Bug 836186 - Don't load FHR providers until they are used; r=rnewman

services/healthreport/healthreporter.jsm

@@ -129,6 +129,8 @@ function HealthReporter(branch, policy, sessionRecorder) {
   this._shutdownComplete = false;
   this._shutdownCompleteCallback = null;
 
+  this._constantOnlyProviders = {};
+
   this._ensureDirectoryExists(this._stateDir)
       .then(this._onStateDirCreated.bind(this),
             this._onInitError.bind(this));
@@ -549,10 +551,15 @@ HealthReporter.prototype = Object.freeze({
         let ns = {};
         Cu.import(uri, ns);
 
-        let provider = new ns[entry]();
-        provider.initPreferences(this._branch + "provider.");
-        provider.healthReporter = this;
-        promises.push(this.registerProvider(provider));
+        let proto = ns[entry].prototype;
+        if (proto.constantOnly) {
+          this._log.info("Provider is constant-only. Deferring initialization: " +
+                         proto.name);
+          this._constantOnlyProviders[proto.name] = ns[entry];
+        } else {
+          let provider = this.initProviderFromType(ns[entry]);
+          promises.push(this.registerProvider(provider));
+        }
       } catch (ex) {
         this._log.warn("Error registering provider from category manager: " +
                        entry + "; " + CommonUtils.exceptionStr(ex));
@@ -567,11 +574,54 @@ HealthReporter.prototype = Object.freeze({
     });
   },
 
+  initProviderFromType: function (providerType) {
+    let provider = new providerType();
+    provider.initPreferences(this._branch + "provider.");
+    provider.healthReporter = this;
+
+    return provider;
+  },
+
   /**
    * Collect all measurements for all registered providers.
    */
   collectMeasurements: function () {
-    return this._collector.collectConstantData();
+    return Task.spawn(function doCollection() {
+      for each (let providerType in this._constantOnlyProviders) {
+        try {
+          let provider = this.initProviderFromType(providerType);
+          yield this.registerProvider(provider);
+        } catch (ex) {
+          this._log.warn("Error registering constant-only provider: " +
+                         CommonUtils.exceptionStr(ex));
+        }
+      }
+
+      let result;
+      try {
+        result = yield this._collector.collectConstantData();
+      } finally {
+        for (let provider of this._collector.providers) {
+          if (!provider.constantOnly) {
+            continue;
+          }
+
+          this._log.info("Shutting down constant-only provider: " +
+                         provider.name);
+
+          try {
+            yield provider.shutdown();
+          } catch (ex) {
+            this._log.warn("Error when shutting down provider: " +
+                           CommonUtils.exceptionStr(ex));
+          } finally {
+            this._collector.unregisterProvider(provider.name);
+          }
+        }
+      }
+
+      throw new Task.Result(result);
+    }.bind(this));
   },
 
   /**

services/healthreport/profile.jsm

@@ -214,6 +214,8 @@ ProfileMetadataProvider.prototype = {
 
   measurementTypes: [ProfileMetadataMeasurement],
 
+  constantOnly: true,
+
   getProfileCreationDays: function () {
     let accessor = new ProfileCreationTimeAccessor(null, this._log);
 

services/healthreport/providers.jsm

@@ -121,6 +121,8 @@ AppInfoProvider.prototype = Object.freeze({
 
   measurementTypes: [AppInfoMeasurement, AppVersionMeasurement],
 
+  constantOnly: true,
+
   appInfoFields: {
     // From nsIXULAppInfo.
     vendor: "vendor",
@@ -296,6 +298,8 @@ SysInfoProvider.prototype = Object.freeze({
 
   measurementTypes: [SysInfoMeasurement],
 
+  constantOnly: true,
+
   sysInfoFields: {
     cpucount: "cpuCount",
     memsize: "memoryMB",
@@ -477,6 +481,8 @@ SessionsProvider.prototype = Object.freeze({
 
   measurementTypes: [CurrentSessionMeasurement, PreviousSessionsMeasurement],
 
+  constantOnly: true,
+
   collectConstantData: function () {
     let previous = this.getMeasurement("previous", 2);
 
@@ -746,6 +752,8 @@ CrashesProvider.prototype = Object.freeze({
 
   measurementTypes: [DailyCrashesMeasurement],
 
+  constantOnly: true,
+
   collectConstantData: function () {
     return Task.spawn(this._populateCrashCounts.bind(this));
   },

services/healthreport/tests/xpcshell/test_healthreporter.js

@@ -171,6 +171,39 @@ add_task(function test_register_providers_from_category_manager() {
   reporter._shutdown();
 });
 
+// Constant only providers are only initialized at constant collect
+// time.
+add_task(function test_constant_only_providers() {
+  const category = "healthreporter-constant-only";
+
+  let cm = Cc["@mozilla.org/categorymanager;1"]
+             .getService(Ci.nsICategoryManager);
+  cm.addCategoryEntry(category, "DummyProvider",
+                      "resource://testing-common/services/metrics/mocks.jsm",
+                      false, true);
+  cm.addCategoryEntry(category, "DummyConstantProvider",
+                      "resource://testing-common/services/metrics/mocks.jsm",
+                      false, true);
+
+  let reporter = yield getReporter("constant_only_providers");
+  do_check_eq(reporter._collector._providers.size, 0);
+  yield reporter.registerProvidersFromCategoryManager(category);
+  do_check_eq(reporter._collector._providers.size, 1);
+  do_check_true(reporter._storage.hasProvider("DummyProvider"));
+  do_check_false(reporter._storage.hasProvider("DummyConstantProvider"));
+
+  yield reporter.collectMeasurements();
+
+  do_check_eq(reporter._collector._providers.size, 1);
+  do_check_true(reporter._storage.hasProvider("DummyConstantProvider"));
+
+  let mID = reporter._storage.measurementID("DummyConstantProvider", "DummyMeasurement", 1);
+  let values = yield reporter._storage.getMeasurementValues(mID);
+  do_check_true(values.singular.size > 0);
+
+  reporter._shutdown();
+});
+
 add_task(function test_json_payload_simple() {
   let reporter = yield getReporter("json_payload_simple");
 

services/metrics/collector.jsm

@@ -81,6 +81,16 @@ Collector.prototype = Object.freeze({
     return deferred.promise;
   },
 
+  /**
+   * Remove a named provider from the collector.
+   *
+   * It is the caller's responsibility to shut down the provider
+   * instance.
+   */
+  unregisterProvider: function (name) {
+    this._providers.delete(name);
+  },
+
   _popAndInitProvider: function () {
     if (!this._providerInitQueue.length || this._providerInitializing) {
       return;

services/metrics/dataprovider.jsm

@@ -391,6 +391,20 @@ this.Provider = function () {
 }
 
 Provider.prototype = Object.freeze({
+  /**
+   * Whether the provider provides only constant data.
+   *
+   * If this is true, the provider likely isn't instantiated until
+   * `collectConstantData` is called and the provider may be torn down after
+   * this function has finished.
+   *
+   * This is an optimization so provider instances aren't dead weight while the
+   * application is running.
+   *
+   * This must be set on the prototype for the optimization to be realized.
+   */
+  constantOnly: false,
+
   /**
    * Obtain a `Measurement` from its name and version.
    *

services/metrics/modules-testing/mocks.jsm

@@ -7,6 +7,7 @@
 this.EXPORTED_SYMBOLS = [
   "DummyMeasurement",
   "DummyProvider",
+  "DummyConstantProvider",
 ];
 
 const {utils: Cu} = Components;
@@ -87,3 +88,14 @@ DummyProvider.prototype = {
 
 };
 
+
+this.DummyConstantProvider = function () {
+  DummyProvider.call(this, "DummyConstantProvider");
+}
+
+DummyConstantProvider.prototype = {
+  __proto__: DummyProvider.prototype,
+
+  constantOnly: true,
+};
+

services/metrics/tests/xpcshell/test_metrics_collector.js

@@ -42,6 +42,9 @@ add_task(function test_register_provider() {
     failed = false;
   }
 
+  collector.unregisterProvider(dummy.name);
+  do_check_eq(collector._providers.size, 0);
+
   yield storage.close();
 });