package filesys import ( "bytes" "io" "math" ) type IntervalNode struct { Data []byte Offset int64 Size int64 Next *IntervalNode } type IntervalLinkedList struct { Head *IntervalNode Tail *IntervalNode } type ContinuousIntervals struct { lists []*IntervalLinkedList } func (list *IntervalLinkedList) Offset() int64 { return list.Head.Offset } func (list *IntervalLinkedList) Size() int64 { return list.Tail.Offset + list.Tail.Size - list.Head.Offset } func (list *IntervalLinkedList) addNodeToTail(node *IntervalNode) { // glog.V(4).Infof("add to tail [%d,%d) + [%d,%d) => [%d,%d)", list.Head.Offset, list.Tail.Offset+list.Tail.Size, node.Offset, node.Offset+node.Size, list.Head.Offset, node.Offset+node.Size) list.Tail.Next = node list.Tail = node } func (list *IntervalLinkedList) addNodeToHead(node *IntervalNode) { // glog.V(4).Infof("add to head [%d,%d) + [%d,%d) => [%d,%d)", node.Offset, node.Offset+node.Size, list.Head.Offset, list.Tail.Offset+list.Tail.Size, node.Offset, list.Tail.Offset+list.Tail.Size) node.Next = list.Head list.Head = node } func (list *IntervalLinkedList) ReadData(buf []byte, start, stop int64) { t := list.Head for { nodeStart, nodeStop := max(start, t.Offset), min(stop, t.Offset+t.Size) if nodeStart < nodeStop { // glog.V(0).Infof("copying start=%d stop=%d t=[%d,%d) t.data=%d => bufSize=%d nodeStart=%d, nodeStop=%d", start, stop, t.Offset, t.Offset+t.Size, len(t.Data), len(buf), nodeStart, nodeStop) copy(buf[nodeStart-start:], t.Data[nodeStart-t.Offset:nodeStop-t.Offset]) } if t.Next == nil { break } t = t.Next } } func (c *ContinuousIntervals) TotalSize() (total int64) { for _, list := range c.lists { total += list.Size() } return } func subList(list *IntervalLinkedList, start, stop int64) *IntervalLinkedList { var nodes []*IntervalNode for t := list.Head; t != nil; t = t.Next { nodeStart, nodeStop := max(start, t.Offset), min(stop, t.Offset+t.Size) if nodeStart >= nodeStop { // skip non overlapping IntervalNode continue } nodes = append(nodes, &IntervalNode{ Data: t.Data[nodeStart-t.Offset : nodeStop-t.Offset], Offset: nodeStart, Size: nodeStop - nodeStart, Next: nil, }) } for i := 1; i < len(nodes); i++ { nodes[i-1].Next = nodes[i] } return &IntervalLinkedList{ Head: nodes[0], Tail: nodes[len(nodes)-1], } } func (c *ContinuousIntervals) AddInterval(data []byte, offset int64) { interval := &IntervalNode{Data: data, Offset: offset, Size: int64(len(data))} var newLists []*IntervalLinkedList for _, list := range c.lists { // if list is to the left of new interval, add to the new list if list.Tail.Offset+list.Tail.Size <= interval.Offset { newLists = append(newLists, list) } // if list is to the right of new interval, add to the new list if interval.Offset+interval.Size <= list.Head.Offset { newLists = append(newLists, list) } // if new interval overwrite the right part of the list if list.Head.Offset < interval.Offset && interval.Offset < list.Tail.Offset+list.Tail.Size { // create a new list of the left part of existing list newLists = append(newLists, subList(list, list.Offset(), interval.Offset)) } // if new interval overwrite the left part of the list if list.Head.Offset < interval.Offset+interval.Size && interval.Offset+interval.Size < list.Tail.Offset+list.Tail.Size { // create a new list of the right part of existing list newLists = append(newLists, subList(list, interval.Offset+interval.Size, list.Tail.Offset+list.Tail.Size)) } // skip anything that is fully overwritten by the new interval } c.lists = newLists // add the new interval to the lists, connecting neighbor lists var prevList, nextList *IntervalLinkedList for _, list := range c.lists { if list.Head.Offset == interval.Offset+interval.Size { nextList = list break } } for _, list := range c.lists { if list.Head.Offset+list.Size() == offset { list.addNodeToTail(interval) prevList = list break } } if prevList != nil && nextList != nil { // glog.V(4).Infof("connecting [%d,%d) + [%d,%d) => [%d,%d)", prevList.Head.Offset, prevList.Tail.Offset+prevList.Tail.Size, nextList.Head.Offset, nextList.Tail.Offset+nextList.Tail.Size, prevList.Head.Offset, nextList.Tail.Offset+nextList.Tail.Size) prevList.Tail.Next = nextList.Head prevList.Tail = nextList.Tail c.removeList(nextList) } else if nextList != nil { // add to head was not done when checking nextList.addNodeToHead(interval) } if prevList == nil && nextList == nil { c.lists = append(c.lists, &IntervalLinkedList{ Head: interval, Tail: interval, }) } return } func (c *ContinuousIntervals) RemoveLargestIntervalLinkedList() *IntervalLinkedList { var maxSize int64 maxIndex := -1 for k, list := range c.lists { if maxSize <= list.Size() { maxSize = list.Size() maxIndex = k } } if maxSize <= 0 { return nil } t := c.lists[maxIndex] c.lists = append(c.lists[0:maxIndex], c.lists[maxIndex+1:]...) return t } func (c *ContinuousIntervals) removeList(target *IntervalLinkedList) { index := -1 for k, list := range c.lists { if list.Offset() == target.Offset() { index = k } } if index < 0 { return } c.lists = append(c.lists[0:index], c.lists[index+1:]...) } func (c *ContinuousIntervals) ReadData(data []byte, startOffset int64) (offset int64, size int) { var minOffset int64 = math.MaxInt64 var maxStop int64 for _, list := range c.lists { start := max(startOffset, list.Offset()) stop := min(startOffset+int64(len(data)), list.Offset()+list.Size()) if start <= stop { list.ReadData(data[start-startOffset:], start, stop) minOffset = min(minOffset, start) maxStop = max(maxStop, stop) } } if minOffset == math.MaxInt64 { return 0, 0 } offset = minOffset size = int(maxStop - offset) return } func (l *IntervalLinkedList) ToReader() io.Reader { var readers []io.Reader t := l.Head readers = append(readers, bytes.NewReader(t.Data)) for t.Next != nil { t = t.Next readers = append(readers, bytes.NewReader(t.Data)) } return io.MultiReader(readers...) }