[Lldb-commits] [lldb] New ThreadPlanSingleThreadTimeout to resolve potential deadlock in single thread stepping (PR #90930)

[via lldb-commits]

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+//===-- ThreadPlanSingleThreadTimeout.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
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLDB_TARGET_THREADPLANSINGLETHREADTIMEOUT_H
+#define LLDB_TARGET_THREADPLANSINGLETHREADTIMEOUT_H
+
+#include "lldb/Target/Thread.h"
+#include "lldb/Target/ThreadPlan.h"
+#include "lldb/Utility/Event.h"
+#include "lldb/Utility/LLDBLog.h"
+#include "lldb/Utility/State.h"
+
+#include <thread>
+
+namespace lldb_private {
+
+//
+// Thread plan used by single thread execution to issue timeout. This is useful
+// to detect potential deadlock in single thread execution. The timeout measures
+// the elapsed time from the last internal stop and gets reset by each internal
+// stop to ensure we are accurately detecting execution not moving forward.
+// This means this thread plan may be created/destroyed multiple times by the
+// parent execution plan.
+//
+// When timeout happens, the thread plan resolves the potential deadlock by
+// issuing a thread specific async interrupt to enter stop state, then all
+// threads execution are resumed to resolve the potential deadlock.
+//
+class ThreadPlanSingleThreadTimeout : public ThreadPlan {
+  enum class State {
+    WaitTimeout,    // Waiting for timeout.
+    AsyncInterrupt, // Async interrupt has been issued.
+    Done,           // Finished resume all threads.
+  };
+
+public:
+  struct TimeoutInfo {
+    ThreadPlanSingleThreadTimeout *m_instance = nullptr;
+    ThreadPlanSingleThreadTimeout::State m_last_state = State::WaitTimeout;
+  };
+
+  ~ThreadPlanSingleThreadTimeout() override;
+
+  // Create a new instance from fresh new state.
----------------
jimingham wrote:

Since this API doesn't return the Created thread plan, then this API has to do more than just create it - it also pushes the plan, and sometimes doesn't.  So CreateNew is not a good name, and the description of what the function does is too abbreviated.

https://github.com/llvm/llvm-project/pull/90930