Merge pull request #7231 from cpitchford/wip/cpitchford/synchronize_d…

…excom_fetch_times

Optimize time between polling share2nightscout-bridge to reduce ingest lag

lib/plugins/bridge.js

@@ -24,6 +24,7 @@ function bridged (entries) {
             mostRecentRecord = glucose[i].date;
           }
         }
+        //console.log("DEXCOM: Most recent entry received; "+new Date(mostRecentRecord).toString());
       }
       entries.create(glucose, function stored (err) {
         if (err) {
@@ -46,12 +47,12 @@ function options (env) {
     , minutes: env.extendedSettings.bridge.minutes || 1440
   };
 
-  var interval = env.extendedSettings.bridge.interval || 60000 * 2.5; // Default: 2.5 minutes
+  var interval = env.extendedSettings.bridge.interval || 60000 * 2.6; // Default: 2.6 minutes
 
   if (interval < 1000 || interval > 300000) {
         // Invalid interval range. Revert to default
-        console.error("Invalid interval set: [" + interval + "ms]. Defaulting to 2.5 minutes.")
-        interval = 60000 * 2.5 // 2.5 minutes
+        console.error("Invalid interval set: [" + interval + "ms]. Defaulting to 2.6 minutes.")
+        interval = 60000 * 2.6 // 2.6 minutes
   }
 
   return {
@@ -75,15 +76,53 @@ function create (env, bus) {
 
   bridge.startEngine = function startEngine (entries) {
 
+
     opts.callback = bridged(entries);
 
+    let last_run = new Date(0).getTime();
+    let last_ondemand = new Date(0).getTime();
+
+    function should_run() {
+      // Time we expect to have to collect again
+      const msRUN_AFTER = (300+20) * 1000;
+      const msNow = new Date().getTime();
+
+      const next_entry_expected = mostRecentRecord + msRUN_AFTER;
+
+      if (next_entry_expected > msNow) {
+        // we're not due to collect a new slot yet. Use interval
+        const ms_since_last_run = msNow - last_run;
+        if (ms_since_last_run < interval) {
+          return false;
+        }
+
+        last_run = msNow;
+        last_ondemand = new Date(0).getTime();
+        console.log("DEXCOM: Running poll");
+        return true;
+      }
+
+      const ms_since_last_run = msNow - last_ondemand;
+
+      if (ms_since_last_run < interval) {
+        return false;
+      }
+      last_run = msNow;
+      last_ondemand = msNow;
+      console.log("DEXCOM: Data due, running extra poll");
+      return true;
+    }
+
     let timer = setInterval(function () {
+      if  (!should_run()) return;
+
+
       opts.fetch.minutes = parseInt((new Date() - mostRecentRecord) / 60000);
       opts.fetch.maxCount = parseInt((opts.fetch.minutes / 5) + 1);
       opts.firstFetchCount = opts.fetch.maxCount;
       console.log("Fetching Share Data: ", 'minutes', opts.fetch.minutes, 'maxCount', opts.fetch.maxCount);
       engine(opts);
-    }, interval);
+    }, 1000 /*interval*/);
 
     if (bus) {
       bus.on('teardown', function serverTeardown () {

tests/bridge.test.js

@@ -51,7 +51,7 @@ describe('bridge', function ( ) {
     var opts = bridge.options(tooLowInterval);
     should.exist(opts);
 
-    opts.interval.should.equal(150000);
+    opts.interval.should.equal(156000);
   });
 
   it('set too high bridge interval option from env', function () {
@@ -64,7 +64,7 @@ describe('bridge', function ( ) {
     var opts = bridge.options(tooHighInterval);
     should.exist(opts);
 
-    opts.interval.should.equal(150000);
+    opts.interval.should.equal(156000);
   });
 
   it('set no bridge interval option from env', function () {
@@ -77,7 +77,7 @@ describe('bridge', function ( ) {
     var opts = bridge.options(noInterval);
     should.exist(opts);
 
-    opts.interval.should.equal(150000);
+    opts.interval.should.equal(156000);
   });
 
 });