Commit f195ad99 authored by Kirill Smelkov's avatar Kirill Smelkov

X xcontainer moved -> go123

parent 348ac802
// Copyright (C) 2017 Nexedi SA and Contributors.
// Kirill Smelkov <kirr@nexedi.com>
//
// This program is free software: you can Use, Study, Modify and Redistribute
// it under the terms of the GNU General Public License version 3, or (at your
// option) any later version, as published by the Free Software Foundation.
//
// You can also Link and Combine this program with other software covered by
// the terms of any of the Free Software licenses or any of the Open Source
// Initiative approved licenses and Convey the resulting work. Corresponding
// source of such a combination shall include the source code for all other
// software used.
//
// This program is distributed WITHOUT ANY WARRANTY; without even the implied
// warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
//
// See COPYING file for full licensing terms.
// See https://www.nexedi.com/licensing for rationale and options.
// Package list provides intrusive double-linked lists.
//
// Go standard library has container/list package which already provides
// double-linked lists. However in that implementation list itself is kept
// separate from data structures representing elements. This package provides
// alternative approach where elements embed necessary list heads which is
// sometimes more convenient, for example when one wants to move a list
// element in O(1) starting from pointer to just its data.
//
// TODO doc how to get to container of list head via unsafe.OffsetOf.
package list
// Head is a list head entry for an element in an intrusive doubly-linked list.
//
// Zero HEAD value is NOT valid - always call Init() to initialize a head
// before using it.
type Head struct {
next, prev *Head
}
func (h *Head) Next() *Head { return h.next }
func (h *Head) Prev() *Head { return h.prev }
// Init initializes a head making it point to itself via .next and .prev
func (h *Head) Init() {
h.next = h
h.prev = h
}
// Delete deletes h from its list
func (h *Head) Delete() {
h.next.prev = h.prev
h.prev.next = h.next
h.Init()
}
// MoveBefore moves a to be before b
// XXX ok to move if a was not previously on the list?
func (a *Head) MoveBefore(b *Head) {
a.Delete()
a.next = b
a.prev = b.prev
b.prev = a
a.prev.next = a
}
...@@ -28,8 +28,7 @@ import ( ...@@ -28,8 +28,7 @@ import (
"unsafe" "unsafe"
"lab.nexedi.com/kirr/go123/mem" "lab.nexedi.com/kirr/go123/mem"
"lab.nexedi.com/kirr/go123/xcontainer/list"
"lab.nexedi.com/kirr/neo/go/xcommon/xcontainer/list"
) )
// XXX managing LRU under 1 big gcMu might be bad for scalability. // XXX managing LRU under 1 big gcMu might be bad for scalability.
......
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