ThreadList.h

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//===-- ThreadList.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_THREADLIST_H
#define LLDB_TARGET_THREADLIST_H
 
#include <mutex>
#include <vector>
 
#include "lldb/Target/Thread.h"
#include "lldb/Target/ThreadCollection.h"
#include "lldb/Utility/Iterable.h"
#include "lldb/Utility/UserID.h"
#include "lldb/lldb-private.h"
 
#include "llvm/ADT/DenseMap.h"
#include "llvm/ADT/DenseSet.h"
 
namespace lldb_private {
 
// This is a thread list with lots of functionality for use only by the process
// for which this is the thread list.  A generic container class with iterator
// functionality is ThreadCollection.
class ThreadList : public ThreadCollection {
  friend class Process;
 
public:
  ThreadList(Process &process);
 
  ThreadList(const ThreadList &rhs);
 
  ~ThreadList() override;
 
  /// Precondition: both thread lists must be belong to the same process.
  const ThreadList &operator=(const ThreadList &rhs);
 
  uint32_t GetSize(bool can_update = true);
 
  // Return the selected thread if there is one.  Otherwise, return the thread
  // selected at index 0.
  lldb::ThreadSP GetSelectedThread();
 
  // Manage the thread to use for running expressions.  This is usually the
  // Selected thread, but sometimes (e.g. when evaluating breakpoint conditions
  // & stop hooks) it isn't.
  class ExpressionExecutionThreadPusher {
  public:
    ExpressionExecutionThreadPusher(ThreadList &thread_list, lldb::tid_t tid)
        : m_thread_list(&thread_list), m_tid(tid) {
      m_thread_list->PushExpressionExecutionThread(m_tid);
    }
 
    ExpressionExecutionThreadPusher(lldb::ThreadSP thread_sp);
 
    ~ExpressionExecutionThreadPusher() {
      if (m_thread_list && m_tid != LLDB_INVALID_THREAD_ID)
        m_thread_list->PopExpressionExecutionThread(m_tid);
    }
 
  private:
    ThreadList *m_thread_list;
    lldb::tid_t m_tid;
  };
 
  lldb::ThreadSP GetExpressionExecutionThread();
 
protected:
  void PushExpressionExecutionThread(lldb::tid_t tid);
 
  void PopExpressionExecutionThread(lldb::tid_t tid);
 
public:
  bool SetSelectedThreadByID(lldb::tid_t tid, bool notify = false);
 
  bool SetSelectedThreadByIndexID(uint32_t index_id, bool notify = false);
 
  void Clear();
 
  void Flush();
 
  void Destroy();
 
  // Note that "idx" is not the same as the "thread_index". It is a zero based
  // index to accessing the current threads, whereas "thread_index" is a unique
  // index assigned
  lldb::ThreadSP GetThreadAtIndex(uint32_t idx, bool can_update = true);
 
  lldb::ThreadSP FindThreadByID(lldb::tid_t tid, bool can_update = true);
 
  lldb::ThreadSP FindThreadByProtocolID(lldb::tid_t tid,
                                        bool can_update = true);
 
  lldb::ThreadSP RemoveThreadByID(lldb::tid_t tid, bool can_update = true);
 
  lldb::ThreadSP RemoveThreadByProtocolID(lldb::tid_t tid,
                                          bool can_update = true);
 
  lldb::ThreadSP FindThreadByIndexID(uint32_t index_id, bool can_update = true);
 
  lldb::ThreadSP GetThreadSPForThreadPtr(Thread *thread_ptr);
 
  bool ShouldStop(Event *event_ptr);
 
  Vote ShouldReportStop(Event *event_ptr);
 
  Vote ShouldReportRun(Event *event_ptr);
 
  void RefreshStateAfterStop();
 
  /// The thread list asks tells all the threads it is about to resume.
  /// If a thread can "resume" without having to resume the target, it
  /// will return false for WillResume, and then the process will not be
  /// restarted.
  /// Sets *direction to the run direction of the thread(s) that will
  /// be resumed. If threads that we want to run disagree about the
  /// direction, we execute forwards and pop any of the thread plans
  /// that requested reverse execution.
  ///
  /// \return
  ///    \b true instructs the process to resume normally,
  ///    \b false means start & stopped events will be generated, but
  ///    the process will not actually run.  The thread must then return
  ///    the correct StopInfo when asked.
  ///
  bool WillResume(lldb::RunDirection &direction);
 
  void DidResume();
 
  void DidStop();
 
  void DiscardThreadPlans();
 
  uint32_t GetStopID() const;
 
  void SetStopID(uint32_t stop_id);
 
  std::recursive_mutex &GetMutex() const override;
 
  /// Precondition: both thread lists must be belong to the same process.
  void Update(ThreadList &rhs);
 
  /// Called by ThreadPlanStepOverBreakpoint when a thread finishes stepping
  /// over a breakpoint. This tracks which threads are still stepping over
  /// each breakpoint address, and only re-enables the breakpoint when ALL
  /// threads have finished stepping over it.
  void ThreadFinishedSteppingOverBreakpoint(lldb::addr_t breakpoint_addr,
                                            lldb::tid_t tid);
 
  /// Register a thread that is about to step over a breakpoint.
  /// The breakpoint will be re-enabled only after all registered threads
  /// have called ThreadFinishedSteppingOverBreakpoint.
  void RegisterThreadSteppingOverBreakpoint(lldb::addr_t breakpoint_addr,
                                            lldb::tid_t tid);
 
protected:
  void SetShouldReportStop(Vote vote);
 
  void NotifySelectedThreadChanged(lldb::tid_t tid);
 
  // Classes that inherit from Process can see and modify these
  Process &m_process; ///< The process that manages this thread list.
  uint32_t
      m_stop_id; ///< The process stop ID that this thread list is valid for.
  lldb::tid_t
      m_selected_tid; ///< For targets that need the notion of a current thread.
  std::vector<lldb::tid_t> m_expression_tid_stack;
 
  /// Tracks which threads are currently stepping over each breakpoint address.
  /// Key: breakpoint address, Value: set of thread IDs stepping over it.
  /// When a thread finishes stepping, it's removed from the set. When the set
  /// becomes empty, the breakpoint is re-enabled.
  llvm::DenseMap<lldb::addr_t, llvm::DenseSet<lldb::tid_t>>
      m_threads_stepping_over_bp;
 
private:
  ThreadList() = delete;
};
 
} // namespace lldb_private
 
#endif // LLDB_TARGET_THREADLIST_H