The Tor Browser: services/metrics/providermanager.jsm@97036ab72558 (annotated)

services/metrics/providermanager.jsm@97036ab72558 (annotated)

services/metrics/providermanager.jsm

Tue, 06 Jan 2015 21:39:09 +0100

author: Michael Schloh von Bennewitz <michael@schloh.com>
date: Tue, 06 Jan 2015 21:39:09 +0100
branch: TOR_BUG_9701
changeset 8: 97036ab72558
permissions: -rw-r--r--

Conditionally force memory storage according to privacy.thirdparty.isolate;
This solves Tor bug #9701, complying with disk avoidance documented in
https://www.torproject.org/projects/torbrowser/design/#disk-avoidance.

 /* This Source Code Form is subject to the terms of the Mozilla Public
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 "use strict";
 #ifndef MERGED_COMPARTMENT
 this.EXPORTED_SYMBOLS = ["ProviderManager"];
 const {classes: Cc, interfaces: Ci, utils: Cu} = Components;
 Cu.import("resource://gre/modules/services/metrics/dataprovider.jsm");
 #endif
 Cu.import("resource://gre/modules/Promise.jsm");
 Cu.import("resource://gre/modules/Task.jsm");
 Cu.import("resource://gre/modules/Log.jsm");
 Cu.import("resource://services-common/utils.js");
 /**
  * Handles and coordinates the collection of metrics data from providers.
  *
  * This provides an interface for managing `Metrics.Provider` instances. It
  * provides APIs for bulk collection of data.
  */
 this.ProviderManager = function (storage) {
   this._log = Log.repository.getLogger("Services.Metrics.ProviderManager");
   this._providers = new Map();
   this._storage = storage;
   this._providerInitQueue = [];
   this._providerInitializing = false;
   this._pullOnlyProviders = {};
   this._pullOnlyProvidersRegisterCount = 0;
   this._pullOnlyProvidersState = this.PULL_ONLY_NOT_REGISTERED;
   this._pullOnlyProvidersCurrentPromise = null;
   // Callback to allow customization of providers after they are constructed
   // but before they call out into their initialization code.
   this.onProviderInit = null;
 }
 this.ProviderManager.prototype = Object.freeze({
   PULL_ONLY_NOT_REGISTERED: "none",
   PULL_ONLY_REGISTERING: "registering",
   PULL_ONLY_UNREGISTERING: "unregistering",
   PULL_ONLY_REGISTERED: "registered",
   get providers() {
     let providers = [];
     for (let [name, entry] of this._providers) {
       providers.push(entry.provider);
     }
     return providers;
   },
   /**
    * Obtain a provider from its name.
    */
   getProvider: function (name) {
     let provider = this._providers.get(name);
     if (!provider) {
       return null;
     }
     return provider.provider;
   },
   /**
    * Registers providers from a category manager category.
    *
    * This examines the specified category entries and registers found
    * providers.
    *
    * Category entries are essentially JS modules and the name of the symbol
    * within that module that is a `Metrics.Provider` instance.
    *
    * The category entry name is the name of the JS type for the provider. The
    * value is the resource:// URI to import which makes this type available.
    *
    * Example entry:
    *
    *   FooProvider resource://gre/modules/foo.jsm
    *
    * One can register entries in the application's .manifest file. e.g.
    *
    *   category healthreport-js-provider-default FooProvider resource://gre/modules/foo.jsm
    *   category healthreport-js-provider-nightly EyeballProvider resource://gre/modules/eyeball.jsm
    *
    * Then to load them:
    *
    *   let reporter = getHealthReporter("healthreport.");
    *   reporter.registerProvidersFromCategoryManager("healthreport-js-provider-default");
    *
    * If the category has no defined members, this call has no effect, and no error is raised.
    *
    * @param category
    *        (string) Name of category from which to query and load.
    * @return a newly spawned Task.
    */
   registerProvidersFromCategoryManager: function (category) {
     this._log.info("Registering providers from category: " + category);
     let cm = Cc["@mozilla.org/categorymanager;1"]
                .getService(Ci.nsICategoryManager);
     let promises = [];
     let enumerator = cm.enumerateCategory(category);
     while (enumerator.hasMoreElements()) {
       let entry = enumerator.getNext()
                             .QueryInterface(Ci.nsISupportsCString)
                             .toString();
       let uri = cm.getCategoryEntry(category, entry);
       this._log.info("Attempting to load provider from category manager: " +
                      entry + " from " + uri);
       try {
         let ns = {};
         Cu.import(uri, ns);
         let promise = this.registerProviderFromType(ns[entry]);
         if (promise) {
           promises.push(promise);
         }
       } catch (ex) {
         this._recordProviderError(entry,
                                   "Error registering provider from category manager",
                                   ex);
         continue;
       }
     }
     return Task.spawn(function wait() {
       for (let promise of promises) {
         yield promise;
       }
     });
   },
   /**
    * Registers a `MetricsProvider` with this manager.
    *
    * Once a `MetricsProvider` is registered, data will be collected from it
    * whenever we collect data.
    *
    * The returned value is a promise that will be resolved once registration
    * is complete.
    *
    * Providers are initialized as part of registration by calling
    * provider.init().
    *
    * @param provider
    *        (Metrics.Provider) The provider instance to register.
    *
    * @return Promise<null>
    */
   registerProvider: function (provider) {
     // We should perform an instanceof check here. However, due to merged
     // compartments, the Provider type may belong to one of two JSMs
     // isinstance gets confused depending on which module Provider comes
     // from. Some code references Provider from dataprovider.jsm; others from
     // Metrics.jsm.
     if (!provider.name) {
       throw new Error("Provider is not valid: does not have a name.");
     }
     if (this._providers.has(provider.name)) {
       return CommonUtils.laterTickResolvingPromise();
     }
     let deferred = Promise.defer();
     this._providerInitQueue.push([provider, deferred]);
     if (this._providerInitQueue.length == 1) {
       this._popAndInitProvider();
     }
     return deferred.promise;
   },
   /**
    * Registers a provider from its constructor function.
    *
    * If the provider is pull-only, it will be stashed away and
    * initialized later. Null will be returned.
    *
    * If it is not pull-only, it will be initialized immediately and a
    * promise will be returned. The promise will be resolved when the
    * provider has finished initializing.
    */
   registerProviderFromType: function (type) {
     let proto = type.prototype;
     if (proto.pullOnly) {
       this._log.info("Provider is pull-only. Deferring initialization: " +
                      proto.name);
       this._pullOnlyProviders[proto.name] = type;
       return null;
     }
     let provider = this._initProviderFromType(type);
     return this.registerProvider(provider);
   },
   /**
    * Initializes a provider from its type.
    *
    * This is how a constructor function should be turned into a provider
    * instance.
    *
    * A side-effect is the provider is registered with the manager.
    */
   _initProviderFromType: function (type) {
     let provider = new type();
     if (this.onProviderInit) {
       this.onProviderInit(provider);
     }
     return provider;
   },
   /**
    * Remove a named provider from the manager.
    *
    * It is the caller's responsibility to shut down the provider
    * instance.
    */
   unregisterProvider: function (name) {
     this._providers.delete(name);
   },
   /**
    * Ensure that pull-only providers are registered.
    */
   ensurePullOnlyProvidersRegistered: function () {
     let state = this._pullOnlyProvidersState;
     this._pullOnlyProvidersRegisterCount++;
     if (state == this.PULL_ONLY_REGISTERED) {
       this._log.debug("Requested pull-only provider registration and " +
                       "providers are already registered.");
       return CommonUtils.laterTickResolvingPromise();
     }
     // If we're in the process of registering, chain off that request.
     if (state == this.PULL_ONLY_REGISTERING) {
       this._log.debug("Requested pull-only provider registration and " +
                       "registration is already in progress.");
       return this._pullOnlyProvidersCurrentPromise;
     }
     this._log.debug("Pull-only provider registration requested.");
     // A side-effect of setting this is that an active unregistration will
     // effectively short circuit and finish as soon as the in-flight
     // unregistration (if any) finishes.
     this._pullOnlyProvidersState = this.PULL_ONLY_REGISTERING;
     let inFlightPromise = this._pullOnlyProvidersCurrentPromise;
     this._pullOnlyProvidersCurrentPromise =
       Task.spawn(function registerPullProviders() {
       if (inFlightPromise) {
         this._log.debug("Waiting for in-flight pull-only provider activity " +
                         "to finish before registering.");
         try {
           yield inFlightPromise;
         } catch (ex) {
           this._log.warn("Error when waiting for existing pull-only promise: " +
                          CommonUtils.exceptionStr(ex));
         }
       }
       for each (let providerType in this._pullOnlyProviders) {
         // Short-circuit if we're no longer registering.
         if (this._pullOnlyProvidersState != this.PULL_ONLY_REGISTERING) {
           this._log.debug("Aborting pull-only provider registration.");
           break;
         }
         try {
           let provider = this._initProviderFromType(providerType);
           // This is a no-op if the provider is already registered. So, the
           // only overhead is constructing an instance. This should be cheap
           // and isn't worth optimizing.
           yield this.registerProvider(provider);
         } catch (ex) {
           this._recordProviderError(providerType.prototype.name,
                                     "Error registering pull-only provider",
                                     ex);
         }
       }
       // It's possible we changed state while registering. Only mark as
       // registered if we didn't change state.
       if (this._pullOnlyProvidersState == this.PULL_ONLY_REGISTERING) {
         this._pullOnlyProvidersState = this.PULL_ONLY_REGISTERED;
         this._pullOnlyProvidersCurrentPromise = null;
       }
     }.bind(this));
     return this._pullOnlyProvidersCurrentPromise;
   },
   ensurePullOnlyProvidersUnregistered: function () {
     let state = this._pullOnlyProvidersState;
     // If we're not registered, this is a no-op.
     if (state == this.PULL_ONLY_NOT_REGISTERED) {
       this._log.debug("Requested pull-only provider unregistration but none " +
                       "are registered.");
       return CommonUtils.laterTickResolvingPromise();
     }
     // If we're currently unregistering, recycle the promise from last time.
     if (state == this.PULL_ONLY_UNREGISTERING) {
       this._log.debug("Requested pull-only provider unregistration and " +
                  "unregistration is in progress.");
       this._pullOnlyProvidersRegisterCount =
         Math.max(0, this._pullOnlyProvidersRegisterCount - 1);
       return this._pullOnlyProvidersCurrentPromise;
     }
     // We ignore this request while multiple entities have requested
     // registration because we don't want a request from an "inner,"
     // short-lived request to overwrite the desire of the "parent,"
     // longer-lived request.
     if (this._pullOnlyProvidersRegisterCount > 1) {
       this._log.debug("Requested pull-only provider unregistration while " +
                       "other callers still want them registered. Ignoring.");
       this._pullOnlyProvidersRegisterCount--;
       return CommonUtils.laterTickResolvingPromise();
     }
     // We are either fully registered or registering with a single consumer.
     // In both cases we are authoritative and can commence unregistration.
     this._log.debug("Pull-only providers being unregistered.");
     this._pullOnlyProvidersRegisterCount =
       Math.max(0, this._pullOnlyProvidersRegisterCount - 1);
     this._pullOnlyProvidersState = this.PULL_ONLY_UNREGISTERING;
     let inFlightPromise = this._pullOnlyProvidersCurrentPromise;
     this._pullOnlyProvidersCurrentPromise =
       Task.spawn(function unregisterPullProviders() {
       if (inFlightPromise) {
         this._log.debug("Waiting for in-flight pull-only provider activity " +
                         "to complete before unregistering.");
         try {
           yield inFlightPromise;
         } catch (ex) {
           this._log.warn("Error when waiting for existing pull-only promise: " +
                          CommonUtils.exceptionStr(ex));
         }
       }
       for (let provider of this.providers) {
         if (this._pullOnlyProvidersState != this.PULL_ONLY_UNREGISTERING) {
           return;
         }
         if (!provider.pullOnly) {
           continue;
         }
         this._log.info("Shutting down pull-only provider: " +
                        provider.name);
         try {
           yield provider.shutdown();
         } catch (ex) {
           this._recordProviderError(provider.name,
                                     "Error when shutting down provider",
                                     ex);
         } finally {
           this.unregisterProvider(provider.name);
         }
       }
       if (this._pullOnlyProvidersState == this.PULL_ONLY_UNREGISTERING) {
         this._pullOnlyProvidersState = this.PULL_ONLY_NOT_REGISTERED;
         this._pullOnlyProvidersCurrentPromise = null;
       }
     }.bind(this));
     return this._pullOnlyProvidersCurrentPromise;
   },
   _popAndInitProvider: function () {
     if (!this._providerInitQueue.length || this._providerInitializing) {
       return;
     }
     let [provider, deferred] = this._providerInitQueue.shift();
     this._providerInitializing = true;
     this._log.info("Initializing provider with storage: " + provider.name);
     Task.spawn(function initProvider() {
       try {
         let result = yield provider.init(this._storage);
         this._log.info("Provider successfully initialized: " + provider.name);
         this._providers.set(provider.name, {
           provider: provider,
           constantsCollected: false,
         });
         deferred.resolve(result);
       } catch (ex) {
         this._recordProviderError(provider.name, "Failed to initialize", ex);
         deferred.reject(ex);
       } finally {
         this._providerInitializing = false;
         this._popAndInitProvider();
       }
     }.bind(this));
   },
   /**
    * Collects all constant measurements from all providers.
    *
    * Returns a Promise that will be fulfilled once all data providers have
    * provided their constant data. A side-effect of this promise fulfillment
    * is that the manager is populated with the obtained collection results.
    * The resolved value to the promise is this `ProviderManager` instance.
    */
   collectConstantData: function () {
     let entries = [];
     for (let [name, entry] of this._providers) {
       if (entry.constantsCollected) {
         this._log.trace("Provider has already provided constant data: " +
                         name);
         continue;
       }
       entries.push(entry);
     }
     let onCollect = function (entry, result) {
       entry.constantsCollected = true;
     };
     return this._callCollectOnProviders(entries, "collectConstantData",
                                         onCollect);
   },
   /**
    * Calls collectDailyData on all providers.
    */
   collectDailyData: function () {
     return this._callCollectOnProviders(this._providers.values(),
                                         "collectDailyData");
   },
   _callCollectOnProviders: function (entries, fnProperty, onCollect=null) {
     let promises = [];
     for (let entry of entries) {
       let provider = entry.provider;
       let collectPromise;
       try {
         collectPromise = provider[fnProperty].call(provider);
       } catch (ex) {
         this._recordProviderError(provider.name, "Exception when calling " +
                                   "collect function: " + fnProperty, ex);
         continue;
       }
       if (!collectPromise) {
         this._recordProviderError(provider.name, "Does not return a promise " +
                                   "from " + fnProperty + "()");
         continue;
       }
       let promise = collectPromise.then(function onCollected(result) {
         if (onCollect) {
           try {
             onCollect(entry, result);
           } catch (ex) {
             this._log.warn("onCollect callback threw: " +
                            CommonUtils.exceptionStr(ex));
           }
         }
         return CommonUtils.laterTickResolvingPromise(result);
       });
       promises.push([provider.name, promise]);
     }
     return this._handleCollectionPromises(promises);
   },
   /**
    * Handles promises returned by the collect* functions.
    *
    * This consumes the data resolved by the promises and returns a new promise
    * that will be resolved once all promises have been resolved.
    *
    * The promise is resolved even if one of the underlying collection
    * promises is rejected.
    */
   _handleCollectionPromises: function (promises) {
     return Task.spawn(function waitForPromises() {
       for (let [name, promise] of promises) {
         try {
           yield promise;
           this._log.debug("Provider collected successfully: " + name);
         } catch (ex) {
           this._recordProviderError(name, "Failed to collect", ex);
         }
       }
       throw new Task.Result(this);
     }.bind(this));
   },
   /**
    * Record an error that occurred operating on a provider.
    */
   _recordProviderError: function (name, msg, ex) {
     let msg = "Provider error: " + name + ": " + msg;
     if (ex) {
       msg += ": " + CommonUtils.exceptionStr(ex);
     }
     this._log.warn(msg);
     if (this.onProviderError) {
       try {
         this.onProviderError(msg);
       } catch (callError) {
         this._log.warn("Exception when calling onProviderError callback: " +
                        CommonUtils.exceptionStr(callError));
       }
     }
   },
 });

The Tor Browser / annotate

services/metrics/providermanager.jsm@97036ab72558 (annotated)

services/metrics/providermanager.jsm