From 33337d5df2297ca3973955afe9463ec990352108 Mon Sep 17 00:00:00 2001
From: "Sascha L. Teichmann" <sascha.teichmann@intevation.de>
Date: Sun, 21 Sep 2014 12:57:21 +0200
Subject: [PATCH] mtwebmapper: Added scaffold for updating the pyramid tiles.
 TODO: Implement th actual imaging stuff.

---
 cmd/mtwebmapper/tilesupdater.go | 67 +++++++++++++++++++++++++++++----
 1 file changed, 59 insertions(+), 8 deletions(-)

diff --git a/cmd/mtwebmapper/tilesupdater.go b/cmd/mtwebmapper/tilesupdater.go
index 70f9ab9..11df3c3 100644
--- a/cmd/mtwebmapper/tilesupdater.go
+++ b/cmd/mtwebmapper/tilesupdater.go
@@ -29,10 +29,27 @@ type xz struct {
 	Z int16
 }
 
+type xzm struct {
+	P    xz
+	Mask uint16
+}
+
 func (c xz) quantize() xz {
 	return xz{X: (c.X - -1933) / 16, Z: (c.Z - -1933) / 16}
 }
 
+func (c xz) dequantize() xz {
+	return xz{X: c.X*16 + -1933, Z: c.Z*16 + -1933}
+}
+
+func (c xz) parent() xzm {
+	xp, xr := c.X>>1, uint16(c.X&1)
+	zp, zr := c.Z>>1, uint16(c.Z&1)
+	return xzm{
+		P:    xz{X: xp, Z: zp},
+		Mask: ((1 << xr) << 2) | (1 << zr)}
+}
+
 func newTileUpdater(mapDir, redisAddress string, colors *common.Colors, workers int) *tileUpdater {
 	tu := tileUpdater{
 		mapDir:       mapDir,
@@ -95,24 +112,58 @@ func (tu *tileUpdater) doUpdates() {
 			go updateBaseTiles(jobs, btc, &done)
 		}
 
+		parentJobs := make(map[xz]uint16)
+
 		for c, _ := range changes {
-			log.Printf("job: %+v", c)
+			//log.Printf("job: %+v", c)
 			jobs <- c
+			pxz := c.parent()
+			parentJobs[pxz.P] |= pxz.Mask
 		}
+		close(jobs)
 		done.Wait()
+
+		for level := 7; level >= 0; level-- {
+			pJobs := make(chan xzm)
+			for i, n := 0, min(len(parentJobs), tu.workers); i < n; i++ {
+				done.Add(1)
+				go updatePyramidTiles(level, baseDir, pJobs, &done)
+			}
+			ppJobs := make(map[xz]uint16)
+			for c, mask := range parentJobs {
+				pJobs <- xzm{P: c, Mask: mask}
+				pxz := c.parent()
+				ppJobs[pxz.P] |= pxz.Mask
+			}
+			close(pJobs)
+			done.Wait()
+			parentJobs = ppJobs
+		}
+	}
+}
+
+func min(a, b int) int {
+	if a < b {
+		return a
+	}
+	return b
+}
+
+func updatePyramidTiles(level int, baseDir string, jobs chan xzm, done *sync.WaitGroup) {
+	defer done.Done()
+	for job := range jobs {
+		_ = job
 	}
-	return
 }
 
 func updateBaseTiles(jobs chan xz, btc *common.BaseTileCreator, done *sync.WaitGroup) {
+	defer btc.Close()
+	defer done.Done()
 	for job := range jobs {
-		x := job.X*16 + -1933 - 1
-		z := job.Z*16 + -1933 - 1
-		log.Printf("%d/%d %d/%d", x, z, job.X, job.Z)
-		if err := btc.CreateTile(x, z, int(job.X), int(job.Z)); err != nil {
+		xz := job.dequantize()
+		//log.Printf("%d/%d %d/%d", x, z, job.X, job.Z)
+		if err := btc.CreateTile(xz.X-1, xz.Z-1, int(job.X), int(job.Z)); err != nil {
 			log.Printf("WARN: create tile failed: %s", err)
 		}
 	}
-	btc.Close() // TODO: Keep redis connection open to update the pyramid tiles.
-	done.Done()
 }