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diff --git a/lib/libtsan/sanitizer_common/sanitizer_thread_registry.h b/lib/libtsan/sanitizer_common/sanitizer_thread_registry.h
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+++ b/lib/libtsan/sanitizer_common/sanitizer_thread_registry.h
@@ -0,0 +1,173 @@
+//===-- sanitizer_thread_registry.h -----------------------------*- C++ -*-===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+//
+// This file is shared between sanitizer tools.
+//
+// General thread bookkeeping functionality.
+//===----------------------------------------------------------------------===//
+
+#ifndef SANITIZER_THREAD_REGISTRY_H
+#define SANITIZER_THREAD_REGISTRY_H
+
+#include "sanitizer_common.h"
+#include "sanitizer_dense_map.h"
+#include "sanitizer_list.h"
+#include "sanitizer_mutex.h"
+
+namespace __sanitizer {
+
+enum ThreadStatus {
+  ThreadStatusInvalid,   // Non-existent thread, data is invalid.
+  ThreadStatusCreated,   // Created but not yet running.
+  ThreadStatusRunning,   // The thread is currently running.
+  ThreadStatusFinished,  // Joinable thread is finished but not yet joined.
+  ThreadStatusDead       // Joined, but some info is still available.
+};
+
+enum class ThreadType {
+  Regular, // Normal thread
+  Worker,  // macOS Grand Central Dispatch (GCD) worker thread
+  Fiber,   // Fiber
+};
+
+// Generic thread context. Specific sanitizer tools may inherit from it.
+// If thread is dead, context may optionally be reused for a new thread.
+class ThreadContextBase {
+ public:
+  explicit ThreadContextBase(u32 tid);
+  const u32 tid;  // Thread ID. Main thread should have tid = 0.
+  u64 unique_id;  // Unique thread ID.
+  u32 reuse_count;  // Number of times this tid was reused.
+  tid_t os_id;     // PID (used for reporting).
+  uptr user_id;   // Some opaque user thread id (e.g. pthread_t).
+  char name[64];  // As annotated by user.
+
+  ThreadStatus status;
+  bool detached;
+  ThreadType thread_type;
+
+  u32 parent_tid;
+  u32 stack_id;
+  ThreadContextBase *next;  // For storing thread contexts in a list.
+
+  atomic_uint32_t thread_destroyed; // To address race of Joined vs Finished
+
+  void SetName(const char *new_name);
+
+  void SetDead();
+  void SetJoined(void *arg);
+  void SetFinished();
+  void SetStarted(tid_t _os_id, ThreadType _thread_type, void *arg);
+  void SetCreated(uptr _user_id, u64 _unique_id, bool _detached,
+                  u32 _parent_tid, u32 _stack_tid, void *arg);
+  void Reset();
+
+  void SetDestroyed();
+  bool GetDestroyed();
+
+  // The following methods may be overriden by subclasses.
+  // Some of them take opaque arg that may be optionally be used
+  // by subclasses.
+  virtual void OnDead() {}
+  virtual void OnJoined(void *arg) {}
+  virtual void OnFinished() {}
+  virtual void OnStarted(void *arg) {}
+  virtual void OnCreated(void *arg) {}
+  virtual void OnReset() {}
+  virtual void OnDetached(void *arg) {}
+
+ protected:
+  ~ThreadContextBase();
+};
+
+typedef ThreadContextBase* (*ThreadContextFactory)(u32 tid);
+
+class SANITIZER_MUTEX ThreadRegistry {
+ public:
+  ThreadRegistry(ThreadContextFactory factory);
+  ThreadRegistry(ThreadContextFactory factory, u32 max_threads,
+                 u32 thread_quarantine_size, u32 max_reuse);
+  void GetNumberOfThreads(uptr *total = nullptr, uptr *running = nullptr,
+                          uptr *alive = nullptr);
+  uptr GetMaxAliveThreads();
+
+  void Lock() SANITIZER_ACQUIRE() { mtx_.Lock(); }
+  void CheckLocked() const SANITIZER_CHECK_LOCKED() { mtx_.CheckLocked(); }
+  void Unlock() SANITIZER_RELEASE() { mtx_.Unlock(); }
+
+  // Should be guarded by ThreadRegistryLock.
+  ThreadContextBase *GetThreadLocked(u32 tid) {
+    return tid < threads_.size() ? threads_[tid] : nullptr;
+  }
+
+  u32 NumThreadsLocked() const { return threads_.size(); }
+
+  u32 CreateThread(uptr user_id, bool detached, u32 parent_tid, u32 stack_tid,
+                   void *arg);
+  u32 CreateThread(uptr user_id, bool detached, u32 parent_tid, void *arg) {
+    return CreateThread(user_id, detached, parent_tid, 0, arg);
+  }
+
+  typedef void (*ThreadCallback)(ThreadContextBase *tctx, void *arg);
+  // Invokes callback with a specified arg for each thread context.
+  // Should be guarded by ThreadRegistryLock.
+  void RunCallbackForEachThreadLocked(ThreadCallback cb, void *arg);
+
+  typedef bool (*FindThreadCallback)(ThreadContextBase *tctx, void *arg);
+  // Finds a thread using the provided callback. Returns kInvalidTid if no
+  // thread is found.
+  u32 FindThread(FindThreadCallback cb, void *arg);
+  // Should be guarded by ThreadRegistryLock. Return 0 if no thread
+  // is found.
+  ThreadContextBase *FindThreadContextLocked(FindThreadCallback cb,
+                                             void *arg);
+  ThreadContextBase *FindThreadContextByOsIDLocked(tid_t os_id);
+
+  void SetThreadName(u32 tid, const char *name);
+  void SetThreadNameByUserId(uptr user_id, const char *name);
+  void DetachThread(u32 tid, void *arg);
+  void JoinThread(u32 tid, void *arg);
+  // Finishes thread and returns previous status.
+  ThreadStatus FinishThread(u32 tid);
+  void StartThread(u32 tid, tid_t os_id, ThreadType thread_type, void *arg);
+  u32 ConsumeThreadUserId(uptr user_id);
+  void SetThreadUserId(u32 tid, uptr user_id);
+
+  // OnFork must be called in the child process after fork to purge old
+  // threads that don't exist anymore (except for the current thread tid).
+  // Returns number of alive threads before fork.
+  u32 OnFork(u32 tid);
+
+ private:
+  const ThreadContextFactory context_factory_;
+  const u32 max_threads_;
+  const u32 thread_quarantine_size_;
+  const u32 max_reuse_;
+
+  Mutex mtx_;
+
+  u64 total_threads_;   // Total number of created threads. May be greater than
+                        // max_threads_ if contexts were reused.
+  uptr alive_threads_;  // Created or running.
+  uptr max_alive_threads_;
+  uptr running_threads_;
+
+  InternalMmapVector<ThreadContextBase *> threads_;
+  IntrusiveList<ThreadContextBase> dead_threads_;
+  IntrusiveList<ThreadContextBase> invalid_threads_;
+  DenseMap<uptr, Tid> live_;
+
+  void QuarantinePush(ThreadContextBase *tctx);
+  ThreadContextBase *QuarantinePop();
+};
+
+typedef GenericScopedLock<ThreadRegistry> ThreadRegistryLock;
+
+} // namespace __sanitizer
+
+#endif // SANITIZER_THREAD_REGISTRY_H