src/span.cc

// -*- Mode: C++; c-basic-offset: 2; indent-tabs-mode: nil -*-
// Copyright (c) 2008, Google Inc.
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//
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// in the documentation and/or other materials provided with the
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// ---
// Author: Sanjay Ghemawat <opensource@google.com>

#include <config.h>
#include "span.h"

#include <string.h>                     // for NULL, memset

#include "internal_logging.h"  // for ASSERT
#include "page_heap_allocator.h"  // for PageHeapAllocator
#include "static_vars.h"       // for Static

namespace tcmalloc {

#ifdef SPAN_HISTORY
void Event(Span* span, char op, int v = 0) {
  span->history[span->nexthistory] = op;
  span->value[span->nexthistory] = v;
  span->nexthistory++;
  if (span->nexthistory == sizeof(span->history)) span->nexthistory = 0;
}
#endif

Span* NewSpan(PageID p, Length len) {
  Span* result = Static::span_allocator()->New();
  memset(result, 0, sizeof(*result));
  result->start = p;
  result->length = len;
#ifdef SPAN_HISTORY
  result->nexthistory = 0;
#endif
  return result;
}

void DeleteSpan(Span* span) {
#ifndef NDEBUG
  // In debug mode, trash the contents of deleted Spans
  memset(span, 0x3f, sizeof(*span));
#endif
  Static::span_allocator()->Delete(span);
}

void DLL_Init(Span* list) {
  list->next = list;
  list->prev = list;
}

void DLL_Remove(Span* span) {
  span->prev->next = span->next;
  span->next->prev = span->prev;
  span->prev = NULL;
  span->next = NULL;
}

int DLL_Length(const Span* list) {
  int result = 0;
  for (Span* s = list->next; s != list; s = s->next) {
    result++;
  }
  return result;
}

void DLL_Prepend(Span* list, Span* span) {
  ASSERT(span->next == NULL);
  ASSERT(span->prev == NULL);
  span->next = list->next;
  span->prev = list;
  list->next->prev = span;
  list->next = span;
}

}  // namespace tcmalloc