From 470b47f70a7d16b515866249b1177241c5e26127 Mon Sep 17 00:00:00 2001
From: "Sascha L. Teichmann" <sascha.teichmann@intevation.de>
Date: Tue, 21 Jul 2015 12:53:55 +0200
Subject: [PATCH] Fixed endless loop in Z order range query code in SQLite3
 backend.

---
 cmd/mtredisalize/sqlite.go | 69 +++++++++++++++++++-------------------
 1 file changed, 35 insertions(+), 34 deletions(-)

diff --git a/cmd/mtredisalize/sqlite.go b/cmd/mtredisalize/sqlite.go
index 8fd0d53..1e7ea63 100644
--- a/cmd/mtredisalize/sqlite.go
+++ b/cmd/mtredisalize/sqlite.go
@@ -327,49 +327,50 @@ func (ss *SqliteSession) interleavedSpatialQuery(first, second []byte, done chan
 		zmin, zmax = order(zmin, zmax)
 		cub := common.Cuboid{P1: c1, P2: c2}
 		rangeStmt := ss.txStmt(ss.backend.rangeStmt)
-	OUTER:
-		for {
-			var (
-				err  error
-				rows *sql.Rows
-			)
-			if rows, err = rangeStmt.Query(zmin, zmax); err != nil {
-				log.Printf("Error in range query: %s\n", err)
+		var (
+			err  error
+			rows *sql.Rows
+		)
+	loop:
+		// log.Printf("query %d %d\n", zmin, zmax)
+		if rows, err = rangeStmt.Query(zmin, zmax); err != nil {
+			log.Printf("Error in range query: %s\n", err)
+			return
+		}
+		for rows.Next() {
+			var zcode int64
+			var data []byte
+			if err = rows.Scan(&zcode, &data); err != nil {
+				log.Printf("Error in scanning row: %s\n", err)
+				rows.Close()
 				return
 			}
-			for rows.Next() {
-				var zcode int64
-				var data []byte
-				if err = rows.Scan(&zcode, &data); err != nil {
-					log.Printf("Error in scanning row: %s\n", err)
+			// log.Printf("zcode: %d\n", zcode)
+			c := common.InterleavedToCoord(zcode)
+			if cub.Contains(c) {
+				var encodedKey []byte
+				if encodedKey, err = common.EncodeStringToBytes(common.CoordToPlain(c)); err != nil {
+					log.Printf("Key encoding failed: %s\n", err)
 					rows.Close()
 					return
 				}
-				c := common.InterleavedToCoord(zcode)
-				if cub.Contains(c) {
-					var encodedKey []byte
-					if encodedKey, err = common.EncodeStringToBytes(common.CoordToPlain(c)); err != nil {
-						log.Printf("Key encoding failed: %s\n", err)
-						rows.Close()
-						return
-					}
-					select {
-					case blocks <- Block{Key: encodedKey, Data: data}:
-					case <-done:
-						rows.Close()
-						return
-					}
-				} else { // Left the cuboid
+				select {
+				case blocks <- Block{Key: encodedKey, Data: data}:
+				case <-done:
 					rows.Close()
-					zmin = common.BigMin(zmin, zmax, zcode)
-					continue OUTER
+					return
 				}
+			} else { // Left the cuboid
+				// log.Printf("Left cuboid %d\n", zcode)
+				rows.Close()
+				zmin = common.BigMin(zmin, zmax, zcode)
+				goto loop
 			}
-			if err = rows.Err(); err != nil {
-				log.Printf("Error in range query: %s\n", err)
-			}
-			rows.Close()
 		}
+		if err = rows.Err(); err != nil {
+			log.Printf("Error in range query: %s\n", err)
+		}
+		rows.Close()
 	}()
 
 	return