Function ArenaInit

BeefRT/gperftools/src/base/low_level_alloc.cc:263–292

Initialize the fields of an Arena

// Initialize the fields of an Arena
static void ArenaInit(LowLevelAlloc::Arena *arena) {
  if (arena->pagesize == 0) {
    arena->pagesize = getpagesize();
    // Round up block sizes to a power of two close to the header size.
    arena->roundup = 16;
    while (arena->roundup < sizeof (arena->freelist.header)) {
      arena->roundup += arena->roundup;
    }
    // Don't allocate blocks less than twice the roundup size to avoid tiny
    // free blocks.
    arena->min_size = 2 * arena->roundup;
    arena->freelist.header.size = 0;
    arena->freelist.header.magic =
        Magic(kMagicUnallocated, &arena->freelist.header);
    arena->freelist.header.arena = arena;
    arena->freelist.levels = 0;
    memset(arena->freelist.next, 0, sizeof (arena->freelist.next));
    arena->allocation_count = 0;
    if (arena == &default_arena) {
      // Default arena should be hooked, e.g. for heap-checker to trace
      // pointer chains through objects in the default arena.
      arena->flags = LowLevelAlloc::kCallMallocHook;
    } else if (arena == &unhooked_async_sig_safe_arena) {
      arena->flags = LowLevelAlloc::kAsyncSignalSafe;
    } else {
      arena->flags = 0;   // other arenas' flags may be overridden by client,
                          // but unhooked_arena will have 0 in 'flags'.
    }
  }
}

// L < meta_data_arena->mu
LowLevelAlloc::Arena *LowLevelAlloc::NewArena(int32 flags,