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* Replace signed integer overflow, since that's undefined behavior, with ↵Gravatar Abseil Team2024-07-02
| | | | | | | unsigned integer overflow. PiperOrigin-RevId: 648730502 Change-Id: I662c365c59be9e51f565fd215d284a96b7bd8743
* Disable flaky test cases in kernel_timeout_internal_test.Gravatar Evan Brown2024-06-20
| | | | | PiperOrigin-RevId: 645054874 Change-Id: Ic4a820b47edfa71bd3e1f149d54f00ac3c1d16a6
* Increase slop time on MSVC in PerThreadSemTest.Timeouts again due to ↵Gravatar Evan Brown2024-06-14
| | | | | | | continued flakiness. PiperOrigin-RevId: 643372086 Change-Id: I8fb2acc0e5ad35113e865bf008a531f3442a9295
* Remove test references to absl::SharedBitGen, which was never part ofGravatar Derek Mauro2024-05-22
| | | | | | | | the open source release. This was only used in tests that never ran as part in the open source release. PiperOrigin-RevId: 636167506 Change-Id: Iafc33bd768307fe9ee77b181369635012abf2245
* Apply ABSL_MUST_USE_RESULT to try lock functions.Gravatar Chris Kennelly2024-04-25
| | | | | PiperOrigin-RevId: 628091370 Change-Id: I2dd20b7f33ab99e78d63688832ab475a513aa3fd
* Annotate that Mutex should warn when unused.Gravatar Chris Kennelly2024-04-04
| | | | | | | This often indicates a bug from adding synchronization logic but not using it. PiperOrigin-RevId: 621921486 Change-Id: Iec49134c5e4bb50d9fc728c1f8a4fd2e86856782
* Fix flaky test failures on MSVC.Gravatar Evan Brown2024-03-18
| | | | | PiperOrigin-RevId: 616951235 Change-Id: I2d6e95a432285c3f79ef8484848e88e06973f51f
* Fix flaky MSVC test failures by using longer slop time.Gravatar Evan Brown2024-03-06
| | | | | PiperOrigin-RevId: 613326708 Change-Id: I6e5ca195f208b8da0d21d70b5a035bfdc64f866d
* Increase GraphCycles::PointerMap sizeGravatar Abseil Team2024-03-04
| | | | | PiperOrigin-RevId: 612509928 Change-Id: I90de2e6bd229bf5cf71a27e9c491bc2794e9265f
* Minor changes to the BUILD file for absl/synchronizationGravatar Abseil Team2024-02-02
| | | | | PiperOrigin-RevId: 603816996 Change-Id: Ifc7dc6299e65043697b4a0c6e9e8eef869297ce3
* Replace `testonly = 1` with `testonly = True` in abseil BUILD files.Gravatar Shahriar Rouf2024-01-31
| | | | | | | https://bazel.build/build/style-guide#other-conventions PiperOrigin-RevId: 603084345 Change-Id: Ibd7c9573d820f88059d12c46ff82d7d322d002ae
* Remove code pieces for no longer supported MSVC versions.Gravatar Abseil Team2024-01-19
| | | | | | | The current support policy is `_MSC_VER >= 1920`. PiperOrigin-RevId: 599833619 Change-Id: I9cf7393a5b659d1680765e37e0328539ccb870fa
* PR #1589: Use compare_exchange_weak in the loop in Mutex::ReaderLockGravatar AtariDreams2024-01-02
| | | | | | | | | | | | | Imported from GitHub PR https://github.com/abseil/abseil-cpp/pull/1589 It makes sense because even if it fails spuriously, we can just try again since we have to check for other readers anyway. Merge 0b1780299b9e43205202d6b25f6e57759722d063 into 6a19ff47352a2112e953f4ab813d820e0ecfe1e3 Merging this change closes #1589 COPYBARA_INTEGRATE_REVIEW=https://github.com/abseil/abseil-cpp/pull/1589 from AtariDreams:atomics 0b1780299b9e43205202d6b25f6e57759722d063 PiperOrigin-RevId: 595149382 Change-Id: I24f678f6bf95c6a37b2ed541a2b6668a58a67702
* [absl] Rename `absl::internal::identity` to `absl::internal::type_identity`Gravatar Lawrence Wolf-Sonkin2023-12-28
| | | | | | | | * Also does this for `absl::internal::identity_t` which is now `absl::internal::type_identity_t` * This is clearer naming as this is a backfill of `std::type_identity` (the identity type), and not `std::identity` (the identity function) PiperOrigin-RevId: 594316002 Change-Id: I5fb8cf7e3d07c1bc736cbecd202e7d556b6ea33e
* Migrate static objects to NoDestructor in tests, testing libraries and ↵Gravatar Abseil Team2023-12-26
| | | | | | | benchmarks. PiperOrigin-RevId: 593918110 Change-Id: Ide100c69b10e28011af17c7f82bb10eea072cad4
* Mutex: Prevent false race in EnableInvariantDebugging.Gravatar Dmitry Vyukov2023-12-19
| | | | | | | | | | | | | | The added test exposes a false TSan race report in EnableInvariantDebugging/EnableDebugLog related to SynchEvent reuse. We ignore most of the stuff that happens inside of the Mutex code, but not for the code inside of EnableInvariantDebugging/EnableDebugLog. So these can cause occasional false reports on SynchEvent bankruptcy. Also ignore accesses in EnableInvariantDebugging/EnableDebugLog. PiperOrigin-RevId: 592226791 Change-Id: I066edb1ef5661ba6cf86a195f91a9d5328b93d10
* Mutex: Fix Condition pointer-to-member cast to respect const qualifierGravatar Abseil Team2023-12-18
| | | | | | | | | | | | | | | | Previously, `absl::Condition` incorrectly used the same (non-`const`) pointer-to-method type when wrapping both `const` and non-`const` methods. Unfortunately, this is undefined behavior according to `[expr.reinterpret.cast]` in the C++ standard: > The effect of calling a function through a pointer to a function type that is > not the same as the type used in the definition of the function is undefined. This fixes the UB. PiperOrigin-RevId: 591981682 Change-Id: Iaca955346699417232383d3a1800ea9b82ea5761
* Avoid using both Win32Waiter and PthreadWaiter on MinGW,Gravatar Derek Mauro2023-11-08
| | | | | | | | | | | and use StdcppWaiter instead. There are various flavors of MinGW, some of which support pthread, and some of which support Win32. Instead of figuring out which platform is being used, just use the generic implementation. PiperOrigin-RevId: 580565507 Change-Id: Ia85fd7496f1e6ebdeadb95202f0039e844826118
* Mutex: Remove destructor in release buildGravatar Dmitry Vyukov2023-10-31
| | | | | | | | | | | | | | | | The Mutex destructor is needed only to clean up debug logging and invariant checking synch events. These are not supposed to be used in production, but the non-empty destructor has costs for production builds. Instead of removing synch events in destructor, drop all of them if we accumulated too many. For tests is should not matter (we maybe only consume a bit more memory). Production builds should be either unaffected (if don't use debug logging), or use periodic reset of all synch events. PiperOrigin-RevId: 578123259 Change-Id: I0ec59183a5f63ea0a6b7fc50f0a77974e7f677be
* absl: speed up Mutex::LockGravatar Dmitry Vyukov2023-10-30
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Currently Mutex::Lock contains not inlined non-tail call: TryAcquireWithSpinning -> GetMutexGlobals -> LowLevelCallOnce -> init closure This turns the function into non-leaf with stack frame allocation and additional register use. Remove this non-tail call to make the function leaf. Move spin iterations initialization to LockSlow. Current Lock happy path: 00000000001edc20 <absl::Mutex::Lock()>: 1edc20: 55 push %rbp 1edc21: 48 89 e5 mov %rsp,%rbp 1edc24: 53 push %rbx 1edc25: 50 push %rax 1edc26: 48 89 fb mov %rdi,%rbx 1edc29: 48 8b 07 mov (%rdi),%rax 1edc2c: a8 19 test $0x19,%al 1edc2e: 75 0e jne 1edc3e <absl::Mutex::Lock()+0x1e> 1edc30: 48 89 c1 mov %rax,%rcx 1edc33: 48 83 c9 08 or $0x8,%rcx 1edc37: f0 48 0f b1 0b lock cmpxchg %rcx,(%rbx) 1edc3c: 74 42 je 1edc80 <absl::Mutex::Lock()+0x60> ... unhappy path ... 1edc80: 48 83 c4 08 add $0x8,%rsp 1edc84: 5b pop %rbx 1edc85: 5d pop %rbp 1edc86: c3 ret New Lock happy path: 00000000001eea80 <absl::Mutex::Lock()>: 1eea80: 48 8b 07 mov (%rdi),%rax 1eea83: a8 19 test $0x19,%al 1eea85: 75 0f jne 1eea96 <absl::Mutex::Lock()+0x16> 1eea87: 48 89 c1 mov %rax,%rcx 1eea8a: 48 83 c9 08 or $0x8,%rcx 1eea8e: f0 48 0f b1 0f lock cmpxchg %rcx,(%rdi) 1eea93: 75 01 jne 1eea96 <absl::Mutex::Lock()+0x16> 1eea95: c3 ret ... unhappy path ... PiperOrigin-RevId: 577790105 Change-Id: I20793534050302ff9f7a20aed93791c088d98562
* Rollback "Mutex: Remove destructor in release build"Gravatar Dmitry Vyukov2023-10-27
| | | | | PiperOrigin-RevId: 577180526 Change-Id: Iec53709456805ca8dc5327669cc0f6c95825d0e9
* Mutex: Remove destructor in release buildGravatar Dmitry Vyukov2023-10-27
| | | | | | | | | | | | | | | | The Mutex destructor is needed only to clean up debug logging and invariant checking synch events. These are not supposed to be used in production, but the non-empty destructor has costs for production builds. Instead of removing synch events in destructor, drop all of them if we accumulated too many. For tests is should not matter (we maybe only consume a bit more memory). Production builds should be either unaffected (if don't use debug logging), or use periodic reset of all synch events. PiperOrigin-RevId: 577106805 Change-Id: Icaaf7166b99afcd5dce92b4acd1be661fb72f10b
* absl: requeue waiters as LIFOGravatar Dmitry Vyukov2023-10-24
| | | | | | | | | | | Currently if a thread already blocked on a Mutex, but then failed to acquire the Mutex, we queue it in FIFO order again. As the result unlucky threads can suffer bad latency if they are requeued several times. The least we can do for them is to queue in LIFO order after blocking. PiperOrigin-RevId: 576174725 Change-Id: I9e2a329d34279a26bd1075b42e3217a5dc065f0a
* Bazel: Enable the header_modules featureGravatar Derek Mauro2023-10-11
| | | | | PiperOrigin-RevId: 572575394 Change-Id: Ic1c5ac2423b1634e50c43bad6daa14e82a8f3e2c
* Bazel: Support layering_check and parse_headersGravatar Derek Mauro2023-10-10
| | | | | | | | | | | | | The layering_check feature ensures that rules that include a header explicitly depend on a rule that exports that header. Compiler support is required, and currently only Clang 16+ supports diagnoses layering_check failures. The parse_headers feature ensures headers are self-contained by compiling them with -fsyntax-only on supported compilers. PiperOrigin-RevId: 572350144 Change-Id: I37297f761566d686d9dd58d318979d688b7e36d1
* Mutex: Rollback requeing waiters as LIFOGravatar Abseil Team2023-09-21
| | | | | PiperOrigin-RevId: 567415671 Change-Id: I59bfcb5ac9fbde227a4cdb3b497b0bd5969b0770
* Rollback "absl: speed up Mutex::Lock"Gravatar Dmitry Vyukov2023-09-20
| | | | | | | There are some regressions reported. PiperOrigin-RevId: 567181925 Change-Id: I4ee8a61afd336de7ecb22ec307adb2068932bc8b
* absl:speed up Mutex::[Reader]TryLockGravatar Dmitry Vyukov2023-09-20
| | | | | | | | | | | | | | | | | | | Tidy up Mutex::[Reader]TryLock codegen by outlining slow path and non-tail function call, and un-unrolling the loop. Current codegen: https://gist.githubusercontent.com/dvyukov/a4d353fd71ac873af9332c1340675b60/raw/226537ffa305b25a79ef3a85277fa870fee5191d/gistfile1.txt New codegen: https://gist.githubusercontent.com/dvyukov/686a094c5aa357025689764f155e5a29/raw/e3125c1cdb5669fac60faf336e2f60395e29d888/gistfile1.txt name old cpu/op new cpu/op delta BM_TryLock 18.0ns ± 0% 17.7ns ± 0% -1.64% (p=0.016 n=4+5) BM_ReaderTryLock/real_time/threads:1 17.9ns ± 0% 17.9ns ± 0% -0.10% (p=0.016 n=5+5) BM_ReaderTryLock/real_time/threads:72 9.61µs ± 8% 8.42µs ± 7% -12.37% (p=0.008 n=5+5) PiperOrigin-RevId: 567006472 Change-Id: Iea0747e71bbf2dc1f00c70a4235203071d795b99
* absl: add Mutex::[Reader]TryLock benchmarkGravatar Dmitry Vyukov2023-09-20
| | | | | PiperOrigin-RevId: 566991965 Change-Id: I6c4d64de79d303e69b18330bda04fdc84d40893d
* absl: speed up Mutex::ReaderLock/UnlockGravatar Dmitry Vyukov2023-09-20
| | | | | | | | | | | | | | | | Currently ReaderLock/Unlock tries CAS only once. Even if there is moderate contention from other readers only, ReaderLock/Unlock go onto slow path, which does lots of additional work before retrying the CAS (since there are only readers, the slow path logic is not really needed for anything). Retry CAS while there are only readers. name old cpu/op new cpu/op delta BM_ReaderLock/real_time/threads:1 17.9ns ± 0% 17.9ns ± 0% ~ (p=0.071 n=5+5) BM_ReaderLock/real_time/threads:72 11.4µs ± 3% 8.4µs ± 4% -26.24% (p=0.008 n=5+5) PiperOrigin-RevId: 566981511 Change-Id: I432a3c1d85b84943d0ad4776a34fa5bfcf5b3b8e
* absl: add Mutex::ReaderLock benchmarkGravatar Dmitry Vyukov2023-09-20
| | | | | PiperOrigin-RevId: 566961701 Change-Id: Id04e4c5a598f508a0fe7532ae8f084c583865f2d
* absl: speed up Mutex::LockGravatar Dmitry Vyukov2023-09-18
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Currently Mutex::Lock contains not inlined non-tail call: TryAcquireWithSpinning -> GetMutexGlobals -> LowLevelCallOnce -> init closure This turns the function into non-leaf with stack frame allocation and additional register use. Remove this non-tail call to make the function leaf. Move spin iterations initialization to LockSlow. Current Lock happy path: 00000000001edc20 <absl::Mutex::Lock()>: 1edc20: 55 push %rbp 1edc21: 48 89 e5 mov %rsp,%rbp 1edc24: 53 push %rbx 1edc25: 50 push %rax 1edc26: 48 89 fb mov %rdi,%rbx 1edc29: 48 8b 07 mov (%rdi),%rax 1edc2c: a8 19 test $0x19,%al 1edc2e: 75 0e jne 1edc3e <absl::Mutex::Lock()+0x1e> 1edc30: 48 89 c1 mov %rax,%rcx 1edc33: 48 83 c9 08 or $0x8,%rcx 1edc37: f0 48 0f b1 0b lock cmpxchg %rcx,(%rbx) 1edc3c: 74 42 je 1edc80 <absl::Mutex::Lock()+0x60> ... unhappy path ... 1edc80: 48 83 c4 08 add $0x8,%rsp 1edc84: 5b pop %rbx 1edc85: 5d pop %rbp 1edc86: c3 ret New Lock happy path: 00000000001eea80 <absl::Mutex::Lock()>: 1eea80: 48 8b 07 mov (%rdi),%rax 1eea83: a8 19 test $0x19,%al 1eea85: 75 0f jne 1eea96 <absl::Mutex::Lock()+0x16> 1eea87: 48 89 c1 mov %rax,%rcx 1eea8a: 48 83 c9 08 or $0x8,%rcx 1eea8e: f0 48 0f b1 0f lock cmpxchg %rcx,(%rdi) 1eea93: 75 01 jne 1eea96 <absl::Mutex::Lock()+0x16> 1eea95: c3 ret ... unhappy path ... PiperOrigin-RevId: 566488042 Change-Id: I62f854b82a322cfb1d42c34f8ed01b4677693fca
* absl: requeue waiters as LIFOGravatar Dmitry Vyukov2023-09-18
| | | | | | | | | | | Currently if a thread already blocked on a Mutex, but then failed to acquire the Mutex, we queue it in FIFO order again. As the result unlucky threads can suffer bad latency if they are requeued several times. The least we can do for them is to queue in LIFO order after blocking. PiperOrigin-RevId: 566478783 Change-Id: I8bac08325f20ff6ccc2658e04e1847fd4614c653
* absl: remove special case for timed CondVar waitsGravatar Dmitry Vyukov2023-09-15
| | | | | | | | | | | | CondVar wait morhping has a special case for timed waits. The code goes back to 2006, it seems that there might have been some reasons to do this back then. But now it does not seem to be necessary. Wait morphing should work just fine after timed CondVar waits. Remove the special case and simplify code. PiperOrigin-RevId: 565798838 Change-Id: I4e4d61ae7ebd521f5c32dfc673e57a0c245e7cfb
* absl: optimize Condition checks in Mutex codeGravatar Dmitry Vyukov2023-09-15
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | 1. Remove special handling of Condition::kTrue. Condition::kTrue is used very rarely (frequently its uses even indicate confusion and bugs). But we pay few additional branches for kTrue on all Condition operations. Remove that special handling and simplify logic. 2. And remove known_false condition in Mutex code. Checking known_false condition only causes slow down because: 1. We already built skip list with equivalent conditions (and keep improving it on every Skip call). And when we built the skip list, we used more capable GuaranteedEqual function (it does not just check for equality of pointers, but for also for equality of function/arg). 2. Condition pointer are rarely equal even for equivalent conditions becuase temp Condition objects are usually created on the stack. We could call GuaranteedEqual(cond, known_false) instead of cond == known_false, but that slows down things even more (see point 1). So remove the known_false optimization. Benchmark results for this and the previous change: name old cpu/op new cpu/op delta BM_ConditionWaiters/0/1 36.0ns ± 0% 34.9ns ± 0% -3.02% (p=0.008 n=5+5) BM_ConditionWaiters/1/1 36.0ns ± 0% 34.9ns ± 0% -2.98% (p=0.008 n=5+5) BM_ConditionWaiters/2/1 35.9ns ± 0% 34.9ns ± 0% -3.03% (p=0.016 n=5+4) BM_ConditionWaiters/0/8 55.5ns ± 5% 49.8ns ± 3% -10.33% (p=0.008 n=5+5) BM_ConditionWaiters/1/8 36.2ns ± 0% 35.2ns ± 0% -2.90% (p=0.016 n=5+4) BM_ConditionWaiters/2/8 53.2ns ± 7% 48.3ns ± 7% ~ (p=0.056 n=5+5) BM_ConditionWaiters/0/64 295ns ± 1% 254ns ± 2% -13.73% (p=0.008 n=5+5) BM_ConditionWaiters/1/64 36.2ns ± 0% 35.2ns ± 0% -2.85% (p=0.008 n=5+5) BM_ConditionWaiters/2/64 290ns ± 6% 250ns ± 4% -13.68% (p=0.008 n=5+5) BM_ConditionWaiters/0/512 5.50µs ±12% 4.99µs ± 8% ~ (p=0.056 n=5+5) BM_ConditionWaiters/1/512 36.7ns ± 3% 35.2ns ± 0% -4.10% (p=0.008 n=5+5) BM_ConditionWaiters/2/512 4.44µs ±13% 4.01µs ± 3% -9.74% (p=0.008 n=5+5) BM_ConditionWaiters/0/4096 104µs ± 6% 101µs ± 3% ~ (p=0.548 n=5+5) BM_ConditionWaiters/1/4096 36.2ns ± 0% 35.1ns ± 0% -3.03% (p=0.008 n=5+5) BM_ConditionWaiters/2/4096 90.4µs ± 5% 85.3µs ± 7% ~ (p=0.222 n=5+5) BM_ConditionWaiters/0/8192 384µs ± 5% 367µs ± 7% ~ (p=0.222 n=5+5) BM_ConditionWaiters/1/8192 36.2ns ± 0% 35.2ns ± 0% -2.84% (p=0.008 n=5+5) BM_ConditionWaiters/2/8192 363µs ± 3% 316µs ± 7% -12.84% (p=0.008 n=5+5) PiperOrigin-RevId: 565669535 Change-Id: I5180c4a787933d2ce477b004a111853753304684
* Rollback:Gravatar Abseil Team2023-09-08
| | | | | | | | | absl: remove special handling of Condition::kTrue absl: remove known_false condition in Mutex code There are some test breakages. PiperOrigin-RevId: 563751370 Change-Id: Ie14dc799e0a0d286a7e1b47f0a9bbe59dfb23f70
* absl: remove leftovers of CondVar support for other mutexesGravatar Abseil Team2023-09-08
| | | | | | | | | | When CondVar accepted generic non-Mutex mutexes, Mutex pointer could be nullptr. Now that support is removed, but we still have some lingering checks for Mutex* == nullptr. Remove them. PiperOrigin-RevId: 563740239 Change-Id: Ib744e0b991f411dd8dba1b0da6477c13832e0f65
* absl: inline and de-dup Mutex::Await/LockWhen/CondVar::WaitGravatar Abseil Team2023-09-08
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Mutex::Await/LockWhen/CondVar::Wait duplicate code, and cause additional calls at runtime and code bloat. Inline thin wrappers that just convert argument types and add a single de-duped implementation for these methods. This reduces code size, shaves off 55K from the mutex_test in release build, and should make things marginally faster. $ nm -nS mutex_test | egrep "(_ZN4absl5Mutex.*(Await|LockWhen))|(_ZN4absl7CondVar.*Wait)" before: 00000000000912c0 00000000000001a8 T _ZN4absl7CondVar4WaitEPNS_5MutexE 00000000000988c0 0000000000000c36 T _ZN4absl7CondVar16WaitWithDeadlineEPNS_5MutexENS_4TimeE 000000000009a6e0 0000000000000041 T _ZN4absl5Mutex19LockWhenWithTimeoutERKNS_9ConditionENS_8DurationE 00000000000a28c0 0000000000000779 T _ZN4absl5Mutex17AwaitWithDeadlineERKNS_9ConditionENS_4TimeE 00000000000cf4e0 0000000000000011 T _ZN4absl5Mutex8LockWhenERKNS_9ConditionE 00000000000cf500 0000000000000041 T _ZN4absl5Mutex20LockWhenWithDeadlineERKNS_9ConditionENS_4TimeE 00000000000cf560 0000000000000011 T _ZN4absl5Mutex14ReaderLockWhenERKNS_9ConditionE 00000000000cf580 0000000000000041 T _ZN4absl5Mutex26ReaderLockWhenWithDeadlineERKNS_9ConditionENS_4TimeE 00000000000cf5e0 0000000000000766 T _ZN4absl5Mutex5AwaitERKNS_9ConditionE 00000000000cfd60 00000000000007b5 T _ZN4absl5Mutex16AwaitWithTimeoutERKNS_9ConditionENS_8DurationE 00000000000d0700 00000000000003cf T _ZN4absl7CondVar15WaitWithTimeoutEPNS_5MutexENS_8DurationE 000000000011c280 0000000000000041 T _ZN4absl5Mutex25ReaderLockWhenWithTimeoutERKNS_9ConditionENS_8DurationE after: 000000000009c300 00000000000007ed T _ZN4absl7CondVar10WaitCommonEPNS_5MutexENS_24synchronization_internal13KernelTimeoutE 00000000000a03c0 00000000000006fe T _ZN4absl5Mutex11AwaitCommonERKNS_9ConditionENS_24synchronization_internal13KernelTimeoutE 000000000011ae00 0000000000000025 T _ZN4absl5Mutex14LockWhenCommonERKNS_9ConditionENS_24synchronization_internal13KernelTimeoutEb PiperOrigin-RevId: 563729364 Change-Id: Ic6b43761f76719c01e03d43cc0e0c419e41a85c1
* absl: remove known_false condition in Mutex codeGravatar Abseil Team2023-09-08
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Checking known_false condition only causes slow down because: 1. We already built skip list with equivalent conditions (and keep improving it on every Skip call). And when we built the skip list, we used more capable GuaranteedEqual function (it does not just check for equality of pointers, but for also for equality of function/arg). 2. Condition pointer are rarely equal even for equivalent conditions becuase temp Condition objects are usually created on the stack. We could call GuaranteedEqual(cond, known_false) instead of cond == known_false, but that slows down things even more (see point 1). So remove the known_false optimization. Benchmark results for this and the previous change: name old cpu/op new cpu/op delta BM_ConditionWaiters/0/1 36.0ns ± 0% 34.9ns ± 0% -3.02% (p=0.008 n=5+5) BM_ConditionWaiters/1/1 36.0ns ± 0% 34.9ns ± 0% -2.98% (p=0.008 n=5+5) BM_ConditionWaiters/2/1 35.9ns ± 0% 34.9ns ± 0% -3.03% (p=0.016 n=5+4) BM_ConditionWaiters/0/8 55.5ns ± 5% 49.8ns ± 3% -10.33% (p=0.008 n=5+5) BM_ConditionWaiters/1/8 36.2ns ± 0% 35.2ns ± 0% -2.90% (p=0.016 n=5+4) BM_ConditionWaiters/2/8 53.2ns ± 7% 48.3ns ± 7% ~ (p=0.056 n=5+5) BM_ConditionWaiters/0/64 295ns ± 1% 254ns ± 2% -13.73% (p=0.008 n=5+5) BM_ConditionWaiters/1/64 36.2ns ± 0% 35.2ns ± 0% -2.85% (p=0.008 n=5+5) BM_ConditionWaiters/2/64 290ns ± 6% 250ns ± 4% -13.68% (p=0.008 n=5+5) BM_ConditionWaiters/0/512 5.50µs ±12% 4.99µs ± 8% ~ (p=0.056 n=5+5) BM_ConditionWaiters/1/512 36.7ns ± 3% 35.2ns ± 0% -4.10% (p=0.008 n=5+5) BM_ConditionWaiters/2/512 4.44µs ±13% 4.01µs ± 3% -9.74% (p=0.008 n=5+5) BM_ConditionWaiters/0/4096 104µs ± 6% 101µs ± 3% ~ (p=0.548 n=5+5) BM_ConditionWaiters/1/4096 36.2ns ± 0% 35.1ns ± 0% -3.03% (p=0.008 n=5+5) BM_ConditionWaiters/2/4096 90.4µs ± 5% 85.3µs ± 7% ~ (p=0.222 n=5+5) BM_ConditionWaiters/0/8192 384µs ± 5% 367µs ± 7% ~ (p=0.222 n=5+5) BM_ConditionWaiters/1/8192 36.2ns ± 0% 35.2ns ± 0% -2.84% (p=0.008 n=5+5) BM_ConditionWaiters/2/8192 363µs ± 3% 316µs ± 7% -12.84% (p=0.008 n=5+5) PiperOrigin-RevId: 563717887 Change-Id: I9a62670628510d764a4f2f88a047abb8f85009e2
* absl: remove special handling of Condition::kTrueGravatar Abseil Team2023-09-08
| | | | | | | | | Condition::kTrue is used very rarely (frequently its uses even indicate confusion and bugs). But we pay few additional branches for kTrue on all Condition operations. Remove that special handling and simplify logic. PiperOrigin-RevId: 563691160 Change-Id: I76125adde4872489da069dd9c894ed73a65d1d83
* absl: fix a priority bug in CondVar wait morphingGravatar Abseil Team2023-08-29
| | | | | | | | | | | | | | Enqueue updates priority of the queued thread. It was assumed that the queued thread is the current thread. But it's not the case in CondVar wait morhping, where we requeue an existing CondVar waiter on the Mutex. As the result one thread can falsely get priority of another thread. Fix this by not updating priority in this case. And make the assumption explicit and checked. PiperOrigin-RevId: 561249402 Change-Id: I9476c047757090b893a88a2839b795b85fe220ad
* kernel_timeout_test: Add Apple to the list of slow platforms becauseGravatar Derek Mauro2023-08-21
| | | | | | | it runs on non-dedicated Kokoro PiperOrigin-RevId: 558874605 Change-Id: Iba35f558ab8c967f98a3176af056e76341fb67c3
* Add StdcppWaiter to the end of the list of waiter implementationsGravatar Derek Mauro2023-08-10
| | | | | | | | | Since ABSL_INTERNAL_HAVE_STDCPP_WAITER is defined on all systems it is effectively a fallback. I left the condition there in case we have to disable it on some platform in the future. PiperOrigin-RevId: 555629066 Change-Id: I76ca78c7f36d1d02dc4950a44c66903a2aaf2a52
* Add Support for mmap on Qualcomm Hexagon DSP targets.Gravatar Abseil Team2023-07-17
| | | | | PiperOrigin-RevId: 548709037 Change-Id: I6eb03553299265660aa0abc180ae0f197a416ba4
* Use an allowlist visibility model for //absl/synchronizationGravatar Derek Mauro2023-07-10
| | | | | PiperOrigin-RevId: 546914671 Change-Id: I6f0419103efdd8125e4027e7d5eec124ca604156
* absl: extend Condition::kTrue commentGravatar Abseil Team2023-07-01
| | | | | | | | | Explain when kTrue may be useful. Note that Mutex::Await/LockWhen with kTrue condition and a timeout do not return when the timeout is reached. PiperOrigin-RevId: 544846222 Change-Id: I7a14ae5a9314b2e500919f0c7b3a907d4d97c127
* absl: add a Mutex::Await/LockWhen testGravatar Abseil Team2023-06-20
| | | | | | | | | Check various corner cases for Await/LockWhen return value with always true/always false conditions. I don't see this explicitly tested anywhere else. PiperOrigin-RevId: 542141533 Change-Id: Ia116c6dc199de606ad446c205951169ec5e2abe1
* absl: fix lint errors in MutexGravatar Abseil Team2023-06-20
| | | | | | | | | | | | | | | Currently linter warns on all changes: missing #include <cstdlib> for 'std::atexit' and single-argument constructors must be marked explicit to avoid unintentional implicit conversions Fix that. PiperOrigin-RevId: 542135136 Change-Id: Ic86649de6baef7f2de71f45875bb66bd730bf6e1
* absl: cosmetic changes for MutexGravatar Abseil Team2023-06-20
| | | | | | | | | | Few pure cosmetic changes: - remove unused headers - add using for CycleClock since it's used multiple times - restructure GetMutexGlobals to be more consistent PiperOrigin-RevId: 542002120 Change-Id: I117faae05cb8224041f7e3771999f3a35bdf4aef
* absl: reformat Mutex-related filesGravatar Abseil Team2023-06-20
| | | | | | | | | | | Reformat Mutex-related files so that incremental formatting changes don't distract during review of logical changes. These files are subtle and any unnecessary diffs make reviews harder. No changes besides running clang-format. PiperOrigin-RevId: 541981737 Change-Id: I41cccb7a97158c78d17adaff6fe553c2c9c2b9ed
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