diff options
author | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-04-07 09:22:09 +0000 |
---|---|---|
committer | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-04-07 09:22:09 +0000 |
commit | 43a97878ce14b72f0981164f87f2e35e14151312 (patch) | |
tree | 620249daf56c0258faa40cbdcf9cfba06de2a846 /mozglue/baseprofiler/public/ProfileBufferIndex.h | |
parent | Initial commit. (diff) | |
download | firefox-43a97878ce14b72f0981164f87f2e35e14151312.tar.xz firefox-43a97878ce14b72f0981164f87f2e35e14151312.zip |
Adding upstream version 110.0.1.upstream/110.0.1upstream
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
Diffstat (limited to 'mozglue/baseprofiler/public/ProfileBufferIndex.h')
-rw-r--r-- | mozglue/baseprofiler/public/ProfileBufferIndex.h | 97 |
1 files changed, 97 insertions, 0 deletions
diff --git a/mozglue/baseprofiler/public/ProfileBufferIndex.h b/mozglue/baseprofiler/public/ProfileBufferIndex.h new file mode 100644 index 0000000000..5cda6bd89e --- /dev/null +++ b/mozglue/baseprofiler/public/ProfileBufferIndex.h @@ -0,0 +1,97 @@ +/* -*- Mode: C++; tab-width: 2; 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 ProfileBufferIndex_h +#define ProfileBufferIndex_h + +#include "mozilla/Attributes.h" + +#include <cstddef> +#include <cstdint> + +namespace mozilla { + +// Generic index into a Profiler buffer, mostly for internal usage. +// Intended to appear infinite (it should effectively never wrap). +// 0 (zero) is reserved as nullptr-like value; it may indicate failure result, +// or it may point at the earliest available block. +using ProfileBufferIndex = uint64_t; + +// Externally-opaque class encapsulating a block index, i.e. a +// ProfileBufferIndex that is guaranteed to point at the start of a Profile +// buffer block (until it is destroyed, but then that index cannot be reused and +// functions should gracefully handle expired blocks). +// Users may get these from Profile buffer functions, to later access previous +// blocks; they should avoid converting and operating on their value. +class ProfileBufferBlockIndex { + public: + // Default constructor with internal 0 value, for which Profile buffers must + // guarantee that it is before any valid entries; All public APIs should + // fail gracefully, doing and/or returning Nothing. + ProfileBufferBlockIndex() : mBlockIndex(0) {} + + // Implicit conversion from literal `nullptr` to internal 0 value, to allow + // convenient init/reset/comparison with 0 index. + MOZ_IMPLICIT ProfileBufferBlockIndex(std::nullptr_t) : mBlockIndex(0) {} + + // Explicit conversion to bool, works in `if` and other tests. + // Only returns false for default `ProfileBufferBlockIndex{}` value. + explicit operator bool() const { return mBlockIndex != 0; } + + // Comparison operators. Default `ProfileBufferBlockIndex{}` value is always + // the lowest. + [[nodiscard]] bool operator==(const ProfileBufferBlockIndex& aRhs) const { + return mBlockIndex == aRhs.mBlockIndex; + } + [[nodiscard]] bool operator!=(const ProfileBufferBlockIndex& aRhs) const { + return mBlockIndex != aRhs.mBlockIndex; + } + [[nodiscard]] bool operator<(const ProfileBufferBlockIndex& aRhs) const { + return mBlockIndex < aRhs.mBlockIndex; + } + [[nodiscard]] bool operator<=(const ProfileBufferBlockIndex& aRhs) const { + return mBlockIndex <= aRhs.mBlockIndex; + } + [[nodiscard]] bool operator>(const ProfileBufferBlockIndex& aRhs) const { + return mBlockIndex > aRhs.mBlockIndex; + } + [[nodiscard]] bool operator>=(const ProfileBufferBlockIndex& aRhs) const { + return mBlockIndex >= aRhs.mBlockIndex; + } + + // Explicit conversion to ProfileBufferIndex, mostly used by internal Profile + // buffer code. + [[nodiscard]] ProfileBufferIndex ConvertToProfileBufferIndex() const { + return mBlockIndex; + } + + // Explicit creation from ProfileBufferIndex, mostly used by internal + // Profile buffer code. + [[nodiscard]] static ProfileBufferBlockIndex CreateFromProfileBufferIndex( + ProfileBufferIndex aIndex) { + return ProfileBufferBlockIndex(aIndex); + } + + private: + // Private to prevent easy construction from any value. Use + // `CreateFromProfileBufferIndex()` instead. + // The main reason for this indirection is to make it harder to create these + // objects, because only the profiler code should need to do it. Ideally, this + // class should be used wherever a block index should be stored, but there is + // so much code that uses `uint64_t` that it would be a big task to change + // them all. So for now we allow conversions to/from numbers, but it's as ugly + // as possible to make sure it doesn't get too common; and if one day we want + // to tackle a global change, it should be easy to find all these locations + // thanks to the explicit conversion functions. + explicit ProfileBufferBlockIndex(ProfileBufferIndex aBlockIndex) + : mBlockIndex(aBlockIndex) {} + + ProfileBufferIndex mBlockIndex; +}; + +} // namespace mozilla + +#endif // ProfileBufferIndex_h |