Bug 1505522: Part 1 - Wait for async reports from gatherMemory() to complete when assembling pings. r=chutten

Several call sites assume that gatherMemory() does all of its work
synchronously. This is not true as it is, and will be even less true after my
subsequent patches.

This patch changes gatherMemory() to return a promise which resolves when all
of its in-process work is done, and changes two call sites to wait for it to
resolve before continuing.

One remaining call site, unfortunately, needs to return ping data
synchronously, and therefore cannot wait for async work to complete.

Differential Revision: https://phabricator.services.mozilla.com/D13871

--HG--
extra : rebase_source : 8f417bc042b0ca1917e6ef8e396f6cb52d079df4

Author: kmaglione

toolkit/components/telemetry/other/MemoryTelemetry.jsm

@@ -130,7 +130,7 @@ var Impl = {
             getService(Ci.nsIMemoryReporterManager);
     } catch (e) {
       // OK to skip memory reporters in xpcshell
-      return;
+      return Promise.resolve();
     }
 
     let histogram = Telemetry.getHistogramById("TELEMETRY_MEMORY_REPORTER_MS");
@@ -176,7 +176,7 @@ var Impl = {
     c("GHOST_WINDOWS", "ghostWindows");
 
     if (!Telemetry.canRecordExtended) {
-      return;
+      return Promise.resolve();
     }
 
     b("MEMORY_VSIZE", "vsize");
@@ -196,14 +196,18 @@ var Impl = {
     cc("LOW_MEMORY_EVENTS_PHYSICAL", "lowMemoryEventsPhysical");
     cc("PAGE_FAULTS_HARD", "pageFaultsHard");
 
-    try {
-      mgr.getHeapAllocatedAsync(heapAllocated => {
-        boundHandleMemoryReport("MEMORY_HEAP_ALLOCATED",
-                                Ci.nsIMemoryReporter.UNITS_BYTES,
-                                heapAllocated);
-      });
-    } catch (e) {
-    }
+    let promise = new Promise(resolve => {
+      try {
+        mgr.getHeapAllocatedAsync(heapAllocated => {
+          boundHandleMemoryReport("MEMORY_HEAP_ALLOCATED",
+                                  Ci.nsIMemoryReporter.UNITS_BYTES,
+                                  heapAllocated);
+          resolve();
+        });
+      } catch (e) {
+        resolve();
+      }
+    });
 
     if (!Utils.isContentProcess && !this._totalMemoryTimeout) {
       // Only the chrome process should gather total memory
@@ -240,6 +244,8 @@ var Impl = {
     }
 
     histogram.add(new Date() - startTime);
+
+    return promise;
   },
 
   handleMemoryReport(id, units, amount, key) {

toolkit/components/telemetry/pings/TelemetrySession.jsm

@@ -1048,10 +1048,10 @@ var Impl = {
   /**
    * Send data to the server. Record success/send-time in histograms
    */
-  send: function send(reason) {
+  send: async function send(reason) {
     this._log.trace("send - Reason " + reason);
     // populate histograms one last time
-    MemoryTelemetry.gatherMemory();
+    await MemoryTelemetry.gatherMemory();
 
     const isSubsession = !this._isClassicReason(reason);
     let payload = this.getSessionPayload(reason, isSubsession);
@@ -1138,7 +1138,7 @@ var Impl = {
         await TelemetryStorage.saveSessionData(this._getSessionDataObject());
 
         this.addObserver("idle-daily");
-        MemoryTelemetry.gatherMemory();
+        await MemoryTelemetry.gatherMemory();
 
         Telemetry.asyncFetchTelemetryData(function() {});