From 26a029d407be480d791972afb5975cf62c9360a6 Mon Sep 17 00:00:00 2001 From: Daniel Baumann Date: Fri, 19 Apr 2024 02:47:55 +0200 Subject: Adding upstream version 124.0.1. Signed-off-by: Daniel Baumann --- xpcom/base/SizeOfState.h | 67 ++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 67 insertions(+) create mode 100644 xpcom/base/SizeOfState.h (limited to 'xpcom/base/SizeOfState.h') diff --git a/xpcom/base/SizeOfState.h b/xpcom/base/SizeOfState.h new file mode 100644 index 0000000000..2df0b24e93 --- /dev/null +++ b/xpcom/base/SizeOfState.h @@ -0,0 +1,67 @@ +/* -*- 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 SizeOfState_h +#define SizeOfState_h + +#include "mozilla/fallible.h" +#include "mozilla/MemoryReporting.h" +#include "mozilla/Unused.h" +#include "nsTHashtable.h" +#include "nsHashKeys.h" + +// This file includes types that are useful during memory reporting, but which +// cannot be put into mfbt/MemoryReporting.h because they depend on things that +// are not in MFBT. + +namespace mozilla { + +// A table of seen pointers. Useful when measuring structures that contain +// nodes that may be pointed to from multiple places, e.g. via RefPtr (in C++ +// code) or Arc (in Rust code). +class SeenPtrs : public nsTHashtable> { + public: + // Returns true if we have seen this pointer before, false otherwise. Also + // remembers this pointer for later queries. + bool HaveSeenPtr(const void* aPtr) { + uint32_t oldCount = Count(); + + mozilla::Unused << PutEntry(aPtr, fallible); + + // If the counts match, there are two possibilities. + // + // - Lookup succeeded: we've seen the pointer before, and didn't need to + // add a new entry. + // + // - PutEntry() tried to add the entry and failed due to lack of memory. In + // this case we can't tell if this pointer has been seen before (because + // the table is in an unreliable state and may have dropped previous + // insertions). When doing memory reporting it's better to err on the + // side of under-reporting rather than over-reporting, so we assume we've + // seen the pointer before. + // + return oldCount == Count(); + } +}; + +// Memory reporting state. Some memory measuring functions +// (SizeOfIncludingThis(), etc.) just need a MallocSizeOf parameter, but some +// also need a record of pointers that have been seen and should not be +// re-measured. This class encapsulates both of those things. +class SizeOfState { + public: + explicit SizeOfState(MallocSizeOf aMallocSizeOf) + : mMallocSizeOf(aMallocSizeOf) {} + + bool HaveSeenPtr(const void* aPtr) { return mSeenPtrs.HaveSeenPtr(aPtr); } + + MallocSizeOf mMallocSizeOf; + SeenPtrs mSeenPtrs; +}; + +} // namespace mozilla + +#endif // SizeOfState_h -- cgit v1.2.3