From b476f4d1674662068e21630414532deff9384b3c Mon Sep 17 00:00:00 2001
From: Nikita <abracham.mitchell@gmail.com>
Date: Tue, 1 May 2018 18:11:33 +0300
Subject: [PATCH] Fixed - RSemaphore doesn't work with zero permit

---
 .../src/main/java/org/redisson/RedissonSemaphore.java |  6 ++++++
 .../test/java/org/redisson/RedissonSemaphoreTest.java | 11 ++++++++---
 2 files changed, 14 insertions(+), 3 deletions(-)

diff --git a/redisson/src/main/java/org/redisson/RedissonSemaphore.java b/redisson/src/main/java/org/redisson/RedissonSemaphore.java
index c78bb59f4..4f5d9d086 100644
--- a/redisson/src/main/java/org/redisson/RedissonSemaphore.java
+++ b/redisson/src/main/java/org/redisson/RedissonSemaphore.java
@@ -288,6 +288,9 @@ public class RedissonSemaphore extends RedissonExpirable implements RSemaphore {
         if (permits < 0) {
             throw new IllegalArgumentException("Permits amount can't be negative");
         }
+        if (permits == 0) {
+            return RedissonPromise.newSucceededFuture(true);
+        }
 
         return commandExecutor.evalWriteAsync(getName(), LongCodec.INSTANCE, RedisCommands.EVAL_BOOLEAN,
                   "local value = redis.call('get', KEYS[1]); " +
@@ -469,6 +472,9 @@ public class RedissonSemaphore extends RedissonExpirable implements RSemaphore {
         if (permits < 0) {
             throw new IllegalArgumentException("Permits amount can't be negative");
         }
+        if (permits == 0) {
+            return RedissonPromise.newSucceededFuture(null);
+        }
 
         return commandExecutor.evalWriteAsync(getName(), StringCodec.INSTANCE, RedisCommands.EVAL_VOID,
             "local value = redis.call('incrby', KEYS[1], ARGV[1]); " +
diff --git a/redisson/src/test/java/org/redisson/RedissonSemaphoreTest.java b/redisson/src/test/java/org/redisson/RedissonSemaphoreTest.java
index d0551d510..1c1ade8f5 100644
--- a/redisson/src/test/java/org/redisson/RedissonSemaphoreTest.java
+++ b/redisson/src/test/java/org/redisson/RedissonSemaphoreTest.java
@@ -2,17 +2,22 @@ package org.redisson;
 
 import static org.assertj.core.api.Assertions.assertThat;
 
-import java.util.concurrent.BrokenBarrierException;
-import java.util.concurrent.CyclicBarrier;
 import java.util.concurrent.TimeUnit;
 import java.util.concurrent.atomic.AtomicInteger;
 
-import org.junit.Assume;
 import org.junit.Test;
 import org.redisson.api.RSemaphore;
 
 public class RedissonSemaphoreTest extends BaseConcurrentTest {
 
+    @Test
+    public void testZero() throws InterruptedException {
+        RSemaphore s = redisson.getSemaphore("test");
+        assertThat(s.tryAcquire(0, 10, TimeUnit.MINUTES)).isTrue();
+        s.release(0);
+        assertThat(s.availablePermits()).isZero();
+    }
+    
     @Test
     public void testAcquireWithoutSetPermits() throws InterruptedException {
         RSemaphore s = redisson.getSemaphore("test");