.

wcfs/δbtail.go

@@ -77,6 +77,7 @@ import (
 	"fmt"
 	"math"
 	"reflect"
+	"sort"
 
 	"lab.nexedi.com/kirr/go123/xerr"
 	"lab.nexedi.com/kirr/neo/go/transaction"
@@ -496,6 +497,38 @@ func (δBtail *ΔBtail) δZConnectTracked(δZv *zodb.EventCommit) (δZTC SetOid,
 	return δZTC, δtopsByRoot
 }
 
+
+// XXX place
+// nodeInRange represents a Node coming under [lo, hi_] key range in its tree.
+type nodeInRange struct {
+	lo, hi_  Key  // [lo, hi_]	NOTE _not_ hi) not to overflow at ∞
+	node     Node
+}
+
+// rangeCover represents set of nodes covering a range.
+// nodes come with key↑ and not intersection [lo,hi)
+type rangeCover []*nodeInRange // key↑
+
+// Get returns node covering key k.
+// Get panics if k is outside covered range.
+func (rc rangeCover) Get(k Key) *nodeInRange {
+	i := sort.Search(len(rc), func(i int) bool {
+		return k <= rc[i].hi_
+	})
+	if i == len(rc) {
+		panicf("key %v not covered", k) // XXX + coverage: ...
+	}
+
+	rn := rc[i]
+	if !(rn.lo <= k && k <= rn.hi_) {
+		panicf("BUG: get(%v) -> [%v, %v]", k, rn.lo, rn.hi_)
+	}
+
+	return rn
+}
+
+
+
 // treediff computes δT for tree specified by root in between old..new.
 //
 // δtops is set of top nodes for changed subtrees.