arena.go | Explore in Territory

// arena_newArena is a wrapper around newUserArena.
//
//go:linkname arena_newArena arena.runtime_arena_newArena
func arena_newArena() unsafe.Pointer { … }

// arena_arena_New is a wrapper around (*userArena).new, except that typ
// is an any (must be a *_type, still) and typ must be a type descriptor
// for a pointer to the type to actually be allocated, i.e. pass a *T
// to allocate a T. This is necessary because this function returns a *T.
//
//go:linkname arena_arena_New arena.runtime_arena_arena_New
func arena_arena_New(arena unsafe.Pointer, typ any) any { … }

// arena_arena_Slice is a wrapper around (*userArena).slice.
//
//go:linkname arena_arena_Slice arena.runtime_arena_arena_Slice
func arena_arena_Slice(arena unsafe.Pointer, slice any, cap int) { … }

// arena_arena_Free is a wrapper around (*userArena).free.
//
//go:linkname arena_arena_Free arena.runtime_arena_arena_Free
func arena_arena_Free(arena unsafe.Pointer) { … }

// arena_heapify takes a value that lives in an arena and makes a copy
// of it on the heap. Values that don't live in an arena are returned unmodified.
//
//go:linkname arena_heapify arena.runtime_arena_heapify
func arena_heapify(s any) any { … }

const userArenaChunkBytesMax …

const userArenaChunkBytes …

const userArenaChunkPages …

const userArenaChunkMaxAllocBytes …

func init() { … }

// userArenaChunkReserveBytes returns the amount of additional bytes to reserve for
// heap metadata.
func userArenaChunkReserveBytes() uintptr { … }

type userArena …

// newUserArena creates a new userArena ready to be used.
func newUserArena() *userArena { … }

// new allocates a new object of the provided type into the arena, and returns
// its pointer.
//
// This operation is not safe to call concurrently with other operations on the
// same arena.
func (a *userArena) new(typ *_type) unsafe.Pointer { … }

// slice allocates a new slice backing store. slice must be a pointer to a slice
// (i.e. *[]T), because userArenaSlice will update the slice directly.
//
// cap determines the capacity of the slice backing store and must be non-negative.
//
// This operation is not safe to call concurrently with other operations on the
// same arena.
func (a *userArena) slice(sl any, cap int) { … }

// free returns the userArena's chunks back to mheap and marks it as defunct.
//
// Must be called at most once for any given arena.
//
// This operation is not safe to call concurrently with other operations on the
// same arena.
func (a *userArena) free() { … }

// alloc reserves space in the current chunk or calls refill and reserves space
// in a new chunk. If cap is negative, the type will be taken literally, otherwise
// it will be considered as an element type for a slice backing store with capacity
// cap.
func (a *userArena) alloc(typ *_type, cap int) unsafe.Pointer { … }

// refill inserts the current arena chunk onto the full list and obtains a new
// one, either from the partial list or allocating a new one, both from mheap.
func (a *userArena) refill() *mspan { … }

type liveUserArenaChunk …

var userArenaState …

// userArenaNextFree reserves space in the user arena for an item of the specified
// type. If cap is not -1, this is for an array of cap elements of type t.
func (s *mspan) userArenaNextFree(typ *_type, cap int) unsafe.Pointer { … }

// userArenaHeapBitsSetSliceType is the equivalent of heapBitsSetType but for
// Go slice backing store values allocated in a user arena chunk. It sets up the
// heap bitmap for n consecutive values with type typ allocated at address ptr.
func userArenaHeapBitsSetSliceType(typ *_type, n int, ptr unsafe.Pointer, s *mspan) { … }

// userArenaHeapBitsSetType is the equivalent of heapSetType but for
// non-slice-backing-store Go values allocated in a user arena chunk. It
// sets up the type metadata for the value with type typ allocated at address ptr.
// base is the base address of the arena chunk.
func userArenaHeapBitsSetType(typ *_type, ptr unsafe.Pointer, s *mspan) { … }

type writeUserArenaHeapBits …

func (s *mspan) writeUserArenaHeapBits(addr uintptr) (h writeUserArenaHeapBits) { … }

// write appends the pointerness of the next valid pointer slots
// using the low valid bits of bits. 1=pointer, 0=scalar.
func (h writeUserArenaHeapBits) write(s *mspan, bits, valid uintptr) writeUserArenaHeapBits { … }

// Add padding of size bytes.
func (h writeUserArenaHeapBits) pad(s *mspan, size uintptr) writeUserArenaHeapBits { … }

// Flush the bits that have been written, and add zeros as needed
// to cover the full object [addr, addr+size).
func (h writeUserArenaHeapBits) flush(s *mspan, addr, size uintptr) { … }

// bswapIfBigEndian swaps the byte order of the uintptr on goarch.BigEndian platforms,
// and leaves it alone elsewhere.
func bswapIfBigEndian(x uintptr) uintptr { … }

// newUserArenaChunk allocates a user arena chunk, which maps to a single
// heap arena and single span. Returns a pointer to the base of the chunk
// (this is really important: we need to keep the chunk alive) and the span.
func newUserArenaChunk() (unsafe.Pointer, *mspan) { … }

// isUnusedUserArenaChunk indicates that the arena chunk has been set to fault
// and doesn't contain any scannable memory anymore. However, it might still be
// mSpanInUse as it sits on the quarantine list, since it needs to be swept.
//
// This is not safe to execute unless the caller has ownership of the mspan or
// the world is stopped (preemption is prevented while the relevant state changes).
//
// This is really only meant to be used by accounting tests in the runtime to
// distinguish when a span shouldn't be counted (since mSpanInUse might not be
// enough).
func (s *mspan) isUnusedUserArenaChunk() bool { … }

// setUserArenaChunkToFault sets the address space for the user arena chunk to fault
// and releases any underlying memory resources.
//
// Must be in a non-preemptible state to ensure the consistency of statistics
// exported to MemStats.
func (s *mspan) setUserArenaChunkToFault() { … }

// inUserArenaChunk returns true if p points to a user arena chunk.
func inUserArenaChunk(p uintptr) bool { … }

// freeUserArenaChunk releases the user arena represented by s back to the runtime.
//
// x must be a live pointer within s.
//
// The runtime will set the user arena to fault once it's safe (the GC is no longer running)
// and then once the user arena is no longer referenced by the application, will allow it to
// be reused.
func freeUserArenaChunk(s *mspan, x unsafe.Pointer) { … }

// allocUserArenaChunk attempts to reuse a free user arena chunk represented
// as a span.
//
// Must be in a non-preemptible state to ensure the consistency of statistics
// exported to MemStats.
//
// Acquires the heap lock. Must run on the system stack for that reason.
//
//go:systemstack
func (h *mheap) allocUserArenaChunk() *mspan { … }
go/src/runtime/arena.go
