Reusable retry function for RESTMessage - Retries a given function multiple times with a delay between each attempt. (#1111)

Co-authored-by: Templeton Tsai <[email protected]>

Author: templetontsai

RESTMessageV2/Reusable RESTMessageV2 retry pattern/Readme.md

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+# Function: `retry(func, retries, delayTime)`
+
+Retries a given function multiple times with a delay between each attempt.
+
+## Parameters
+
+- **`func`** (`Function`): The function to be executed and potentially retried on failure.
+- **`retries`** (`number`): The number of times to retry the function if it fails or returns a null/undefined result.
+- **`delayTime`** (`number`): The delay time between retries, in milliseconds.
+
+## Returns
+
+- **`any`**: Returns the result of the function if successful within the allowed retries; otherwise, returns the last result (which may be `null` or `undefined`).
+
+## Description
+
+The function attempts to execute the provided `func()` and checks for a non-null result. If the result is null or an exception occurs, it retries the function up to the specified `retries`, with a delay of `delayTime` milliseconds between each attempt.
+
+## Example Usage
+
+```javascript
+function getToken() {
+    // Simulated operation that might fail
+    var request = new sn_ws.RESTMessageV2("token", "GET");
+    var response = request.execute();
+    var statusCode = response.getStatusCode();
+    var result = null;
+    switch(statusCode) {
+        case 200:
+            result = JSON.parse(response.getBody());
+            break;
+        default:
+            throw new Error("request failed, http status code: " + statusCode);
+    }
+    return result;
+}
+
+var result = retry(getToken, 3, 2000);  // Try 3 times, with a 2-second delay between each attempt
+gs.info("Operation result: " + result);
+```

RESTMessageV2/Reusable RESTMessageV2 retry pattern/ReusableRESTMesaageV2Retry.js

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+/**
+ * Retries a given function multiple times with a delay between each attempt.
+ *
+ * @param {Function} func - The function to be executed and potentially retried on failure.
+ * @param {number} retries - The number of times to retry the function if it fails or returns a null/undefined result.
+ * @param {number} delayTime - The delay time between retries, in milliseconds.
+ * 
+ * @returns {any} - Returns the result of the function if successful within the allowed retries; 
+ *                  otherwise, returns the last result (which may be null or undefined).
+ *
+ * The function attempts to execute the provided `func()` and checks for a non-null result. If the result is null
+ * or an exception occurs, it retries the function up to the specified `retries`, with a delay of `delayTime`
+ * milliseconds between each attempt.
+ *
+ * Example usage:
+ * 
+ * function getToken() {
+ *     // Simulated operation that might fail
+ *     var request = new sn_ws.RESTMessageV2("token", "GET");
+ *     var response = request.execute();
+ *     var statusCode = response.getStatusCode();
+ *     var result = null;
+ *     switch(statusCode) {
+ *         case 200:
+ *             result = JSON.parse(response.getBody());
+ *             break;
+ *         default:
+ *             throw new Error("request failed, http status code: " + statusCode);
+ *     }
+ *     return result;
+ * }
+ * 
+ * var result = retry(getToken, 3, 2000);  // Try 3 times, with a 2-second delay between each attempt
+ * gs.info("Operation result: " + result);
+ */
+function retry(func, retires, delayTime) {
+    var result = null;
+    for(var i = 0; i < retires; i++) {
+        try {
+            result = func();
+            //error handling could depending on the implementation of func
+            if(!gs.nil(result)) return result;
+        } catch (error) {
+            gs.error(error);
+        }
+        gs.sleep(delayTime);
+    }
+    return result;
+}
+
+