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Diffstat (limited to 'third_party/abseil_cpp/absl/base/internal/thread_identity.h')
| -rw-r--r-- | third_party/abseil_cpp/absl/base/internal/thread_identity.h | 259 |
1 files changed, 0 insertions, 259 deletions
diff --git a/third_party/abseil_cpp/absl/base/internal/thread_identity.h b/third_party/abseil_cpp/absl/base/internal/thread_identity.h deleted file mode 100644 index ceb109b41c..0000000000 --- a/third_party/abseil_cpp/absl/base/internal/thread_identity.h +++ /dev/null @@ -1,259 +0,0 @@ -// Copyright 2017 The Abseil Authors. -// -// Licensed under the Apache License, Version 2.0 (the "License"); -// you may not use this file except in compliance with the License. -// You may obtain a copy of the License at -// -// https://www.apache.org/licenses/LICENSE-2.0 -// -// Unless required by applicable law or agreed to in writing, software -// distributed under the License is distributed on an "AS IS" BASIS, -// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. -// See the License for the specific language governing permissions and -// limitations under the License. -// -// Each active thread has an ThreadIdentity that may represent the thread in -// various level interfaces. ThreadIdentity objects are never deallocated. -// When a thread terminates, its ThreadIdentity object may be reused for a -// thread created later. - -#ifndef ABSL_BASE_INTERNAL_THREAD_IDENTITY_H_ -#define ABSL_BASE_INTERNAL_THREAD_IDENTITY_H_ - -#ifndef _WIN32 -#include <pthread.h> -// Defines __GOOGLE_GRTE_VERSION__ (via glibc-specific features.h) when -// supported. -#include <unistd.h> -#endif - -#include <atomic> -#include <cstdint> - -#include "absl/base/config.h" -#include "absl/base/internal/per_thread_tls.h" - -namespace absl { -ABSL_NAMESPACE_BEGIN - -struct SynchLocksHeld; -struct SynchWaitParams; - -namespace base_internal { - -class SpinLock; -struct ThreadIdentity; - -// Used by the implementation of absl::Mutex and absl::CondVar. -struct PerThreadSynch { - // The internal representation of absl::Mutex and absl::CondVar rely - // on the alignment of PerThreadSynch. Both store the address of the - // PerThreadSynch in the high-order bits of their internal state, - // which means the low kLowZeroBits of the address of PerThreadSynch - // must be zero. - static constexpr int kLowZeroBits = 8; - static constexpr int kAlignment = 1 << kLowZeroBits; - - // Returns the associated ThreadIdentity. - // This can be implemented as a cast because we guarantee - // PerThreadSynch is the first element of ThreadIdentity. - ThreadIdentity* thread_identity() { - return reinterpret_cast<ThreadIdentity*>(this); - } - - PerThreadSynch *next; // Circular waiter queue; initialized to 0. - PerThreadSynch *skip; // If non-zero, all entries in Mutex queue - // up to and including "skip" have same - // condition as this, and will be woken later - bool may_skip; // if false while on mutex queue, a mutex unlocker - // 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; - - // State values: - // kAvailable: This PerThreadSynch is available. - // kQueued: This PerThreadSynch is unavailable, it's currently queued on a - // Mutex or CondVar waistlist. - // - // Transitions from kQueued to kAvailable require a release - // barrier. This is needed as a waiter may use "state" to - // independently observe that it's no longer queued. - // - // Transitions from kAvailable to kQueued require no barrier, they - // are externally ordered by the Mutex. - enum State { - kAvailable, - kQueued - }; - 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 - - 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; - - // Locks held; used during deadlock detection. - // Allocated in Synch_GetAllLocks() and freed in ReclaimThreadIdentity(). - SynchLocksHeld *all_locks; -}; - -struct ThreadIdentity { - // Must be the first member. The Mutex implementation requires that - // the PerThreadSynch object associated with each thread is - // PerThreadSynch::kAlignment aligned. We provide this alignment on - // ThreadIdentity itself. - PerThreadSynch per_thread_synch; - - // Private: Reserved for absl::synchronization_internal::Waiter. - struct WaiterState { - char data[128]; - } waiter_state; - - // Used by PerThreadSem::{Get,Set}ThreadBlockedCounter(). - std::atomic<int>* blocked_count_ptr; - - // The following variables are mostly read/written just by the - // thread itself. The only exception is that these are read by - // a ticker thread as a hint. - std::atomic<int> ticker; // Tick counter, incremented once per second. - std::atomic<int> wait_start; // Ticker value when thread started waiting. - std::atomic<bool> is_idle; // Has thread become idle yet? - - ThreadIdentity* next; -}; - -// Returns the ThreadIdentity object representing the calling thread; guaranteed -// to be unique for its lifetime. The returned object will remain valid for the -// program's lifetime; although it may be re-assigned to a subsequent thread. -// If one does not exist, return nullptr instead. -// -// Does not malloc(*), and is async-signal safe. -// [*] Technically pthread_setspecific() does malloc on first use; however this -// is handled internally within tcmalloc's initialization already. -// -// New ThreadIdentity objects can be constructed and associated with a thread -// by calling GetOrCreateCurrentThreadIdentity() in per-thread-sem.h. -ThreadIdentity* CurrentThreadIdentityIfPresent(); - -using ThreadIdentityReclaimerFunction = void (*)(void*); - -// Sets the current thread identity to the given value. 'reclaimer' is a -// pointer to the global function for cleaning up instances on thread -// destruction. -void SetCurrentThreadIdentity(ThreadIdentity* identity, - ThreadIdentityReclaimerFunction reclaimer); - -// Removes the currently associated ThreadIdentity from the running thread. -// This must be called from inside the ThreadIdentityReclaimerFunction, and only -// from that function. -void ClearCurrentThreadIdentity(); - -// May be chosen at compile time via: -DABSL_FORCE_THREAD_IDENTITY_MODE=<mode -// index> -#ifdef ABSL_THREAD_IDENTITY_MODE_USE_POSIX_SETSPECIFIC -#error ABSL_THREAD_IDENTITY_MODE_USE_POSIX_SETSPECIFIC cannot be direcly set -#else -#define ABSL_THREAD_IDENTITY_MODE_USE_POSIX_SETSPECIFIC 0 -#endif - -#ifdef ABSL_THREAD_IDENTITY_MODE_USE_TLS -#error ABSL_THREAD_IDENTITY_MODE_USE_TLS cannot be direcly set -#else -#define ABSL_THREAD_IDENTITY_MODE_USE_TLS 1 -#endif - -#ifdef ABSL_THREAD_IDENTITY_MODE_USE_CPP11 -#error ABSL_THREAD_IDENTITY_MODE_USE_CPP11 cannot be direcly set -#else -#define ABSL_THREAD_IDENTITY_MODE_USE_CPP11 2 -#endif - -#ifdef ABSL_THREAD_IDENTITY_MODE -#error ABSL_THREAD_IDENTITY_MODE cannot be direcly set -#elif defined(ABSL_FORCE_THREAD_IDENTITY_MODE) -#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__) && \ - (__GOOGLE_GRTE_VERSION__ >= 20140228L) -// Support for async-safe TLS was specifically added in GRTEv4. It's not -// present in the upstream eglibc. -// Note: Current default for production systems. -#define ABSL_THREAD_IDENTITY_MODE ABSL_THREAD_IDENTITY_MODE_USE_TLS -#else -#define ABSL_THREAD_IDENTITY_MODE \ - ABSL_THREAD_IDENTITY_MODE_USE_POSIX_SETSPECIFIC -#endif - -#if ABSL_THREAD_IDENTITY_MODE == ABSL_THREAD_IDENTITY_MODE_USE_TLS || \ - ABSL_THREAD_IDENTITY_MODE == ABSL_THREAD_IDENTITY_MODE_USE_CPP11 - -#if ABSL_PER_THREAD_TLS -ABSL_CONST_INIT extern ABSL_PER_THREAD_TLS_KEYWORD ThreadIdentity* - thread_identity_ptr; -#elif defined(ABSL_HAVE_THREAD_LOCAL) -ABSL_CONST_INIT extern thread_local ThreadIdentity* thread_identity_ptr; -#else -#error Thread-local storage not detected on this platform -#endif - -// thread_local variables cannot be in headers exposed by DLLs. However, it is -// important for performance reasons in general that -// `CurrentThreadIdentityIfPresent` be inlined. This is not possible across a -// DLL boundary so, with DLLs, we opt to have the function not be inlined. Note -// that `CurrentThreadIdentityIfPresent` is declared above so we can exclude -// this entire inline definition when compiling as a DLL. -#if !defined(ABSL_BUILD_DLL) && !defined(ABSL_CONSUME_DLL) -inline ThreadIdentity* CurrentThreadIdentityIfPresent() { - return thread_identity_ptr; -} -#endif - -#elif ABSL_THREAD_IDENTITY_MODE != \ - ABSL_THREAD_IDENTITY_MODE_USE_POSIX_SETSPECIFIC -#error Unknown ABSL_THREAD_IDENTITY_MODE -#endif - -} // namespace base_internal -ABSL_NAMESPACE_END -} // namespace absl - -#endif // ABSL_BASE_INTERNAL_THREAD_IDENTITY_H_ |