Merge pull request #6295 from seakider/fix_bitset_length

Fixed - method lengthAsync of RedissonBitSet

redisson/src/main/java/org/redisson/RedissonBitSet.java

@@ -427,14 +427,22 @@ public class RedissonBitSet extends RedissonExpirable implements RBitSet {
     @Override
     public RFuture<Long> lengthAsync() {
         return commandExecutor.evalReadAsync(getRawName(), LongCodec.INSTANCE, RedisCommands.EVAL_LONG,
-                "local fromBit = redis.call('bitpos', KEYS[1], 1, -1);"
-                + "local toBit = 8*(fromBit/8 + 1) - fromBit % 8;"
-                        + "for i = toBit, fromBit, -1 do "
-                            + "if redis.call('getbit', KEYS[1], i) == 1 then "
-                                + "return i+1;"
-                            + "end;"
-                       + "end;" +
-                     "return fromBit+1",
+                "local i = redis.call('bitpos', KEYS[1], 1, -1); "
+                        + "local pos = i < 0 and redis.call('bitpos', KEYS[1], 0, -1) or math.floor(i / 8) * 8; "
+                        + "while  (pos >= 0) "
+                        + "do "
+                            + "i = redis.call('bitpos', KEYS[1], 1, math.floor(pos / 8), math.floor(pos / 8)); "
+                            + "if i < 0 then "
+                                + "pos = pos - 8; "
+                            + "else "
+                                + "for j = pos + 7, pos, -1 do "
+                                    + "if redis.call('getbit', KEYS[1], j) == 1 then "
+                                        + "return j + 1; "
+                                    + "end; "
+                                + "end; "
+                            + "end; "
+                        + "end; "
+                        + "return 0; ",
                 Collections.<Object>singletonList(getRawName()));
     }
 

redisson/src/test/java/org/redisson/RedissonBitSetTest.java

@@ -91,6 +91,20 @@ public class RedissonBitSetTest extends RedisDockerTest {
         bs.clear();
         bs.set(0);
         assertThat(bs.length()).isEqualTo(1);
+        
+        // no exception happened, but return is unexpected.
+        bs.clear();
+        bs.set(0, 2);
+        bs.set(9);
+        bs.clear(9, 10);
+        assertThat(bs.length()).isEqualTo(2);
+        
+        // cause exception
+        bs.clear();
+        bs.set(7);
+        bs.set(9);
+        bs.clear(9, 10);
+        assertThat(bs.length()).isEqualTo(8);
     }
 
     @Test