diff options
Diffstat (limited to 'absl/synchronization/mutex.h')
| -rw-r--r-- | absl/synchronization/mutex.h | 22 |
1 files changed, 22 insertions, 0 deletions
diff --git a/absl/synchronization/mutex.h b/absl/synchronization/mutex.h index aeef3c95978c..4b65e92cb3d0 100644 --- a/absl/synchronization/mutex.h +++ b/absl/synchronization/mutex.h @@ -61,6 +61,7 @@ #include <cstdint> #include <string> +#include "absl/base/const_init.h" #include "absl/base/internal/identity.h" #include "absl/base/internal/low_level_alloc.h" #include "absl/base/internal/thread_identity.h" @@ -136,7 +137,26 @@ struct SynchWaitParams; class LOCKABLE Mutex { public: + // Creates a `Mutex` that is not held by anyone. This constructor is + // typically used for Mutexes allocated on the heap or the stack. + // + // To create `Mutex` instances with static storage duration + // (e.g. a namespace-scoped or global variable), see + // `Mutex::Mutex(absl::kConstInit)` below instead. Mutex(); + + // Creates a mutex with static storage duration. A global variable + // constructed this way avoids the lifetime issues that can occur on program + // startup and shutdown. (See absl/base/const_init.h.) + // + // For Mutexes allocated on the heap and stack, instead use the default + // constructor, which can interact more fully with the thread sanitizer. + // + // Example usage: + // namespace foo { + // ABSL_CONST_INIT Mutex mu(absl::kConstInit); + // } + explicit constexpr Mutex(absl::ConstInitType); ~Mutex(); // Mutex::Lock() @@ -879,10 +899,12 @@ class 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); } +inline constexpr Mutex::Mutex(absl::ConstInitType) : mu_(0) {} inline CondVar::CondVar() : cv_(0) {} #endif |