Replace long[] arrays by a TileIndex abstraction

Dealing with `long[]` everywhere and knowing it means `{x,y,z}` is
tiring.

Introducing a `TileIndex` abstraction improves the semantics, and at the
same time allows to save memory on TileObject by storing the
coordinates as internal long,long,int fields and saving the object
reference to a `long` array.

---

> This is a **proposal**. Can we please stop using `long[]` everywhere?
> If accepted, there would be more places to get rid of `long` arrays
> and introduce higher level abstractions (e.g. `TileRangeInterator`)

geowebcache/arcgiscache/src/main/java/org/geowebcache/arcgis/layer/ArcGISCacheLayer.java

@@ -51,6 +51,7 @@
 import org.geowebcache.layer.ExpirationRule;
 import org.geowebcache.mime.MimeException;
 import org.geowebcache.mime.MimeType;
+import org.geowebcache.storage.TileIndex;
 import org.geowebcache.util.GWCVars;
 
 /**
@@ -268,18 +269,18 @@ public ConveyorTile getTile(final ConveyorTile tile)
 
         if (storageFormat.equals(CacheStorageInfo.COMPACT_FORMAT_CODE)
                 || storageFormat.equals(CacheStorageInfo.COMPACT_FORMAT_CODE_V2)) {
-            final long[] tileIndex = tile.getTileIndex();
+            final TileIndex tileIndex = tile.getIndex();
             final String gridSetId = tile.getGridSetId();
             final GridSubset gridSubset = this.getGridSubset(gridSetId);
 
             GridSet gridSet = gridSubset.getGridSet();
-            final int zoom = (int) tileIndex[2];
+            final int zoom = tileIndex.getZ();
 
             Grid grid = gridSet.getGrid(zoom);
             long coverageMaxY = grid.getNumTilesHigh() - 1;
 
-            final int col = (int) tileIndex[0];
-            final int row = (int) (coverageMaxY - tileIndex[1]);
+            final int col = (int) tileIndex.getX();
+            final int row = (int) (coverageMaxY - tileIndex.getY());
 
             tileContent = compactCache.getBundleFileResource(zoom, row, col);
 
@@ -298,7 +299,7 @@ public ConveyorTile getTile(final ConveyorTile tile)
         } else {
             tile.setCacheResult(CacheResult.MISS);
             if (!setLayerBlankTile(tile)) {
-                throw new OutsideCoverageException(tile.getTileIndex(), 0, 0);
+                throw new OutsideCoverageException(tile.getIndex().getZ(), 0, 0);
             }
         }
 
@@ -370,23 +371,23 @@ private boolean setLayerBlankTile(ConveyorTile tile) {
     private String getTilePath(final ConveyorTile tile) {
 
         final MimeType mimeType = tile.getMimeType();
-        final long[] tileIndex = tile.getTileIndex();
+        final TileIndex tileIndex = tile.getIndex();
         final String gridSetId = tile.getGridSetId();
         final GridSubset gridSubset = this.getGridSubset(gridSetId);
 
         GridSet gridSet = gridSubset.getGridSet();
-        final int z = (int) tileIndex[2];
+        final int z = tileIndex.getZ();
 
         Grid grid = gridSet.getGrid(z);
 
         // long[] coverage = gridSubset.getCoverage(z);
         // long coverageMinY = coverage[1];
         long coverageMaxY = grid.getNumTilesHigh() - 1;
 
-        final long x = tileIndex[0];
+        final long x = tileIndex.getX();
         // invert the order of the requested Y ordinate, since ArcGIS caches are top-left to
         // bottom-right, and GWC computes tiles in bottom-left to top-right order
-        final long y = (coverageMaxY - tileIndex[1]);
+        final long y = (coverageMaxY - tileIndex.getY());
 
         String level = (this.hexZoom) ? Integer.toHexString(z) : Integer.toString(z);
         level = zeroPadder(level, 2);

geowebcache/core/src/main/java/org/geowebcache/conveyor/ConveyorTile.java

@@ -28,6 +28,7 @@
 import org.geowebcache.mime.MimeType;
 import org.geowebcache.storage.StorageBroker;
 import org.geowebcache.storage.StorageException;
+import org.geowebcache.storage.TileIndex;
 import org.geowebcache.storage.TileObject;
 
 /** Represents a request for a tile and carries the information needed to complete it. */
@@ -72,7 +73,7 @@ public ConveyorTile(
             StorageBroker sb,
             String layerId,
             String gridSetId,
-            long[] tileIndex,
+            TileIndex tileIndex,
             MimeType mimeType,
             Map<String, String[]> fullParameters,
             Map<String, String> filteringParameters,
@@ -95,7 +96,7 @@ public ConveyorTile(
             StorageBroker sb,
             String layerId,
             String gridSetId,
-            long[] tileIndex,
+            TileIndex tileIndex,
             MimeType mimeType,
             Map<String, String> filteringParameters,
             HttpServletRequest servletReq,
@@ -104,18 +105,11 @@ public ConveyorTile(
         super(layerId, sb, servletReq, servletResp);
         this.gridSetId = gridSetId;
 
-        long[] idx = new long[3];
-
-        if (tileIndex != null) {
-            idx[0] = tileIndex[0];
-            idx[1] = tileIndex[1];
-            idx[2] = tileIndex[2];
-        }
-
         super.mimeType = mimeType;
 
         this.filteringParameters = filteringParameters;
 
+        TileIndex idx = tileIndex == null ? null : TileIndex.copyOf(tileIndex);
         stObj =
                 TileObject.createQueryTileObject(
                         layerId, idx, gridSetId, mimeType.getFormat(), filteringParameters);
@@ -180,6 +174,10 @@ public long[] getTileIndex() {
         return stObj.getXYZ();
     }
 
+    public TileIndex getIndex() {
+        return stObj.getIndex();
+    }
+
     public synchronized GridSubset getGridSubset() {
         if (gridSubset == null && gridSetId != null) {
             gridSubset = tileLayer.getGridSubset(gridSetId);
@@ -248,7 +246,6 @@ public boolean retrieve(long maxAge) throws GeoWebCacheException {
     public String toString() {
         StringBuilder str = new StringBuilder();
         str.append("ConveyorTile[");
-        long[] idx = stObj.getXYZ();
 
         if (getLayerId() != null) {
             str.append(getLayerId()).append(" ");
@@ -258,9 +255,7 @@ public String toString() {
             str.append(gridSetId).append(" ");
         }
 
-        if (idx != null && idx.length == 3) {
-            str.append("{" + idx[0] + "," + idx[1] + "," + idx[2] + "} ");
-        }
+        str.append("{" + stObj.getX() + "," + stObj.getY() + "," + stObj.getZ() + "} ");
 
         if (this.mimeType != null) {
             str.append(this.mimeType.getFormat());

geowebcache/core/src/main/java/org/geowebcache/filter/request/CircularExtentFilter.java

@@ -18,6 +18,7 @@
 import org.geowebcache.conveyor.ConveyorTile;
 import org.geowebcache.grid.GridSubset;
 import org.geowebcache.layer.TileLayer;
+import org.geowebcache.storage.TileIndex;
 
 /**
  * This is a test filter for the new request filter core.
@@ -38,7 +39,8 @@ public void apply(ConveyorTile convTile) throws RequestFilterException {
         // SRS srs = convTile.getSRS();
         GridSubset gridSubset = tl.getGridSubset(convTile.getGridSetId());
 
-        int z = (int) convTile.getTileIndex()[2];
+        TileIndex tileIndex = convTile.getIndex();
+        int z = tileIndex.getZ();
         long[] gridCoverage = gridSubset.getCoverage(z);
 
         // Figure out the radius
@@ -58,8 +60,8 @@ public void apply(ConveyorTile convTile) throws RequestFilterException {
         long midX = gridCoverage[0] + width / 2;
         long midY = gridCoverage[1] + height / 2;
 
-        long xDist = midX - convTile.getTileIndex()[0];
-        long yDist = midY - convTile.getTileIndex()[1];
+        long xDist = midX - tileIndex.getX();
+        long yDist = midY - tileIndex.getY();
 
         long rad = Math.round(Math.sqrt(xDist * xDist + yDist * yDist));
 

geowebcache/core/src/main/java/org/geowebcache/filter/request/RasterFilter.java

@@ -26,6 +26,7 @@
 import org.geowebcache.grid.GridSubset;
 import org.geowebcache.grid.OutsideCoverageException;
 import org.geowebcache.layer.TileLayer;
+import org.geowebcache.storage.TileIndex;
 
 /**
  * A raster filter allows to optimize data loading by avoiding the generation of requests and the
@@ -109,51 +110,54 @@ public void setDebug(Boolean debug) {
 
     @Override
     public void apply(ConveyorTile convTile) throws RequestFilterException {
-        long[] idx = convTile.getTileIndex().clone();
         String gridSetId = convTile.getGridSetId();
 
         // Basic bounds test first
         try {
-            convTile.getGridSubset().checkCoverage(idx);
+            convTile.getGridSubset().checkCoverage(convTile.getIndex());
         } catch (OutsideCoverageException oce) {
             throw new BlankTileException(this);
         }
 
+        long x = convTile.getIndex().getX();
+        long y = convTile.getIndex().getY();
+        int z = convTile.getIndex().getZ();
         int zoomDiff = 0;
 
         // Three scenarios below:
         // 1. z is too low , upsample if resampling is enabled
         // 2. z is within range, downsample one level and apply
         // 3. z is too large , downsample
-        if (zoomStart != null && idx[2] < zoomStart) {
+        if (zoomStart != null && z < zoomStart) {
             if (resample == null || !resample) {
                 // Filter does not apply, zoomlevel is too low
                 return;
             } else {
                 // Upsample
-                zoomDiff = (int) (idx[2] - zoomStart);
-                idx[0] = idx[0] << (-1 * zoomDiff);
-                idx[1] = idx[1] << (-1 * zoomDiff);
-                idx[2] = zoomStart;
+                zoomDiff = z - zoomStart;
+                x = (x << (-1 * zoomDiff));
+                y = (y << (-1 * zoomDiff));
+                z = zoomStart;
             }
-        } else if (idx[2] < zoomStop) {
+        } else if (z < zoomStop) {
             // Sample one level higher
-            idx[0] = idx[0] * 2;
-            idx[1] = idx[1] * 2;
-            idx[2] = idx[2] + 1;
+            x = x * 2;
+            y = y * 2;
+            z = z + 1;
         } else {
             // Reduce to highest supported resolution
-            zoomDiff = (int) (idx[2] - zoomStop);
-            idx[0] = idx[0] >> zoomDiff;
-            idx[1] = idx[1] >> zoomDiff;
-            idx[2] = zoomStop;
+            zoomDiff = z - zoomStop;
+            x = x >> zoomDiff;
+            y = y >> zoomDiff;
+            z = zoomStop;
         }
 
+        TileIndex idx = TileIndex.valueOf(x, y, z);
         if (matrices == null
                 || matrices.get(gridSetId) == null
-                || matrices.get(gridSetId)[(int) idx[2]] == null) {
+                || matrices.get(gridSetId)[idx.getZ()] == null) {
             try {
-                setMatrix(convTile.getLayer(), gridSetId, (int) idx[2], false);
+                setMatrix(convTile.getLayer(), gridSetId, idx.getZ(), false);
             } catch (Exception e) {
                 log.log(
                         Level.SEVERE,
@@ -162,14 +166,14 @@ public void apply(ConveyorTile convTile) throws RequestFilterException {
                                 + ", "
                                 + gridSetId
                                 + ", "
-                                + idx[2]
+                                + idx.getZ()
                                 + " : "
                                 + e.getMessage());
                 throw new RequestFilterException(
                         this,
                         500,
                         "Failed while trying to load filter for "
-                                + idx[2]
+                                + idx.getZ()
                                 + ", please check the logs");
             }
         }
@@ -229,14 +233,14 @@ public void initialize(TileLayer layer) throws GeoWebCacheException {
     }
 
     /** Performs a lookup against an internal raster. */
-    private boolean lookup(GridSubset grid, long[] idx) {
-        BufferedImage mat = matrices.get(grid.getName())[(int) idx[2]];
+    private boolean lookup(GridSubset grid, TileIndex idx) {
+        BufferedImage mat = matrices.get(grid.getName())[idx.getZ()];
 
-        long[] gridCoverage = grid.getCoverage((int) idx[2]);
+        long[] gridCoverage = grid.getCoverage(idx.getZ());
 
         // Changing index to top left hand origin
-        long x = idx[0] - gridCoverage[0];
-        long y = gridCoverage[3] - idx[1];
+        long x = idx.getX() - gridCoverage[0];
+        long y = gridCoverage[3] - idx.getY();
 
         return (mat.getRaster().getSample((int) x, (int) y, 0) == 0);
     }
@@ -245,14 +249,14 @@ private boolean lookup(GridSubset grid, long[] idx) {
      * Performs a lookup against an internal raster. The sampling is actually done against 4 pixels,
      * idx should already have been modified to use one level higher than strictly necessary.
      */
-    private boolean lookupQuad(GridSubset grid, long[] idx) {
-        BufferedImage mat = matrices.get(grid.getName())[(int) idx[2]];
+    private boolean lookupQuad(GridSubset grid, TileIndex idx) {
+        BufferedImage mat = matrices.get(grid.getName())[idx.getZ()];
 
-        long[] gridCoverage = grid.getCoverage((int) idx[2]);
+        long[] gridCoverage = grid.getCoverage(idx.getZ());
 
         // Changing index to top left hand origin
-        int baseX = (int) (idx[0] - gridCoverage[0]);
-        int baseY = (int) (gridCoverage[3] - idx[1]);
+        int baseX = (int) (idx.getX() - gridCoverage[0]);
+        int baseY = (int) (gridCoverage[3] - idx.getY());
 
         int width = mat.getWidth();
         int height = mat.getHeight();
@@ -298,16 +302,16 @@ private boolean lookupQuad(GridSubset grid, long[] idx) {
         return hasData;
     }
 
-    private boolean lookupSubsample(GridSubset grid, long[] idx, int zoomDiff) {
-        BufferedImage mat = matrices.get(grid.getName())[(int) idx[2]];
+    private boolean lookupSubsample(GridSubset grid, TileIndex idx, int zoomDiff) {
+        BufferedImage mat = matrices.get(grid.getName())[idx.getZ()];
 
         int sampleChange = 1 << (-1 * zoomDiff);
 
-        long[] gridCoverage = grid.getCoverage((int) idx[2]);
+        long[] gridCoverage = grid.getCoverage(idx.getZ());
 
         // Changing index to top left hand origin
-        int baseX = (int) (idx[0] - gridCoverage[0]);
-        int baseY = (int) (gridCoverage[3] - idx[1]);
+        int baseX = (int) (idx.getX() - gridCoverage[0]);
+        int baseY = (int) (gridCoverage[3] - idx.getY());
 
         int width = mat.getWidth();
         int height = mat.getHeight();

geowebcache/core/src/main/java/org/geowebcache/filter/security/SecurityDispatcher.java

@@ -50,7 +50,7 @@ public void checkSecurity(final ConveyorTile tile)
         final BoundingBox bounds;
         final SRS srs;
         if (Objects.nonNull(gridSubset)) {
-            bounds = gridSubset.boundsFromIndex(tile.getTileIndex());
+            bounds = gridSubset.boundsFromIndex(tile.getIndex());
             srs = gridSubset.getSRS();
         } else {
             bounds = null;

geowebcache/core/src/main/java/org/geowebcache/grid/GridSet.java

@@ -20,6 +20,7 @@
 import org.apache.commons.lang3.builder.ReflectionToStringBuilder;
 import org.apache.commons.lang3.builder.ToStringStyle;
 import org.geowebcache.config.Info;
+import org.geowebcache.storage.TileIndex;
 
 /** A grid set configuration */
 public class GridSet implements Info {
@@ -110,15 +111,19 @@ void setResolutionsPreserved(boolean resolutionsPreserved) {
     }
 
     public BoundingBox boundsFromIndex(long[] tileIndex) {
-        final int tileZ = (int) tileIndex[2];
+        return boundsFromIndex(TileIndex.valueOf(tileIndex));
+    }
+
+    public BoundingBox boundsFromIndex(TileIndex tileIndex) {
+        final int tileZ = tileIndex.getZ();
         Grid grid = getGrid(tileZ);
 
-        final long tileX = tileIndex[0];
+        final long tileX = tileIndex.getX();
         final long tileY;
         if (yBaseToggle) {
-            tileY = tileIndex[1] - grid.getNumTilesHigh();
+            tileY = tileIndex.getY() - grid.getNumTilesHigh();
         } else {
-            tileY = tileIndex[1];
+            tileY = tileIndex.getY();
         }
 
         double width = grid.getResolution() * getTileWidth();