memory/mozalloc/mozalloc_oom.cpp

   1 /* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 2 -*-
   2  * vim: sw=2 ts=4 et :
   3  */
   4 /* This Source Code Form is subject to the terms of the Mozilla Public
   5  * License, v. 2.0. If a copy of the MPL was not distributed with this
   6  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
   7
   8 #include "mozilla/mozalloc_abort.h"
   9 #include "mozilla/mozalloc_oom.h"
  10 #include "mozilla/Assertions.h"
  11
  12 #define OOM_MSG_LEADER "out of memory: 0x"
  13 #define OOM_MSG_DIGITS "0000000000000000"  // large enough for 2^64
  14 #define OOM_MSG_TRAILER " bytes requested"
  15 #define OOM_MSG_FIRST_DIGIT_OFFSET sizeof(OOM_MSG_LEADER) - 1
  16 #define OOM_MSG_LAST_DIGIT_OFFSET \
  17   sizeof(OOM_MSG_LEADER) + sizeof(OOM_MSG_DIGITS) - 3
  18
  19 MFBT_DATA size_t gOOMAllocationSize = 0;
  20
  21 static const char* hex = "0123456789ABCDEF";
  22
  23 void mozalloc_handle_oom(size_t size) {
  24   char oomMsg[] = OOM_MSG_LEADER OOM_MSG_DIGITS OOM_MSG_TRAILER;
  25   size_t i;
  26
  27   // NB: this is handle_oom() stage 1, which simply aborts on OOM.
  28   // we might proceed to a stage 2 in which an attempt is made to
  29   // reclaim memory
  30   // Warning: when stage 2 is done by, for example, notifying
  31   // "memory-pressure" synchronously, please audit all
  32   // nsExpirationTrackers and ensure that the actions they take
  33   // on memory-pressure notifications (via NotifyExpired) are safe.
  34   // Note that Document::SelectorCache::NotifyExpired is _known_
  35   // to not be safe: it will delete the selector it's caching,
  36   // which might be in use at the time under querySelector or
  37   // querySelectorAll.
  38
  39   gOOMAllocationSize = size;
  40
  41   static_assert(OOM_MSG_FIRST_DIGIT_OFFSET > 0,
  42                 "Loop below will never terminate (i can't go below 0)");
  43
  44   // Insert size into the diagnostic message using only primitive operations
  45   for (i = OOM_MSG_LAST_DIGIT_OFFSET; size && i >= OOM_MSG_FIRST_DIGIT_OFFSET;
  46        i--) {
  47     oomMsg[i] = hex[size % 16];
  48     size /= 16;
  49   }
  50
  51   mozalloc_abort(oomMsg);
  52 }