DATAREDIS-313 - Overhaul SCAN, HSCAN, SSCAN, ZSCAN operations.

Unify naming and return types. Update supported commands documentation. Remove key from BoundHashOperations and use getKey() instead. Prevent error when trying to read values when there are no values present.

Author: christophstrobl

src/main/java/org/springframework/data/redis/connection/lettuce/LettuceConnection.java

@@ -3112,8 +3112,7 @@ protected ScanIteration<Entry<byte[], byte[]>> doScan(byte[] key, long cursorId,
 List<?> result = eval(script.getBytes(), ReturnType.MULTI, 0);
 String nextCursorId = LettuceConverters.bytesToString().convert((byte[]) result.get(0));
 
-@SuppressWarnings("unchecked")
-Map<byte[], byte[]> values = LettuceConverters.toMap((List<byte[]>) result.get(1));
+Map<byte[], byte[]> values = failsafeReadScanValues(result, LettuceConverters.bytesListToMapConverter());
 return new ScanIteration<Entry<byte[], byte[]>>(Long.valueOf(nextCursorId), values.entrySet());
 }
 }.open();
@@ -3139,7 +3138,6 @@ public Cursor<byte[]> sScan(byte[] key, long cursorId, ScanOptions options) {
 
 return new KeyBoundCursor<byte[]>(key, cursorId, options) {
 
-@SuppressWarnings("unchecked")
 @Override
 protected ScanIteration<byte[]> doScan(byte[] key, long cursorId, ScanOptions options) {
 
@@ -3154,7 +3152,8 @@ protected ScanIteration<byte[]> doScan(byte[] key, long cursorId, ScanOptions op
 List<?> result = eval(script.getBytes(), ReturnType.MULTI, 0);
 String nextCursorId = LettuceConverters.bytesToString().convert((byte[]) result.get(0));
 
-return new ScanIteration<byte[]>(Long.valueOf(nextCursorId), ((ArrayList<byte[]>) result.get(1)));
+List<byte[]> values = failsafeReadScanValues(result, null);
+return new ScanIteration<byte[]>(Long.valueOf(nextCursorId), values);
 }
 }.open();
 }
@@ -3179,7 +3178,6 @@ public Cursor<Tuple> zScan(byte[] key, long cursorId, ScanOptions options) {
 
 return new KeyBoundCursor<Tuple>(key, cursorId, options) {
 
-@SuppressWarnings("unchecked")
 @Override
 protected ScanIteration<Tuple> doScan(byte[] key, long cursorId, ScanOptions options) {
 
@@ -3194,12 +3192,23 @@ protected ScanIteration<Tuple> doScan(byte[] key, long cursorId, ScanOptions opt
 List<?> result = eval(script.getBytes(), ReturnType.MULTI, 0);
 String nextCursorId = LettuceConverters.bytesToString().convert((byte[]) result.get(0));
 
-return new ScanIteration<Tuple>(Long.valueOf(nextCursorId), LettuceConverters.toTuple((List<byte[]>) result
-.get(1)));
+List<Tuple> values = failsafeReadScanValues(result, LettuceConverters.bytesListToTupleListConverter());
+return new ScanIteration<Tuple>(Long.valueOf(nextCursorId), values);
 }
 }.open();
 }
 
+@SuppressWarnings("unchecked")
+private <T> T failsafeReadScanValues(List<?> source, @SuppressWarnings("rawtypes") Converter converter) {
+
+try {
+return (T) (converter != null ? converter.convert(source.get(1)) : source.get(1));
+} catch (IndexOutOfBoundsException e) {
+// ignore this one
+}
+return null;
+}
+
 /**
  * Specifies if pipelined and transaction results should be converted to the expected data type. If false, results of
  * {@link #closePipeline()} and {@link #exec()} will be of the type returned by the Lettuce driver

src/main/java/org/springframework/data/redis/connection/lettuce/LettuceConverters.java

@@ -174,6 +174,10 @@ public static List<Tuple> toTuple(List<byte[]> list) {
 return BYTES_LIST_TO_TUPLE_LIST_CONVERTER.convert(list);
 }
 
+public static Converter<List<byte[]>, List<Tuple>> bytesListToTupleListConverter() {
+return BYTES_LIST_TO_TUPLE_LIST_CONVERTER;
+}
+
 public static Converter<String, List<RedisClientInfo>> stringToRedisClientListConverter() {
 return new Converter<String, List<RedisClientInfo>>() {
 
@@ -290,6 +294,10 @@ public static Map<byte[], byte[]> toMap(List<byte[]> source) {
 return BYTES_LIST_TO_MAP.convert(source);
 }
 
+public static Converter<List<byte[]>, Map<byte[], byte[]>> bytesListToMapConverter() {
+return BYTES_LIST_TO_MAP;
+}
+
 public static SortArgs toSortArgs(SortParameters params) {
 SortArgs args = new SortArgs();
 if (params == null) {