src/stack_trace_table.h

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// ---
// Author: Andrew Fikes
//
// Utility class for coalescing sampled stack traces.  Not thread-safe.

#ifndef TCMALLOC_STACK_TRACE_TABLE_H_
#define TCMALLOC_STACK_TRACE_TABLE_H_
#include "config.h"

#include <stdint.h>                     // for uintptr_t

#include <memory>

#include "common.h"
#include "internal_logging.h"
#include "page_heap_allocator.h"

namespace tcmalloc {

// Given snapshot of StackTrace list, new[] list of machine words and
// fill that with profile. See
// MallocExtension::GetStackTraces. next_fn and head are
// representation of generalized iterator over that list. See uses to
// learn how it works.
std::unique_ptr<void*[]> ProduceStackTracesDump(const StackTrace* (*next_fn)(const void** updatable_head),
                                                const void* head);

class StackTraceTable {
 public:
  // REQUIRES: L < pageheap_lock
  StackTraceTable() = default;
  ~StackTraceTable() {
    ASSERT(head_ == nullptr);
  }

  // Adds stack trace "t" to table.
  //
  // REQUIRES: L >= pageheap_lock
  void AddTrace(const StackTrace& t);

  // Returns stack traces formatted per MallocExtension guidelines.
  // May return nullptr on error.  Clears state before returning.
  //
  // REQUIRES: L < pageheap_lock
  void** ReadStackTracesAndClear();

 private:
  struct Entry {
    Entry* next;
    StackTrace trace;
  };

  bool error_{};
  Entry* head_{};
  STLPageHeapAllocator<Entry, void> allocator_;
};

}  // namespace tcmalloc

#endif  // TCMALLOC_STACK_TRACE_TABLE_H_