Update static assets only if enough time elapsed

Instead of unconditionally on every extension startup.

src/js/background.js

@@ -68,8 +68,8 @@ function Badger(from_qunit) {
     self.setPrivacyOverrides();
 
     // kick off async initialization steps
-    let ylistPromise = self.initializeYellowlist().catch(console.error),
-      dntHashesPromise = self.initializeDnt().catch(console.error),
+    let ylistPromise = self.initYellowlist().catch(console.error),
+      dntHashesPromise = self.initDntPolicyHashes().catch(console.error),
       tabDataPromise = self.tabData.initialize().catch(console.error);
 
     // async load known CNAME domain aliases (but don't wait on them)
@@ -123,23 +123,8 @@ function Badger(from_qunit) {
     console.log("Set DEBUG=1 to view console messages.");
     self.INITIALIZED = true;
 
-    // get the latest yellowlist from eff.org
-    self.updateYellowlist(err => {
-      if (err) {
-        console.error(err);
-      }
-    });
-    // set up periodic fetching of the yellowlist from eff.org
-    setInterval(self.updateYellowlist.bind(self), utils.oneDay());
-
-    // get the latest DNT policy hashes from eff.org
-    self.updateDntPolicyHashes(err => {
-      if (err) {
-        console.error(err);
-      }
-    });
-    // set up periodic fetching of hashes from eff.org
-    setInterval(self.updateDntPolicyHashes.bind(self), utils.oneDay() * 4);
+    self.initYellowlistUpdates();
+    self.initDntPolicyUpdates();
   }
 
   /**
@@ -458,7 +443,7 @@ Badger.prototype = {
    *
    * @returns {Promise}
    */
-  initializeYellowlist: function () {
+  initYellowlist: function () {
     let self = this;
 
     return new Promise(function (resolve, reject) {
@@ -484,6 +469,31 @@ Badger.prototype = {
     });
   },
 
+  /**
+   * Checks if it's time to fetch the latest yellowlist from eff.org.
+   * If it isn't yet time, schedules the next update for when it is.
+   */
+  initYellowlistUpdates: function () {
+    let self = this,
+      next_update_time = self.getPrivateSettings().getItem('nextYellowlistUpdateTime'),
+      time_now = Date.now();
+
+    if (time_now < next_update_time) {
+      let msec_remaining = next_update_time - time_now;
+      log("Not yet time to update yellowlist; next update in %s mins",
+        Math.round(msec_remaining / 1000 / 60));
+      // schedule an update for when the extension remains running that long
+      setTimeout(self.updateYellowlist.bind(self), msec_remaining);
+      return;
+    }
+
+    self.updateYellowlist(err => {
+      if (err) {
+        console.error(err);
+      }
+    });
+  },
+
   /**
    * Updates to the latest yellowlist from eff.org.
    * @param {Function} [callback] optional callback
@@ -541,6 +551,11 @@ Badger.prototype = {
       self.storage.updateYellowlist(domains);
       log("Updated yellowlist from remote");
 
+      // refresh next update time so that we don't update too often when the extension gets restarted
+      self.getPrivateSettings().setItem('nextYellowlistUpdateTime', utils.oneDayFromNow());
+      // schedule the next update for when the extension keeps running without restarts
+      setTimeout(self.updateYellowlist.bind(self), utils.oneDay());
+
       return callback(null);
     });
   },
@@ -550,7 +565,7 @@ Badger.prototype = {
    *
    * @returns {Promise}
    */
-  initializeDnt: function () {
+  initDntPolicyHashes: function () {
     let self = this;
 
     return new Promise(function (resolve, reject) {
@@ -586,6 +601,31 @@ Badger.prototype = {
     });
   },
 
+  /**
+   * Checks if it's time to get the latest EFF DNT policy hashes from eff.org.
+   * If it isn't yet time, schedules the next update for when it is.
+   */
+  initDntPolicyUpdates: function () {
+    let self = this,
+      next_update_time = self.getPrivateSettings().getItem('nextDntHashesUpdateTime'),
+      time_now = Date.now();
+
+    if (time_now < next_update_time) {
+      let msec_remaining = next_update_time - time_now;
+      log("Not yet time to update DNT hashes; next update in %s mins",
+        Math.round(msec_remaining / 1000 / 60));
+      // schedule an update for when the extension remains running that long
+      setTimeout(self.updateDntPolicyHashes.bind(self), msec_remaining);
+      return;
+    }
+
+    self.updateDntPolicyHashes(err => {
+      if (err) {
+        console.error(err);
+      }
+    });
+  },
+
   /**
    * Fetch acceptable DNT policy hashes from the EFF server
    * @param {Function} [cb] optional callback
@@ -621,6 +661,12 @@ Badger.prototype = {
 
       self.storage.updateDntHashes(hashes);
       log("Updated hashes from remote");
+
+      // refresh next update time so that we don't update too often when the extension gets restarted
+      self.getPrivateSettings().setItem('nextDntHashesUpdateTime', utils.nDaysFromNow(4));
+      // schedule the next update for when the extension keeps running without restarts
+      setTimeout(self.updateDntPolicyHashes.bind(self), utils.oneDay() * 4);
+
       return cb(null);
     });
   },
@@ -762,6 +808,8 @@ Badger.prototype = {
     let privateDefaultSettings = {
       blockThreshold: constants.TRACKING_THRESHOLD,
       firstRunTimerFinished: true,
+      nextDntHashesUpdateTime: 0,
+      nextYellowlistUpdateTime: 0,
       showLearningPrompt: false,
       shownBreakageNotes: [],
     };