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Refactor MetaEntry remote_and_sizeclass

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Introduce a class that we can use to more completely separate the frontend
encoding details from the backend.
This commit is contained in:
Nathaniel Wesley Filardo
2022-03-16 13:02:26 +00:00
committed by Nathaniel Wesley Filardo
parent 772e46f878
commit 7940fee00c
8 changed files with 124 additions and 109 deletions
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41
src/backend/metatypes.h
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@@ -79,10 +79,6 @@ namespace snmalloc
#endif
// clang-format on
struct RemoteAllocator;
class Metaslab;
class sizeclass_t;
/**
* Entry stored in the pagemap. See docs/AddressSpace.md for the full
* MetaEntry lifecycle.
@@ -140,41 +136,23 @@ namespace snmalloc
* `get_remote_and_sizeclass`.
*/
SNMALLOC_FAST_PATH
MetaEntry(Metaslab* meta, uintptr_t remote_and_sizeclass)
: meta(unsafe_to_uintptr<Metaslab>(meta)),
MetaEntry(MetaCommon* meta, uintptr_t remote_and_sizeclass)
: meta(unsafe_to_uintptr<MetaCommon>(meta)),
remote_and_sizeclass(remote_and_sizeclass)
{}
/* See mem/metaslab.h */
SNMALLOC_FAST_PATH
MetaEntry(Metaslab* meta, RemoteAllocator* remote, sizeclass_t sizeclass);
/**
* Return the Metaslab metadata associated with this chunk, guarded by an
* assert that this chunk is being used as a slab (i.e., has an associated
* owning allocator).
*/
[[nodiscard]] SNMALLOC_FAST_PATH Metaslab* get_metaslab() const
{
SNMALLOC_ASSERT(get_remote() != nullptr);
return unsafe_from_uintptr<Metaslab>(meta & ~META_BOUNDARY_BIT);
}
/**
* Return the remote and sizeclass in an implementation-defined encoding.
* This is not guaranteed to be stable across snmalloc releases and so the
* only safe use for this is to pass it to the two-argument constructor of
* this class.
*/
[[nodiscard]] SNMALLOC_FAST_PATH uintptr_t get_remote_and_sizeclass() const
[[nodiscard]] SNMALLOC_FAST_PATH const uintptr_t&
get_remote_and_sizeclass() const
{
return remote_and_sizeclass;
}
/* See mem/metaslab.h */
[[nodiscard]] SNMALLOC_FAST_PATH RemoteAllocator* get_remote() const;
[[nodiscard]] SNMALLOC_FAST_PATH sizeclass_t get_sizeclass() const;
MetaEntry(const MetaEntry&) = delete;
MetaEntry& operator=(const MetaEntry& other)
@@ -186,6 +164,16 @@ namespace snmalloc
return *this;
}
/**
* Return the Metaslab metadata associated with this chunk, guarded by an
* assert that this chunk is being used as a slab (i.e., has an associated
* owning allocator).
*/
[[nodiscard]] SNMALLOC_FAST_PATH MetaCommon* get_meta() const
{
return reinterpret_cast<MetaCommon*>(meta & ~META_BOUNDARY_BIT);
}
void set_boundary()
{
meta |= META_BOUNDARY_BIT;
@@ -201,5 +189,4 @@ namespace snmalloc
return meta &= ~META_BOUNDARY_BIT;
}
};
} // namespace snmalloc