1 files changed, 466 insertions, 0 deletions
diff --git a/toolkit/components/nimbus/lib/ExperimentStore.jsm b/toolkit/components/nimbus/lib/ExperimentStore.jsm
new file mode 100644
index 0000000000..4b2155e12d
--- /dev/null
+++ b/toolkit/components/nimbus/lib/ExperimentStore.jsm
@@ -0,0 +1,466 @@
+/* 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";
+
+const EXPORTED_SYMBOLS = ["ExperimentStore"];
+
+const { SharedDataMap } = ChromeUtils.import(
+  "resource://nimbus/lib/SharedDataMap.jsm"
+);
+const { XPCOMUtils } = ChromeUtils.importESModule(
+  "resource://gre/modules/XPCOMUtils.sys.mjs"
+);
+const lazy = {};
+XPCOMUtils.defineLazyModuleGetters(lazy, {
+  FeatureManifest: "resource://nimbus/FeatureManifest.js",
+  PrefUtils: "resource://normandy/lib/PrefUtils.jsm",
+});
+
+const IS_MAIN_PROCESS =
+  Services.appinfo.processType === Services.appinfo.PROCESS_TYPE_DEFAULT;
+
+// This branch is used to store experiment data
+const SYNC_DATA_PREF_BRANCH = "nimbus.syncdatastore.";
+// This branch is used to store remote rollouts
+const SYNC_DEFAULTS_PREF_BRANCH = "nimbus.syncdefaultsstore.";
+let tryJSONParse = data => {
+  try {
+    return JSON.parse(data);
+  } catch (e) {}
+
+  return null;
+};
+XPCOMUtils.defineLazyGetter(lazy, "syncDataStore", () => {
+  let experimentsPrefBranch = Services.prefs.getBranch(SYNC_DATA_PREF_BRANCH);
+  let defaultsPrefBranch = Services.prefs.getBranch(SYNC_DEFAULTS_PREF_BRANCH);
+  return {
+    _tryParsePrefValue(branch, pref) {
+      try {
+        return tryJSONParse(branch.getStringPref(pref, ""));
+      } catch (e) {
+        /* This is expected if we don't have anything stored */
+      }
+
+      return null;
+    },
+    _trySetPrefValue(branch, pref, value) {
+      try {
+        branch.setStringPref(pref, JSON.stringify(value));
+      } catch (e) {
+        Cu.reportError(e);
+      }
+    },
+    _trySetTypedPrefValue(pref, value) {
+      let variableType = typeof value;
+      switch (variableType) {
+        case "boolean":
+          Services.prefs.setBoolPref(pref, value);
+          break;
+        case "number":
+          Services.prefs.setIntPref(pref, value);
+          break;
+        case "string":
+          Services.prefs.setStringPref(pref, value);
+          break;
+        case "object":
+          Services.prefs.setStringPref(pref, JSON.stringify(value));
+          break;
+      }
+    },
+    _clearBranchChildValues(prefBranch) {
+      const variablesBranch = Services.prefs.getBranch(prefBranch);
+      const prefChildList = variablesBranch.getChildList("");
+      for (let variable of prefChildList) {
+        variablesBranch.clearUserPref(variable);
+      }
+    },
+    /**
+     * Given a branch pref returns all child prefs and values
+     * { childPref: value }
+     * where value is parsed to the appropriate type
+     *
+     * @returns {Object[]}
+     */
+    _getBranchChildValues(prefBranch, featureId) {
+      const branch = Services.prefs.getBranch(prefBranch);
+      const prefChildList = branch.getChildList("");
+      let values = {};
+      if (!prefChildList.length) {
+        return null;
+      }
+      for (const childPref of prefChildList) {
+        let prefName = `${prefBranch}${childPref}`;
+        let value = lazy.PrefUtils.getPref(prefName);
+        // Try to parse string values that could be stringified objects
+        if (
+          lazy.FeatureManifest[featureId]?.variables[childPref]?.type === "json"
+        ) {
+          let parsedValue = tryJSONParse(value);
+          if (parsedValue) {
+            value = parsedValue;
+          }
+        }
+        values[childPref] = value;
+      }
+
+      return values;
+    },
+    get(featureId) {
+      let metadata = this._tryParsePrefValue(experimentsPrefBranch, featureId);
+      if (!metadata) {
+        return null;
+      }
+      let prefBranch = `${SYNC_DATA_PREF_BRANCH}${featureId}.`;
+      metadata.branch.feature.value = this._getBranchChildValues(
+        prefBranch,
+        featureId
+      );
+
+      return metadata;
+    },
+    getDefault(featureId) {
+      let metadata = this._tryParsePrefValue(defaultsPrefBranch, featureId);
+      if (!metadata) {
+        return null;
+      }
+      let prefBranch = `${SYNC_DEFAULTS_PREF_BRANCH}${featureId}.`;
+      metadata.branch.feature.value = this._getBranchChildValues(
+        prefBranch,
+        featureId
+      );
+
+      return metadata;
+    },
+    set(featureId, value) {
+      /* If the enrollment branch has variables we store those separately
+       * in pref branches of appropriate type:
+       * { featureId: "foo", value: { enabled: true } }
+       * gets stored as `${SYNC_DATA_PREF_BRANCH}foo.enabled=true`
+       */
+      if (value.branch?.feature?.value) {
+        for (let variable of Object.keys(value.branch.feature.value)) {
+          let prefName = `${SYNC_DATA_PREF_BRANCH}${featureId}.${variable}`;
+          this._trySetTypedPrefValue(
+            prefName,
+            value.branch.feature.value[variable]
+          );
+        }
+        this._trySetPrefValue(experimentsPrefBranch, featureId, {
+          ...value,
+          branch: {
+            ...value.branch,
+            feature: {
+              ...value.branch.feature,
+              value: null,
+            },
+          },
+        });
+      } else {
+        this._trySetPrefValue(experimentsPrefBranch, featureId, value);
+      }
+    },
+    setDefault(featureId, enrollment) {
+      /* We store configuration variables separately in pref branches of
+       * appropriate type:
+       * (feature: "foo") { variables: { enabled: true } }
+       * gets stored as `${SYNC_DEFAULTS_PREF_BRANCH}foo.enabled=true`
+       */
+      let { feature } = enrollment.branch;
+      for (let variable of Object.keys(feature.value)) {
+        let prefName = `${SYNC_DEFAULTS_PREF_BRANCH}${featureId}.${variable}`;
+        this._trySetTypedPrefValue(prefName, feature.value[variable]);
+      }
+      this._trySetPrefValue(defaultsPrefBranch, featureId, {
+        ...enrollment,
+        branch: {
+          ...enrollment.branch,
+          feature: {
+            ...enrollment.branch.feature,
+            value: null,
+          },
+        },
+      });
+    },
+    getAllDefaultBranches() {
+      return defaultsPrefBranch.getChildList("").filter(
+        // Filter out remote defaults variable prefs
+        pref => !pref.includes(".")
+      );
+    },
+    delete(featureId) {
+      const prefBranch = `${SYNC_DATA_PREF_BRANCH}${featureId}.`;
+      this._clearBranchChildValues(prefBranch);
+      try {
+        experimentsPrefBranch.clearUserPref(featureId);
+      } catch (e) {}
+    },
+    deleteDefault(featureId) {
+      let prefBranch = `${SYNC_DEFAULTS_PREF_BRANCH}${featureId}.`;
+      this._clearBranchChildValues(prefBranch);
+      try {
+        defaultsPrefBranch.clearUserPref(featureId);
+      } catch (e) {}
+    },
+  };
+});
+
+const DEFAULT_STORE_ID = "ExperimentStoreData";
+
+/**
+ * Returns all feature ids associated with the branch provided.
+ * Fallback for when `featureIds` was not persisted to disk. Can be removed
+ * after bug 1725240 has reached release.
+ *
+ * @param {Branch} branch
+ * @returns {string[]}
+ */
+function getAllBranchFeatureIds(branch) {
+  return featuresCompat(branch).map(f => f.featureId);
+}
+
+function featuresCompat(branch) {
+  if (!branch || (!branch.feature && !branch.features)) {
+    return [];
+  }
+  let { features } = branch;
+  // In <=v1.5.0 of the Nimbus API, experiments had single feature
+  if (!features) {
+    features = [branch.feature];
+  }
+
+  return features;
+}
+
+class ExperimentStore extends SharedDataMap {
+  static SYNC_DATA_PREF_BRANCH = SYNC_DATA_PREF_BRANCH;
+  static SYNC_DEFAULTS_PREF_BRANCH = SYNC_DEFAULTS_PREF_BRANCH;
+
+  constructor(sharedDataKey, options = { isParent: IS_MAIN_PROCESS }) {
+    super(sharedDataKey || DEFAULT_STORE_ID, options);
+  }
+
+  async init() {
+    await super.init();
+
+    this.getAllActive().forEach(({ branch, featureIds }) => {
+      (featureIds || getAllBranchFeatureIds(branch)).forEach(featureId =>
+        this._emitFeatureUpdate(featureId, "feature-experiment-loaded")
+      );
+    });
+    this.getAllRollouts().forEach(({ featureIds }) => {
+      featureIds.forEach(featureId =>
+        this._emitFeatureUpdate(featureId, "feature-rollout-loaded")
+      );
+    });
+
+    Services.tm.idleDispatchToMainThread(() => this._cleanupOldRecipes());
+  }
+
+  /**
+   * Given a feature identifier, find an active experiment that matches that feature identifier.
+   * This assumes, for now, that there is only one active experiment per feature per browser.
+   * Does not activate the experiment (send an exposure event)
+   *
+   * @param {string} featureId
+   * @returns {Enrollment|undefined} An active experiment if it exists
+   * @memberof ExperimentStore
+   */
+  getExperimentForFeature(featureId) {
+    return (
+      this.getAllActive().find(
+        experiment =>
+          experiment.featureIds?.includes(featureId) ||
+          // Supports <v1.3.0, which was when .featureIds was added
+          getAllBranchFeatureIds(experiment.branch).includes(featureId)
+        // Default to the pref store if data is not yet ready
+      ) || lazy.syncDataStore.get(featureId)
+    );
+  }
+
+  /**
+   * Check if an active experiment already exists for a feature.
+   * Does not activate the experiment (send an exposure event)
+   *
+   * @param {string} featureId
+   * @returns {boolean} Does an active experiment exist for that feature?
+   * @memberof ExperimentStore
+   */
+  hasExperimentForFeature(featureId) {
+    if (!featureId) {
+      return false;
+    }
+    return !!this.getExperimentForFeature(featureId);
+  }
+
+  /**
+   * @returns {Enrollment[]}
+   */
+  getAll() {
+    let data = [];
+    try {
+      data = Object.values(this._data || {});
+    } catch (e) {
+      Cu.reportError(e);
+    }
+
+    return data;
+  }
+
+  /**
+   * @returns {Enrollment[]}
+   */
+  getAllActive() {
+    return this.getAll().filter(
+      enrollment => enrollment.active && !enrollment.isRollout
+    );
+  }
+
+  /**
+   * Returns all active rollouts
+   * @returns {array}
+   */
+  getAllRollouts() {
+    return this.getAll().filter(
+      enrollment => enrollment.active && enrollment.isRollout
+    );
+  }
+
+  /**
+   * Query the store for the remote configuration of a feature
+   * @param {string} featureId The feature we want to query for
+   * @returns {{Rollout}|undefined} Remote defaults if available
+   */
+  getRolloutForFeature(featureId) {
+    return (
+      this.getAllRollouts().find(r => r.featureIds.includes(featureId)) ||
+      lazy.syncDataStore.getDefault(featureId)
+    );
+  }
+
+  /**
+   * Remove inactive enrollments older than 6 months
+   */
+  _cleanupOldRecipes() {
+    // Roughly six months
+    const threshold = 15552000000;
+    const nowTimestamp = new Date().getTime();
+    const recipesToRemove = this.getAll().filter(
+      experiment =>
+        !experiment.active &&
+        // Flip the comparison here to catch scenarios in which lastSeen is
+        // invalid or undefined. The result with be a comparison with NaN
+        // which is always false
+        !(nowTimestamp - new Date(experiment.lastSeen).getTime() < threshold)
+    );
+    this._removeEntriesByKeys(recipesToRemove.map(r => r.slug));
+  }
+
+  _emitUpdates(enrollment) {
+    this.emit(`update:${enrollment.slug}`, enrollment);
+    (
+      enrollment.featureIds || getAllBranchFeatureIds(enrollment.branch)
+    ).forEach(featureId => {
+      this.emit(`update:${featureId}`, enrollment);
+      this._emitFeatureUpdate(
+        featureId,
+        enrollment.isRollout ? "rollout-updated" : "experiment-updated"
+      );
+    });
+  }
+
+  _emitFeatureUpdate(featureId, reason) {
+    this.emit(`featureUpdate:${featureId}`, reason);
+  }
+
+  _onFeatureUpdate(featureId, callback) {
+    this.on(`featureUpdate:${featureId}`, callback);
+  }
+
+  _offFeatureUpdate(featureId, callback) {
+    this.off(`featureUpdate:${featureId}`, callback);
+  }
+
+  /**
+   * Persists early startup experiments or rollouts
+   * @param {Enrollment} enrollment Experiment or rollout
+   */
+  _updateSyncStore(enrollment) {
+    let features = featuresCompat(enrollment.branch);
+    for (let feature of features) {
+      if (
+        lazy.FeatureManifest[feature.featureId]?.isEarlyStartup ||
+        feature.isEarlyStartup
+      ) {
+        if (!enrollment.active) {
+          // Remove experiments on un-enroll, no need to check if it exists
+          if (enrollment.isRollout) {
+            lazy.syncDataStore.deleteDefault(feature.featureId);
+          } else {
+            lazy.syncDataStore.delete(feature.featureId);
+          }
+        } else {
+          let updateEnrollmentSyncStore = enrollment.isRollout
+            ? lazy.syncDataStore.setDefault.bind(lazy.syncDataStore)
+            : lazy.syncDataStore.set.bind(lazy.syncDataStore);
+          updateEnrollmentSyncStore(feature.featureId, {
+            ...enrollment,
+            branch: {
+              ...enrollment.branch,
+              feature,
+              // Only store the early startup feature
+              features: null,
+            },
+          });
+        }
+      }
+    }
+  }
+
+  /**
+   * Add an enrollment and notify listeners
+   * @param {Enrollment} enrollment
+   */
+  addEnrollment(enrollment) {
+    if (!enrollment || !enrollment.slug) {
+      throw new Error(
+        `Tried to add an experiment but it didn't have a .slug property.`
+      );
+    }
+
+    this.set(enrollment.slug, enrollment);
+    this._updateSyncStore(enrollment);
+    this._emitUpdates(enrollment);
+  }
+
+  /**
+   * Merge new properties into the properties of an existing experiment
+   * @param {string} slug
+   * @param {Partial<Enrollment>} newProperties
+   */
+  updateExperiment(slug, newProperties) {
+    const oldProperties = this.get(slug);
+    if (!oldProperties) {
+      throw new Error(
+        `Tried to update experiment ${slug} but it doesn't exist`
+      );
+    }
+    const updatedExperiment = { ...oldProperties, ...newProperties };
+    this.set(slug, updatedExperiment);
+    this._updateSyncStore(updatedExperiment);
+    this._emitUpdates(updatedExperiment);
+  }
+
+  /**
+   * Test only helper for cleanup
+   *
+   * @param slugOrFeatureId Can be called with slug (which removes the SharedDataMap entry) or
+   * with featureId which removes the SyncDataStore entry for the feature
+   */
+  _deleteForTests(slugOrFeatureId) {
+    super._deleteForTests(slugOrFeatureId);
+    lazy.syncDataStore.deleteDefault(slugOrFeatureId);
+    lazy.syncDataStore.delete(slugOrFeatureId);
+  }
+}