liming30 commented on code in PR #20405:
URL: https://github.com/apache/flink/pull/20405#discussion_r940189878
##########
flink-state-backends/flink-statebackend-rocksdb/src/main/java/org/apache/flink/contrib/streaming/state/AbstractRocksDBState.java:
##########
@@ -223,4 +223,27 @@ public StateIncrementalVisitor<K, N, V>
getStateIncrementalVisitor(
throw new UnsupportedOperationException(
"Global state entry iterator is unsupported for RocksDb
backend");
}
+
+ /**
+ * Similar to decimal addition, add 1 to the last digit to calculate the
upper bound.
+ *
+ * @param prefix the starting prefix for seek.
+ * @return end prefix for seek.
+ */
+ protected final byte[] calculateUpperBound(byte[] prefix) {
+ byte[] upperBound = new byte[prefix.length];
+ System.arraycopy(prefix, 0, upperBound, 0, prefix.length);
+ boolean overFlow = true;
+ for (int i = prefix.length - 1; i >= 0; i--) {
+ int unsignedValue = prefix[i] & 0xff;
+ int result = unsignedValue + 1;
+ upperBound[i] = (byte) (result & 0xff);
+ if (result >> 8 == 0) {
+ overFlow = false;
+ break;
+ }
+ }
+ Preconditions.checkArgument(!overFlow, "The upper boundary
overflows.");
Review Comment:
Sorry, I still haven't figured out when the `KeyGroup` serialized binary
array will be `0xff`or `0xffff`. If the serialization result is not `0xff` or
`0xffff`, then here I think there will be no overflow. The serialization for
`KeyGroup` looks like this
```
public static void writeKeyGroup(
int keyGroup,
int keyGroupPrefixBytes,
DataOutputView keySerializationDateDataOutputView) throws
IOException {
for (int i = keyGroupPrefixBytes; --i >= 0; ) {
keySerializationDateDataOutputView.writeByte(extractByteAtPosition(keyGroup,
i));
}
}
private static byte extractByteAtPosition(int value, int byteIdx) {
return (byte) ((value >>> (byteIdx << 3)));
}
```
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