1 files changed, 206 insertions, 0 deletions
diff --git a/swarm/network/stream/intervals/intervals.go b/swarm/network/stream/intervals/intervals.go
new file mode 100644
index 000000000..5fd820da8
--- /dev/null
+++ b/swarm/network/stream/intervals/intervals.go
@@ -0,0 +1,206 @@
+// Copyright 2018 The go-ethereum Authors
+// This file is part of the go-ethereum library.
+//
+// The go-ethereum library is free software: you can redistribute it and/or modify
+// it under the terms of the GNU Lesser General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// The go-ethereum library is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+// GNU Lesser General Public License for more details.
+//
+// You should have received a copy of the GNU Lesser General Public License
+// along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.
+
+package intervals
+
+import (
+	"bytes"
+	"fmt"
+	"strconv"
+	"sync"
+)
+
+// Intervals store a list of intervals. Its purpose is to provide
+// methods to add new intervals and retrieve missing intervals that
+// need to be added.
+// It may be used in synchronization of streaming data to persist
+// retrieved data ranges between sessions.
+type Intervals struct {
+	start  uint64
+	ranges [][2]uint64
+	mu     sync.RWMutex
+}
+
+// New creates a new instance of Intervals.
+// Start argument limits the lower bound of intervals.
+// No range bellow start bound will be added by Add method or
+// returned by Next method. This limit may be used for
+// tracking "live" synchronization, where the sync session
+// starts from a specific value, and if "live" sync intervals
+// need to be merged with historical ones, it can be safely done.
+func NewIntervals(start uint64) *Intervals {
+	return &Intervals{
+		start: start,
+	}
+}
+
+// Add adds a new range to intervals. Range start and end are values
+// are both inclusive.
+func (i *Intervals) Add(start, end uint64) {
+	i.mu.Lock()
+	defer i.mu.Unlock()
+
+	i.add(start, end)
+}
+
+func (i *Intervals) add(start, end uint64) {
+	if start < i.start {
+		start = i.start
+	}
+	if end < i.start {
+		return
+	}
+	minStartJ := -1
+	maxEndJ := -1
+	j := 0
+	for ; j < len(i.ranges); j++ {
+		if minStartJ < 0 {
+			if (start <= i.ranges[j][0] && end+1 >= i.ranges[j][0]) || (start <= i.ranges[j][1]+1 && end+1 >= i.ranges[j][1]) {
+				if i.ranges[j][0] < start {
+					start = i.ranges[j][0]
+				}
+				minStartJ = j
+			}
+		}
+		if (start <= i.ranges[j][1] && end+1 >= i.ranges[j][1]) || (start <= i.ranges[j][0] && end+1 >= i.ranges[j][0]) {
+			if i.ranges[j][1] > end {
+				end = i.ranges[j][1]
+			}
+			maxEndJ = j
+		}
+		if end+1 <= i.ranges[j][0] {
+			break
+		}
+	}
+	if minStartJ < 0 && maxEndJ < 0 {
+		i.ranges = append(i.ranges[:j], append([][2]uint64{{start, end}}, i.ranges[j:]...)...)
+		return
+	}
+	if minStartJ >= 0 {
+		i.ranges[minStartJ][0] = start
+	}
+	if maxEndJ >= 0 {
+		i.ranges[maxEndJ][1] = end
+	}
+	if minStartJ >= 0 && maxEndJ >= 0 && minStartJ != maxEndJ {
+		i.ranges[maxEndJ][0] = start
+		i.ranges = append(i.ranges[:minStartJ], i.ranges[maxEndJ:]...)
+	}
+}
+
+// Merge adds all the intervals from the the m Interval to current one.
+func (i *Intervals) Merge(m *Intervals) {
+	m.mu.RLock()
+	defer m.mu.RUnlock()
+	i.mu.Lock()
+	defer i.mu.Unlock()
+
+	for _, r := range m.ranges {
+		i.add(r[0], r[1])
+	}
+}
+
+// Next returns the first range interval that is not fulfilled. Returned
+// start and end values are both inclusive, meaning that the whole range
+// including start and end need to be added in order to full the gap
+// in intervals.
+// Returned value for end is 0 if the next interval is after the whole
+// range that is stored in Intervals. Zero end value represents no limit
+// on the next interval length.
+func (i *Intervals) Next() (start, end uint64) {
+	i.mu.RLock()
+	defer i.mu.RUnlock()
+
+	l := len(i.ranges)
+	if l == 0 {
+		return i.start, 0
+	}
+	if i.ranges[0][0] != i.start {
+		return i.start, i.ranges[0][0] - 1
+	}
+	if l == 1 {
+		return i.ranges[0][1] + 1, 0
+	}
+	return i.ranges[0][1] + 1, i.ranges[1][0] - 1
+}
+
+// Last returns the value that is at the end of the last interval.
+func (i *Intervals) Last() (end uint64) {
+	i.mu.RLock()
+	defer i.mu.RUnlock()
+
+	l := len(i.ranges)
+	if l == 0 {
+		return 0
+	}
+	return i.ranges[l-1][1]
+}
+
+// String returns a descriptive representation of range intervals
+// in [] notation, as a list of two element vectors.
+func (i *Intervals) String() string {
+	return fmt.Sprint(i.ranges)
+}
+
+// MarshalBinary encodes Intervals parameters into a semicolon separated list.
+// The first element in the list is base36-encoded start value. The following
+// elements are two base36-encoded value ranges separated by comma.
+func (i *Intervals) MarshalBinary() (data []byte, err error) {
+	d := make([][]byte, len(i.ranges)+1)
+	d[0] = []byte(strconv.FormatUint(i.start, 36))
+	for j := range i.ranges {
+		r := i.ranges[j]
+		d[j+1] = []byte(strconv.FormatUint(r[0], 36) + "," + strconv.FormatUint(r[1], 36))
+	}
+	return bytes.Join(d, []byte(";")), nil
+}
+
+// UnmarshalBinary decodes data according to the Intervals.MarshalBinary format.
+func (i *Intervals) UnmarshalBinary(data []byte) (err error) {
+	d := bytes.Split(data, []byte(";"))
+	l := len(d)
+	if l == 0 {
+		return nil
+	}
+	if l >= 1 {
+		i.start, err = strconv.ParseUint(string(d[0]), 36, 64)
+		if err != nil {
+			return err
+		}
+	}
+	if l == 1 {
+		return nil
+	}
+
+	i.ranges = make([][2]uint64, 0, l-1)
+	for j := 1; j < l; j++ {
+		r := bytes.SplitN(d[j], []byte(","), 2)
+		if len(r) < 2 {
+			return fmt.Errorf("range %d has less then 2 elements", j)
+		}
+		start, err := strconv.ParseUint(string(r[0]), 36, 64)
+		if err != nil {
+			return fmt.Errorf("parsing the first element in range %d: %v", j, err)
+		}
+		end, err := strconv.ParseUint(string(r[1]), 36, 64)
+		if err != nil {
+			return fmt.Errorf("parsing the second element in range %d: %v", j, err)
+		}
+		i.ranges = append(i.ranges, [2]uint64{start, end})
+	}
+
+	return nil
+}