lldb/source/Plugins/SystemRuntime/MacOSX/AppleGetQueuesHandler.h

//===-- AppleGetQueuesHandler.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_SOURCE_PLUGINS_SYSTEMRUNTIME_MACOSX_APPLEGETQUEUESHANDLER_H
#define LLDB_SOURCE_PLUGINS_SYSTEMRUNTIME_MACOSX_APPLEGETQUEUESHANDLER_H

#include <map>
#include <mutex>
#include <vector>

#include "lldb/Symbol/CompilerType.h"
#include "lldb/Utility/Status.h"
#include "lldb/lldb-public.h"

// This class will insert a UtilityFunction into the inferior process for
// calling libBacktraceRecording's introspection_get_dispatch_queues()
// function.  The function in the inferior will return a struct by value
// with these members:
//
//     struct get_current_queues_return_values
//     {
//         introspection_dispatch_queue_info_t *queues_buffer;
//         uint64_t queues_buffer_size;
//         uint64_t count;
//     };
//
// The queues_buffer pointer is an address in the inferior program's address
// space (queues_buffer_size in size) which must be mach_vm_deallocate'd by
// lldb.  count is the number of queues that were stored in the buffer.
//
// The AppleGetQueuesHandler object should persist so that the UtilityFunction
// can be reused multiple times.

namespace lldb_private {

class AppleGetQueuesHandler {
public:
  AppleGetQueuesHandler(lldb_private::Process *process);

  ~AppleGetQueuesHandler();

  struct GetQueuesReturnInfo {
    lldb::addr_t queues_buffer_ptr =
        LLDB_INVALID_ADDRESS; /* the address of the queues buffer from
          libBacktraceRecording */
    lldb::addr_t queues_buffer_size = 0; /* the size of the queues buffer from
                                        libBacktraceRecording */
    uint64_t count = 0; /* the number of queues included in the queues buffer */

    GetQueuesReturnInfo() = default;
  };

  /// Get the list of queues that exist (with any active or pending items) via
  /// a call to introspection_get_dispatch_queues().  If there's a page of
  /// memory that needs to be freed, pass in the address and size and it will
  /// be freed before getting the list of queues.
  ///
  /// \param [in] thread
  ///     The thread to run this plan on.
  ///
  /// \param [in] page_to_free
  ///     An address of an inferior process vm page that needs to be
  ///     deallocated,
  ///     LLDB_INVALID_ADDRESS if this is not needed.
  ///
  /// \param [in] page_to_free_size
  ///     The size of the vm page that needs to be deallocated if an address was
  ///     passed in to page_to_free.
  ///
  /// \param [out] error
  ///     This object will be updated with the error status / error string from
  ///     any failures encountered.
  ///
  /// \returns
  ///     The result of the inferior function call execution.  If there was a
  ///     failure of any kind while getting
  ///     the information, the queues_buffer_ptr value will be
  ///     LLDB_INVALID_ADDRESS.
  GetQueuesReturnInfo GetCurrentQueues(Thread &thread,
                                       lldb::addr_t page_to_free,
                                       uint64_t page_to_free_size,
                                       lldb_private::Status &error);

  void Detach();

private:
  lldb::addr_t SetupGetQueuesFunction(Thread &thread,
                                      ValueList &get_queues_arglist);

  static const char *g_get_current_queues_function_name;
  static const char *g_get_current_queues_function_code;

  lldb_private::Process *m_process;
  std::unique_ptr<UtilityFunction> m_get_queues_impl_code_up;
  std::mutex m_get_queues_function_mutex;

  lldb::addr_t m_get_queues_return_buffer_addr;
  std::mutex m_get_queues_retbuffer_mutex;
};

} // using namespace lldb_private

#endif // LLDB_SOURCE_PLUGINS_SYSTEMRUNTIME_MACOSX_APPLEGETQUEUESHANDLER_H