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|
package updates
import (
"fmt"
"reflect"
"github.com/ovn-kubernetes/libovsdb/ovsdb"
)
func merge(ts *ovsdb.TableSchema, a, b modelUpdate) (modelUpdate, error) {
// handle model update
switch {
case b.old == nil && b.new == nil:
// noop
case a.old == nil && a.new == nil:
// first op
a.old = b.old
a.new = b.new
case a.new != nil && b.old != nil && b.new != nil:
// update after an insert or an update
a.new = b.new
case b.old != nil && b.new == nil:
// a final delete
a.new = nil
default:
return modelUpdate{}, fmt.Errorf("sequence of updates not supported")
}
// handle row update
ru2, err := mergeRowUpdate(ts, a.rowUpdate2, b.rowUpdate2)
if err != nil {
return modelUpdate{}, err
}
if ru2 == nil {
return modelUpdate{}, nil
}
a.rowUpdate2 = ru2
return a, nil
}
func mergeRowUpdate(ts *ovsdb.TableSchema, a, b *rowUpdate2) (*rowUpdate2, error) {
switch {
case b == nil:
// noop
case a == nil:
// first op
a = b
case a.Insert != nil && b.Modify != nil:
// update after an insert
a.New = b.New
a.Insert = b.New
case a.Modify != nil && b.Modify != nil:
// update after update
a.New = b.New
a.Modify = mergeModifyRow(ts, a.Old, a.Modify, b.Modify)
if a.Modify == nil {
// we merged two modifications that brought back the row to its
// original value which is a no op
a = nil
}
case a.Insert != nil && b.Delete != nil:
// delete after insert
a = nil
case b.Delete != nil:
// a final delete
a.Initial = nil
a.Insert = nil
a.Modify = nil
a.New = nil
a.Delete = b.Delete
default:
return &rowUpdate2{}, fmt.Errorf("sequence of updates not supported")
}
return a, nil
}
// mergeModifyRow merges two modification rows 'a' and 'b' with respect an
// original row 'o'. Two modifications that restore the original value cancel
// each other and won't be included in the result. Returns nil if there are no
// resulting modifications.
func mergeModifyRow(ts *ovsdb.TableSchema, o, a, b *ovsdb.Row) *ovsdb.Row {
original := *o
aMod := *a
bMod := *b
for k, v := range bMod {
if _, ok := aMod[k]; !ok {
aMod[k] = v
continue
}
var result any
var changed bool
// handle maps or sets first
switch v.(type) {
// difference only supports set or map values that are comparable with
// no pointers. This should be currently fine because the set or map
// values should only be non pointer atomic types or the UUID struct.
case ovsdb.OvsSet:
aSet := aMod[k].(ovsdb.OvsSet)
bSet := v.(ovsdb.OvsSet)
// handle sets of multiple values, single value sets are handled as
// atomic values
if ts.Column(k).TypeObj.Max() != 1 {
// set difference is a fully transitive operation so we dont
// need to do anything special to merge two differences
result, changed = setDifference(aSet.GoSet, bSet.GoSet)
result = ovsdb.OvsSet{GoSet: result.([]any)}
}
case ovsdb.OvsMap:
aMap := aMod[k].(ovsdb.OvsMap)
bMap := v.(ovsdb.OvsMap)
var originalMap ovsdb.OvsMap
if v, ok := original[k]; ok {
originalMap = v.(ovsdb.OvsMap)
}
// map difference is not transitive with respect to the original
// value so we have to take the original value into account when
// merging
result, changed = mergeMapDifference(originalMap.GoMap, aMap.GoMap, bMap.GoMap)
result = ovsdb.OvsMap{GoMap: result.(map[any]any)}
}
// was neither a map nor a set
if result == nil {
// atomic difference is not transitive with respect to the original
// value so we have to take the original value into account when
// merging
o := original[k]
if o == nil {
// assume zero value if original does not have the column
o = reflect.Zero(reflect.TypeOf(v)).Interface()
}
if set, ok := o.(ovsdb.OvsSet); ok {
// atomic optional values are cleared out with an empty set
// if the original value was also cleared out, use an empty set
// instead of a nil set so that mergeAtomicDifference notices
// that we are returning to the original value
if set.GoSet == nil {
set.GoSet = []any{}
}
o = set
}
result, changed = mergeAtomicDifference(o, aMod[k], v)
}
if !changed {
delete(aMod, k)
continue
}
aMod[k] = result
}
if len(aMod) == 0 {
return nil
}
return a
}
|
