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2a318e8c71
1. The current asynchronous behavior is pointless, because we still remove the hashtable entry synchronously, which deletes the value, and it's the value we're using. 2. Trying to asynchronously delete the value is difficult, and not currently needed because we can't get a memory-pressure notification while we're using the value, and hence can't expire it from the expiration tracker. Note: we can't get this memory-pressure notification because the stage 2 of mozalloc_handle_oom() to reclaim memory when OOM is not implemented yet.
62 lines
2.1 KiB
C++
62 lines
2.1 KiB
C++
/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*-
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* vim: sw=4 ts=4 et :
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*/
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/* This Source Code Form is subject to the terms of the Mozilla Public
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* License, v. 2.0. If a copy of the MPL was not distributed with this
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* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
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#include "mozilla/mozalloc_abort.h"
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#include "mozilla/mozalloc_oom.h"
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#include "mozilla/Assertions.h"
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static mozalloc_oom_abort_handler gAbortHandler;
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#define OOM_MSG_LEADER "out of memory: 0x"
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#define OOM_MSG_DIGITS "0000000000000000" // large enough for 2^64
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#define OOM_MSG_TRAILER " bytes requested"
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#define OOM_MSG_FIRST_DIGIT_OFFSET sizeof(OOM_MSG_LEADER) - 1
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#define OOM_MSG_LAST_DIGIT_OFFSET sizeof(OOM_MSG_LEADER) + \
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sizeof(OOM_MSG_DIGITS) - 3
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static const char *hex = "0123456789ABCDEF";
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void
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mozalloc_handle_oom(size_t size)
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{
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char oomMsg[] = OOM_MSG_LEADER OOM_MSG_DIGITS OOM_MSG_TRAILER;
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size_t i;
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// NB: this is handle_oom() stage 1, which simply aborts on OOM.
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// we might proceed to a stage 2 in which an attempt is made to
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// reclaim memory
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// Warning: when stage 2 is done by, for example, notifying
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// "memory-pressure" synchronously, please audit all
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// nsExpirationTrackers and ensure that the actions they take
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// on memory-pressure notifications (via NotifyExpired) are safe.
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// Note that nsIDocument::SelectorCache::NotifyExpired is _known_
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// to not be safe: it will delete the selector it's caching,
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// which might be in use at the time under querySelector or
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// querySelectorAll.
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if (gAbortHandler)
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gAbortHandler(size);
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static_assert(OOM_MSG_FIRST_DIGIT_OFFSET > 0,
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"Loop below will never terminate (i can't go below 0)");
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// Insert size into the diagnostic message using only primitive operations
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for (i = OOM_MSG_LAST_DIGIT_OFFSET;
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size && i >= OOM_MSG_FIRST_DIGIT_OFFSET; i--) {
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oomMsg[i] = hex[size % 16];
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size /= 16;
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}
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mozalloc_abort(oomMsg);
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}
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void
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mozalloc_set_oom_abort_handler(mozalloc_oom_abort_handler handler)
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{
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gAbortHandler = handler;
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}
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