about summary refs log tree commit diff
path: root/third_party/abseil_cpp/absl/base/internal/thread_identity.h
diff options
context:
space:
mode:
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.h260
1 files changed, 0 insertions, 260 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 d2a65fd81126..000000000000
--- a/third_party/abseil_cpp/absl/base/internal/thread_identity.h
+++ /dev/null
@@ -1,260 +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"
-#include "absl/base/optimization.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.
-  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.
-  //   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;
-
-  // 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;
-
-  intptr_t readers;     // Number of readers in mutex.
-
-  // 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
-  // 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 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.
-// 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_