From bebe776e54d8bdf55c61ed12bb519583efe03551 Mon Sep 17 00:00:00 2001
From: "Sascha L. Teichmann" <sascha.teichmann@intevation.de>
Date: Mon, 1 Sep 2014 16:12:24 +0200
Subject: [PATCH] Added plain spatial query for LevelDB backend.

---
 leveldb.go | 80 +++++++++++++++++++++++++++++++++++++++++++++++++++++-
 misc.go    | 12 ++++++++
 sqlite.go  |  7 -----
 3 files changed, 91 insertions(+), 8 deletions(-)
 create mode 100644 misc.go

diff --git a/leveldb.go b/leveldb.go
index 7143386..e997bce 100644
--- a/leveldb.go
+++ b/leveldb.go
@@ -223,7 +223,85 @@ func (ldbs *LevelDBSession) AllKeys(hash []byte, done chan struct{}) (keys chan
 	return
 }
 
-func (ldbs *LevelDBSession) SpatialQuery(hash, first, second []byte, done chan struct{}) (blocks chan Block, err error) {
+func (ldbs *LevelDBSession) SpatialQuery(hash, first, second []byte, done chan struct{}) (chan Block, error) {
+	if ldbs.backend.interleaved {
+		return ldbs.interleavedSpatialQuery(first, second, done)
+	}
+	return ldbs.plainSpatialQuery(first, second, done)
+}
+
+func (ldbs *LevelDBSession) plainSpatialQuery(first, second []byte, done chan struct{}) (blocks chan Block, err error) {
+
+	var (
+		firstKey  int64
+		secondKey int64
+	)
+	if firstKey, err = common.DecodeStringFromBytes(first); err != nil {
+		return
+	}
+	if secondKey, err = common.DecodeStringFromBytes(second); err != nil {
+		return
+	}
+	c1 := common.PlainToCoord(firstKey)
+	c2 := common.PlainToCoord(secondKey)
+	c1, c2 = common.MinCoord(c1, c2), common.MaxCoord(c1, c2)
+
+	blocks = make(chan Block)
+
+	go func() {
+		defer close(blocks)
+		ldbs.backend.mutex.RLock()
+		defer ldbs.backend.mutex.RUnlock()
+
+		ro := leveldb.NewReadOptions()
+		defer ro.Close()
+		ro.SetFillCache(false)
+
+		it := ldbs.backend.db.NewIterator(ro)
+		defer it.Close()
+
+		a, b := common.Coord{X: c1.X}, common.Coord{X: c2.X}
+
+		var err error
+
+		for a.Z = c1.Z; a.Z <= c2.Z; a.Z++ {
+			b.Z = a.Z
+			for a.Y = c1.Y; a.Y <= c2.Y; a.Y++ {
+				b.Y = a.Y
+				from, to := order(common.CoordToPlain(a), common.CoordToPlain(b))
+				var encodedFrom []byte
+				if encodedFrom, err = common.EncodeStringToBytes(from); err != nil {
+					log.Printf("encoding key failed: %s", err)
+					return
+				}
+				it.Seek(encodedFrom)
+				for it.Valid() {
+					key := it.Key()
+					var decodedKey int64
+					if decodedKey, err = common.DecodeStringFromBytes(key); err != nil {
+						log.Printf("decoding key failed: %s", err)
+						return
+					}
+					if decodedKey > to {
+						break
+					}
+					select {
+					case blocks <- Block{Key: key, Data: it.Value()}:
+					case <-done:
+						return
+					}
+				}
+				if err = it.GetError(); err != nil {
+					log.Printf("iterating failed: %s", err)
+					return
+				}
+			}
+		}
+	}()
+	return
+}
+
+func (ldbs *LevelDBSession) interleavedSpatialQuery(first, second []byte, done chan struct{}) (blocks chan Block, err error) {
 	err = ErrNotImplemented
 	return
 }
diff --git a/misc.go b/misc.go
new file mode 100644
index 0000000..6c7b32c
--- /dev/null
+++ b/misc.go
@@ -0,0 +1,12 @@
+// Copyright 2014 by Sascha L. Teichmann
+// Use of this source code is governed by the MIT license
+// that can be found in the LICENSE file.
+
+package main
+
+func order(a, b int64) (int64, int64) {
+	if a < b {
+		return a, b
+	}
+	return b, a
+}
diff --git a/sqlite.go b/sqlite.go
index 38dbb05..3ce7c90 100644
--- a/sqlite.go
+++ b/sqlite.go
@@ -292,13 +292,6 @@ func (ss *SqliteSession) SpatialQuery(hash, first, second []byte, done chan stru
 	return ss.plainSpatialQuery(first, second, done)
 }
 
-func order(a, b int64) (int64, int64) {
-	if a < b {
-		return a, b
-	}
-	return b, a
-}
-
 func (ss *SqliteSession) interleavedSpatialQuery(first, second []byte, done chan struct{}) (blocks chan Block, err error) {
 	var (
 		firstKey  int64