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author | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-04-07 19:33:14 +0000 |
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committer | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-04-07 19:33:14 +0000 |
commit | 36d22d82aa202bb199967e9512281e9a53db42c9 (patch) | |
tree | 105e8c98ddea1c1e4784a60a5a6410fa416be2de /layout/base/StackArena.h | |
parent | Initial commit. (diff) | |
download | firefox-esr-36d22d82aa202bb199967e9512281e9a53db42c9.tar.xz firefox-esr-36d22d82aa202bb199967e9512281e9a53db42c9.zip |
Adding upstream version 115.7.0esr.upstream/115.7.0esr
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
Diffstat (limited to 'layout/base/StackArena.h')
-rw-r--r-- | layout/base/StackArena.h | 92 |
1 files changed, 92 insertions, 0 deletions
diff --git a/layout/base/StackArena.h b/layout/base/StackArena.h new file mode 100644 index 0000000000..bb9d205a74 --- /dev/null +++ b/layout/base/StackArena.h @@ -0,0 +1,92 @@ +/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */ +/* vim: set ts=8 sts=2 et sw=2 tw=80: */ +/* This Source Code Form is subject to the terms of the Mozilla Public + * License, v. 2.0. If a copy of the MPL was not distributed with this file, + * You can obtain one at http://mozilla.org/MPL/2.0/. */ + +#ifndef StackArena_h +#define StackArena_h + +#include "nsError.h" +#include "mozilla/Assertions.h" +#include "mozilla/MemoryReporting.h" + +namespace mozilla { + +struct StackBlock; +struct StackMark; +class AutoStackArena; + +// Private helper class for AutoStackArena. +class StackArena { + private: + friend class AutoStackArena; + StackArena(); + ~StackArena(); + + // Memory management functions. + void* Allocate(size_t aSize); + void Push(); + void Pop(); + + size_t SizeOfExcludingThis(mozilla::MallocSizeOf aMallocSizeOf) const; + + // Our current position in memory. + size_t mPos; + + // A list of memory blocks. Usually there is only one + // but if we overrun our stack size we can get more memory. + StackBlock* mBlocks; + + // The current block. + StackBlock* mCurBlock; + + // Our stack of mark where push has been called. + StackMark* mMarks; + + // The current top of the mark list. + uint32_t mStackTop; + + // The size of the mark array. + uint32_t mMarkLength; +}; + +// Class for stack scoped arena memory allocations. +// +// Callers who wish to allocate memory whose lifetime corresponds to the +// lifetime of a stack-allocated object can use this class. First, +// declare an AutoStackArena object on the stack. Then all subsequent +// calls to Allocate will allocate memory from an arena pool that will +// be freed when that variable goes out of scope. Nesting is allowed. +// +// Individual allocations cannot exceed StackBlock::MAX_USABLE_SIZE +// bytes. +// +class MOZ_RAII AutoStackArena { + public: + AutoStackArena() : mOwnsStackArena(false) { + if (!gStackArena) { + gStackArena = new StackArena(); + mOwnsStackArena = true; + } + gStackArena->Push(); + } + + ~AutoStackArena() { + gStackArena->Pop(); + if (mOwnsStackArena) { + delete gStackArena; + gStackArena = nullptr; + } + } + + static void* Allocate(size_t aSize) { return gStackArena->Allocate(aSize); } + + private: + static StackArena* gStackArena; + bool mOwnsStackArena; +}; + +} // namespace mozilla + +#endif |