StackTrace.h

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/*
 * Copyright 2012-present Facebook, Inc.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *   http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

#pragma once

#include <cassert>
#include <cstddef>
#include <cstdint>

namespace folly {
namespace exception_tracer {

constexpr size_t kMaxFrames = 500;

struct StackTrace {
  StackTrace() : frameCount(0) {}

  size_t frameCount;
  uintptr_t addresses[kMaxFrames];
};

// note: no constructor so this can be __thread.
// A StackTraceStack MUST be placed in zero-initialized memory.
class StackTraceStack {
  class Node;

 public:
  bool pushCurrent();

  bool pop();

  bool moveTopFrom(StackTraceStack& other);

  void clear();

  bool empty() const {
    return !top_;
  }

  StackTrace* top();

  StackTrace* next(StackTrace* p);

 private:
  // In debug mode, we assert that we're in zero-initialized memory by
  // checking that the two guards around top_ are zero.
  void checkGuard() const {
#ifndef NDEBUG
    assert(guard1_ == 0 && guard2_ == 0);
#endif
  }

#ifndef NDEBUG
  uintptr_t guard1_;
#endif
  Node* top_;
#ifndef NDEBUG
  uintptr_t guard2_;
#endif
};
} // namespace exception_tracer
} // namespace folly