diff options
Diffstat (limited to 'absl/base/internal/spinlock.cc')
-rw-r--r-- | absl/base/internal/spinlock.cc | 37 |
1 files changed, 8 insertions, 29 deletions
diff --git a/absl/base/internal/spinlock.cc b/absl/base/internal/spinlock.cc index 7cac72f97f28..a7d44f3eb091 100644 --- a/absl/base/internal/spinlock.cc +++ b/absl/base/internal/spinlock.cc @@ -79,29 +79,6 @@ SpinLock::SpinLock(base_internal::SchedulingMode mode) ABSL_TSAN_MUTEX_CREATE(this, __tsan_mutex_not_static); } -SpinLock::SpinLock(base_internal::LinkerInitialized, - base_internal::SchedulingMode mode) { - ABSL_TSAN_MUTEX_CREATE(this, 0); - if (IsCooperative(mode)) { - InitLinkerInitializedAndCooperative(); - } - // Otherwise, lockword_ is already initialized. -} - -// Static (linker initialized) spinlocks always start life as functional -// non-cooperative locks. When their static constructor does run, it will call -// this initializer to augment the lockword with the cooperative bit. By -// actually taking the lock when we do this we avoid the need for an atomic -// operation in the regular unlock path. -// -// SlowLock() must be careful to re-test for this bit so that any outstanding -// waiters may be upgraded to cooperative status. -void SpinLock::InitLinkerInitializedAndCooperative() { - Lock(); - lockword_.fetch_or(kSpinLockCooperative, std::memory_order_relaxed); - Unlock(); -} - // Monitor the lock to see if its value changes within some time period // (adaptive_spin_count loop iterations). The last value read from the lock // is returned from the method. @@ -128,6 +105,14 @@ void SpinLock::SlowLock() { if ((lock_value & kSpinLockHeld) == 0) { return; } + + base_internal::SchedulingMode scheduling_mode; + if ((lock_value & kSpinLockCooperative) != 0) { + scheduling_mode = base_internal::SCHEDULE_COOPERATIVE_AND_KERNEL; + } else { + scheduling_mode = base_internal::SCHEDULE_KERNEL_ONLY; + } + // The lock was not obtained initially, so this thread needs to wait for // it. Record the current timestamp in the local variable wait_start_time // so the total wait time can be stored in the lockword once this thread @@ -158,12 +143,6 @@ void SpinLock::SlowLock() { } } - base_internal::SchedulingMode scheduling_mode; - if ((lock_value & kSpinLockCooperative) != 0) { - scheduling_mode = base_internal::SCHEDULE_COOPERATIVE_AND_KERNEL; - } else { - scheduling_mode = base_internal::SCHEDULE_KERNEL_ONLY; - } // SpinLockDelay() calls into fiber scheduler, we need to see // synchronization there to avoid false positives. ABSL_TSAN_MUTEX_PRE_DIVERT(this, 0); |