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-rw-r--r--absl/synchronization/BUILD.bazel6
-rw-r--r--absl/synchronization/CMakeLists.txt2
-rw-r--r--absl/synchronization/internal/create_thread_identity.cc6
-rw-r--r--absl/synchronization/internal/graphcycles.cc6
-rw-r--r--absl/synchronization/internal/kernel_timeout.h56
-rw-r--r--absl/synchronization/internal/mutex_nonprod.cc7
-rw-r--r--absl/synchronization/internal/mutex_nonprod.inc20
-rw-r--r--absl/synchronization/internal/per_thread_sem.h2
-rw-r--r--absl/synchronization/internal/per_thread_sem_test.cc1
-rw-r--r--absl/synchronization/internal/waiter.cc8
-rw-r--r--absl/synchronization/internal/waiter.h4
-rw-r--r--absl/synchronization/mutex.cc138
-rw-r--r--absl/synchronization/mutex.h21
-rw-r--r--absl/synchronization/mutex_benchmark.cc3
-rw-r--r--absl/synchronization/mutex_test.cc9
15 files changed, 159 insertions, 130 deletions
diff --git a/absl/synchronization/BUILD.bazel b/absl/synchronization/BUILD.bazel
index 3f876b9f..4d4d6806 100644
--- a/absl/synchronization/BUILD.bazel
+++ b/absl/synchronization/BUILD.bazel
@@ -24,7 +24,7 @@ load(
package(default_visibility = ["//visibility:public"])
-licenses(["notice"]) # Apache 2.0
+licenses(["notice"])
# Internal data structure for efficiently detecting mutex dependency cycles
cc_library(
@@ -90,6 +90,7 @@ cc_library(
copts = ABSL_DEFAULT_COPTS,
linkopts = select({
"//absl:windows": [],
+ "//absl:wasm": [],
"//conditions:default": ["-pthread"],
}) + ABSL_DEFAULT_LINKOPTS,
deps = [
@@ -189,6 +190,7 @@ cc_test(
":synchronization",
":thread_pool",
"//absl/base",
+ "//absl/base:config",
"//absl/base:core_headers",
"//absl/base:raw_logging_internal",
"//absl/memory",
@@ -210,6 +212,7 @@ cc_library(
":synchronization",
":thread_pool",
"//absl/base",
+ "//absl/base:config",
"@com_github_google_benchmark//:benchmark_main",
],
alwayslink = 1,
@@ -248,6 +251,7 @@ cc_library(
deps = [
":synchronization",
"//absl/base",
+ "//absl/base:config",
"//absl/strings",
"//absl/time",
"@com_google_googletest//:gtest",
diff --git a/absl/synchronization/CMakeLists.txt b/absl/synchronization/CMakeLists.txt
index dfe5d05d..e5bc52fb 100644
--- a/absl/synchronization/CMakeLists.txt
+++ b/absl/synchronization/CMakeLists.txt
@@ -149,6 +149,7 @@ absl_cc_test(
absl::synchronization
absl::thread_pool
absl::base
+ absl::config
absl::core_headers
absl::memory
absl::raw_logging_internal
@@ -179,6 +180,7 @@ absl_cc_library(
DEPS
absl::synchronization
absl::base
+ absl::config
absl::strings
absl::time
gmock
diff --git a/absl/synchronization/internal/create_thread_identity.cc b/absl/synchronization/internal/create_thread_identity.cc
index fa0070a9..53a71b34 100644
--- a/absl/synchronization/internal/create_thread_identity.cc
+++ b/absl/synchronization/internal/create_thread_identity.cc
@@ -32,9 +32,9 @@ namespace synchronization_internal {
// ThreadIdentity storage is persistent, we maintain a free-list of previously
// released ThreadIdentity objects.
-static base_internal::SpinLock freelist_lock(
- base_internal::kLinkerInitialized);
-static base_internal::ThreadIdentity* thread_identity_freelist;
+ABSL_CONST_INIT static base_internal::SpinLock freelist_lock(
+ absl::kConstInit, base_internal::SCHEDULE_KERNEL_ONLY);
+ABSL_CONST_INIT static base_internal::ThreadIdentity* thread_identity_freelist;
// A per-thread destructor for reclaiming associated ThreadIdentity objects.
// Since we must preserve their storage we cache them for re-use.
diff --git a/absl/synchronization/internal/graphcycles.cc b/absl/synchronization/internal/graphcycles.cc
index 6a2bcdf6..19f9aab5 100644
--- a/absl/synchronization/internal/graphcycles.cc
+++ b/absl/synchronization/internal/graphcycles.cc
@@ -51,9 +51,9 @@ namespace {
// Avoid LowLevelAlloc's default arena since it calls malloc hooks in
// which people are doing things like acquiring Mutexes.
-static absl::base_internal::SpinLock arena_mu(
- absl::base_internal::kLinkerInitialized);
-static base_internal::LowLevelAlloc::Arena* arena;
+ABSL_CONST_INIT static absl::base_internal::SpinLock arena_mu(
+ absl::kConstInit, base_internal::SCHEDULE_KERNEL_ONLY);
+ABSL_CONST_INIT static base_internal::LowLevelAlloc::Arena* arena;
static void InitArenaIfNecessary() {
arena_mu.Lock();
diff --git a/absl/synchronization/internal/kernel_timeout.h b/absl/synchronization/internal/kernel_timeout.h
index d6ac5db0..1084e1e6 100644
--- a/absl/synchronization/internal/kernel_timeout.h
+++ b/absl/synchronization/internal/kernel_timeout.h
@@ -57,6 +57,10 @@ class KernelTimeout {
bool has_timeout() const { return ns_ != 0; }
+ // Convert to parameter for sem_timedwait/futex/similar. Only for approved
+ // users. Do not call if !has_timeout.
+ struct timespec MakeAbsTimespec();
+
private:
// internal rep, not user visible: ns after unix epoch.
// zero = no timeout.
@@ -82,34 +86,6 @@ class KernelTimeout {
return x;
}
- // Convert to parameter for sem_timedwait/futex/similar. Only for approved
- // users. Do not call if !has_timeout.
- struct timespec MakeAbsTimespec() {
- int64_t n = ns_;
- static const int64_t kNanosPerSecond = 1000 * 1000 * 1000;
- if (n == 0) {
- ABSL_RAW_LOG(
- ERROR,
- "Tried to create a timespec from a non-timeout; never do this.");
- // But we'll try to continue sanely. no-timeout ~= saturated timeout.
- n = (std::numeric_limits<int64_t>::max)();
- }
-
- // Kernel APIs validate timespecs as being at or after the epoch,
- // despite the kernel time type being signed. However, no one can
- // tell the difference between a timeout at or before the epoch (since
- // all such timeouts have expired!)
- if (n < 0) n = 0;
-
- struct timespec abstime;
- int64_t seconds = (std::min)(n / kNanosPerSecond,
- int64_t{(std::numeric_limits<time_t>::max)()});
- abstime.tv_sec = static_cast<time_t>(seconds);
- abstime.tv_nsec =
- static_cast<decltype(abstime.tv_nsec)>(n % kNanosPerSecond);
- return abstime;
- }
-
#ifdef _WIN32
// Converts to milliseconds from now, or INFINITE when
// !has_timeout(). For use by SleepConditionVariableSRW on
@@ -148,6 +124,30 @@ class KernelTimeout {
friend class Waiter;
};
+inline struct timespec KernelTimeout::MakeAbsTimespec() {
+ int64_t n = ns_;
+ static const int64_t kNanosPerSecond = 1000 * 1000 * 1000;
+ if (n == 0) {
+ ABSL_RAW_LOG(
+ ERROR, "Tried to create a timespec from a non-timeout; never do this.");
+ // But we'll try to continue sanely. no-timeout ~= saturated timeout.
+ n = (std::numeric_limits<int64_t>::max)();
+ }
+
+ // Kernel APIs validate timespecs as being at or after the epoch,
+ // despite the kernel time type being signed. However, no one can
+ // tell the difference between a timeout at or before the epoch (since
+ // all such timeouts have expired!)
+ if (n < 0) n = 0;
+
+ struct timespec abstime;
+ int64_t seconds = (std::min)(n / kNanosPerSecond,
+ int64_t{(std::numeric_limits<time_t>::max)()});
+ abstime.tv_sec = static_cast<time_t>(seconds);
+ abstime.tv_nsec = static_cast<decltype(abstime.tv_nsec)>(n % kNanosPerSecond);
+ return abstime;
+}
+
} // namespace synchronization_internal
ABSL_NAMESPACE_END
} // namespace absl
diff --git a/absl/synchronization/internal/mutex_nonprod.cc b/absl/synchronization/internal/mutex_nonprod.cc
index 4590b98d..334c3bc0 100644
--- a/absl/synchronization/internal/mutex_nonprod.cc
+++ b/absl/synchronization/internal/mutex_nonprod.cc
@@ -27,11 +27,16 @@
#include <algorithm>
+#include "absl/base/config.h"
#include "absl/base/internal/raw_logging.h"
#include "absl/time/time.h"
namespace absl {
ABSL_NAMESPACE_BEGIN
+
+void SetMutexDeadlockDetectionMode(OnDeadlockCycle) {}
+void EnableMutexInvariantDebugging(bool) {}
+
namespace synchronization_internal {
namespace {
@@ -274,7 +279,7 @@ bool CondVar::WaitWithTimeout(Mutex* mu, absl::Duration timeout) {
void CondVar::EnableDebugLog(const char*) {}
-#ifdef THREAD_SANITIZER
+#ifdef ABSL_HAVE_THREAD_SANITIZER
extern "C" void __tsan_read1(void *addr);
#else
#define __tsan_read1(addr) // do nothing if TSan not enabled
diff --git a/absl/synchronization/internal/mutex_nonprod.inc b/absl/synchronization/internal/mutex_nonprod.inc
index a1502e72..d83bc8a9 100644
--- a/absl/synchronization/internal/mutex_nonprod.inc
+++ b/absl/synchronization/internal/mutex_nonprod.inc
@@ -209,31 +209,22 @@ class SynchronizationStorage {
// Instances allocated on the heap or on the stack should use the default
// constructor.
SynchronizationStorage()
- : is_dynamic_(true), once_() {}
-
- // Instances allocated in static storage (not on the heap, not on the
- // stack) should use this constructor.
- explicit SynchronizationStorage(base_internal::LinkerInitialized) {}
+ : destruct_(true), once_() {}
constexpr explicit SynchronizationStorage(absl::ConstInitType)
- : is_dynamic_(false), once_(), space_{{0}} {}
+ : destruct_(false), once_(), space_{{0}} {}
SynchronizationStorage(SynchronizationStorage&) = delete;
SynchronizationStorage& operator=(SynchronizationStorage&) = delete;
~SynchronizationStorage() {
- if (is_dynamic_) {
+ if (destruct_) {
get()->~T();
}
}
// Retrieve the object in storage. This is fast and thread safe, but does
// incur the cost of absl::call_once().
- //
- // For instances in static storage constructed with the
- // LinkerInitialized constructor, may be called at any time without
- // regard for order of dynamic initialization or destruction of objects
- // in static storage. See the class comment for caveats.
T* get() {
absl::call_once(once_, SynchronizationStorage::Construct, this);
return reinterpret_cast<T*>(&space_);
@@ -245,10 +236,7 @@ class SynchronizationStorage {
}
// When true, T's destructor is run when this is destructed.
- //
- // The LinkerInitialized constructor assumes this value will be set
- // false by static initialization.
- bool is_dynamic_;
+ const bool destruct_;
absl::once_flag once_;
diff --git a/absl/synchronization/internal/per_thread_sem.h b/absl/synchronization/internal/per_thread_sem.h
index 8ab43915..2228b6e8 100644
--- a/absl/synchronization/internal/per_thread_sem.h
+++ b/absl/synchronization/internal/per_thread_sem.h
@@ -78,7 +78,7 @@ class PerThreadSem {
// !t.has_timeout() => Wait(t) will return true.
static inline bool Wait(KernelTimeout t);
- // White-listed callers.
+ // Permitted callers.
friend class PerThreadSemTest;
friend class absl::Mutex;
friend absl::base_internal::ThreadIdentity* CreateThreadIdentity();
diff --git a/absl/synchronization/internal/per_thread_sem_test.cc b/absl/synchronization/internal/per_thread_sem_test.cc
index b5a2f6d4..8cf59e64 100644
--- a/absl/synchronization/internal/per_thread_sem_test.cc
+++ b/absl/synchronization/internal/per_thread_sem_test.cc
@@ -23,6 +23,7 @@
#include <thread> // NOLINT(build/c++11)
#include "gtest/gtest.h"
+#include "absl/base/config.h"
#include "absl/base/internal/cycleclock.h"
#include "absl/base/internal/thread_identity.h"
#include "absl/strings/str_cat.h"
diff --git a/absl/synchronization/internal/waiter.cc b/absl/synchronization/internal/waiter.cc
index 2949f5a8..b6150b9b 100644
--- a/absl/synchronization/internal/waiter.cc
+++ b/absl/synchronization/internal/waiter.cc
@@ -86,6 +86,14 @@ static void MaybeBecomeIdle() {
#endif
#endif
+#if defined(__NR_futex_time64) && !defined(SYS_futex_time64)
+#define SYS_futex_time64 __NR_futex_time64
+#endif
+
+#if defined(SYS_futex_time64) && !defined(SYS_futex)
+#define SYS_futex SYS_futex_time64
+#endif
+
class Futex {
public:
static int WaitUntil(std::atomic<int32_t> *v, int32_t val,
diff --git a/absl/synchronization/internal/waiter.h b/absl/synchronization/internal/waiter.h
index a6e6d4c7..887f9b1b 100644
--- a/absl/synchronization/internal/waiter.h
+++ b/absl/synchronization/internal/waiter.h
@@ -100,8 +100,8 @@ class Waiter {
}
// How many periods to remain idle before releasing resources
-#ifndef THREAD_SANITIZER
- static const int kIdlePeriods = 60;
+#ifndef ABSL_HAVE_THREAD_SANITIZER
+ static constexpr int kIdlePeriods = 60;
#else
// Memory consumption under ThreadSanitizer is a serious concern,
// so we release resources sooner. The value of 1 leads to 1 to 2 second
diff --git a/absl/synchronization/mutex.cc b/absl/synchronization/mutex.cc
index e0879b05..9b7f088a 100644
--- a/absl/synchronization/mutex.cc
+++ b/absl/synchronization/mutex.cc
@@ -39,6 +39,7 @@
#include <thread> // NOLINT(build/c++11)
#include "absl/base/attributes.h"
+#include "absl/base/call_once.h"
#include "absl/base/config.h"
#include "absl/base/dynamic_annotations.h"
#include "absl/base/internal/atomic_hook.h"
@@ -58,6 +59,7 @@
using absl::base_internal::CurrentThreadIdentityIfPresent;
using absl::base_internal::PerThreadSynch;
+using absl::base_internal::SchedulingGuard;
using absl::base_internal::ThreadIdentity;
using absl::synchronization_internal::GetOrCreateCurrentThreadIdentity;
using absl::synchronization_internal::GraphCycles;
@@ -75,7 +77,7 @@ ABSL_NAMESPACE_BEGIN
namespace {
-#if defined(THREAD_SANITIZER)
+#if defined(ABSL_HAVE_THREAD_SANITIZER)
constexpr OnDeadlockCycle kDeadlockDetectionDefault = OnDeadlockCycle::kIgnore;
#else
constexpr OnDeadlockCycle kDeadlockDetectionDefault = OnDeadlockCycle::kAbort;
@@ -85,28 +87,6 @@ ABSL_CONST_INIT std::atomic<OnDeadlockCycle> synch_deadlock_detection(
kDeadlockDetectionDefault);
ABSL_CONST_INIT std::atomic<bool> synch_check_invariants(false);
-// ------------------------------------------ spinlock support
-
-// Make sure read-only globals used in the Mutex code are contained on the
-// same cacheline and cacheline aligned to eliminate any false sharing with
-// other globals from this and other modules.
-static struct MutexGlobals {
- MutexGlobals() {
- // Find machine-specific data needed for Delay() and
- // TryAcquireWithSpinning(). This runs in the global constructor
- // sequence, and before that zeros are safe values.
- num_cpus = absl::base_internal::NumCPUs();
- spinloop_iterations = num_cpus > 1 ? 1500 : 0;
- }
- int num_cpus;
- int spinloop_iterations;
- // Pad this struct to a full cacheline to prevent false sharing.
- char padding[ABSL_CACHELINE_SIZE - 2 * sizeof(int)];
-} ABSL_CACHELINE_ALIGNED mutex_globals;
-static_assert(
- sizeof(MutexGlobals) == ABSL_CACHELINE_SIZE,
- "MutexGlobals must occupy an entire cacheline to prevent false sharing");
-
ABSL_INTERNAL_ATOMIC_HOOK_ATTRIBUTES
absl::base_internal::AtomicHook<void (*)(int64_t wait_cycles)>
submit_profile_data;
@@ -143,33 +123,55 @@ void RegisterSymbolizer(bool (*fn)(const void *pc, char *out, int out_size)) {
symbolizer.Store(fn);
}
-// spinlock delay on iteration c. Returns new c.
+struct ABSL_CACHELINE_ALIGNED MutexGlobals {
+ absl::once_flag once;
+ int num_cpus = 0;
+ int spinloop_iterations = 0;
+};
+
+static const MutexGlobals& GetMutexGlobals() {
+ ABSL_CONST_INIT static MutexGlobals data;
+ absl::base_internal::LowLevelCallOnce(&data.once, [&]() {
+ data.num_cpus = absl::base_internal::NumCPUs();
+ data.spinloop_iterations = data.num_cpus > 1 ? 1500 : 0;
+ });
+ return data;
+}
+
+// Spinlock delay on iteration c. Returns new c.
namespace {
enum DelayMode { AGGRESSIVE, GENTLE };
};
-static int Delay(int32_t c, DelayMode mode) {
+
+namespace synchronization_internal {
+int MutexDelay(int32_t c, int mode) {
// If this a uniprocessor, only yield/sleep. Otherwise, if the mode is
// aggressive then spin many times before yielding. If the mode is
// gentle then spin only a few times before yielding. Aggressive spinning is
// used to ensure that an Unlock() call, which must get the spin lock for
// any thread to make progress gets it without undue delay.
- int32_t limit = (mutex_globals.num_cpus > 1) ?
- ((mode == AGGRESSIVE) ? 5000 : 250) : 0;
+ const int32_t limit =
+ GetMutexGlobals().num_cpus > 1 ? (mode == AGGRESSIVE ? 5000 : 250) : 0;
if (c < limit) {
- c++; // spin
+ // Spin.
+ c++;
} else {
+ SchedulingGuard::ScopedEnable enable_rescheduling;
ABSL_TSAN_MUTEX_PRE_DIVERT(nullptr, 0);
- if (c == limit) { // yield once
+ if (c == limit) {
+ // Yield once.
AbslInternalMutexYield();
c++;
- } else { // then wait
+ } else {
+ // Then wait.
absl::SleepFor(absl::Microseconds(10));
c = 0;
}
ABSL_TSAN_MUTEX_POST_DIVERT(nullptr, 0);
}
- return (c);
+ return c;
}
+} // namespace synchronization_internal
// --------------------------Generic atomic ops
// Ensure that "(*pv & bits) == bits" by doing an atomic update of "*pv" to
@@ -207,12 +209,12 @@ static void AtomicClearBits(std::atomic<intptr_t>* pv, intptr_t bits,
//------------------------------------------------------------------
// Data for doing deadlock detection.
-static absl::base_internal::SpinLock deadlock_graph_mu(
- absl::base_internal::kLinkerInitialized);
+ABSL_CONST_INIT static absl::base_internal::SpinLock deadlock_graph_mu(
+ absl::kConstInit, base_internal::SCHEDULE_KERNEL_ONLY);
-// graph used to detect deadlocks.
-static GraphCycles *deadlock_graph ABSL_GUARDED_BY(deadlock_graph_mu)
- ABSL_PT_GUARDED_BY(deadlock_graph_mu);
+// Graph used to detect deadlocks.
+ABSL_CONST_INIT static GraphCycles *deadlock_graph
+ ABSL_GUARDED_BY(deadlock_graph_mu) ABSL_PT_GUARDED_BY(deadlock_graph_mu);
//------------------------------------------------------------------
// An event mechanism for debugging mutex use.
@@ -273,13 +275,12 @@ static const struct {
{0, "SignalAll on "},
};
-static absl::base_internal::SpinLock synch_event_mu(
- absl::base_internal::kLinkerInitialized);
-// protects synch_event
+ABSL_CONST_INIT static absl::base_internal::SpinLock synch_event_mu(
+ absl::kConstInit, base_internal::SCHEDULE_KERNEL_ONLY);
// Hash table size; should be prime > 2.
// Can't be too small, as it's used for deadlock detection information.
-static const uint32_t kNSynchEvent = 1031;
+static constexpr uint32_t kNSynchEvent = 1031;
static struct SynchEvent { // this is a trivial hash table for the events
// struct is freed when refcount reaches 0
@@ -299,7 +300,7 @@ static struct SynchEvent { // this is a trivial hash table for the events
bool log; // logging turned on
// Constant after initialization
- char name[1]; // actually longer---NUL-terminated std::string
+ char name[1]; // actually longer---NUL-terminated string
} * synch_event[kNSynchEvent] ABSL_GUARDED_BY(synch_event_mu);
// Ensure that the object at "addr" has a SynchEvent struct associated with it,
@@ -704,7 +705,7 @@ static constexpr bool kDebugMode = false;
static constexpr bool kDebugMode = true;
#endif
-#ifdef THREAD_SANITIZER
+#ifdef ABSL_HAVE_THREAD_SANITIZER
static unsigned TsanFlags(Mutex::MuHow how) {
return how == kShared ? __tsan_mutex_read_lock : 0;
}
@@ -1055,6 +1056,7 @@ static PerThreadSynch *DequeueAllWakeable(PerThreadSynch *head,
// Try to remove thread s from the list of waiters on this mutex.
// Does nothing if s is not on the waiter list.
void Mutex::TryRemove(PerThreadSynch *s) {
+ SchedulingGuard::ScopedDisable disable_rescheduling;
intptr_t v = mu_.load(std::memory_order_relaxed);
// acquire spinlock & lock
if ((v & (kMuWait | kMuSpin | kMuWriter | kMuReader)) == kMuWait &&
@@ -1119,7 +1121,7 @@ ABSL_XRAY_LOG_ARGS(1) void Mutex::Block(PerThreadSynch *s) {
this->TryRemove(s);
int c = 0;
while (s->next != nullptr) {
- c = Delay(c, GENTLE);
+ c = synchronization_internal::MutexDelay(c, GENTLE);
this->TryRemove(s);
}
if (kDebugMode) {
@@ -1438,21 +1440,19 @@ void Mutex::AssertNotHeld() const {
// Attempt to acquire *mu, and return whether successful. The implementation
// may spin for a short while if the lock cannot be acquired immediately.
static bool TryAcquireWithSpinning(std::atomic<intptr_t>* mu) {
- int c = mutex_globals.spinloop_iterations;
- int result = -1; // result of operation: 0=false, 1=true, -1=unknown
-
+ int c = GetMutexGlobals().spinloop_iterations;
do { // do/while somewhat faster on AMD
intptr_t v = mu->load(std::memory_order_relaxed);
- if ((v & (kMuReader|kMuEvent)) != 0) { // a reader or tracing -> give up
- result = 0;
+ if ((v & (kMuReader|kMuEvent)) != 0) {
+ return false; // a reader or tracing -> give up
} else if (((v & kMuWriter) == 0) && // no holder -> try to acquire
mu->compare_exchange_strong(v, kMuWriter | v,
std::memory_order_acquire,
std::memory_order_relaxed)) {
- result = 1;
+ return true;
}
- } while (result == -1 && --c > 0);
- return result == 1;
+ } while (--c > 0);
+ return false;
}
ABSL_XRAY_LOG_ARGS(1) void Mutex::Lock() {
@@ -1751,7 +1751,8 @@ static const intptr_t ignore_waiting_writers[] = {
};
// Internal version of LockWhen(). See LockSlowWithDeadline()
-void Mutex::LockSlow(MuHow how, const Condition *cond, int flags) {
+ABSL_ATTRIBUTE_NOINLINE void Mutex::LockSlow(MuHow how, const Condition *cond,
+ int flags) {
ABSL_RAW_CHECK(
this->LockSlowWithDeadline(how, cond, KernelTimeout::Never(), flags),
"condition untrue on return from LockSlow");
@@ -1766,7 +1767,7 @@ static inline bool EvalConditionAnnotated(const Condition *cond, Mutex *mu,
// All memory accesses are ignored inside of mutex operations + for unlock
// operation tsan considers that we've already released the mutex.
bool res = false;
-#ifdef THREAD_SANITIZER
+#ifdef ABSL_HAVE_THREAD_SANITIZER
const int flags = read_lock ? __tsan_mutex_read_lock : 0;
const int tryflags = flags | (trylock ? __tsan_mutex_try_lock : 0);
#endif
@@ -1816,9 +1817,9 @@ static inline bool EvalConditionIgnored(Mutex *mu, const Condition *cond) {
// So we "divert" (which un-ignores both memory accesses and synchronization)
// and then separately turn on ignores of memory accesses.
ABSL_TSAN_MUTEX_PRE_DIVERT(mu, 0);
- ANNOTATE_IGNORE_READS_AND_WRITES_BEGIN();
+ ABSL_ANNOTATE_IGNORE_READS_AND_WRITES_BEGIN();
bool res = cond->Eval();
- ANNOTATE_IGNORE_READS_AND_WRITES_END();
+ ABSL_ANNOTATE_IGNORE_READS_AND_WRITES_END();
ABSL_TSAN_MUTEX_POST_DIVERT(mu, 0);
static_cast<void>(mu); // Prevent unused param warning in non-TSAN builds.
return res;
@@ -1899,6 +1900,7 @@ static void CheckForMutexCorruption(intptr_t v, const char* label) {
}
void Mutex::LockSlowLoop(SynchWaitParams *waitp, int flags) {
+ SchedulingGuard::ScopedDisable disable_rescheduling;
int c = 0;
intptr_t v = mu_.load(std::memory_order_relaxed);
if ((v & kMuEvent) != 0) {
@@ -2000,7 +2002,8 @@ void Mutex::LockSlowLoop(SynchWaitParams *waitp, int flags) {
ABSL_RAW_CHECK(
waitp->thread->waitp == nullptr || waitp->thread->suppress_fatal_errors,
"detected illegal recursion into Mutex code");
- c = Delay(c, GENTLE); // delay, then try again
+ // delay, then try again
+ c = synchronization_internal::MutexDelay(c, GENTLE);
}
ABSL_RAW_CHECK(
waitp->thread->waitp == nullptr || waitp->thread->suppress_fatal_errors,
@@ -2017,7 +2020,8 @@ void Mutex::LockSlowLoop(SynchWaitParams *waitp, int flags) {
// which holds the lock but is not runnable because its condition is false
// or it is in the process of blocking on a condition variable; it must requeue
// itself on the mutex/condvar to wait for its condition to become true.
-void Mutex::UnlockSlow(SynchWaitParams *waitp) {
+ABSL_ATTRIBUTE_NOINLINE void Mutex::UnlockSlow(SynchWaitParams *waitp) {
+ SchedulingGuard::ScopedDisable disable_rescheduling;
intptr_t v = mu_.load(std::memory_order_relaxed);
this->AssertReaderHeld();
CheckForMutexCorruption(v, "Unlock");
@@ -2294,7 +2298,8 @@ void Mutex::UnlockSlow(SynchWaitParams *waitp) {
mu_.store(nv, std::memory_order_release);
break; // out of for(;;)-loop
}
- c = Delay(c, AGGRESSIVE); // aggressive here; no one can proceed till we do
+ // aggressive here; no one can proceed till we do
+ c = synchronization_internal::MutexDelay(c, AGGRESSIVE);
} // end of for(;;)-loop
if (wake_list != kPerThreadSynchNull) {
@@ -2333,6 +2338,7 @@ void Mutex::Trans(MuHow how) {
// It will later acquire the mutex with high probability. Otherwise, we
// enqueue thread w on this mutex.
void Mutex::Fer(PerThreadSynch *w) {
+ SchedulingGuard::ScopedDisable disable_rescheduling;
int c = 0;
ABSL_RAW_CHECK(w->waitp->cond == nullptr,
"Mutex::Fer while waiting on Condition");
@@ -2382,7 +2388,7 @@ void Mutex::Fer(PerThreadSynch *w) {
return;
}
}
- c = Delay(c, GENTLE);
+ c = synchronization_internal::MutexDelay(c, GENTLE);
}
}
@@ -2431,6 +2437,7 @@ CondVar::~CondVar() {
// Remove thread s from the list of waiters on this condition variable.
void CondVar::Remove(PerThreadSynch *s) {
+ SchedulingGuard::ScopedDisable disable_rescheduling;
intptr_t v;
int c = 0;
for (v = cv_.load(std::memory_order_relaxed);;
@@ -2459,7 +2466,8 @@ void CondVar::Remove(PerThreadSynch *s) {
std::memory_order_release);
return;
} else {
- c = Delay(c, GENTLE); // try again after a delay
+ // try again after a delay
+ c = synchronization_internal::MutexDelay(c, GENTLE);
}
}
}
@@ -2492,7 +2500,7 @@ static void CondVarEnqueue(SynchWaitParams *waitp) {
!cv_word->compare_exchange_weak(v, v | kCvSpin,
std::memory_order_acquire,
std::memory_order_relaxed)) {
- c = Delay(c, GENTLE);
+ c = synchronization_internal::MutexDelay(c, GENTLE);
v = cv_word->load(std::memory_order_relaxed);
}
ABSL_RAW_CHECK(waitp->thread->waitp == nullptr, "waiting when shouldn't be");
@@ -2591,6 +2599,7 @@ void CondVar::Wakeup(PerThreadSynch *w) {
}
void CondVar::Signal() {
+ SchedulingGuard::ScopedDisable disable_rescheduling;
ABSL_TSAN_MUTEX_PRE_SIGNAL(nullptr, 0);
intptr_t v;
int c = 0;
@@ -2623,7 +2632,7 @@ void CondVar::Signal() {
ABSL_TSAN_MUTEX_POST_SIGNAL(nullptr, 0);
return;
} else {
- c = Delay(c, GENTLE);
+ c = synchronization_internal::MutexDelay(c, GENTLE);
}
}
ABSL_TSAN_MUTEX_POST_SIGNAL(nullptr, 0);
@@ -2660,7 +2669,8 @@ void CondVar::SignalAll () {
ABSL_TSAN_MUTEX_POST_SIGNAL(nullptr, 0);
return;
} else {
- c = Delay(c, GENTLE); // try again after a delay
+ // try again after a delay
+ c = synchronization_internal::MutexDelay(c, GENTLE);
}
}
ABSL_TSAN_MUTEX_POST_SIGNAL(nullptr, 0);
@@ -2673,7 +2683,7 @@ void ReleasableMutexLock::Release() {
this->mu_ = nullptr;
}
-#ifdef THREAD_SANITIZER
+#ifdef ABSL_HAVE_THREAD_SANITIZER
extern "C" void __tsan_read1(void *addr);
#else
#define __tsan_read1(addr) // do nothing if TSan not enabled
diff --git a/absl/synchronization/mutex.h b/absl/synchronization/mutex.h
index 8c70c4ce..52401fe3 100644
--- a/absl/synchronization/mutex.h
+++ b/absl/synchronization/mutex.h
@@ -331,17 +331,16 @@ class ABSL_LOCKABLE Mutex {
// Mutex::AwaitWithTimeout()
// Mutex::AwaitWithDeadline()
//
- // If `cond` is initially true, do nothing, or act as though `cond` is
- // initially false.
- //
- // If `cond` is initially false, unlock this `Mutex` and block until
- // simultaneously:
+ // Unlocks this `Mutex` and blocks until simultaneously:
// - either `cond` is true or the {timeout has expired, deadline has passed}
// and
// - this `Mutex` can be reacquired,
// then reacquire this `Mutex` in the same mode in which it was previously
// held, returning `true` iff `cond` is `true` on return.
//
+ // If the condition is initially `true`, the implementation *may* skip the
+ // release/re-acquire step and return immediately.
+ //
// Deadlines in the past are equivalent to an immediate deadline.
// Negative timeouts are equivalent to a zero timeout.
//
@@ -686,6 +685,11 @@ class Condition {
// return processed_ >= current;
// };
// mu_.Await(Condition(&reached));
+ //
+ // NOTE: never use "mu_.AssertHeld()" instead of "mu_.AssertReadHeld()" in the
+ // lambda as it may be called when the mutex is being unlocked from a scope
+ // holding only a reader lock, which will make the assertion not fulfilled and
+ // crash the binary.
// See class comment for performance advice. In particular, if there
// might be more than one waiter for the same condition, make sure
@@ -770,6 +774,8 @@ class Condition {
//
class CondVar {
public:
+ // A `CondVar` allocated on the heap or on the stack can use the this
+ // constructor.
CondVar();
~CondVar();
@@ -901,9 +907,11 @@ class ABSL_SCOPED_LOCKABLE ReleasableMutexLock {
};
#ifdef ABSL_INTERNAL_USE_NONPROD_MUTEX
+
inline constexpr Mutex::Mutex(absl::ConstInitType) : impl_(absl::kConstInit) {}
#else
+
inline Mutex::Mutex() : mu_(0) {
ABSL_TSAN_MUTEX_CREATE(this, __tsan_mutex_not_static);
}
@@ -911,7 +919,8 @@ inline Mutex::Mutex() : mu_(0) {
inline constexpr Mutex::Mutex(absl::ConstInitType) : mu_(0) {}
inline CondVar::CondVar() : cv_(0) {}
-#endif
+
+#endif // ABSL_INTERNAL_USE_NONPROD_MUTEX
// static
template <typename T>
diff --git a/absl/synchronization/mutex_benchmark.cc b/absl/synchronization/mutex_benchmark.cc
index ab188001..933ea14f 100644
--- a/absl/synchronization/mutex_benchmark.cc
+++ b/absl/synchronization/mutex_benchmark.cc
@@ -16,6 +16,7 @@
#include <mutex> // NOLINT(build/c++11)
#include <vector>
+#include "absl/base/config.h"
#include "absl/base/internal/cycleclock.h"
#include "absl/base/internal/spinlock.h"
#include "absl/synchronization/blocking_counter.h"
@@ -213,7 +214,7 @@ void BM_ConditionWaiters(benchmark::State& state) {
}
// Some configurations have higher thread limits than others.
-#if defined(__linux__) && !defined(THREAD_SANITIZER)
+#if defined(__linux__) && !defined(ABSL_HAVE_THREAD_SANITIZER)
constexpr int kMaxConditionWaiters = 8192;
#else
constexpr int kMaxConditionWaiters = 1024;
diff --git a/absl/synchronization/mutex_test.cc b/absl/synchronization/mutex_test.cc
index afb363af..16fc9058 100644
--- a/absl/synchronization/mutex_test.cc
+++ b/absl/synchronization/mutex_test.cc
@@ -30,6 +30,7 @@
#include "gtest/gtest.h"
#include "absl/base/attributes.h"
+#include "absl/base/config.h"
#include "absl/base/internal/raw_logging.h"
#include "absl/base/internal/sysinfo.h"
#include "absl/memory/memory.h"
@@ -815,7 +816,7 @@ TEST(Mutex, MutexReaderDecrementBug) ABSL_NO_THREAD_SAFETY_ANALYSIS {
// Test that we correctly handle the situation when a lock is
// held and then destroyed (w/o unlocking).
-#ifdef THREAD_SANITIZER
+#ifdef ABSL_HAVE_THREAD_SANITIZER
// TSAN reports errors when locked Mutexes are destroyed.
TEST(Mutex, DISABLED_LockedMutexDestructionBug) NO_THREAD_SAFETY_ANALYSIS {
#else
@@ -1067,7 +1068,7 @@ class ScopedDisableBazelTestWarnings {
const char ScopedDisableBazelTestWarnings::kVarName[] =
"TEST_WARNINGS_OUTPUT_FILE";
-#ifdef THREAD_SANITIZER
+#ifdef ABSL_HAVE_THREAD_SANITIZER
// This test intentionally creates deadlocks to test the deadlock detector.
TEST(Mutex, DISABLED_DeadlockDetectorBazelWarning) {
#else
@@ -1101,7 +1102,7 @@ TEST(Mutex, DeadlockDetectorBazelWarning) {
// annotation-based static thread-safety analysis is not currently
// predicate-aware and cannot tell if the two for-loops that acquire and
// release the locks have the same predicates.
-TEST(Mutex, DeadlockDetectorStessTest) ABSL_NO_THREAD_SAFETY_ANALYSIS {
+TEST(Mutex, DeadlockDetectorStressTest) ABSL_NO_THREAD_SAFETY_ANALYSIS {
// Stress test: Here we create a large number of locks and use all of them.
// If a deadlock detector keeps a full graph of lock acquisition order,
// it will likely be too slow for this test to pass.
@@ -1119,7 +1120,7 @@ TEST(Mutex, DeadlockDetectorStessTest) ABSL_NO_THREAD_SAFETY_ANALYSIS {
}
}
-#ifdef THREAD_SANITIZER
+#ifdef ABSL_HAVE_THREAD_SANITIZER
// TSAN reports errors when locked Mutexes are destroyed.
TEST(Mutex, DISABLED_DeadlockIdBug) NO_THREAD_SAFETY_ANALYSIS {
#else
generated by cgit v1.2.3 (git 2.39.1) at 2024-05-18 06:15:56 +0000