package epoll // ElementMapper provides an identity mapping by default. // // This can be replaced to provide a struct that maps elements to linker // objects, if they are not the same. An ElementMapper is not typically // required if: Linker is left as is, Element is left as is, or Linker and // Element are the same type. type pollEntryElementMapper struct{} // linkerFor maps an Element to a Linker. // // This default implementation should be inlined. // //go:nosplit func (pollEntryElementMapper) linkerFor(elem *pollEntry) *pollEntry { return elem } // List is an intrusive list. Entries can be added to or removed from the list // in O(1) time and with no additional memory allocations. // // The zero value for List is an empty list ready to use. // // To iterate over a list (where l is a List): // for e := l.Front(); e != nil; e = e.Next() { // // do something with e. // } // // +stateify savable type pollEntryList struct { head *pollEntry tail *pollEntry } // Reset resets list l to the empty state. func (l *pollEntryList) Reset() { l.head = nil l.tail = nil } // Empty returns true iff the list is empty. func (l *pollEntryList) Empty() bool { return l.head == nil } // Front returns the first element of list l or nil. func (l *pollEntryList) Front() *pollEntry { return l.head } // Back returns the last element of list l or nil. func (l *pollEntryList) Back() *pollEntry { return l.tail } // PushFront inserts the element e at the front of list l. func (l *pollEntryList) PushFront(e *pollEntry) { linker := pollEntryElementMapper{}.linkerFor(e) linker.SetNext(l.head) linker.SetPrev(nil) if l.head != nil { pollEntryElementMapper{}.linkerFor(l.head).SetPrev(e) } else { l.tail = e } l.head = e } // PushBack inserts the element e at the back of list l. func (l *pollEntryList) PushBack(e *pollEntry) { linker := pollEntryElementMapper{}.linkerFor(e) linker.SetNext(nil) linker.SetPrev(l.tail) if l.tail != nil { pollEntryElementMapper{}.linkerFor(l.tail).SetNext(e) } else { l.head = e } l.tail = e } // PushBackList inserts list m at the end of list l, emptying m. func (l *pollEntryList) PushBackList(m *pollEntryList) { if l.head == nil { l.head = m.head l.tail = m.tail } else if m.head != nil { pollEntryElementMapper{}.linkerFor(l.tail).SetNext(m.head) pollEntryElementMapper{}.linkerFor(m.head).SetPrev(l.tail) l.tail = m.tail } m.head = nil m.tail = nil } // InsertAfter inserts e after b. func (l *pollEntryList) InsertAfter(b, e *pollEntry) { bLinker := pollEntryElementMapper{}.linkerFor(b) eLinker := pollEntryElementMapper{}.linkerFor(e) a := bLinker.Next() eLinker.SetNext(a) eLinker.SetPrev(b) bLinker.SetNext(e) if a != nil { pollEntryElementMapper{}.linkerFor(a).SetPrev(e) } else { l.tail = e } } // InsertBefore inserts e before a. func (l *pollEntryList) InsertBefore(a, e *pollEntry) { aLinker := pollEntryElementMapper{}.linkerFor(a) eLinker := pollEntryElementMapper{}.linkerFor(e) b := aLinker.Prev() eLinker.SetNext(a) eLinker.SetPrev(b) aLinker.SetPrev(e) if b != nil { pollEntryElementMapper{}.linkerFor(b).SetNext(e) } else { l.head = e } } // Remove removes e from l. func (l *pollEntryList) Remove(e *pollEntry) { prev := pollEntryElementMapper{}.linkerFor(e).Prev() next := pollEntryElementMapper{}.linkerFor(e).Next() if prev != nil { pollEntryElementMapper{}.linkerFor(prev).SetNext(next) } else { l.head = next } if next != nil { pollEntryElementMapper{}.linkerFor(next).SetPrev(prev) } else { l.tail = prev } } // Entry is a default implementation of Linker. Users can add anonymous fields // of this type to their structs to make them automatically implement the // methods needed by List. // // +stateify savable type pollEntryEntry struct { next *pollEntry prev *pollEntry } // Next returns the entry that follows e in the list. func (e *pollEntryEntry) Next() *pollEntry { return e.next } // Prev returns the entry that precedes e in the list. func (e *pollEntryEntry) Prev() *pollEntry { return e.prev } // SetNext assigns 'entry' as the entry that follows e in the list. func (e *pollEntryEntry) SetNext(elem *pollEntry) { e.next = elem } // SetPrev assigns 'entry' as the entry that precedes e in the list. func (e *pollEntryEntry) SetPrev(elem *pollEntry) { e.prev = elem }