Make max retry duration configurable

saukk900 · Oct 14, 2015 · 5981f46 · 5981f46
1 parent fde60cc
commit 5981f46
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Showing 3 changed files with 32 additions and 8 deletions.
diff --git a/README.md b/README.md
@@ -34,6 +34,7 @@
 
 * `CARELINK_REQUEST_INTERVAL` - number of milliseconds to wait between requests to the CareLink server (default: 60000)
 * `CARELINK_SGV_LIMIT` - maximum number of recent sensor glucose values to send to Nightscout (default: 24)
+* `CARELINK_MAX_RETRY_DURATION` - maximum number of seconds to spend retrying failed requests to CareLink, ideally a power of 2 (default: 512)
 * `NS` - a fully-qualified Nightscout URL (e.g. `https://sitename.azurewebsites.net`) which overrides `WEBSITE_HOSTNAME`
 
 ## Currently supported data

diff --git a/carelink.js b/carelink.js
@@ -8,13 +8,15 @@ var common = require('common'),
 
 var logger = require('./logger');
 
+var DEFAULT_MAX_RETRY_DURATION = module.exports.defaultMaxRetryDuration = 512;
+
 var CARELINK_SECURITY_URL = 'https://carelink.minimed.com/patient/j_security_check';
 var CARELINK_AFTER_LOGIN_URL = 'https://carelink.minimed.com/patient/main/login.do';
+var CARELINK_JSON_BASE_URL = 'https://carelink.minimed.com/patient/connect/ConnectViewerServlet?cpSerialNumber=NONE&msgType=last24hours&requestTime=';
 var CARELINK_LOGIN_COOKIE = '_WL_AUTHCOOKIE_JSESSIONID';
-var MAX_RETRY_COUNT = 10;
 
 var carelinkJsonUrlNow = function() {
-  return 'https://carelink.minimed.com/patient/connect/ConnectViewerServlet?cpSerialNumber=NONE&msgType=last24hours&requestTime=' + Date.now();
+  return CARELINK_JSON_BASE_URL + Date.now();
 };
 
 function reqOptions(extra) {
@@ -55,13 +57,29 @@ function checkResponseThen(fn) {
   };
 }
 
+function retryDurationOnAttempt(n) {
+  return Math.pow(2, n);
+}
+
+function totalDurationAfterNextRetry(n) {
+  var sum = 0;
+  for(var i = 0; i <= n; i++) {
+    sum += retryDurationOnAttempt(i);
+  }
+  return sum;
+}
+
 var Client = exports.Client = function (options) {
   if (!(this instanceof Client)) {
     return new Client(arguments[0]);
   }
 
   var jar = request.jar();
 
+  if (options.maxRetryDuration === undefined) {
+    options.maxRetryDuration = DEFAULT_MAX_RETRY_DURATION;
+  }
+
   function doLogin(next) {
     logger.log('POST ' + CARELINK_SECURITY_URL);
     request.post(
@@ -94,11 +112,11 @@ var Client = exports.Client = function (options) {
           logger.log(err);
           if (retryCount === undefined ) {
             retryCount = 0;
-          } else if (retryCount >= MAX_RETRY_COUNT) {
-            logger.log('Retried too many times.');
+          } else if (totalDurationAfterNextRetry(retryCount) >= options.maxRetryDuration) {
+            logger.log('Retried for too long (' + totalDurationAfterNextRetry(retryCount - 1) + ' seconds).');
             next(err);
           }
-          var timeout = Math.pow(2, retryCount);
+          var timeout = retryDurationOnAttempt(retryCount);
           logger.log('Trying again in ' + timeout + ' second(s)...');
           setTimeout(function() {
             getConnectData(response, next, retryCount + 1);

diff --git a/run.js b/run.js
@@ -20,8 +20,9 @@ var config = {
   nsHost: readEnv('WEBSITE_HOSTNAME'),
   nsBaseUrl: readEnv('NS'),
   nsSecret: readEnv('API_SECRET'),
-  interval: parseInt(readEnv('CARELINK_REQUEST_INTERVAL', 60 * 1000)),
-  sgvLimit: parseInt(readEnv('CARELINK_SGV_LIMIT', 24))
+  interval: parseInt(readEnv('CARELINK_REQUEST_INTERVAL', 60 * 1000), 10),
+  sgvLimit: parseInt(readEnv('CARELINK_SGV_LIMIT', 24), 10),
+  maxRetryDuration: parseInt(readEnv('CARELINK_MAX_RETRY_DURATION', carelink.defaultMaxRetryDuration), 10)
 };
 
 if (!config.username) {
@@ -30,7 +31,11 @@ if (!config.username) {
   throw new Error('Missing CareLink password');
 }
 
-var client = carelink.Client({username: config.username, password: config.password});
+var client = carelink.Client({
+  username: config.username,
+  password: config.password,
+  maxRetryDuration: config.maxRetryDuration
+});
 var endpoint = (config.nsBaseUrl ? config.nsBaseUrl : 'https://' + config.nsHost) + '/api/v1/entries.json';
 
 (function requestLoop() {