[Mlir-commits] [llvm] [mlir] Split the llvm::ThreadPool into an abstract base class and an impleme… (PR #82094)

[Mehdi Amini]

================
@@ -137,44 +156,70 @@ class ThreadPool {
             },
             std::move(F)};
   }
+};
+
+/// A ThreadPool implementation using std::threads.
+///
+/// The pool keeps a vector of threads alive, waiting on a condition variable
+/// for some work to become available.
+class ThreadPool : public ThreadPoolInterface {
+public:
+  /// Construct a pool using the hardware strategy \p S for mapping hardware
+  /// execution resources (threads, cores, CPUs)
+  /// Defaults to using the maximum execution resources in the system, but
+  /// accounting for the affinity mask.
+  ThreadPool(ThreadPoolStrategy S = hardware_concurrency());
+
+  /// Blocking destructor: the pool will wait for all the threads to complete.
+  ~ThreadPool() override;
+
+
+  /// Blocking wait for all the threads to complete and the queue to be empty.
+  /// It is an error to try to add new tasks while blocking on this call.
+  /// Calling wait() from a task would deadlock waiting for itself.
+  void wait() override;
+
+  /// Blocking wait for only all the threads in the given group to complete.
+  /// It is possible to wait even inside a task, but waiting (directly or
+  /// indirectly) on itself will deadlock. If called from a task running on a
+  /// worker thread, the call may process pending tasks while waiting in order
+  /// not to waste the thread.
+  void wait(ThreadPoolTaskGroup &Group) override;
+
+  // TODO: misleading legacy name warning!
+  // Returns the maximum number of worker threads in the pool, not the current
+  // number of threads!
+  unsigned getThreadCount() const { return MaxThreadCount; }
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joker-eph wrote:

Happy to do a mass replacement in the codebase and deprecate this! Let me send a PR separately for this.

https://github.com/llvm/llvm-project/pull/82094