retry interval (#7146)

Author: RoshanKumarMicrosoft

Tasks/Common/azure-arm-rest/webClient.ts

@@ -43,17 +43,17 @@ export class WebRequestOptions {
 export async function sendRequest(request: WebRequest, options?: WebRequestOptions): Promise<WebResponse> {
     let i = 0;
     let retryCount = options && options.retryCount ? options.retryCount : 5;
-    let retryIntervalInSeconds = options && options.retryIntervalInSeconds ? options.retryIntervalInSeconds : 5;
+    let retryIntervalInSeconds = options && options.retryIntervalInSeconds ? options.retryIntervalInSeconds : 2;
     let retriableErrorCodes = options && options.retriableErrorCodes ? options.retriableErrorCodes : ["ETIMEDOUT", "ECONNRESET", "ENOTFOUND", "ESOCKETTIMEDOUT", "ECONNREFUSED", "EHOSTUNREACH", "EPIPE", "EA_AGAIN"];
     let retriableStatusCodes = options && options.retriableStatusCodes ? options.retriableStatusCodes: [408, 409, 500, 502, 503, 504];
-
+    let timeToWait : number = retryIntervalInSeconds;
     while (true) {
         try {
             let response: WebResponse = await sendRequestInternal(request);
             if(retriableStatusCodes.indexOf(response.statusCode) != -1 && ++i < retryCount) {
-                
                 tl.debug(util.format("Encountered a retriable status code: %s. Message: '%s'.", response.statusCode, response.statusMessage));
-                await sleepFor(retryIntervalInSeconds);
+                await sleepFor(timeToWait);
+                timeToWait = timeToWait * retryIntervalInSeconds + retryIntervalInSeconds;
                 continue;
             }
 
@@ -62,7 +62,8 @@ export async function sendRequest(request: WebRequest, options?: WebRequestOptio
         catch (error) {
             if (retriableErrorCodes.indexOf(error.code) != -1 && ++i < retryCount) {
                 tl.debug(util.format("Encountered a retriable error:%s. Message: %s.", error.code, error.message));
-                await sleepFor(retryIntervalInSeconds);
+                await sleepFor(timeToWait);
+                timeToWait = timeToWait * retryIntervalInSeconds + retryIntervalInSeconds;
             }
             else {
                 if (error.code) {