updated by GasGit automation

scripts/Utils.js

@@ -115,7 +115,145 @@ var Utils = (function (ns) {
   */
   ns.isVanObject = function (value) {
     return typeof value === "object" && !Array.isArray(value);
+  };
+   /**
+  * recursive rateLimitExpBackoff()
+  * @param {function} callBack some function to call that might return rate limit exception
+  * @param {object} options properties as below
+  * @param {number} [attempts=1] optional the attempt number of this instance - usually only used recursively and not user supplied
+  * @param {number} [options.sleepFor=750] optional amount of time to sleep for on the first failure in missliseconds
+  * @param {number} [options.maxAttempts=5] optional maximum number of amounts to try
+  * @param {boolean} [options.logAttempts=true] log re-attempts to Logger
+  * @param {function} [options.checker] function to check whether error is retryable
+  * @param {function} [options.lookahead] function to check response and force retry (passes response,attemprs)
+  * @return {*} results of the callback 
+  */
+  
+  ns.expBackoff = function ( callBack,options,attempts) {
+    
+    //sleepFor = Math.abs(options.sleepFor ||
+    
+    options = options || {};
+    optionsDefault = { 
+      sleepFor:  750,
+      maxAttempts:5,                  
+      checker:errorQualifies,
+      logAttempts:true
     }
     
+    // mixin
+    Object.keys(optionsDefault).forEach(function(k) {
+      if (!options.hasOwnProperty(k)) {
+        options[k] = optionsDefault[k];
+      }
+    });
+    
+    
+    // for recursion
+    attempts = attempts || 1;
+    
+    // make sure that the checker is really a function
+    if (typeof(options.checker) !== "function") {
+      throw ns.errorStack("if you specify a checker it must be a function");
+    }
+    
+    // check properly constructed
+    if (!callBack || typeof(callBack) !== "function") {
+      throw ns.errorStack("you need to specify a function for rateLimitBackoff to execute");
+    }
+    
+    function waitABit (theErr) {
+      
+      //give up?
+      if (attempts > options.maxAttempts) {
+        throw errorStack(theErr + " (tried backing off " + (attempts-1) + " times");
+      }
+      else {
+        // wait for some amount of time based on how many times we've tried plus a small random bit to avoid races
+        Utilities.sleep (
+          Math.pow(2,attempts)*options.sleepFor + 
+          Math.round(Math.random() * options.sleepFor)
+        );
+        
+      }
+    }
+    
+    // try to execute it
+    try {
+      var response = callBack(options, attempts);
+      
+      // maybe not throw an error but is problem nevertheless
+      if (options.lookahead && options.lookahead(response,attempts)) {
+        if(options.logAttempts) { 
+          Logger.log("backoff lookahead:" + attempts);
+        }
+        waitABit('lookahead:');
+        return ns.expBackoff ( callBack, options, attempts+1) ;
+        
+      }
+      return response;
+    }
+    
+    // there was an error
+    catch(err) {
+      
+      if(options.logAttempts) { 
+        Logger.log("backoff " + attempts + ":" +err);
+      }
+      
+      // failed due to rate limiting?
+      if (options.checker(err)) {
+        waitABit(err);
+        return ns.expBackoff ( callBack, options, attempts+1) ;
+      }
+      else {
+        // some other error
+        throw ns.errorStack(err);
+      }
+    }
+    
+    
+  }
+  
+  /**
+  * get the stack
+  * @param {Error} e the error
+  * @return {string} the stack trace
+  */
+  ns.errorStack = function  (e) {
+    try {
+      // throw a fake error
+      throw new Error();  //x is undefined and will fail under use struct- ths will provoke an error so i can get the call stack
+    }
+    catch(err) {
+      return 'Error:' + e + '\n' + err.stack.split('\n').slice(1).join('\n');
+    }
+  }
+  
+  
+  // default checker
+  function errorQualifies (errorText) {
+    
+    return ["Exception: Service invoked too many times",
+            "Exception: Rate Limit Exceeded",
+            "Exception: Quota Error: User Rate Limit Exceeded",
+            "Service error:",
+            "Exception: Service error:", 
+            "Exception: User rate limit exceeded",
+            "Exception: Internal error. Please try again.",
+            "Exception: Cannot execute AddColumn because another task",
+            "Service invoked too many times in a short time:",
+            "Exception: Internal error.",
+            "User Rate Limit Exceeded",
+            "Exception: ???????? ?????: DriveApp.",
+            "Exception: Address unavailable"
+           ]
+    .some(function(e){
+      return  errorText.toString().slice(0,e.length) == e  ;
+    }) ;
+    
+  };
+  
+
   return ns;
 })(Utils || {});