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Fix subtractAll bugs. 

The logic of range subtraction [a,b)-[c,d) can be viewed as intersection
of [a,b) with (-inf, c) and [d, +inf), respectively. This makes the
logic simpler, that we no longer need to check 5 different cases.

It also fixes bugs that returns incorrect range.

Closes #763
Signed-off-by: Kan Li <likan@google.com>
This commit is contained in:
Kan Li 2020-11-01 09:57:55 -08:00 committed by Kan Li
parent 4188292d57
commit d27c88d3ef
2 changed files with 52 additions and 75 deletions
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121
userns.go
View File

@ -221,94 +221,71 @@ outer:
return size, nil
}
func minInt(a, b int) int {
if a < b {
return a
}
return b
}
func maxInt(a, b int) int {
if a < b {
return b
}
return a
}
// subtractHostIDs return the subtraction of the range USED from AVAIL. The range is specified
// by [HostID, HostID+Size).
// ContainerID is ignored.
func subtractHostIDs(avail idtools.IDMap, used idtools.IDMap) []idtools.IDMap {
switch {
case used.HostID <= avail.HostID && used.HostID+used.Size >= avail.HostID+avail.Size:
return nil
case used.HostID <= avail.HostID && used.HostID+used.Size > avail.HostID && used.HostID+used.Size < avail.HostID+avail.Size:
newContainerID := avail.ContainerID + used.Size
newHostID := used.HostID + used.Size
r := idtools.IDMap{
ContainerID: newContainerID,
HostID: newHostID,
Size: avail.Size + avail.HostID - newHostID,
}
return []idtools.IDMap{r}
case used.HostID > avail.HostID && used.HostID < avail.HostID+avail.Size && used.HostID+used.Size >= avail.HostID+avail.Size:
r := idtools.IDMap{
var out []idtools.IDMap
availEnd := avail.HostID + avail.Size
usedEnd := used.HostID + used.Size
// Intersection of [avail.HostID, availEnd) and (-inf, used.HostID) is [avail.HostID, newEnd).
if newEnd := minInt(availEnd, used.HostID); newEnd > avail.HostID {
out = append(out, idtools.IDMap{
ContainerID: avail.ContainerID,
HostID: avail.HostID,
Size: used.HostID - avail.HostID,
}
return []idtools.IDMap{r}
case used.HostID > avail.HostID && used.HostID < avail.HostID+avail.Size && used.HostID+used.Size < avail.HostID+avail.Size:
r1 := idtools.IDMap{
ContainerID: avail.ContainerID,
HostID: avail.HostID,
Size: used.HostID - avail.HostID,
}
r2 := idtools.IDMap{
ContainerID: used.ContainerID + used.Size,
HostID: avail.HostID + (used.HostID - avail.HostID),
Size: avail.HostID + avail.Size - used.HostID - used.Size,
}
return []idtools.IDMap{r1, r2}
default:
r := idtools.IDMap{
ContainerID: 0,
HostID: avail.HostID,
Size: avail.Size,
}
return []idtools.IDMap{r}
Size: newEnd - avail.HostID,
})
}
// Intersection of [avail.HostID, availEnd) and [usedEnd, +inf) is [newStart, availEnd).
if newStart := maxInt(avail.HostID, usedEnd); newStart < availEnd {
out = append(out, idtools.IDMap{
ContainerID: newStart + avail.ContainerID - avail.HostID,
HostID: newStart,
Size: availEnd - newStart,
})
}
return out
}
// subtractContainerIDs return the subtraction of the range USED from AVAIL. The range is specified
// by [ContainerID, ContainerID+Size).
// HostID is ignored.
func subtractContainerIDs(avail idtools.IDMap, used idtools.IDMap) []idtools.IDMap {
switch {
case used.ContainerID <= avail.ContainerID && used.ContainerID+used.Size >= avail.ContainerID+avail.Size:
return nil
case used.ContainerID <= avail.ContainerID && used.ContainerID+used.Size > avail.ContainerID && used.ContainerID+used.Size < avail.ContainerID+avail.Size:
newContainerID := used.ContainerID + used.Size
newHostID := avail.HostID + used.Size
r := idtools.IDMap{
ContainerID: newContainerID,
HostID: newHostID,
Size: avail.Size + avail.ContainerID - newContainerID,
}
return []idtools.IDMap{r}
case used.ContainerID > avail.ContainerID && used.ContainerID < avail.ContainerID+avail.Size && used.ContainerID+used.Size >= avail.ContainerID+avail.Size:
r := idtools.IDMap{
var out []idtools.IDMap
availEnd := avail.ContainerID + avail.Size
usedEnd := used.ContainerID + used.Size
// Intersection of [avail.ContainerID, availEnd) and (-inf, used.ContainerID) is
// [avail.ContainerID, newEnd).
if newEnd := minInt(availEnd, used.ContainerID); newEnd > avail.ContainerID {
out = append(out, idtools.IDMap{
ContainerID: avail.ContainerID,
HostID: avail.HostID,
Size: used.ContainerID - avail.ContainerID,
}
return []idtools.IDMap{r}
case used.ContainerID > avail.ContainerID && used.ContainerID < avail.ContainerID+avail.Size && used.ContainerID+used.Size < avail.ContainerID+avail.Size:
r1 := idtools.IDMap{
ContainerID: avail.ContainerID,
HostID: avail.HostID,
Size: used.ContainerID - avail.ContainerID,
}
r2 := idtools.IDMap{
ContainerID: used.ContainerID + used.Size,
HostID: avail.HostID + (used.ContainerID - avail.ContainerID),
Size: avail.ContainerID + avail.Size - used.ContainerID - used.Size,
}
return []idtools.IDMap{r1, r2}
default:
r := idtools.IDMap{
ContainerID: avail.ContainerID,
HostID: avail.HostID,
Size: avail.Size,
}
return []idtools.IDMap{r}
Size: newEnd - avail.ContainerID,
})
}
// Intersection of [avail.ContainerID, availEnd) and [usedEnd, +inf) is [newStart, availEnd).
if newStart := maxInt(avail.ContainerID, usedEnd); newStart < availEnd {
out = append(out, idtools.IDMap{
ContainerID: newStart,
HostID: newStart + avail.HostID - avail.ContainerID,
Size: availEnd - newStart,
})
}
return out
}
// subtractAll subtracts all usedIDs from the available IDs.

6
userns_test.go
View File

@ -72,7 +72,7 @@ func TestSubtractHostID(t *testing.T) {
assert.Equal(t, len(ret), 2)
assert.Equal(t, ret[0].HostID, avail.HostID)
assert.Equal(t, ret[0].Size, 32768)
assert.Equal(t, ret[1].HostID, avail.HostID+32768)
assert.Equal(t, ret[1].HostID, avail.HostID+32768+4096)
assert.Equal(t, ret[1].Size, 32768-4096)
used = idtools.IDMap{
@ -211,7 +211,7 @@ func TestSubtractContainerID(t *testing.T) {
assert.Equal(t, ret[0].HostID, 1000)
assert.Equal(t, ret[0].Size, 10)
assert.Equal(t, ret[1].ContainerID, 11)
assert.Equal(t, ret[1].HostID, 1010)
assert.Equal(t, ret[1].HostID, 1011)
assert.Equal(t, ret[1].Size, 65525)
}
@ -268,5 +268,5 @@ func TestFindAvailableIDRange(t *testing.T) {
assert.Nil(t, err)
assert.Equal(t, len(ret), 2)
assert.Equal(t, ret[0].HostID, 100000)
assert.Equal(t, ret[1].HostID, 100010)
assert.Equal(t, ret[1].HostID, 100020)
}