chore(3p/abseil_cpp): unvendor abseil_cpp r/3786

we weren't actually using these sources anymore, okay?

Change-Id: If701571d9716de308d3512e1eb22c35db0877a66
Reviewed-on: https://cl.tvl.fyi/c/depot/+/5248
Tested-by: BuildkiteCI
Reviewed-by: grfn <grfn@gws.fyi>
Autosubmit: tazjin <tazjin@tvl.su>

1 files changed, 0 insertions, 1084 deletions

diff --git a/third_party/abseil_cpp/absl/synchronization/mutex.h b/third_party/abseil_cpp/absl/synchronization/mutex.h
deleted file mode 100644
index 598d1e0617cf..000000000000
--- a/third_party/abseil_cpp/absl/synchronization/mutex.h
+++ /dev/null
@@ -1,1084 +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.
-//
-// -----------------------------------------------------------------------------
-// mutex.h
-// -----------------------------------------------------------------------------
-//
-// This header file defines a `Mutex` -- a mutually exclusive lock -- and the
-// most common type of synchronization primitive for facilitating locks on
-// shared resources. A mutex is used to prevent multiple threads from accessing
-// and/or writing to a shared resource concurrently.
-//
-// Unlike a `std::mutex`, the Abseil `Mutex` provides the following additional
-// features:
-//   * Conditional predicates intrinsic to the `Mutex` object
-//   * Shared/reader locks, in addition to standard exclusive/writer locks
-//   * Deadlock detection and debug support.
-//
-// The following helper classes are also defined within this file:
-//
-//  MutexLock - An RAII wrapper to acquire and release a `Mutex` for exclusive/
-//              write access within the current scope.
-//
-//  ReaderMutexLock
-//            - An RAII wrapper to acquire and release a `Mutex` for shared/read
-//              access within the current scope.
-//
-//  WriterMutexLock
-//            - Effectively an alias for `MutexLock` above, designed for use in
-//              distinguishing reader and writer locks within code.
-//
-// In addition to simple mutex locks, this file also defines ways to perform
-// locking under certain conditions.
-//
-//  Condition - (Preferred) Used to wait for a particular predicate that
-//              depends on state protected by the `Mutex` to become true.
-//  CondVar   - A lower-level variant of `Condition` that relies on
-//              application code to explicitly signal the `CondVar` when
-//              a condition has been met.
-//
-// See below for more information on using `Condition` or `CondVar`.
-//
-// Mutexes and mutex behavior can be quite complicated. The information within
-// this header file is limited, as a result. Please consult the Mutex guide for
-// more complete information and examples.
-
-#ifndef ABSL_SYNCHRONIZATION_MUTEX_H_
-#define ABSL_SYNCHRONIZATION_MUTEX_H_
-
-#include <atomic>
-#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"
-#include "absl/base/internal/tsan_mutex_interface.h"
-#include "absl/base/port.h"
-#include "absl/base/thread_annotations.h"
-#include "absl/synchronization/internal/kernel_timeout.h"
-#include "absl/synchronization/internal/per_thread_sem.h"
-#include "absl/time/time.h"
-
-namespace absl {
-ABSL_NAMESPACE_BEGIN
-
-class Condition;
-struct SynchWaitParams;
-
-// -----------------------------------------------------------------------------
-// Mutex
-// -----------------------------------------------------------------------------
-//
-// A `Mutex` is a non-reentrant (aka non-recursive) Mutually Exclusive lock
-// on some resource, typically a variable or data structure with associated
-// invariants. Proper usage of mutexes prevents concurrent access by different
-// threads to the same resource.
-//
-// A `Mutex` has two basic operations: `Mutex::Lock()` and `Mutex::Unlock()`.
-// The `Lock()` operation *acquires* a `Mutex` (in a state known as an
-// *exclusive* -- or write -- lock), while the `Unlock()` operation *releases* a
-// Mutex. During the span of time between the Lock() and Unlock() operations,
-// a mutex is said to be *held*. By design all mutexes support exclusive/write
-// locks, as this is the most common way to use a mutex.
-//
-// The `Mutex` state machine for basic lock/unlock operations is quite simple:
-//
-// |                | Lock()     | Unlock() |
-// |----------------+------------+----------|
-// | Free           | Exclusive  | invalid  |
-// | Exclusive      | blocks     | Free     |
-//
-// Attempts to `Unlock()` must originate from the thread that performed the
-// corresponding `Lock()` operation.
-//
-// An "invalid" operation is disallowed by the API. The `Mutex` implementation
-// is allowed to do anything on an invalid call, including but not limited to
-// crashing with a useful error message, silently succeeding, or corrupting
-// data structures. In debug mode, the implementation attempts to crash with a
-// useful error message.
-//
-// `Mutex` is not guaranteed to be "fair" in prioritizing waiting threads; it
-// is, however, approximately fair over long periods, and starvation-free for
-// threads at the same priority.
-//
-// The lock/unlock primitives are now annotated with lock annotations
-// defined in (base/thread_annotations.h). When writing multi-threaded code,
-// you should use lock annotations whenever possible to document your lock
-// synchronization policy. Besides acting as documentation, these annotations
-// also help compilers or static analysis tools to identify and warn about
-// issues that could potentially result in race conditions and deadlocks.
-//
-// For more information about the lock annotations, please see
-// [Thread Safety Analysis](http://clang.llvm.org/docs/ThreadSafetyAnalysis.html)
-// in the Clang documentation.
-//
-// See also `MutexLock`, below, for scoped `Mutex` acquisition.
-
-class ABSL_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()
-  //
-  // Blocks the calling thread, if necessary, until this `Mutex` is free, and
-  // then acquires it exclusively. (This lock is also known as a "write lock.")
-  void Lock() ABSL_EXCLUSIVE_LOCK_FUNCTION();
-
-  // Mutex::Unlock()
-  //
-  // Releases this `Mutex` and returns it from the exclusive/write state to the
-  // free state. Caller must hold the `Mutex` exclusively.
-  void Unlock() ABSL_UNLOCK_FUNCTION();
-
-  // Mutex::TryLock()
-  //
-  // If the mutex can be acquired without blocking, does so exclusively and
-  // returns `true`. Otherwise, returns `false`. Returns `true` with high
-  // probability if the `Mutex` was free.
-  bool TryLock() ABSL_EXCLUSIVE_TRYLOCK_FUNCTION(true);
-
-  // Mutex::AssertHeld()
-  //
-  // Return immediately if this thread holds the `Mutex` exclusively (in write
-  // mode). Otherwise, may report an error (typically by crashing with a
-  // diagnostic), or may return immediately.
-  void AssertHeld() const ABSL_ASSERT_EXCLUSIVE_LOCK();
-
-  // ---------------------------------------------------------------------------
-  // Reader-Writer Locking
-  // ---------------------------------------------------------------------------
-
-  // A Mutex can also be used as a starvation-free reader-writer lock.
-  // Neither read-locks nor write-locks are reentrant/recursive to avoid
-  // potential client programming errors.
-  //
-  // The Mutex API provides `Writer*()` aliases for the existing `Lock()`,
-  // `Unlock()` and `TryLock()` methods for use within applications mixing
-  // reader/writer locks. Using `Reader*()` and `Writer*()` operations in this
-  // manner can make locking behavior clearer when mixing read and write modes.
-  //
-  // Introducing reader locks necessarily complicates the `Mutex` state
-  // machine somewhat. The table below illustrates the allowed state transitions
-  // of a mutex in such cases. Note that ReaderLock() may block even if the lock
-  // is held in shared mode; this occurs when another thread is blocked on a
-  // call to WriterLock().
-  //
-  // ---------------------------------------------------------------------------
-  //     Operation: WriterLock() Unlock()  ReaderLock()           ReaderUnlock()
-  // ---------------------------------------------------------------------------
-  // State
-  // ---------------------------------------------------------------------------
-  // Free           Exclusive    invalid   Shared(1)              invalid
-  // Shared(1)      blocks       invalid   Shared(2) or blocks    Free
-  // Shared(n) n>1  blocks       invalid   Shared(n+1) or blocks  Shared(n-1)
-  // Exclusive      blocks       Free      blocks                 invalid
-  // ---------------------------------------------------------------------------
-  //
-  // In comments below, "shared" refers to a state of Shared(n) for any n > 0.
-
-  // Mutex::ReaderLock()
-  //
-  // Blocks the calling thread, if necessary, until this `Mutex` is either free,
-  // or in shared mode, and then acquires a share of it. Note that
-  // `ReaderLock()` will block if some other thread has an exclusive/writer lock
-  // on the mutex.
-
-  void ReaderLock() ABSL_SHARED_LOCK_FUNCTION();
-
-  // Mutex::ReaderUnlock()
-  //
-  // Releases a read share of this `Mutex`. `ReaderUnlock` may return a mutex to
-  // the free state if this thread holds the last reader lock on the mutex. Note
-  // that you cannot call `ReaderUnlock()` on a mutex held in write mode.
-  void ReaderUnlock() ABSL_UNLOCK_FUNCTION();
-
-  // Mutex::ReaderTryLock()
-  //
-  // If the mutex can be acquired without blocking, acquires this mutex for
-  // shared access and returns `true`. Otherwise, returns `false`. Returns
-  // `true` with high probability if the `Mutex` was free or shared.
-  bool ReaderTryLock() ABSL_SHARED_TRYLOCK_FUNCTION(true);
-
-  // Mutex::AssertReaderHeld()
-  //
-  // Returns immediately if this thread holds the `Mutex` in at least shared
-  // mode (read mode). Otherwise, may report an error (typically by
-  // crashing with a diagnostic), or may return immediately.
-  void AssertReaderHeld() const ABSL_ASSERT_SHARED_LOCK();
-
-  // Mutex::WriterLock()
-  // Mutex::WriterUnlock()
-  // Mutex::WriterTryLock()
-  //
-  // Aliases for `Mutex::Lock()`, `Mutex::Unlock()`, and `Mutex::TryLock()`.
-  //
-  // These methods may be used (along with the complementary `Reader*()`
-  // methods) to distingish simple exclusive `Mutex` usage (`Lock()`,
-  // etc.) from reader/writer lock usage.
-  void WriterLock() ABSL_EXCLUSIVE_LOCK_FUNCTION() { this->Lock(); }
-
-  void WriterUnlock() ABSL_UNLOCK_FUNCTION() { this->Unlock(); }
-
-  bool WriterTryLock() ABSL_EXCLUSIVE_TRYLOCK_FUNCTION(true) {
-    return this->TryLock();
-  }
-
-  // ---------------------------------------------------------------------------
-  // Conditional Critical Regions
-  // ---------------------------------------------------------------------------
-
-  // Conditional usage of a `Mutex` can occur using two distinct paradigms:
-  //
-  //   * Use of `Mutex` member functions with `Condition` objects.
-  //   * Use of the separate `CondVar` abstraction.
-  //
-  // In general, prefer use of `Condition` and the `Mutex` member functions
-  // listed below over `CondVar`. When there are multiple threads waiting on
-  // distinctly different conditions, however, a battery of `CondVar`s may be
-  // more efficient. This section discusses use of `Condition` objects.
-  //
-  // `Mutex` contains member functions for performing lock operations only under
-  // certain conditions, of class `Condition`. For correctness, the `Condition`
-  // must return a boolean that is a pure function, only of state protected by
-  // the `Mutex`. The condition must be invariant w.r.t. environmental state
-  // such as thread, cpu id, or time, and must be `noexcept`. The condition will
-  // always be invoked with the mutex held in at least read mode, so you should
-  // not block it for long periods or sleep it on a timer.
-  //
-  // Since a condition must not depend directly on the current time, use
-  // `*WithTimeout()` member function variants to make your condition
-  // effectively true after a given duration, or `*WithDeadline()` variants to
-  // make your condition effectively true after a given time.
-  //
-  // The condition function should have no side-effects aside from debug
-  // logging; as a special exception, the function may acquire other mutexes
-  // provided it releases all those that it acquires.  (This exception was
-  // required to allow logging.)
-
-  // Mutex::Await()
-  //
-  // Unlocks this `Mutex` and blocks until simultaneously both `cond` is `true`
-  // and this `Mutex` can be reacquired, then reacquires this `Mutex` in the
-  // same mode in which it was previously held. If the condition is initially
-  // `true`, `Await()` *may* skip the release/re-acquire step.
-  //
-  // `Await()` requires that this thread holds this `Mutex` in some mode.
-  void Await(const Condition &cond);
-
-  // Mutex::LockWhen()
-  // Mutex::ReaderLockWhen()
-  // Mutex::WriterLockWhen()
-  //
-  // Blocks until simultaneously both `cond` is `true` and this `Mutex` can
-  // be acquired, then atomically acquires this `Mutex`. `LockWhen()` is
-  // logically equivalent to `*Lock(); Await();` though they may have different
-  // performance characteristics.
-  void LockWhen(const Condition &cond) ABSL_EXCLUSIVE_LOCK_FUNCTION();
-
-  void ReaderLockWhen(const Condition &cond) ABSL_SHARED_LOCK_FUNCTION();
-
-  void WriterLockWhen(const Condition &cond) ABSL_EXCLUSIVE_LOCK_FUNCTION() {
-    this->LockWhen(cond);
-  }
-
-  // ---------------------------------------------------------------------------
-  // Mutex Variants with Timeouts/Deadlines
-  // ---------------------------------------------------------------------------
-
-  // Mutex::AwaitWithTimeout()
-  // Mutex::AwaitWithDeadline()
-  //
-  // 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.
-  //
-  // This method requires that this thread holds this `Mutex` in some mode.
-  bool AwaitWithTimeout(const Condition &cond, absl::Duration timeout);
-
-  bool AwaitWithDeadline(const Condition &cond, absl::Time deadline);
-
-  // Mutex::LockWhenWithTimeout()
-  // Mutex::ReaderLockWhenWithTimeout()
-  // Mutex::WriterLockWhenWithTimeout()
-  //
-  // Blocks until simultaneously both:
-  //   - either `cond` is `true` or the timeout has expired, and
-  //   - this `Mutex` can be acquired,
-  // then atomically acquires this `Mutex`, returning `true` iff `cond` is
-  // `true` on return.
-  //
-  // Negative timeouts are equivalent to a zero timeout.
-  bool LockWhenWithTimeout(const Condition &cond, absl::Duration timeout)
-      ABSL_EXCLUSIVE_LOCK_FUNCTION();
-  bool ReaderLockWhenWithTimeout(const Condition &cond, absl::Duration timeout)
-      ABSL_SHARED_LOCK_FUNCTION();
-  bool WriterLockWhenWithTimeout(const Condition &cond, absl::Duration timeout)
-      ABSL_EXCLUSIVE_LOCK_FUNCTION() {
-    return this->LockWhenWithTimeout(cond, timeout);
-  }
-
-  // Mutex::LockWhenWithDeadline()
-  // Mutex::ReaderLockWhenWithDeadline()
-  // Mutex::WriterLockWhenWithDeadline()
-  //
-  // Blocks until simultaneously both:
-  //   - either `cond` is `true` or the deadline has been passed, and
-  //   - this `Mutex` can be acquired,
-  // then atomically acquires this Mutex, returning `true` iff `cond` is `true`
-  // on return.
-  //
-  // Deadlines in the past are equivalent to an immediate deadline.
-  bool LockWhenWithDeadline(const Condition &cond, absl::Time deadline)
-      ABSL_EXCLUSIVE_LOCK_FUNCTION();
-  bool ReaderLockWhenWithDeadline(const Condition &cond, absl::Time deadline)
-      ABSL_SHARED_LOCK_FUNCTION();
-  bool WriterLockWhenWithDeadline(const Condition &cond, absl::Time deadline)
-      ABSL_EXCLUSIVE_LOCK_FUNCTION() {
-    return this->LockWhenWithDeadline(cond, deadline);
-  }
-
-  // ---------------------------------------------------------------------------
-  // Debug Support: Invariant Checking, Deadlock Detection, Logging.
-  // ---------------------------------------------------------------------------
-
-  // Mutex::EnableInvariantDebugging()
-  //
-  // If `invariant`!=null and if invariant debugging has been enabled globally,
-  // cause `(*invariant)(arg)` to be called at moments when the invariant for
-  // this `Mutex` should hold (for example: just after acquire, just before
-  // release).
-  //
-  // The routine `invariant` should have no side-effects since it is not
-  // guaranteed how many times it will be called; it should check the invariant
-  // and crash if it does not hold. Enabling global invariant debugging may
-  // substantially reduce `Mutex` performance; it should be set only for
-  // non-production runs.  Optimization options may also disable invariant
-  // checks.
-  void EnableInvariantDebugging(void (*invariant)(void *), void *arg);
-
-  // Mutex::EnableDebugLog()
-  //
-  // Cause all subsequent uses of this `Mutex` to be logged via
-  // `ABSL_RAW_LOG(INFO)`. Log entries are tagged with `name` if no previous
-  // call to `EnableInvariantDebugging()` or `EnableDebugLog()` has been made.
-  //
-  // Note: This method substantially reduces `Mutex` performance.
-  void EnableDebugLog(const char *name);
-
-  // Deadlock detection
-
-  // Mutex::ForgetDeadlockInfo()
-  //
-  // Forget any deadlock-detection information previously gathered
-  // about this `Mutex`. Call this method in debug mode when the lock ordering
-  // of a `Mutex` changes.
-  void ForgetDeadlockInfo();
-
-  // Mutex::AssertNotHeld()
-  //
-  // Return immediately if this thread does not hold this `Mutex` in any
-  // mode; otherwise, may report an error (typically by crashing with a
-  // diagnostic), or may return immediately.
-  //
-  // Currently this check is performed only if all of:
-  //    - in debug mode
-  //    - SetMutexDeadlockDetectionMode() has been set to kReport or kAbort
-  //    - number of locks concurrently held by this thread is not large.
-  // are true.
-  void AssertNotHeld() const;
-
-  // Special cases.
-
-  // A `MuHow` is a constant that indicates how a lock should be acquired.
-  // Internal implementation detail.  Clients should ignore.
-  typedef const struct MuHowS *MuHow;
-
-  // Mutex::InternalAttemptToUseMutexInFatalSignalHandler()
-  //
-  // Causes the `Mutex` implementation to prepare itself for re-entry caused by
-  // future use of `Mutex` within a fatal signal handler. This method is
-  // intended for use only for last-ditch attempts to log crash information.
-  // It does not guarantee that attempts to use Mutexes within the handler will
-  // not deadlock; it merely makes other faults less likely.
-  //
-  // WARNING:  This routine must be invoked from a signal handler, and the
-  // signal handler must either loop forever or terminate the process.
-  // Attempts to return from (or `longjmp` out of) the signal handler once this
-  // call has been made may cause arbitrary program behaviour including
-  // crashes and deadlocks.
-  static void InternalAttemptToUseMutexInFatalSignalHandler();
-
- private:
-  std::atomic<intptr_t> mu_;  // The Mutex state.
-
-  // Post()/Wait() versus associated PerThreadSem; in class for required
-  // friendship with PerThreadSem.
-  static inline void IncrementSynchSem(Mutex *mu,
-                                       base_internal::PerThreadSynch *w);
-  static inline bool DecrementSynchSem(
-      Mutex *mu, base_internal::PerThreadSynch *w,
-      synchronization_internal::KernelTimeout t);
-
-  // slow path acquire
-  void LockSlowLoop(SynchWaitParams *waitp, int flags);
-  // wrappers around LockSlowLoop()
-  bool LockSlowWithDeadline(MuHow how, const Condition *cond,
-                            synchronization_internal::KernelTimeout t,
-                            int flags);
-  void LockSlow(MuHow how, const Condition *cond,
-                int flags) ABSL_ATTRIBUTE_COLD;
-  // slow path release
-  void UnlockSlow(SynchWaitParams *waitp) ABSL_ATTRIBUTE_COLD;
-  // Common code between Await() and AwaitWithTimeout/Deadline()
-  bool AwaitCommon(const Condition &cond,
-                   synchronization_internal::KernelTimeout t);
-  // Attempt to remove thread s from queue.
-  void TryRemove(base_internal::PerThreadSynch *s);
-  // Block a thread on mutex.
-  void Block(base_internal::PerThreadSynch *s);
-  // Wake a thread; return successor.
-  base_internal::PerThreadSynch *Wakeup(base_internal::PerThreadSynch *w);
-
-  friend class CondVar;   // for access to Trans()/Fer().
-  void Trans(MuHow how);  // used for CondVar->Mutex transfer
-  void Fer(
-      base_internal::PerThreadSynch *w);  // used for CondVar->Mutex transfer
-
-  // Catch the error of writing Mutex when intending MutexLock.
-  Mutex(const volatile Mutex * /*ignored*/) {}  // NOLINT(runtime/explicit)
-
-  Mutex(const Mutex&) = delete;
-  Mutex& operator=(const Mutex&) = delete;
-};
-
-// -----------------------------------------------------------------------------
-// Mutex RAII Wrappers
-// -----------------------------------------------------------------------------
-
-// MutexLock
-//
-// `MutexLock` is a helper class, which acquires and releases a `Mutex` via
-// RAII.
-//
-// Example:
-//
-// Class Foo {
-//  public:
-//   Foo::Bar* Baz() {
-//     MutexLock lock(&mu_);
-//     ...
-//     return bar;
-//   }
-//
-// private:
-//   Mutex mu_;
-// };
-class ABSL_SCOPED_LOCKABLE MutexLock {
- public:
-  // Constructors
-
-  // Calls `mu->Lock()` and returns when that call returns. That is, `*mu` is
-  // guaranteed to be locked when this object is constructed. Requires that
-  // `mu` be dereferenceable.
-  explicit MutexLock(Mutex *mu) ABSL_EXCLUSIVE_LOCK_FUNCTION(mu) : mu_(mu) {
-    this->mu_->Lock();
-  }
-
-  // Like above, but calls `mu->LockWhen(cond)` instead. That is, in addition to
-  // the above, the condition given by `cond` is also guaranteed to hold when
-  // this object is constructed.
-  explicit MutexLock(Mutex *mu, const Condition &cond)
-      ABSL_EXCLUSIVE_LOCK_FUNCTION(mu)
-      : mu_(mu) {
-    this->mu_->LockWhen(cond);
-  }
-
-  MutexLock(const MutexLock &) = delete;  // NOLINT(runtime/mutex)
-  MutexLock(MutexLock&&) = delete;  // NOLINT(runtime/mutex)
-  MutexLock& operator=(const MutexLock&) = delete;
-  MutexLock& operator=(MutexLock&&) = delete;
-
-  ~MutexLock() ABSL_UNLOCK_FUNCTION() { this->mu_->Unlock(); }
-
- private:
-  Mutex *const mu_;
-};
-
-// ReaderMutexLock
-//
-// The `ReaderMutexLock` is a helper class, like `MutexLock`, which acquires and
-// releases a shared lock on a `Mutex` via RAII.
-class ABSL_SCOPED_LOCKABLE ReaderMutexLock {
- public:
-  explicit ReaderMutexLock(Mutex *mu) ABSL_SHARED_LOCK_FUNCTION(mu) : mu_(mu) {
-    mu->ReaderLock();
-  }
-
-  explicit ReaderMutexLock(Mutex *mu, const Condition &cond)
-      ABSL_SHARED_LOCK_FUNCTION(mu)
-      : mu_(mu) {
-    mu->ReaderLockWhen(cond);
-  }
-
-  ReaderMutexLock(const ReaderMutexLock&) = delete;
-  ReaderMutexLock(ReaderMutexLock&&) = delete;
-  ReaderMutexLock& operator=(const ReaderMutexLock&) = delete;
-  ReaderMutexLock& operator=(ReaderMutexLock&&) = delete;
-
-  ~ReaderMutexLock() ABSL_UNLOCK_FUNCTION() { this->mu_->ReaderUnlock(); }
-
- private:
-  Mutex *const mu_;
-};
-
-// WriterMutexLock
-//
-// The `WriterMutexLock` is a helper class, like `MutexLock`, which acquires and
-// releases a write (exclusive) lock on a `Mutex` via RAII.
-class ABSL_SCOPED_LOCKABLE WriterMutexLock {
- public:
-  explicit WriterMutexLock(Mutex *mu) ABSL_EXCLUSIVE_LOCK_FUNCTION(mu)
-      : mu_(mu) {
-    mu->WriterLock();
-  }
-
-  explicit WriterMutexLock(Mutex *mu, const Condition &cond)
-      ABSL_EXCLUSIVE_LOCK_FUNCTION(mu)
-      : mu_(mu) {
-    mu->WriterLockWhen(cond);
-  }
-
-  WriterMutexLock(const WriterMutexLock&) = delete;
-  WriterMutexLock(WriterMutexLock&&) = delete;
-  WriterMutexLock& operator=(const WriterMutexLock&) = delete;
-  WriterMutexLock& operator=(WriterMutexLock&&) = delete;
-
-  ~WriterMutexLock() ABSL_UNLOCK_FUNCTION() { this->mu_->WriterUnlock(); }
-
- private:
-  Mutex *const mu_;
-};
-
-// -----------------------------------------------------------------------------
-// Condition
-// -----------------------------------------------------------------------------
-//
-// As noted above, `Mutex` contains a number of member functions which take a
-// `Condition` as an argument; clients can wait for conditions to become `true`
-// before attempting to acquire the mutex. These sections are known as
-// "condition critical" sections. To use a `Condition`, you simply need to
-// construct it, and use within an appropriate `Mutex` member function;
-// everything else in the `Condition` class is an implementation detail.
-//
-// A `Condition` is specified as a function pointer which returns a boolean.
-// `Condition` functions should be pure functions -- their results should depend
-// only on passed arguments, should not consult any external state (such as
-// clocks), and should have no side-effects, aside from debug logging. Any
-// objects that the function may access should be limited to those which are
-// constant while the mutex is blocked on the condition (e.g. a stack variable),
-// or objects of state protected explicitly by the mutex.
-//
-// No matter which construction is used for `Condition`, the underlying
-// function pointer / functor / callable must not throw any
-// exceptions. Correctness of `Mutex` / `Condition` is not guaranteed in
-// the face of a throwing `Condition`. (When Abseil is allowed to depend
-// on C++17, these function pointers will be explicitly marked
-// `noexcept`; until then this requirement cannot be enforced in the
-// type system.)
-//
-// Note: to use a `Condition`, you need only construct it and pass it to a
-// suitable `Mutex' member function, such as `Mutex::Await()`, or to the
-// constructor of one of the scope guard classes.
-//
-// Example using LockWhen/Unlock:
-//
-//   // assume count_ is not internal reference count
-//   int count_ ABSL_GUARDED_BY(mu_);
-//   Condition count_is_zero(+[](int *count) { return *count == 0; }, &count_);
-//
-//   mu_.LockWhen(count_is_zero);
-//   // ...
-//   mu_.Unlock();
-//
-// Example using a scope guard:
-//
-//   {
-//     MutexLock lock(&mu_, count_is_zero);
-//     // ...
-//   }
-//
-// When multiple threads are waiting on exactly the same condition, make sure
-// that they are constructed with the same parameters (same pointer to function
-// + arg, or same pointer to object + method), so that the mutex implementation
-// can avoid redundantly evaluating the same condition for each thread.
-class Condition {
- public:
-  // A Condition that returns the result of "(*func)(arg)"
-  Condition(bool (*func)(void *), void *arg);
-
-  // Templated version for people who are averse to casts.
-  //
-  // To use a lambda, prepend it with unary plus, which converts the lambda
-  // into a function pointer:
-  //     Condition(+[](T* t) { return ...; }, arg).
-  //
-  // Note: lambdas in this case must contain no bound variables.
-  //
-  // See class comment for performance advice.
-  template<typename T>
-  Condition(bool (*func)(T *), T *arg);
-
-  // Templated version for invoking a method that returns a `bool`.
-  //
-  // `Condition(object, &Class::Method)` constructs a `Condition` that evaluates
-  // `object->Method()`.
-  //
-  // Implementation Note: `absl::internal::identity` is used to allow methods to
-  // come from base classes. A simpler signature like
-  // `Condition(T*, bool (T::*)())` does not suffice.
-  template<typename T>
-  Condition(T *object, bool (absl::internal::identity<T>::type::* method)());
-
-  // Same as above, for const members
-  template<typename T>
-  Condition(const T *object,
-            bool (absl::internal::identity<T>::type::* method)() const);
-
-  // A Condition that returns the value of `*cond`
-  explicit Condition(const bool *cond);
-
-  // Templated version for invoking a functor that returns a `bool`.
-  // This approach accepts pointers to non-mutable lambdas, `std::function`,
-  // the result of` std::bind` and user-defined functors that define
-  // `bool F::operator()() const`.
-  //
-  // Example:
-  //
-  //   auto reached = [this, current]() {
-  //     mu_.AssertReaderHeld();                // For annotalysis.
-  //     return processed_ >= current;
-  //   };
-  //   mu_.Await(Condition(&reached));
-  //
-  // NOTE: never use "mu_.AssertHeld()" instead of "mu_.AssertReaderHeld()" 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
-  // that all waiters construct the condition with the same pointers.
-
-  // Implementation note: The second template parameter ensures that this
-  // constructor doesn't participate in overload resolution if T doesn't have
-  // `bool operator() const`.
-  template <typename T, typename E = decltype(
-      static_cast<bool (T::*)() const>(&T::operator()))>
-  explicit Condition(const T *obj)
-      : Condition(obj, static_cast<bool (T::*)() const>(&T::operator())) {}
-
-  // A Condition that always returns `true`.
-  static const Condition kTrue;
-
-  // Evaluates the condition.
-  bool Eval() const;
-
-  // Returns `true` if the two conditions are guaranteed to return the same
-  // value if evaluated at the same time, `false` if the evaluation *may* return
-  // different results.
-  //
-  // Two `Condition` values are guaranteed equal if both their `func` and `arg`
-  // components are the same. A null pointer is equivalent to a `true`
-  // condition.
-  static bool GuaranteedEqual(const Condition *a, const Condition *b);
-
- private:
-  typedef bool (*InternalFunctionType)(void * arg);
-  typedef bool (Condition::*InternalMethodType)();
-  typedef bool (*InternalMethodCallerType)(void * arg,
-                                           InternalMethodType internal_method);
-
-  bool (*eval_)(const Condition*);  // Actual evaluator
-  InternalFunctionType function_;   // function taking pointer returning bool
-  InternalMethodType method_;       // method returning bool
-  void *arg_;                       // arg of function_ or object of method_
-
-  Condition();        // null constructor used only to create kTrue
-
-  // Various functions eval_ can point to:
-  static bool CallVoidPtrFunction(const Condition*);
-  template <typename T> static bool CastAndCallFunction(const Condition* c);
-  template <typename T> static bool CastAndCallMethod(const Condition* c);
-};
-
-// -----------------------------------------------------------------------------
-// CondVar
-// -----------------------------------------------------------------------------
-//
-// A condition variable, reflecting state evaluated separately outside of the
-// `Mutex` object, which can be signaled to wake callers.
-// This class is not normally needed; use `Mutex` member functions such as
-// `Mutex::Await()` and intrinsic `Condition` abstractions. In rare cases
-// with many threads and many conditions, `CondVar` may be faster.
-//
-// The implementation may deliver signals to any condition variable at
-// any time, even when no call to `Signal()` or `SignalAll()` is made; as a
-// result, upon being awoken, you must check the logical condition you have
-// been waiting upon.
-//
-// Examples:
-//
-// Usage for a thread waiting for some condition C protected by mutex mu:
-//       mu.Lock();
-//       while (!C) { cv->Wait(&mu); }        // releases and reacquires mu
-//       //  C holds; process data
-//       mu.Unlock();
-//
-// Usage to wake T is:
-//       mu.Lock();
-//      // process data, possibly establishing C
-//      if (C) { cv->Signal(); }
-//      mu.Unlock();
-//
-// If C may be useful to more than one waiter, use `SignalAll()` instead of
-// `Signal()`.
-//
-// With this implementation it is efficient to use `Signal()/SignalAll()` inside
-// the locked region; this usage can make reasoning about your program easier.
-//
-class CondVar {
- public:
-  // A `CondVar` allocated on the heap or on the stack can use the this
-  // constructor.
-  CondVar();
-  ~CondVar();
-
-  // CondVar::Wait()
-  //
-  // Atomically releases a `Mutex` and blocks on this condition variable.
-  // Waits until awakened by a call to `Signal()` or `SignalAll()` (or a
-  // spurious wakeup), then reacquires the `Mutex` and returns.
-  //
-  // Requires and ensures that the current thread holds the `Mutex`.
-  void Wait(Mutex *mu);
-
-  // CondVar::WaitWithTimeout()
-  //
-  // Atomically releases a `Mutex` and blocks on this condition variable.
-  // Waits until awakened by a call to `Signal()` or `SignalAll()` (or a
-  // spurious wakeup), or until the timeout has expired, then reacquires
-  // the `Mutex` and returns.
-  //
-  // Returns true if the timeout has expired without this `CondVar`
-  // being signalled in any manner. If both the timeout has expired
-  // and this `CondVar` has been signalled, the implementation is free
-  // to return `true` or `false`.
-  //
-  // Requires and ensures that the current thread holds the `Mutex`.
-  bool WaitWithTimeout(Mutex *mu, absl::Duration timeout);
-
-  // CondVar::WaitWithDeadline()
-  //
-  // Atomically releases a `Mutex` and blocks on this condition variable.
-  // Waits until awakened by a call to `Signal()` or `SignalAll()` (or a
-  // spurious wakeup), or until the deadline has passed, then reacquires
-  // the `Mutex` and returns.
-  //
-  // Deadlines in the past are equivalent to an immediate deadline.
-  //
-  // Returns true if the deadline has passed without this `CondVar`
-  // being signalled in any manner. If both the deadline has passed
-  // and this `CondVar` has been signalled, the implementation is free
-  // to return `true` or `false`.
-  //
-  // Requires and ensures that the current thread holds the `Mutex`.
-  bool WaitWithDeadline(Mutex *mu, absl::Time deadline);
-
-  // CondVar::Signal()
-  //
-  // Signal this `CondVar`; wake at least one waiter if one exists.
-  void Signal();
-
-  // CondVar::SignalAll()
-  //
-  // Signal this `CondVar`; wake all waiters.
-  void SignalAll();
-
-  // CondVar::EnableDebugLog()
-  //
-  // Causes all subsequent uses of this `CondVar` to be logged via
-  // `ABSL_RAW_LOG(INFO)`. Log entries are tagged with `name` if `name != 0`.
-  // Note: this method substantially reduces `CondVar` performance.
-  void EnableDebugLog(const char *name);
-
- private:
-  bool WaitCommon(Mutex *mutex, synchronization_internal::KernelTimeout t);
-  void Remove(base_internal::PerThreadSynch *s);
-  void Wakeup(base_internal::PerThreadSynch *w);
-  std::atomic<intptr_t> cv_;  // Condition variable state.
-  CondVar(const CondVar&) = delete;
-  CondVar& operator=(const CondVar&) = delete;
-};
-
-
-// Variants of MutexLock.
-//
-// If you find yourself using one of these, consider instead using
-// Mutex::Unlock() and/or if-statements for clarity.
-
-// MutexLockMaybe
-//
-// MutexLockMaybe is like MutexLock, but is a no-op when mu is null.
-class ABSL_SCOPED_LOCKABLE MutexLockMaybe {
- public:
-  explicit MutexLockMaybe(Mutex *mu) ABSL_EXCLUSIVE_LOCK_FUNCTION(mu)
-      : mu_(mu) {
-    if (this->mu_ != nullptr) {
-      this->mu_->Lock();
-    }
-  }
-
-  explicit MutexLockMaybe(Mutex *mu, const Condition &cond)
-      ABSL_EXCLUSIVE_LOCK_FUNCTION(mu)
-      : mu_(mu) {
-    if (this->mu_ != nullptr) {
-      this->mu_->LockWhen(cond);
-    }
-  }
-
-  ~MutexLockMaybe() ABSL_UNLOCK_FUNCTION() {
-    if (this->mu_ != nullptr) { this->mu_->Unlock(); }
-  }
-
- private:
-  Mutex *const mu_;
-  MutexLockMaybe(const MutexLockMaybe&) = delete;
-  MutexLockMaybe(MutexLockMaybe&&) = delete;
-  MutexLockMaybe& operator=(const MutexLockMaybe&) = delete;
-  MutexLockMaybe& operator=(MutexLockMaybe&&) = delete;
-};
-
-// ReleasableMutexLock
-//
-// ReleasableMutexLock is like MutexLock, but permits `Release()` of its
-// mutex before destruction. `Release()` may be called at most once.
-class ABSL_SCOPED_LOCKABLE ReleasableMutexLock {
- public:
-  explicit ReleasableMutexLock(Mutex *mu) ABSL_EXCLUSIVE_LOCK_FUNCTION(mu)
-      : mu_(mu) {
-    this->mu_->Lock();
-  }
-
-  explicit ReleasableMutexLock(Mutex *mu, const Condition &cond)
-      ABSL_EXCLUSIVE_LOCK_FUNCTION(mu)
-      : mu_(mu) {
-    this->mu_->LockWhen(cond);
-  }
-
-  ~ReleasableMutexLock() ABSL_UNLOCK_FUNCTION() {
-    if (this->mu_ != nullptr) { this->mu_->Unlock(); }
-  }
-
-  void Release() ABSL_UNLOCK_FUNCTION();
-
- private:
-  Mutex *mu_;
-  ReleasableMutexLock(const ReleasableMutexLock&) = delete;
-  ReleasableMutexLock(ReleasableMutexLock&&) = delete;
-  ReleasableMutexLock& operator=(const ReleasableMutexLock&) = delete;
-  ReleasableMutexLock& operator=(ReleasableMutexLock&&) = delete;
-};
-
-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) {}
-
-// static
-template <typename T>
-bool Condition::CastAndCallMethod(const Condition *c) {
-  typedef bool (T::*MemberType)();
-  MemberType rm = reinterpret_cast<MemberType>(c->method_);
-  T *x = static_cast<T *>(c->arg_);
-  return (x->*rm)();
-}
-
-// static
-template <typename T>
-bool Condition::CastAndCallFunction(const Condition *c) {
-  typedef bool (*FuncType)(T *);
-  FuncType fn = reinterpret_cast<FuncType>(c->function_);
-  T *x = static_cast<T *>(c->arg_);
-  return (*fn)(x);
-}
-
-template <typename T>
-inline Condition::Condition(bool (*func)(T *), T *arg)
-    : eval_(&CastAndCallFunction<T>),
-      function_(reinterpret_cast<InternalFunctionType>(func)),
-      method_(nullptr),
-      arg_(const_cast<void *>(static_cast<const void *>(arg))) {}
-
-template <typename T>
-inline Condition::Condition(T *object,
-                            bool (absl::internal::identity<T>::type::*method)())
-    : eval_(&CastAndCallMethod<T>),
-      function_(nullptr),
-      method_(reinterpret_cast<InternalMethodType>(method)),
-      arg_(object) {}
-
-template <typename T>
-inline Condition::Condition(const T *object,
-                            bool (absl::internal::identity<T>::type::*method)()
-                                const)
-    : eval_(&CastAndCallMethod<T>),
-      function_(nullptr),
-      method_(reinterpret_cast<InternalMethodType>(method)),
-      arg_(reinterpret_cast<void *>(const_cast<T *>(object))) {}
-
-// Register a hook for profiling support.
-//
-// The function pointer registered here will be called whenever a mutex is
-// contended.  The callback is given the absl/base/cycleclock.h timestamp when
-// waiting began.
-//
-// Calls to this function do not race or block, but there is no ordering
-// guaranteed between calls to this function and call to the provided hook.
-// In particular, the previously registered hook may still be called for some
-// time after this function returns.
-void RegisterMutexProfiler(void (*fn)(int64_t wait_timestamp));
-
-// Register a hook for Mutex tracing.
-//
-// The function pointer registered here will be called whenever a mutex is
-// contended.  The callback is given an opaque handle to the contended mutex,
-// an event name, and the number of wait cycles (as measured by
-// //absl/base/internal/cycleclock.h, and which may not be real
-// "cycle" counts.)
-//
-// The only event name currently sent is "slow release".
-//
-// This has the same memory ordering concerns as RegisterMutexProfiler() above.
-void RegisterMutexTracer(void (*fn)(const char *msg, const void *obj,
-                                    int64_t wait_cycles));
-
-// TODO(gfalcon): Combine RegisterMutexProfiler() and RegisterMutexTracer()
-// into a single interface, since they are only ever called in pairs.
-
-// Register a hook for CondVar tracing.
-//
-// The function pointer registered here will be called here on various CondVar
-// events.  The callback is given an opaque handle to the CondVar object and
-// a string identifying the event.  This is thread-safe, but only a single
-// tracer can be registered.
-//
-// Events that can be sent are "Wait", "Unwait", "Signal wakeup", and
-// "SignalAll wakeup".
-//
-// This has the same memory ordering concerns as RegisterMutexProfiler() above.
-void RegisterCondVarTracer(void (*fn)(const char *msg, const void *cv));
-
-// Register a hook for symbolizing stack traces in deadlock detector reports.
-//
-// 'pc' is the program counter being symbolized, 'out' is the buffer to write
-// into, and 'out_size' is the size of the buffer.  This function can return
-// false if symbolizing failed, or true if a NUL-terminated symbol was written
-// to 'out.'
-//
-// This has the same memory ordering concerns as RegisterMutexProfiler() above.
-//
-// DEPRECATED: The default symbolizer function is absl::Symbolize() and the
-// ability to register a different hook for symbolizing stack traces will be
-// removed on or after 2023-05-01.
-ABSL_DEPRECATED("absl::RegisterSymbolizer() is deprecated and will be removed "
-                "on or after 2023-05-01")
-void RegisterSymbolizer(bool (*fn)(const void *pc, char *out, int out_size));
-
-// EnableMutexInvariantDebugging()
-//
-// Enable or disable global support for Mutex invariant debugging.  If enabled,
-// then invariant predicates can be registered per-Mutex for debug checking.
-// See Mutex::EnableInvariantDebugging().
-void EnableMutexInvariantDebugging(bool enabled);
-
-// When in debug mode, and when the feature has been enabled globally, the
-// implementation will keep track of lock ordering and complain (or optionally
-// crash) if a cycle is detected in the acquired-before graph.
-
-// Possible modes of operation for the deadlock detector in debug mode.
-enum class OnDeadlockCycle {
-  kIgnore,  // Neither report on nor attempt to track cycles in lock ordering
-  kReport,  // Report lock cycles to stderr when detected
-  kAbort,  // Report lock cycles to stderr when detected, then abort
-};
-
-// SetMutexDeadlockDetectionMode()
-//
-// Enable or disable global support for detection of potential deadlocks
-// due to Mutex lock ordering inversions.  When set to 'kIgnore', tracking of
-// lock ordering is disabled.  Otherwise, in debug builds, a lock ordering graph
-// will be maintained internally, and detected cycles will be reported in
-// the manner chosen here.
-void SetMutexDeadlockDetectionMode(OnDeadlockCycle mode);
-
-ABSL_NAMESPACE_END
-}  // namespace absl
-
-// In some build configurations we pass --detect-odr-violations to the
-// gold linker.  This causes it to flag weak symbol overrides as ODR
-// violations.  Because ODR only applies to C++ and not C,
-// --detect-odr-violations ignores symbols not mangled with C++ names.
-// By changing our extension points to be extern "C", we dodge this
-// check.
-extern "C" {
-void AbslInternalMutexYield();
-}  // extern "C"
-
-#endif  // ABSL_SYNCHRONIZATION_MUTEX_H_