Distinguish Element and Linker for ilist.
Furthermore, allow for the specification of an ElementMapper. This allows a single "Element" type to exist on multiple inline lists, and work without having to embed the entry type. This is a requisite change for supporting a per-Inode list of Dirents. PiperOrigin-RevId: 211467497 Change-Id: If2768999b43e03fdaecf8ed15f435fe37518d163
This commit is contained in:
parent
66c03b3dd7
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@ -28,6 +28,7 @@ go_template_instance(
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prefix = "direct",
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template = ":generic_list",
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types = {
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"Element": "*direct",
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"Linker": "*direct",
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},
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)
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@ -47,6 +48,10 @@ go_template(
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srcs = [
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"list.go",
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],
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opt_types = ["Linker"],
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opt_types = [
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"Element",
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"ElementMapper",
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"Linker",
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],
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visibility = ["//visibility:public"],
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)
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@ -21,12 +21,34 @@ package ilist
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// N.B. When substituted in a template instantiation, Linker doesn't need to
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// be an interface, and in most cases won't be.
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type Linker interface {
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Next() Linker
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Prev() Linker
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SetNext(Linker)
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SetPrev(Linker)
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Next() Element
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Prev() Element
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SetNext(Element)
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SetPrev(Element)
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}
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// Element the item that is used at the API level.
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//
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// N.B. Like Linker, this is unlikely to be an interface in most cases.
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type Element interface {
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Linker
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}
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// ElementMapper provides an identity mapping by default.
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//
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// This can be replaced to provide a struct that maps elements to linker
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// objects, if they are not the same. An ElementMapper is not typically
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// required if: Linker is left as is, Element is left as is, or Linker and
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// Element are the same type.
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type ElementMapper struct{}
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// linkerFor maps an Element to a Linker.
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//
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// This default implementation should be inlined.
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//
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//go:nosplit
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func (ElementMapper) linkerFor(elem Element) Linker { return elem }
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// List is an intrusive list. Entries can be added to or removed from the list
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// in O(1) time and with no additional memory allocations.
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//
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@ -39,8 +61,8 @@ type Linker interface {
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//
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// +stateify savable
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type List struct {
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head Linker
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tail Linker
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head Element
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tail Element
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}
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// Reset resets list l to the empty state.
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@ -55,22 +77,22 @@ func (l *List) Empty() bool {
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}
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// Front returns the first element of list l or nil.
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func (l *List) Front() Linker {
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func (l *List) Front() Element {
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return l.head
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}
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// Back returns the last element of list l or nil.
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func (l *List) Back() Linker {
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func (l *List) Back() Element {
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return l.tail
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}
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// PushFront inserts the element e at the front of list l.
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func (l *List) PushFront(e Linker) {
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e.SetNext(l.head)
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e.SetPrev(nil)
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func (l *List) PushFront(e Element) {
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ElementMapper{}.linkerFor(e).SetNext(l.head)
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ElementMapper{}.linkerFor(e).SetPrev(nil)
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if l.head != nil {
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l.head.SetPrev(e)
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ElementMapper{}.linkerFor(l.head).SetPrev(e)
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} else {
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l.tail = e
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}
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@ -79,12 +101,12 @@ func (l *List) PushFront(e Linker) {
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}
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// PushBack inserts the element e at the back of list l.
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func (l *List) PushBack(e Linker) {
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e.SetNext(nil)
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e.SetPrev(l.tail)
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func (l *List) PushBack(e Element) {
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ElementMapper{}.linkerFor(e).SetNext(nil)
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ElementMapper{}.linkerFor(e).SetPrev(l.tail)
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if l.tail != nil {
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l.tail.SetNext(e)
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ElementMapper{}.linkerFor(l.tail).SetNext(e)
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} else {
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l.head = e
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}
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@ -98,8 +120,8 @@ func (l *List) PushBackList(m *List) {
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l.head = m.head
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l.tail = m.tail
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} else if m.head != nil {
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l.tail.SetNext(m.head)
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m.head.SetPrev(l.tail)
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ElementMapper{}.linkerFor(l.tail).SetNext(m.head)
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ElementMapper{}.linkerFor(m.head).SetPrev(l.tail)
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l.tail = m.tail
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}
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@ -109,46 +131,46 @@ func (l *List) PushBackList(m *List) {
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}
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// InsertAfter inserts e after b.
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func (l *List) InsertAfter(b, e Linker) {
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a := b.Next()
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e.SetNext(a)
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e.SetPrev(b)
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b.SetNext(e)
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func (l *List) InsertAfter(b, e Element) {
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a := ElementMapper{}.linkerFor(b).Next()
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ElementMapper{}.linkerFor(e).SetNext(a)
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ElementMapper{}.linkerFor(e).SetPrev(b)
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ElementMapper{}.linkerFor(b).SetNext(e)
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if a != nil {
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a.SetPrev(e)
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ElementMapper{}.linkerFor(a).SetPrev(e)
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} else {
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l.tail = e
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}
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}
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// InsertBefore inserts e before a.
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func (l *List) InsertBefore(a, e Linker) {
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b := a.Prev()
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e.SetNext(a)
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e.SetPrev(b)
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a.SetPrev(e)
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func (l *List) InsertBefore(a, e Element) {
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b := ElementMapper{}.linkerFor(a).Prev()
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ElementMapper{}.linkerFor(e).SetNext(a)
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ElementMapper{}.linkerFor(e).SetPrev(b)
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ElementMapper{}.linkerFor(a).SetPrev(e)
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if b != nil {
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b.SetNext(e)
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ElementMapper{}.linkerFor(b).SetNext(e)
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} else {
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l.head = e
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}
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}
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// Remove removes e from l.
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func (l *List) Remove(e Linker) {
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prev := e.Prev()
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next := e.Next()
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func (l *List) Remove(e Element) {
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prev := ElementMapper{}.linkerFor(e).Prev()
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next := ElementMapper{}.linkerFor(e).Next()
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if prev != nil {
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prev.SetNext(next)
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ElementMapper{}.linkerFor(prev).SetNext(next)
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} else {
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l.head = next
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}
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if next != nil {
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next.SetPrev(prev)
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ElementMapper{}.linkerFor(next).SetPrev(prev)
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} else {
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l.tail = prev
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}
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@ -160,26 +182,26 @@ func (l *List) Remove(e Linker) {
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//
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// +stateify savable
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type Entry struct {
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next Linker
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prev Linker
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next Element
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prev Element
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}
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// Next returns the entry that follows e in the list.
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func (e *Entry) Next() Linker {
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func (e *Entry) Next() Element {
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return e.next
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}
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// Prev returns the entry that precedes e in the list.
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func (e *Entry) Prev() Linker {
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func (e *Entry) Prev() Element {
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return e.prev
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}
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// SetNext assigns 'entry' as the entry that follows e in the list.
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func (e *Entry) SetNext(entry Linker) {
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e.next = entry
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func (e *Entry) SetNext(elem Element) {
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e.next = elem
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}
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// SetPrev assigns 'entry' as the entry that precedes e in the list.
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func (e *Entry) SetPrev(entry Linker) {
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e.prev = entry
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func (e *Entry) SetPrev(elem Element) {
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e.prev = elem
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}
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@ -1,16 +1,29 @@
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package(licenses = ["notice"]) # Apache 2.0
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load("//tools/go_generics:defs.bzl", "go_template_instance")
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load("//tools/go_stateify:defs.bzl", "go_library", "go_test")
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go_template_instance(
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name = "weak_ref_list",
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out = "weak_ref_list.go",
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package = "refs",
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prefix = "weakRef",
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template = "//pkg/ilist:generic_list",
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types = {
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"Element": "*WeakRef",
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"Linker": "*WeakRef",
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},
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)
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go_library(
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name = "refs",
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srcs = [
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"refcounter.go",
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"refcounter_state.go",
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"weak_ref_list.go",
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],
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importpath = "gvisor.googlesource.com/gvisor/pkg/refs",
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visibility = ["//:sandbox"],
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deps = ["//pkg/ilist"],
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)
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go_test(
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@ -20,8 +20,6 @@ import (
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"reflect"
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"sync"
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"sync/atomic"
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"gvisor.googlesource.com/gvisor/pkg/ilist"
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)
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// RefCounter is the interface to be implemented by objects that are reference
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@ -61,7 +59,7 @@ type WeakRefUser interface {
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//
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// +stateify savable
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type WeakRef struct {
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ilist.Entry `state:"nosave"`
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weakRefEntry `state:"nosave"`
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// obj is an atomic value that points to the refCounter.
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obj atomic.Value `state:".(savedReference)"`
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@ -195,7 +193,7 @@ type AtomicRefCount struct {
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mu sync.Mutex `state:"nosave"`
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// weakRefs is our collection of weak references.
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weakRefs ilist.List `state:"nosave"`
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weakRefs weakRefList `state:"nosave"`
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}
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// ReadRefs returns the current number of references. The returned count is
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// return false due to the reference count check.
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r.mu.Lock()
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for !r.weakRefs.Empty() {
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w := r.weakRefs.Front().(*WeakRef)
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w := r.weakRefs.Front()
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// Capture the callback because w cannot be touched
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// after it's zapped -- the owner is free it reuse it
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// after that.
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@ -78,6 +78,7 @@ go_template_instance(
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template = "//pkg/ilist:generic_list",
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types = {
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"Linker": "*Dirent",
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"Element": "*Dirent",
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},
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)
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@ -10,6 +10,7 @@ go_template_instance(
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prefix = "pendingSignal",
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template = "//pkg/ilist:generic_list",
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types = {
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"Element": "*pendingSignal",
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"Linker": "*pendingSignal",
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},
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)
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@ -21,6 +22,7 @@ go_template_instance(
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prefix = "processGroup",
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template = "//pkg/ilist:generic_list",
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types = {
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"Element": "*ProcessGroup",
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"Linker": "*ProcessGroup",
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},
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)
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@ -43,6 +45,7 @@ go_template_instance(
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prefix = "session",
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template = "//pkg/ilist:generic_list",
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types = {
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"Element": "*Session",
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"Linker": "*Session",
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},
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)
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@ -54,6 +57,7 @@ go_template_instance(
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prefix = "task",
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template = "//pkg/ilist:generic_list",
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types = {
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"Element": "*Task",
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"Linker": "*Task",
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},
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)
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@ -10,6 +10,7 @@ go_template_instance(
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prefix = "waiter",
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template = "//pkg/ilist:generic_list",
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types = {
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"Element": "*Waiter",
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"Linker": "*Waiter",
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},
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)
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@ -10,6 +10,7 @@ go_template_instance(
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prefix = "waiter",
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template = "//pkg/ilist:generic_list",
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types = {
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"Element": "*waiter",
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"Linker": "*waiter",
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},
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)
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@ -67,6 +67,7 @@ go_template_instance(
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prefix = "io",
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template = "//pkg/ilist:generic_list",
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types = {
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"Element": "*ioResult",
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"Linker": "*ioResult",
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},
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)
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@ -10,6 +10,7 @@ go_template_instance(
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prefix = "reassembler",
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template = "//pkg/ilist:generic_list",
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types = {
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"Element": "*reassembler",
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"Linker": "*reassembler",
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},
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)
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@ -10,6 +10,7 @@ go_template_instance(
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prefix = "pingPacket",
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template = "//pkg/ilist:generic_list",
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types = {
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"Element": "*pingPacket",
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"Linker": "*pingPacket",
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},
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)
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@ -10,6 +10,7 @@ go_template_instance(
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prefix = "segment",
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template = "//pkg/ilist:generic_list",
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types = {
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"Element": "*segment",
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"Linker": "*segment",
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},
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)
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@ -10,6 +10,7 @@ go_template_instance(
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prefix = "udpPacket",
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template = "//pkg/ilist:generic_list",
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types = {
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"Element": "*udpPacket",
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"Linker": "*udpPacket",
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},
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)
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