RPermitExpirableSemaphore.availablePermits doesn't return actual permits account under certain conditions #659

redisson/src/main/java/org/redisson/RedissonPermitExpirableSemaphore.java

@@ -662,7 +662,18 @@ public class RedissonPermitExpirableSemaphore extends RedissonExpirable implemen
     
     @Override
     public RFuture<Integer> availablePermitsAsync() {
-        return commandExecutor.writeAsync(getName(), LongCodec.INSTANCE, RedisCommands.GET_INTEGER, getName());
+        return commandExecutor.evalWriteAsync(getName(), LongCodec.INSTANCE, RedisCommands.EVAL_INTEGER, 
+                "local expiredIds = redis.call('zrangebyscore', KEYS[2], 0, ARGV[1], 'limit', 0, -1); " +
+                "if #expiredIds > 0 then " +
+                    "redis.call('zrem', KEYS[2], unpack(expiredIds)); " +
+                    "local value = redis.call('incrby', KEYS[1], #expiredIds); " + 
+                    "if tonumber(value) > 0 then " +
+                        "redis.call('publish', KEYS[3], value); " +
+                    "end;" + 
+                    "return value; " +
+                "end; " +
+                "return redis.call('get', KEYS[1]); ",
+                Arrays.<Object>asList(getName(), timeoutName, getChannelName()), System.currentTimeMillis());
     }
 
     @Override

redisson/src/test/java/org/redisson/RedissonPermitExpirableSemaphoreTest.java

@@ -6,12 +6,32 @@ import java.util.concurrent.TimeUnit;
 import java.util.concurrent.atomic.AtomicBoolean;
 import java.util.concurrent.atomic.AtomicInteger;
 
+import org.junit.Assert;
 import org.junit.Test;
 import org.redisson.api.RPermitExpirableSemaphore;
 import org.redisson.client.RedisException;
 
 public class RedissonPermitExpirableSemaphoreTest extends BaseConcurrentTest {
 
+    @Test
+    public void testAvailablePermits() throws InterruptedException {
+        RPermitExpirableSemaphore semaphore = redisson.getPermitExpirableSemaphore("test-semaphore");
+        assertThat(semaphore.trySetPermits(2)).isTrue();
+        Assert.assertEquals(2, semaphore.availablePermits());
+        String acquire1 = semaphore.tryAcquire(200, 1000, TimeUnit.MILLISECONDS);
+        assertThat(acquire1).isNotNull();
+        String acquire2 = semaphore.tryAcquire(200, 1000, TimeUnit.MILLISECONDS);
+        assertThat(acquire2).isNotNull();
+        String acquire3 = semaphore.tryAcquire(200, 1000, TimeUnit.MILLISECONDS);
+        assertThat(acquire3).isNull();
+        Assert.assertEquals(0, semaphore.availablePermits());
+        Thread.sleep(1100);
+        String acquire4 = semaphore.tryAcquire(200, 1000, TimeUnit.MILLISECONDS);
+        assertThat(acquire4).isNotNull();
+        Thread.sleep(1100);
+        Assert.assertEquals(2, semaphore.availablePermits());
+    }
+    
     @Test
     public void testExpire() throws InterruptedException {
         RPermitExpirableSemaphore s = redisson.getPermitExpirableSemaphore("test");