex fast paths are entirely inline in the caller, which means we need to annotate its operations directly or TSAN doesn't know what's going on. Also annotate QRecursiveMutex. The tryLock code could be in principle simplified via a QScopeGuard but I didn't want to make a central class like QMutex depend on it. [ChangeLog][QtCore][QMutex] QMutex now has annotations for ThreadSanitizer. Change-Id: Ibb130404e63a5ec9bcef9675f9addd16a2c38b7f Reviewed-by: David Faure <david.faure@kdab.com> Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>
* Make sure all qtbase private headers include at least one otherThiago Macieira2022-02-241-1/+1
| | | | | | | | | | See script in qtbase/util/includeprivate for the rules. Since these files are being touched anyway, I also ran the updatecopyright.pl script too. Change-Id: Ib056b47dde3341ef9a52ffff13ef677e471674b6 Reviewed-by: Marc Mutz <marc.mutz@qt.io>
* Fix build on riscv32Fabrice Fontaine2021-09-021-0/+5
| | | | | | | | | | | | | | | | | | riscv32 fails to build because __NR_futex is not defined on this architecture: In file included from thread/qmutex_linux.cpp:45, from thread/qmutex.cpp:804: thread/qfutex_p.h: In function 'int QtLinuxFutex::_q_futex(int*, int, int, quintptr, int*, int)': thread/qfutex_p.h:116:30: error: '__NR_futex' was not declared in this scope; did you mean '_q_futex'? 116 | int result = syscall(__NR_futex, addr, op | FUTEX_PRIVATE_FLAG, val, val2, addr2, val3); | ^~~~~~~~~~ | _q_futex Pick-to: 6.1 6.2 Fixes: QTBUG-96067 Change-Id: Ib6a9bcc496f37e69ac39362cb0a021fccaf311f5 Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>
* Futex/Windows: add support for notifying TSanThiago Macieira2021-03-111-22/+24
| | | | | | | | | The code was already there, just only implemented for Linux. Change-Id: Ib709fc1585f647a98d54fffd16663881b6d24d6f Reviewed-by: Volker Hilsheimer <volker.hilsheimer@qt.io> Reviewed-by: Mårten Nordheim <marten.nordheim@qt.io> Reviewed-by: Giuseppe D'Angelo <giuseppe.dangelo@kdab.com>
* Implement futexes for WindowsThiago Macieira2021-02-131-0/+30
| | | | | | | | | | | | | Windows 8 added this pair of functions that can be used to implement the same functionality as we have on Linux. For ease of understanding, I'm calling them "futex" on Windows too. From Qt 6 our minimum platform is Windows 10 so we can use this unconditionally. Change-Id: Ifea6e497f11a461db432ffff1448c6806ecfc36c Reviewed-by: Qt CI Bot <qt_ci_bot@qt-project.org> Reviewed-by: Fabian Kosmale <fabian.kosmale@qt.io>
* Fix build when configuring with -sanitize thread on gccMitch Curtis2020-10-121-1/+1
| | | | | | | | | There is no <sanitizer/tsan_interface.h> header when building with gcc, at least on Ubuntu 18.04.3. Fixes: QTBUG-87317 Change-Id: Ie933f6fa478f11b5062c665007e91be68e31ebe3 Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>
* Replace Qt CONSTEXPR defines with constexprAllan Sandfeld Jensen2020-08-141-1/+1
| | | | | | | | Both normal and relaxed constexpr are required by our new minimum of C++17. Change-Id: Ic028b88a2e7a6cb7d5925f3133b9d54859a81744 Reviewed-by: Sona Kurazyan <sona.kurazyan@qt.io>
* Don't wrap feature detection macros with QT_HAS_FOO() variantsTor Arne Vestbø2019-12-101-2/+2
| | | | | | | | | | | | | | | | | Using wrappers for these macros is problematic when for example passing the -frewrite-includes flag to preprocess sources before shipping off to distcc or Icecream. It will also start producing warnings when compilers implement http://eel.is/c++draft/cpp.cond#7.sentence-2. See for example https://reviews.llvm.org/D49091 Both https://clang.llvm.org/docs/LanguageExtensions.html and the SD-6 document at https://isocpp.org/std/standing-documents/sd-6-sg10-feature-test-recommendations recommend defining '__has_foo(x) 0' as a fallback for compilers without the macros, so that's what we go for. Change-Id: I0298cd3b4a6ff6618821e34642a5ddd6728be767 Reviewed-by: Alex Richardson <arichardson.kde@gmail.com> Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>
* Annotate the futex implementation for TSANGiuseppe D'Angelo2019-05-221-1/+29
| | | | | | | | | | | | | | | | | | | | | | | | | | | TSAN does not understand the futex system call. Now, in QMutex and QSemaphore usage, futex is always wrapped by atomic operations that always do an acquire (before waiting) and a release (before waking waiters). That alone realizes a synchronizes-with, and since Qt uses std::atomics, TSAN knows what's going on and does not complain. But what if one uses futex directly, or we change the algorithms, or introduce some other new synchronization primitive somewhere? Luckily TSAN offers annotations for this that we can use. This patch annotates the main entry point for the futex syscall with a pair of acquire/release semantics. A futex call guarantees total ordering on the operations on the futex word(s), whether the call succeeds or fails. Change-Id: Ib80ff898c09fbb6fc73989247eb757bf70971a8a Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>
* Replace Q_DECL_NOEXCEPT with noexcept in corelibAllan Sandfeld Jensen2019-04-031-1/+1
| | | | | | | In preparation of Qt6 move away from pre-C++11 macros. Change-Id: I44126693c20c18eca5620caab4f7e746218e0ce3 Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>
* Add the "we mean it" warning to qfutex_p.hMårten Nordheim2017-09-221-0/+11
| | | | | Change-Id: I77a0899532e2a38fa390991bbad11300672544bf Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>
* Port QSemaphore to use futexesThiago Macieira2017-09-181-9/+12
| | | | | | | | This is interesting because QSemaphore now needs to allocate no memory: it's just a simple 31-bit counter and the contention flag. Change-Id: I6e9274c1e7444ad48c81fffd14dbc0ab42bc2e00 Reviewed-by: Lars Knoll <lars.knoll@qt.io>
* Move the futex implementation to a headerThiago Macieira2017-09-181-0/+128
So I can use it in QSemaphore and provide a Windows implementation. Change-Id: I6e9274c1e7444ad48c81fffd14dbc0a8e2201302 Reviewed-by: Lars Knoll <lars.knoll@qt.io>
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