diff -r 000000000000 -r 6474c204b198 services/metrics/dataprovider.jsm
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/services/metrics/dataprovider.jsm	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,727 @@
+/* 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 = [
+  "Measurement",
+  "Provider",
+];
+
+const {utils: Cu} = Components;
+
+const MILLISECONDS_PER_DAY = 24 * 60 * 60 * 1000;
+
+#endif
+
+Cu.import("resource://gre/modules/Promise.jsm");
+Cu.import("resource://gre/modules/Preferences.jsm");
+Cu.import("resource://gre/modules/Task.jsm");
+Cu.import("resource://gre/modules/Log.jsm");
+Cu.import("resource://services-common/utils.js");
+
+
+
+/**
+ * Represents a collection of related pieces/fields of data.
+ *
+ * This is an abstract base type.
+ *
+ * This type provides the primary interface for storing, retrieving, and
+ * serializing data.
+ *
+ * Each measurement consists of a set of named fields. Each field is primarily
+ * identified by a string name, which must be unique within the measurement.
+ *
+ * Each derived type must define the following properties:
+ *
+ *   name -- String name of this measurement. This is the primary way
+ *     measurements are distinguished within a provider.
+ *
+ *   version -- Integer version of this measurement. This is a secondary
+ *     identifier for a measurement within a provider. The version denotes
+ *     the behavior of this measurement and the composition of its fields over
+ *     time. When a new field is added or the behavior of an existing field
+ *     changes, the version should be incremented. The initial version of a
+ *     measurement is typically 1.
+ *
+ *   fields -- Object defining the fields this measurement holds. Keys in the
+ *     object are string field names. Values are objects describing how the
+ *     field works. The following properties are recognized:
+ *
+ *       type -- The string type of this field. This is typically one of the
+ *         FIELD_* constants from the Metrics.Storage type.
+ *
+ *
+ * FUTURE: provide hook points for measurements to supplement with custom
+ * storage needs.
+ */
+this.Measurement = function () {
+  if (!this.name) {
+    throw new Error("Measurement must have a name.");
+  }
+
+  if (!this.version) {
+    throw new Error("Measurement must have a version.");
+  }
+
+  if (!Number.isInteger(this.version)) {
+    throw new Error("Measurement's version must be an integer: " + this.version);
+  }
+
+  if (!this.fields) {
+    throw new Error("Measurement must define fields.");
+  }
+
+  for (let [name, info] in Iterator(this.fields)) {
+    if (!info) {
+      throw new Error("Field does not contain metadata: " + name);
+    }
+
+    if (!info.type) {
+      throw new Error("Field is missing required type property: " + name);
+    }
+  }
+
+  this._log = Log.repository.getLogger("Services.Metrics.Measurement." + this.name);
+
+  this.id = null;
+  this.storage = null;
+  this._fields = {};
+
+  this._serializers = {};
+  this._serializers[this.SERIALIZE_JSON] = {
+    singular: this._serializeJSONSingular.bind(this),
+    daily: this._serializeJSONDay.bind(this),
+  };
+}
+
+Measurement.prototype = Object.freeze({
+  SERIALIZE_JSON: "json",
+
+  /**
+   * Obtain a serializer for this measurement.
+   *
+   * Implementations should return an object with the following keys:
+   *
+   *   singular -- Serializer for singular data.
+   *   daily -- Serializer for daily data.
+   *
+   * Each item is a function that takes a single argument: the data to
+   * serialize. The passed data is a subset of that returned from
+   * this.getValues(). For "singular," data.singular is passed. For "daily",
+   * data.days.get(<day>) is passed.
+   *
+   * This function receives a single argument: the serialization format we
+   * are requesting. This is one of the SERIALIZE_* constants on this base type.
+   *
+   * For SERIALIZE_JSON, the function should return an object that
+   * JSON.stringify() knows how to handle. This could be an anonymous object or
+   * array or any object with a property named `toJSON` whose value is a
+   * function. The returned object will be added to a larger document
+   * containing the results of all `serialize` calls.
+   *
+   * The default implementation knows how to serialize built-in types using
+   * very simple logic. If small encoding size is a goal, the default
+   * implementation may not be suitable. If an unknown field type is
+   * encountered, the default implementation will error.
+   *
+   * @param format
+   *        (string) A SERIALIZE_* constant defining what serialization format
+   *        to use.
+   */
+  serializer: function (format) {
+    if (!(format in this._serializers)) {
+      throw new Error("Don't know how to serialize format: " + format);
+    }
+
+    return this._serializers[format];
+  },
+
+  /**
+   * Whether this measurement contains the named field.
+   *
+   * @param name
+   *        (string) Name of field.
+   *
+   * @return bool
+   */
+  hasField: function (name) {
+    return name in this.fields;
+  },
+
+  /**
+   * The unique identifier for a named field.
+   *
+   * This will throw if the field is not known.
+   *
+   * @param name
+   *        (string) Name of field.
+   */
+  fieldID: function (name) {
+    let entry = this._fields[name];
+
+    if (!entry) {
+      throw new Error("Unknown field: " + name);
+    }
+
+    return entry[0];
+  },
+
+  fieldType: function (name) {
+    let entry = this._fields[name];
+
+    if (!entry) {
+      throw new Error("Unknown field: " + name);
+    }
+
+    return entry[1];
+  },
+
+  _configureStorage: function () {
+    let missing = [];
+    for (let [name, info] in Iterator(this.fields)) {
+      if (this.storage.hasFieldFromMeasurement(this.id, name)) {
+        this._fields[name] =
+          [this.storage.fieldIDFromMeasurement(this.id, name), info.type];
+        continue;
+      }
+
+      missing.push([name, info.type]);
+    }
+
+    if (!missing.length) {
+      return CommonUtils.laterTickResolvingPromise();
+    }
+
+    // We only perform a transaction if we have work to do (to avoid
+    // extra SQLite overhead).
+    return this.storage.enqueueTransaction(function registerFields() {
+      for (let [name, type] of missing) {
+        this._log.debug("Registering field: " + name + " " + type);
+        let id = yield this.storage.registerField(this.id, name, type);
+        this._fields[name] = [id, type];
+      }
+    }.bind(this));
+  },
+
+  //---------------------------------------------------------------------------
+  // Data Recording Functions
+  //
+  // Functions in this section are used to record new values against this
+  // measurement instance.
+  //
+  // Generally speaking, these functions will throw if the specified field does
+  // not exist or if the storage function requested is not appropriate for the
+  // type of that field. These functions will also return a promise that will
+  // be resolved when the underlying storage operation has completed.
+  //---------------------------------------------------------------------------
+
+  /**
+   * Increment a daily counter field in this measurement by 1.
+   *
+   * By default, the counter for the current day will be incremented.
+   *
+   * If the field is not known or is not a daily counter, this will throw.
+   *
+   *
+   *
+   * @param field
+   *        (string) The name of the field whose value to increment.
+   * @param date
+   *        (Date) Day on which to increment the counter.
+   * @param by
+   *        (integer) How much to increment by.
+   * @return Promise<>
+   */
+  incrementDailyCounter: function (field, date=new Date(), by=1) {
+    return this.storage.incrementDailyCounterFromFieldID(this.fieldID(field),
+                                                         date, by);
+  },
+
+  /**
+   * Record a new numeric value for a daily discrete numeric field.
+   *
+   * @param field
+   *        (string) The name of the field to append a value to.
+   * @param value
+   *        (Number) Number to append.
+   * @param date
+   *        (Date) Day on which to append the value.
+   *
+   * @return Promise<>
+   */
+  addDailyDiscreteNumeric: function (field, value, date=new Date()) {
+    return this.storage.addDailyDiscreteNumericFromFieldID(
+                          this.fieldID(field), value, date);
+  },
+
+  /**
+   * Record a new text value for a daily discrete text field.
+   *
+   * This is like `addDailyDiscreteNumeric` but for daily discrete text fields.
+   */
+  addDailyDiscreteText: function (field, value, date=new Date()) {
+    return this.storage.addDailyDiscreteTextFromFieldID(
+                          this.fieldID(field), value, date);
+  },
+
+  /**
+   * Record the last seen value for a last numeric field.
+   *
+   * @param field
+   *        (string) The name of the field to set the value of.
+   * @param value
+   *        (Number) The value to set.
+   * @param date
+   *        (Date) When this value was recorded.
+   *
+   * @return Promise<>
+   */
+  setLastNumeric: function (field, value, date=new Date()) {
+    return this.storage.setLastNumericFromFieldID(this.fieldID(field), value,
+                                                  date);
+  },
+
+  /**
+   * Record the last seen value for a last text field.
+   *
+   * This is like `setLastNumeric` except for last text fields.
+   */
+  setLastText: function (field, value, date=new Date()) {
+    return this.storage.setLastTextFromFieldID(this.fieldID(field), value,
+                                               date);
+  },
+
+  /**
+   * Record the most recent value for a daily last numeric field.
+   *
+   * @param field
+   *        (string) The name of a daily last numeric field.
+   * @param value
+   *        (Number) The value to set.
+   * @param date
+   *        (Date) Day on which to record the last value.
+   *
+   * @return Promise<>
+   */
+  setDailyLastNumeric: function (field, value, date=new Date()) {
+    return this.storage.setDailyLastNumericFromFieldID(this.fieldID(field),
+                                                       value, date);
+  },
+
+  /**
+   * Record the most recent value for a daily last text field.
+   *
+   * This is like `setDailyLastNumeric` except for a daily last text field.
+   */
+  setDailyLastText: function (field, value, date=new Date()) {
+    return this.storage.setDailyLastTextFromFieldID(this.fieldID(field),
+                                                    value, date);
+  },
+
+  //---------------------------------------------------------------------------
+  // End of data recording APIs.
+  //---------------------------------------------------------------------------
+
+  /**
+   * Obtain all values stored for this measurement.
+   *
+   * The default implementation obtains all known types from storage. If the
+   * measurement provides custom types or stores values somewhere other than
+   * storage, it should define its own implementation.
+   *
+   * This returns a promise that resolves to a data structure which is
+   * understood by the measurement's serialize() function.
+   */
+  getValues: function () {
+    return this.storage.getMeasurementValues(this.id);
+  },
+
+  deleteLastNumeric: function (field) {
+    return this.storage.deleteLastNumericFromFieldID(this.fieldID(field));
+  },
+
+  deleteLastText: function (field) {
+    return this.storage.deleteLastTextFromFieldID(this.fieldID(field));
+  },
+
+  /**
+   * This method is used by the default serializers to control whether a field
+   * is included in the output.
+   *
+   * There could be legacy fields in storage we no longer care about.
+   *
+   * This method is a hook to allow measurements to change this behavior, e.g.,
+   * to implement a dynamic fieldset.
+   *
+   * You will also need to override `fieldType`.
+   *
+   * @return (boolean) true if the specified field should be included in
+   *                   payload output.
+   */
+  shouldIncludeField: function (field) {
+    return field in this._fields;
+  },
+
+  _serializeJSONSingular: function (data) {
+    let result = {"_v": this.version};
+
+    for (let [field, data] of data) {
+      // There could be legacy fields in storage we no longer care about.
+      if (!this.shouldIncludeField(field)) {
+        continue;
+      }
+
+      let type = this.fieldType(field);
+
+      switch (type) {
+        case this.storage.FIELD_LAST_NUMERIC:
+        case this.storage.FIELD_LAST_TEXT:
+          result[field] = data[1];
+          break;
+
+        case this.storage.FIELD_DAILY_COUNTER:
+        case this.storage.FIELD_DAILY_DISCRETE_NUMERIC:
+        case this.storage.FIELD_DAILY_DISCRETE_TEXT:
+        case this.storage.FIELD_DAILY_LAST_NUMERIC:
+        case this.storage.FIELD_DAILY_LAST_TEXT:
+          continue;
+
+        default:
+          throw new Error("Unknown field type: " + type);
+      }
+    }
+
+    return result;
+  },
+
+  _serializeJSONDay: function (data) {
+    let result = {"_v": this.version};
+
+    for (let [field, data] of data) {
+      if (!this.shouldIncludeField(field)) {
+        continue;
+      }
+
+      let type = this.fieldType(field);
+
+      switch (type) {
+        case this.storage.FIELD_DAILY_COUNTER:
+        case this.storage.FIELD_DAILY_DISCRETE_NUMERIC:
+        case this.storage.FIELD_DAILY_DISCRETE_TEXT:
+        case this.storage.FIELD_DAILY_LAST_NUMERIC:
+        case this.storage.FIELD_DAILY_LAST_TEXT:
+          result[field] = data;
+          break;
+
+        case this.storage.FIELD_LAST_NUMERIC:
+        case this.storage.FIELD_LAST_TEXT:
+          continue;
+
+        default:
+          throw new Error("Unknown field type: " + type);
+      }
+    }
+
+    return result;
+  },
+});
+
+
+/**
+ * An entity that emits data.
+ *
+ * A `Provider` consists of a string name (must be globally unique among all
+ * known providers) and a set of `Measurement` instances.
+ *
+ * The main role of a `Provider` is to produce metrics data and to store said
+ * data in the storage backend.
+ *
+ * Metrics data collection is initiated either by a manager calling a
+ * `collect*` function on `Provider` instances or by the `Provider` registering
+ * to some external event and then reacting whenever they occur.
+ *
+ * `Provider` implementations interface directly with a storage backend. For
+ * common stored values (daily counters, daily discrete values, etc),
+ * implementations should interface with storage via the various helper
+ * functions on the `Measurement` instances. For custom stored value types,
+ * implementations will interact directly with the low-level storage APIs.
+ *
+ * Because multiple providers exist and could be responding to separate
+ * external events simultaneously and because not all operations performed by
+ * storage can safely be performed in parallel, writing directly to storage at
+ * event time is dangerous. Therefore, interactions with storage must be
+ * deferred until it is safe to perform them.
+ *
+ * This typically looks something like:
+ *
+ *   // This gets called when an external event worthy of recording metrics
+ *   // occurs. The function receives a numeric value associated with the event.
+ *   function onExternalEvent (value) {
+ *     let now = new Date();
+ *     let m = this.getMeasurement("foo", 1);
+ *
+ *     this.enqueueStorageOperation(function storeExternalEvent() {
+ *
+ *       // We interface with storage via the `Measurement` helper functions.
+ *       // These each return a promise that will be resolved when the
+ *       // operation finishes. We rely on behavior of storage where operations
+ *       // are executed single threaded and sequentially. Therefore, we only
+ *       // need to return the final promise.
+ *       m.incrementDailyCounter("foo", now);
+ *       return m.addDailyDiscreteNumericValue("my_value", value, now);
+ *     }.bind(this));
+ *
+ *   }
+ *
+ *
+ * `Provider` is an abstract base class. Implementations must define a few
+ * properties:
+ *
+ *   name
+ *     The `name` property should be a string defining the provider's name. The
+ *     name must be globally unique for the application. The name is used as an
+ *     identifier to distinguish providers from each other.
+ *
+ *   measurementTypes
+ *     This must be an array of `Measurement`-derived types. Note that elements
+ *     in the array are the type functions, not instances. Instances of the
+ *     `Measurement` are created at run-time by the `Provider` and are bound
+ *     to the provider and to a specific storage backend.
+ */
+this.Provider = function () {
+  if (!this.name) {
+    throw new Error("Provider must define a name.");
+  }
+
+  if (!Array.isArray(this.measurementTypes)) {
+    throw new Error("Provider must define measurement types.");
+  }
+
+  this._log = Log.repository.getLogger("Services.Metrics.Provider." + this.name);
+
+  this.measurements = null;
+  this.storage = null;
+}
+
+Provider.prototype = Object.freeze({
+  /**
+   * Whether the provider only pulls data from other sources.
+   *
+   * If this is true, the provider pulls data from other sources. By contrast,
+   * "push-based" providers subscribe to foreign sources and record/react to
+   * external events as they happen.
+   *
+   * Pull-only providers likely aren't instantiated until a data collection
+   * is performed. Thus, implementations cannot rely on a provider instance
+   * always being alive. This is an optimization so provider instances aren't
+   * dead weight while the application is running.
+   *
+   * This must be set on the prototype to have an effect.
+   */
+  pullOnly: false,
+
+  /**
+   * Obtain a `Measurement` from its name and version.
+   *
+   * If the measurement is not found, an Error is thrown.
+   */
+  getMeasurement: function (name, version) {
+    if (!Number.isInteger(version)) {
+      throw new Error("getMeasurement expects an integer version. Got: " + version);
+    }
+
+    let m = this.measurements.get([name, version].join(":"));
+
+    if (!m) {
+      throw new Error("Unknown measurement: " + name + " v" + version);
+    }
+
+    return m;
+  },
+
+  init: function (storage) {
+    if (this.storage !== null) {
+      throw new Error("Provider() not called. Did the sub-type forget to call it?");
+    }
+
+    if (this.storage) {
+      throw new Error("Provider has already been initialized.");
+    }
+
+    this.measurements = new Map();
+    this.storage = storage;
+
+    let self = this;
+    return Task.spawn(function init() {
+      let pre = self.preInit();
+      if (!pre || typeof(pre.then) != "function") {
+        throw new Error("preInit() does not return a promise.");
+      }
+      yield pre;
+
+      for (let measurementType of self.measurementTypes) {
+        let measurement = new measurementType();
+
+        measurement.provider = self;
+        measurement.storage = self.storage;
+
+        let id = yield storage.registerMeasurement(self.name, measurement.name,
+                                                   measurement.version);
+
+        measurement.id = id;
+
+        yield measurement._configureStorage();
+
+        self.measurements.set([measurement.name, measurement.version].join(":"),
+                              measurement);
+      }
+
+      let post = self.postInit();
+      if (!post || typeof(post.then) != "function") {
+        throw new Error("postInit() does not return a promise.");
+      }
+      yield post;
+    });
+  },
+
+  shutdown: function () {
+    let promise = this.onShutdown();
+
+    if (!promise || typeof(promise.then) != "function") {
+      throw new Error("onShutdown implementation does not return a promise.");
+    }
+
+    return promise;
+  },
+
+  /**
+   * Hook point for implementations to perform pre-initialization activity.
+   *
+   * This method will be called before measurement registration.
+   *
+   * Implementations should return a promise which is resolved when
+   * initialization activities have completed.
+   */
+  preInit: function () {
+    return CommonUtils.laterTickResolvingPromise();
+  },
+
+  /**
+   * Hook point for implementations to perform post-initialization activity.
+   *
+   * This method will be called after `preInit` and measurement registration,
+   * but before initialization is finished.
+   *
+   * If a `Provider` instance needs to register observers, etc, it should
+   * implement this function.
+   *
+   * Implementations should return a promise which is resolved when
+   * initialization activities have completed.
+   */
+  postInit: function () {
+    return CommonUtils.laterTickResolvingPromise();
+  },
+
+  /**
+   * Hook point for shutdown of instances.
+   *
+   * This is the opposite of `onInit`. If a `Provider` needs to unregister
+   * observers, etc, this is where it should do it.
+   *
+   * Implementations should return a promise which is resolved when
+   * shutdown activities have completed.
+   */
+  onShutdown: function () {
+    return CommonUtils.laterTickResolvingPromise();
+  },
+
+  /**
+   * Collects data that doesn't change during the application's lifetime.
+   *
+   * Implementations should return a promise that resolves when all data has
+   * been collected and storage operations have been finished.
+   *
+   * @return Promise<>
+   */
+  collectConstantData: function () {
+    return CommonUtils.laterTickResolvingPromise();
+  },
+
+  /**
+   * Collects data approximately every day.
+   *
+   * For long-running applications, this is called approximately every day.
+   * It may or may not be called every time the application is run. It also may
+   * be called more than once per day.
+   *
+   * Implementations should return a promise that resolves when all data has
+   * been collected and storage operations have completed.
+   *
+   * @return Promise<>
+   */
+  collectDailyData: function () {
+    return CommonUtils.laterTickResolvingPromise();
+  },
+
+  /**
+   * Queue a deferred storage operation.
+   *
+   * Deferred storage operations are the preferred method for providers to
+   * interact with storage. When collected data is to be added to storage,
+   * the provider creates a function that performs the necessary storage
+   * interactions and then passes that function to this function. Pending
+   * storage operations will be executed sequentially by a coordinator.
+   *
+   * The passed function should return a promise which will be resolved upon
+   * completion of storage interaction.
+   */
+  enqueueStorageOperation: function (func) {
+    return this.storage.enqueueOperation(func);
+  },
+
+  /**
+   * Obtain persisted provider state.
+   *
+   * Provider state consists of key-value pairs of string names and values.
+   * Providers can stuff whatever they want into state. They are encouraged to
+   * store as little as possible for performance reasons.
+   *
+   * State is backed by storage and is robust.
+   *
+   * These functions do not enqueue on storage automatically, so they should
+   * be guarded by `enqueueStorageOperation` or some other mutex.
+   *
+   * @param key
+   *        (string) The property to retrieve.
+   *
+   * @return Promise<string|null> String value on success. null if no state
+   *         is available under this key.
+   */
+  getState: function (key) {
+    return this.storage.getProviderState(this.name, key);
+  },
+
+  /**
+   * Set state for this provider.
+   *
+   * This is the complementary API for `getState` and obeys the same
+   * storage restrictions.
+   */
+  setState: function (key, value) {
+    return this.storage.setProviderState(this.name, key, value);
+  },
+
+  _dateToDays: function (date) {
+    return Math.floor(date.getTime() / MILLISECONDS_PER_DAY);
+  },
+
+  _daysToDate: function (days) {
+    return new Date(days * MILLISECONDS_PER_DAY);
+  },
+});
+