.

go/zodb/db.go

@@ -113,7 +113,8 @@ type DB struct {
 	// waiters for δtail.Head to become ≥ their at.
 	hwait map[hwaiter]struct{} // set{(at, ready)}
 
-	// XXX δtail/hwait -> Storage. XXX or -> Cache? (so it is not duplicated many times for many DB case)
+	// XXX δtail/hwait -> Storage or -> Cache?
+	// (so it is not duplicated many times for many DB case)
 }
 
 
@@ -427,6 +428,7 @@ func (db *DB) open(at Tid, noPool bool) *Connection {
 	}
 
 	// at ∈ (δtail, δhead]	; try to get nearby idle connection or make a new one
+	//conn = db.get(δtail.Tail()+1, at)
 	conn = db.get(δtail.Tail(), at)
 	if conn == nil {
 		conn = newConnection(db, at)
@@ -570,7 +572,7 @@ func (conn *Connection) resync1(at Tid) {
 
 // get returns connection from db pool most close to at with conn.at ∈ [atMin, at].
 //
-// XXX recheck [atMin    or   (atMin	-- see "= δtail.Tail" in resync.
+// Note: contraty to e.g. δtail.Tail, atMin is inclusive.
 //
 // If there is no such connection in the pool - nil is returned.
 // Must be called with db.mu locked.
@@ -651,7 +653,7 @@ func (db *DB) put(conn *Connection) {
 	copy(db.pool[i+1:], db.pool[i:])
 	db.pool[i] = conn
 
-	// XXX GC too idle connections here? XXX
+	// XXX GC too idle connections here
 }
 
 // ---- txn sync ----

go/zodb/δtail.go

@@ -59,7 +59,7 @@ import (
 type ΔTail struct {
 	head  Tid
 	tail  Tid
-	tailv []ΔRevEntry	// XXX -> revv ?
+	tailv []ΔRevEntry	// XXX -> revv ? δv? δvec? changev ?
 
 	lastRevOf map[Oid]Tid // index for LastRevOf queries
 	// XXX -> lastRevOf = {} oid -> []rev↑ if linear scan in LastRevOf starts to eat cpu
@@ -98,6 +98,8 @@ func (δtail *ΔTail) Head() Tid {
 
 // Tail returns oldest database state for which δtail has history coverage.
 //
+// XXX not inclusive?
+//
 // Tail is ↑= on Forget, even if δtail becomes empty.
 func (δtail *ΔTail) Tail() Tid {
 	return δtail.tail