Function emmalloc_mallinfo

system/lib/emmalloc.c:1170–1235

}

struct mallinfo emmalloc_mallinfo() {
  MALLOC_ACQUIRE();

  struct mallinfo info;
  // Non-mmapped space allocated (bytes): For emmalloc,
  // let's define this as the difference between heap size and dynamic top end.
  info.arena = emscripten_get_heap_size() - (size_t)_sbrk64(0);
  // Number of "ordinary" blocks. Let's define this as the number of highest
  // size blocks. (subtract one from each, since there is a sentinel node in each list)
  info.ordblks = count_linked_list_size(&freeRegionBuckets[NUM_FREE_BUCKETS-1])-1;
  // Number of free "fastbin" blocks. For emmalloc, define this as the number
  // of blocks that are not in the largest pristine block.
  info.smblks = 0;
  // The total number of bytes in free "fastbin" blocks.
  info.fsmblks = 0;
  for (int i = 0; i < NUM_FREE_BUCKETS-1; ++i) {
    info.smblks += count_linked_list_size(&freeRegionBuckets[i])-1;
    info.fsmblks += count_linked_list_space(&freeRegionBuckets[i]);
  }

  info.hblks = 0; // Number of mmapped regions: always 0. (no mmap support)
  info.hblkhd = 0; // Amount of bytes in mmapped regions: always 0. (no mmap support)

  // Walk through all the heap blocks to report the following data:
  // The "highwater mark" for allocated space—that is, the maximum amount of
  // space that was ever allocated. Emmalloc does not want to pay code to
  // track this, so this is only reported from current allocation data, and
  // may not be accurate.
  info.usmblks = 0;
  info.uordblks = 0; // The total number of bytes used by in-use allocations.
  info.fordblks = 0; // The total number of bytes in free blocks.
  // The total amount of releasable free space at the top of the heap.
  // This is the maximum number of bytes that could ideally be released by malloc_trim(3).
  Region *lastActualRegion = prev_region((Region*)(listOfAllRegions->endPtr - sizeof(Region)));
  info.keepcost = region_is_free(lastActualRegion) ? lastActualRegion->size : 0;

  RootRegion *root = listOfAllRegions;
  while (root) {
    Region *r = (Region*)root;
    assert(debug_region_is_consistent(r));
    uint8_t *lastRegionEnd = root->endPtr;
    while ((uint8_t*)r < lastRegionEnd) {
      assert(debug_region_is_consistent(r));

      if (region_is_free(r)) {
        // Count only the payload of the free block towards free memory.
        info.fordblks += region_payload_end_ptr(r) - region_payload_start_ptr(r);
        // But the header data of the free block goes towards used memory.
        info.uordblks += REGION_HEADER_SIZE;
      } else {
        info.uordblks += r->size;
      }
      // Update approximate watermark data
      info.usmblks = MAX(info.usmblks, (intptr_t)r + r->size);

      if (r->size == 0) {
        break;
      }