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// Copyright 2019 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#include <vector>
#include "base/base_export.h"
#include "base/profiler/frame.h"
#include "base/profiler/register_context.h"
namespace base {
// Platform-specific thread and stack manipulation delegate, for use by the
// platform-independent stack copying/walking implementation in
// StackSamplerImpl.
// IMPORTANT NOTE: Most methods in this interface are invoked while the target
// thread is suspended so must not do any allocation from the heap, including
// indirectly via use of DCHECK/CHECK or other logging statements. Otherwise the
// implementation can deadlock on heap locks acquired by the target thread
// before it was suspended. These functions are commented with "NO HEAP
class BASE_EXPORT ThreadDelegate {
// Implementations of this interface should suspend the thread for the
// object's lifetime. NO HEAP ALLOCATIONS between the time the thread is
// suspended and resumed.
class BASE_EXPORT ScopedSuspendThread {
ScopedSuspendThread() = default;
virtual ~ScopedSuspendThread() = default;
ScopedSuspendThread(const ScopedSuspendThread&) = delete;
ScopedSuspendThread& operator=(const ScopedSuspendThread&) = delete;
virtual bool WasSuccessful() const = 0;
ThreadDelegate() = default;
virtual ~ThreadDelegate() = default;
ThreadDelegate(const ThreadDelegate&) = delete;
ThreadDelegate& operator=(const ThreadDelegate&) = delete;
// Creates an object that holds the thread suspended for its lifetime.
virtual std::unique_ptr<ScopedSuspendThread> CreateScopedSuspendThread() = 0;
// Gets the register context for the thread.
virtual bool GetThreadContext(RegisterContext* thread_context) = 0;
// Gets the base address of the thread's stack.
virtual uintptr_t GetStackBaseAddress() const = 0;
// Returns true if the thread's stack can be copied, where the bottom address
// of the thread is at |stack_pointer|.
virtual bool CanCopyStack(uintptr_t stack_pointer) = 0;
// Returns a list of registers that should be rewritten to point into the
// stack copy, if they originally pointed into the original stack.
// May heap allocate.
virtual std::vector<uintptr_t*> GetRegistersToRewrite(
RegisterContext* thread_context) = 0;
} // namespace base