1 files changed, 59 insertions, 0 deletions
diff --git a/components/slice-analysis-ms/src/main/java/org/onap/slice/analysis/ms/service/RateLimiter.java b/components/slice-analysis-ms/src/main/java/org/onap/slice/analysis/ms/service/RateLimiter.java
new file mode 100644
index 00000000..77ee61f2
--- /dev/null
+++ b/components/slice-analysis-ms/src/main/java/org/onap/slice/analysis/ms/service/RateLimiter.java
@@ -0,0 +1,59 @@
+/*******************************************************************************
+ *  ============LICENSE_START=======================================================
+ *  slice-analysis-ms
+ *  ================================================================================
+ *   Copyright (C) 2022 Huawei Canada Limited.
+ *  ==============================================================================
+ *     Licensed under the Apache License, Version 2.0 (the "License");
+ *     you may not use this file except in compliance with the License.
+ *     You may obtain a copy of the License at
+ *
+ *          http://www.apache.org/licenses/LICENSE-2.0
+ *
+ *     Unless required by applicable law or agreed to in writing, software
+ *     distributed under the License is distributed on an "AS IS" BASIS,
+ *     WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ *     See the License for the specific language governing permissions and
+ *     limitations under the License.
+ *     ============LICENSE_END=========================================================
+ *
+ *******************************************************************************/
+package org.onap.slice.analysis.ms.service;
+
+/**
+ * A simple rate-limiter; make sure bandwidth adjustment requests don't swarm underlying network controller
+ */
+class RateLimiter {
+    private int MAX_TOKENS;
+    private long lastRequestTime = System.currentTimeMillis();
+    private long possibleTokens = 0;
+    private long interval = 1000;
+
+    /**
+     * Constructor for rate limiter (simple token bucket filter)
+     * @param maxTokens max number of token allowed
+     * @param interval interval(ms) between received new token
+     */
+    public RateLimiter(int maxTokens, int interval){
+        MAX_TOKENS = maxTokens;
+        this.interval = interval;
+    }
+
+    /**
+     * Trying to get a new token for execution, if no token left, stall for interval ms.
+     * @throws InterruptedException
+     */
+    synchronized public void getToken() throws InterruptedException {
+        possibleTokens += (System.currentTimeMillis() - lastRequestTime) / interval;
+        if (possibleTokens > MAX_TOKENS){
+            possibleTokens = MAX_TOKENS;
+        }
+        if (possibleTokens == 0){
+            Thread.sleep(interval);
+        } else {
+            possibleTokens--;
+        }
+        // granting token
+        lastRequestTime = System.currentTimeMillis();
+    }
+}