Merge pull request #160 from cristipufu/fix/token_buckets_multi_permits

Token bucket support for multi permits

Author: cristipufu

src/RedisRateLimiting/TokenBucket/RedisTokenBucketManager.cs

@@ -76,7 +76,7 @@ public RedisTokenBucketManager(
             RateLimitTimestampKey = new RedisKey($"rl:tb:{{{partitionKey}}}:ts");
         }
 
-        internal async Task<RedisTokenBucketResponse> TryAcquireLeaseAsync()
+        internal async Task<RedisTokenBucketResponse> TryAcquireLeaseAsync(int permitCount)
         {
             var database = _connectionMultiplexer.GetDatabase();
 
@@ -89,7 +89,7 @@ internal async Task<RedisTokenBucketResponse> TryAcquireLeaseAsync()
                     tokens_per_period = (RedisValue)_options.TokensPerPeriod,
                     token_limit = (RedisValue)_options.TokenLimit,
                     replenish_period = (RedisValue)_options.ReplenishmentPeriod.TotalMilliseconds,
-                    permit_count = (RedisValue)1D,
+                    permit_count = (RedisValue)permitCount,
                     current_time = (RedisValue)DateTimeOffset.UtcNow.ToUnixTimeMilliseconds(),
                 });
 

src/RedisRateLimiting/TokenBucket/RedisTokenBucketRateLimiter.cs

@@ -62,7 +62,7 @@ protected override ValueTask<RateLimitLease> AcquireAsyncCore(int permitCount, C
                 throw new ArgumentOutOfRangeException(nameof(permitCount), permitCount, string.Format("{0} permit(s) exceeds the permit limit of {1}.", permitCount, _options.TokenLimit));
             }
 
-            return AcquireAsyncCoreInternal();
+            return AcquireAsyncCoreInternal(permitCount);
         }
 
         protected override RateLimitLease AttemptAcquireCore(int permitCount)
@@ -71,14 +71,14 @@ protected override RateLimitLease AttemptAcquireCore(int permitCount)
             return FailedLease;
         }
 
-        private async ValueTask<RateLimitLease> AcquireAsyncCoreInternal()
+        private async ValueTask<RateLimitLease> AcquireAsyncCoreInternal(int permitCount)
         {
             var leaseContext = new TokenBucketLeaseContext
             {
                 Limit = _options.TokenLimit,
             };
 
-            var response = await _redisManager.TryAcquireLeaseAsync();
+            var response = await _redisManager.TryAcquireLeaseAsync(permitCount);
 
             leaseContext.Allowed = response.Allowed;
             leaseContext.Count = response.Count;

test/RedisRateLimiting.Tests/UnitTests/TokenBucketUnitTests.cs

@@ -100,5 +100,28 @@ public async Task CanAcquireAsyncResource()
             using var lease2 = await limiter.AcquireAsync();
             Assert.False(lease2.IsAcquired);
         }
+
+        [Fact]
+        public async Task CanAcquireMultiPermits()
+        {
+            using var limiter = new RedisTokenBucketRateLimiter<string>(
+                partitionKey: Guid.NewGuid().ToString(),
+                new RedisTokenBucketRateLimiterOptions
+                {
+                    TokenLimit = 5,
+                    TokensPerPeriod = 5,
+                    ReplenishmentPeriod = TimeSpan.FromMinutes(1),
+                    ConnectionMultiplexerFactory = Fixture.ConnectionMultiplexerFactory,
+                });
+
+            using var lease = await limiter.AcquireAsync(4);
+            Assert.True(lease.IsAcquired);
+
+            using var lease2 = await limiter.AcquireAsync(3);
+            Assert.False(lease2.IsAcquired);
+
+            using var lease3 = await limiter.AcquireAsync(1);
+            Assert.True(lease3.IsAcquired);
+        }
     }
 }