diff options
Diffstat (limited to 'absl/base/internal/thread_identity.h')
| -rw-r--r-- | absl/base/internal/thread_identity.h | 85 |
1 files changed, 43 insertions, 42 deletions
diff --git a/absl/base/internal/thread_identity.h b/absl/base/internal/thread_identity.h index ceb109b4..9ee651a3 100644 --- a/absl/base/internal/thread_identity.h +++ b/absl/base/internal/thread_identity.h @@ -32,6 +32,7 @@ #include "absl/base/config.h" #include "absl/base/internal/per_thread_tls.h" +#include "absl/base/optimization.h" namespace absl { ABSL_NAMESPACE_BEGIN @@ -69,30 +70,28 @@ struct PerThreadSynch { // is using this PerThreadSynch as a terminator. Its // skip field must not be filled in because the loop // might then skip over the terminator. - - // The wait parameters of the current wait. waitp is null if the - // thread is not waiting. Transitions from null to non-null must - // occur before the enqueue commit point (state = kQueued in - // Enqueue() and CondVarEnqueue()). Transitions from non-null to - // null must occur after the wait is finished (state = kAvailable in - // Mutex::Block() and CondVar::WaitCommon()). This field may be - // changed only by the thread that describes this PerThreadSynch. A - // special case is Fer(), which calls Enqueue() on another thread, - // but with an identical SynchWaitParams pointer, thus leaving the - // pointer unchanged. - SynchWaitParams *waitp; - - bool suppress_fatal_errors; // If true, try to proceed even in the face of - // broken invariants. This is used within fatal - // signal handlers to improve the chances of - // debug logging information being output - // successfully. - - intptr_t readers; // Number of readers in mutex. - int priority; // Priority of thread (updated every so often). - - // When priority will next be read (cycles). - int64_t next_priority_read_cycles; + bool wake; // This thread is to be woken from a Mutex. + // If "x" is on a waiter list for a mutex, "x->cond_waiter" is true iff the + // waiter is waiting on the mutex as part of a CV Wait or Mutex Await. + // + // The value of "x->cond_waiter" is meaningless if "x" is not on a + // Mutex waiter list. + bool cond_waiter; + bool maybe_unlocking; // Valid at head of Mutex waiter queue; + // true if UnlockSlow could be searching + // for a waiter to wake. Used for an optimization + // in Enqueue(). true is always a valid value. + // Can be reset to false when the unlocker or any + // writer releases the lock, or a reader fully + // releases the lock. It may not be set to false + // by a reader that decrements the count to + // non-zero. protected by mutex spinlock + bool suppress_fatal_errors; // If true, try to proceed even in the face + // of broken invariants. This is used within + // fatal signal handlers to improve the + // chances of debug logging information being + // output successfully. + int priority; // Priority of thread (updated every so often). // State values: // kAvailable: This PerThreadSynch is available. @@ -111,30 +110,30 @@ struct PerThreadSynch { }; std::atomic<State> state; - bool maybe_unlocking; // Valid at head of Mutex waiter queue; - // true if UnlockSlow could be searching - // for a waiter to wake. Used for an optimization - // in Enqueue(). true is always a valid value. - // Can be reset to false when the unlocker or any - // writer releases the lock, or a reader fully releases - // the lock. It may not be set to false by a reader - // that decrements the count to non-zero. - // protected by mutex spinlock + // The wait parameters of the current wait. waitp is null if the + // thread is not waiting. Transitions from null to non-null must + // occur before the enqueue commit point (state = kQueued in + // Enqueue() and CondVarEnqueue()). Transitions from non-null to + // null must occur after the wait is finished (state = kAvailable in + // Mutex::Block() and CondVar::WaitCommon()). This field may be + // changed only by the thread that describes this PerThreadSynch. A + // special case is Fer(), which calls Enqueue() on another thread, + // but with an identical SynchWaitParams pointer, thus leaving the + // pointer unchanged. + SynchWaitParams* waitp; - bool wake; // This thread is to be woken from a Mutex. + intptr_t readers; // Number of readers in mutex. - // If "x" is on a waiter list for a mutex, "x->cond_waiter" is true iff the - // waiter is waiting on the mutex as part of a CV Wait or Mutex Await. - // - // The value of "x->cond_waiter" is meaningless if "x" is not on a - // Mutex waiter list. - bool cond_waiter; + // When priority will next be read (cycles). + int64_t next_priority_read_cycles; // Locks held; used during deadlock detection. // Allocated in Synch_GetAllLocks() and freed in ReclaimThreadIdentity(). SynchLocksHeld *all_locks; }; +// The instances of this class are allocated in NewThreadIdentity() with an +// alignment of PerThreadSynch::kAlignment. struct ThreadIdentity { // Must be the first member. The Mutex implementation requires that // the PerThreadSynch object associated with each thread is @@ -144,7 +143,7 @@ struct ThreadIdentity { // Private: Reserved for absl::synchronization_internal::Waiter. struct WaiterState { - char data[128]; + alignas(void*) char data[128]; } waiter_state; // Used by PerThreadSem::{Get,Set}ThreadBlockedCounter(). @@ -212,7 +211,9 @@ void ClearCurrentThreadIdentity(); #define ABSL_THREAD_IDENTITY_MODE ABSL_FORCE_THREAD_IDENTITY_MODE #elif defined(_WIN32) && !defined(__MINGW32__) #define ABSL_THREAD_IDENTITY_MODE ABSL_THREAD_IDENTITY_MODE_USE_CPP11 -#elif ABSL_PER_THREAD_TLS && defined(__GOOGLE_GRTE_VERSION__) && \ +#elif defined(__APPLE__) && defined(ABSL_HAVE_THREAD_LOCAL) +#define ABSL_THREAD_IDENTITY_MODE ABSL_THREAD_IDENTITY_MODE_USE_CPP11 +#elif ABSL_PER_THREAD_TLS && defined(__GOOGLE_GRTE_VERSION__) && \ (__GOOGLE_GRTE_VERSION__ >= 20140228L) // Support for async-safe TLS was specifically added in GRTEv4. It's not // present in the upstream eglibc. |