add indexLocation in ShardingCodec.

Author: brokkoli71

.gitignore

@@ -36,5 +36,5 @@ build/
 
 
 ### Custom ###
-/testdata
+/testdata/l4_sample
 /testoutput

src/main/java/dev/zarr/zarrjava/v3/codec/CodecBuilder.java

@@ -109,23 +109,30 @@ public CodecBuilder withZstd(int clevel) {
   public CodecBuilder withSharding(int[] chunkShape) {
     try {
       codecs.add(
-          new ShardingIndexedCodec(new ShardingIndexedCodec.Configuration(chunkShape,
-              new Codec[]{new BytesCodec(new Configuration(Endian.LITTLE))},
-              new Codec[]{new BytesCodec(new Configuration(Endian.LITTLE)), new Crc32cCodec()})));
+              new ShardingIndexedCodec(new ShardingIndexedCodec.Configuration(chunkShape,
+                      new Codec[]{new BytesCodec(new Configuration(Endian.LITTLE))},
+                      new Codec[]{new BytesCodec(new Configuration(Endian.LITTLE)), new Crc32cCodec()},
+                      "end")));
     } catch (ZarrException e) {
       throw new RuntimeException(e);
     }
     return this;
   }
 
   public CodecBuilder withSharding(int[] chunkShape,
-      Function<CodecBuilder, CodecBuilder> codecBuilder) {
+                                   Function<CodecBuilder, CodecBuilder> codecBuilder) {
+    return withSharding(chunkShape, codecBuilder, "end");
+  }
+
+  public CodecBuilder withSharding(int[] chunkShape,
+                                   Function<CodecBuilder, CodecBuilder> codecBuilder, String indexLocation) {
     CodecBuilder nestedBuilder = new CodecBuilder(dataType);
     try {
       codecs.add(new ShardingIndexedCodec(
-          new ShardingIndexedCodec.Configuration(chunkShape,
-              codecBuilder.apply(nestedBuilder).build(),
-              new Codec[]{new BytesCodec(Endian.LITTLE), new Crc32cCodec()})));
+              new ShardingIndexedCodec.Configuration(chunkShape,
+                      codecBuilder.apply(nestedBuilder).build(),
+                      new Codec[]{new BytesCodec(Endian.LITTLE), new Crc32cCodec()},
+                      indexLocation)));
     } catch (ZarrException e) {
       throw new RuntimeException(e);
     }

src/main/java/dev/zarr/zarrjava/v3/codec/core/ShardingIndexedCodec.java

@@ -257,15 +257,21 @@ public static final class Configuration {
     public final Codec[] indexCodecs;
     @Nonnull
     @JsonProperty("index_location")
-    public final String indexLocation;
+    public String indexLocation;
 
     @JsonCreator(mode = JsonCreator.Mode.PROPERTIES)
     public Configuration(
             @JsonProperty(value = "chunk_shape", required = true) int[] chunkShape,
             @Nonnull @JsonProperty("codecs") Codec[] codecs,
             @Nonnull @JsonProperty("index_codecs") Codec[] indexCodecs,
-            @Nonnull @JsonProperty("index_location") String indexLocation
-    ) {
+            @JsonProperty(value = "index_location", defaultValue = "end") String indexLocation
+    ) throws ZarrException {
+      if (indexLocation == null) {
+        indexLocation = "end";
+      }
+      if (!indexLocation.equals("start") && !indexLocation.equals("end")) {
+        throw new ZarrException("Only index_location \"start\" or \"end\" are supported.");
+      }
       this.chunkShape = chunkShape;
       this.codecs = codecs;
       this.indexCodecs = indexCodecs;

src/main/java/dev/zarr/zarrjava/v3/codec/core/ZstdCodec.java

@@ -59,7 +59,7 @@ public ByteBuffer encode(ByteBuffer chunkBytes)
       zstdStream.close();
       return ByteBuffer.wrap(outputStream.toByteArray());
     } catch (IOException ex) {
-      throw new ZarrException("Error in decoding zstd.", ex);
+      throw new ZarrException("Error in encoding zstd.", ex);
     }
   }
 

src/test/java/dev/zarr/zarrjava/ZarrTest.java

@@ -349,20 +349,21 @@ public void testV3Access() throws IOException, ZarrException {
         writeArray.access().withOffset(0, 3073, 3073, 513).write(outArray);
     }
 
-    @Disabled("uses excessive memory")
-    @Test
-    public void testV3ShardingReadWrite() throws IOException, ZarrException {
+
+    @ParameterizedTest
+    @ValueSource(strings = {"start", "end"})
+    public void testV3ShardingReadWrite(String indexLocation) throws IOException, ZarrException {
         Array readArray = Array.open(
-                new FilesystemStore(TESTDATA).resolve("l4_sample", "color", "8-8-2"));
+                new FilesystemStore(TESTDATA).resolve("sharding_index_location", indexLocation));
         ucar.ma2.Array readArrayContent = readArray.read();
         Array writeArray = Array.create(
-                new FilesystemStore(TESTOUTPUT).resolve("l4_sample_3", "color", "8-8-2"),
+                new FilesystemStore(TESTOUTPUT).resolve("sharding_index_location", indexLocation),
                 readArray.metadata
         );
         writeArray.write(readArrayContent);
         ucar.ma2.Array outArray = writeArray.read();
 
-        assert MultiArrayUtils.allValuesEqual(outArray, readArrayContent);
+        assert MultiArrayUtils.allValuesEqual(readArrayContent, outArray);
     }
 
     @Test

testdata/sharding_index_location/end/c/0/0/0

@@ -0,0 +1,76 @@
+{
+  "shape": [
+    16,
+    16,
+    16
+  ],
+  "data_type": "int32",
+  "chunk_grid": {
+    "configuration": {
+      "chunk_shape": [
+        16,
+        8,
+        8
+      ]
+    },
+    "name": "regular"
+  },
+  "chunk_key_encoding": {
+    "configuration": {
+      "separator": "/"
+    },
+    "name": "default"
+  },
+  "fill_value": 0,
+  "codecs": [
+    {
+      "configuration": {
+        "chunk_shape": [
+          8,
+          4,
+          8
+        ],
+        "codecs": [
+          {
+            "configuration": {
+              "order": [2, 1, 0]
+            },
+            "name": "transpose"
+          },
+          {
+            "configuration": {
+              "endian": "little"
+            },
+            "name": "bytes"
+          },
+          {
+            "configuration": {
+              "typesize": 4,
+              "cname": "lz4",
+              "clevel": 5,
+              "shuffle": "noshuffle",
+              "blocksize": 0
+            },
+            "name": "blosc"
+          }
+        ],
+        "index_codecs": [
+          {
+            "configuration": {
+              "endian": "little"
+            },
+            "name": "bytes"
+          },
+          {
+            "name": "crc32c"
+          }
+        ],
+        "index_location": "end"
+      },
+      "name": "sharding_indexed"
+    }
+  ],
+  "attributes": {},
+  "zarr_format": 3,
+  "node_type": "array"
+}