1 files changed, 201 insertions, 0 deletions
diff --git a/services/sync/modules/doctor.sys.mjs b/services/sync/modules/doctor.sys.mjs
new file mode 100644
index 0000000000..ebcf38e2a2
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+++ b/services/sync/modules/doctor.sys.mjs
@@ -0,0 +1,201 @@
+/* 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/. */
+
+// A doctor for our collections. She can be asked to make a consultation, and
+// may just diagnose an issue without attempting to cure it, may diagnose and
+// attempt to cure, or may decide she is overworked and underpaid.
+// Or something - naming is hard :)
+
+import { Log } from "resource://gre/modules/Log.sys.mjs";
+
+import { Async } from "resource://services-common/async.sys.mjs";
+import { Observers } from "resource://services-common/observers.sys.mjs";
+import { Service } from "resource://services-sync/service.sys.mjs";
+import { Resource } from "resource://services-sync/resource.sys.mjs";
+import { Svc } from "resource://services-sync/util.sys.mjs";
+
+const log = Log.repository.getLogger("Sync.Doctor");
+
+export var Doctor = {
+  async consult(recentlySyncedEngines) {
+    if (!Services.telemetry.canRecordBase) {
+      log.info("Skipping consultation: telemetry reporting is disabled");
+      return;
+    }
+
+    let engineInfos = this._getEnginesToValidate(recentlySyncedEngines);
+
+    await this._runValidators(engineInfos);
+  },
+
+  _getEnginesToValidate(recentlySyncedEngines) {
+    let result = {};
+    for (let e of recentlySyncedEngines) {
+      let prefPrefix = `engine.${e.name}.`;
+      if (
+        !Svc.PrefBranch.getBoolPref(prefPrefix + "validation.enabled", false)
+      ) {
+        log.info(`Skipping check of ${e.name} - disabled via preferences`);
+        continue;
+      }
+      // Check the last validation time for the engine.
+      let lastValidation = Svc.PrefBranch.getIntPref(
+        prefPrefix + "validation.lastTime",
+        0
+      );
+      let validationInterval = Svc.PrefBranch.getIntPref(
+        prefPrefix + "validation.interval"
+      );
+      let nowSeconds = this._now();
+
+      if (nowSeconds - lastValidation < validationInterval) {
+        log.info(
+          `Skipping validation of ${e.name}: too recent since last validation attempt`
+        );
+        continue;
+      }
+      // Update the time now, even if we decline to actually perform a
+      // validation. We don't want to check the rest of these more frequently
+      // than once a day.
+      Svc.PrefBranch.setIntPref(
+        prefPrefix + "validation.lastTime",
+        Math.floor(nowSeconds)
+      );
+
+      // Validation only occurs a certain percentage of the time.
+      let validationProbability =
+        Svc.PrefBranch.getIntPref(
+          prefPrefix + "validation.percentageChance",
+          0
+        ) / 100.0;
+      if (validationProbability < Math.random()) {
+        log.info(
+          `Skipping validation of ${e.name}: Probability threshold not met`
+        );
+        continue;
+      }
+
+      let maxRecords = Svc.PrefBranch.getIntPref(
+        prefPrefix + "validation.maxRecords"
+      );
+      if (!maxRecords) {
+        log.info(`Skipping validation of ${e.name}: No maxRecords specified`);
+        continue;
+      }
+      // OK, so this is a candidate - the final decision will be based on the
+      // number of records actually found.
+      result[e.name] = { engine: e, maxRecords };
+    }
+    return result;
+  },
+
+  async _runValidators(engineInfos) {
+    if (!Object.keys(engineInfos).length) {
+      log.info("Skipping validation: no engines qualify");
+      return;
+    }
+
+    if (Object.values(engineInfos).filter(i => i.maxRecords != -1).length) {
+      // at least some of the engines have maxRecord restrictions which require
+      // us to ask the server for the counts.
+      let countInfo = await this._fetchCollectionCounts();
+      for (let [engineName, recordCount] of Object.entries(countInfo)) {
+        if (engineName in engineInfos) {
+          engineInfos[engineName].recordCount = recordCount;
+        }
+      }
+    }
+
+    for (let [
+      engineName,
+      { engine, maxRecords, recordCount },
+    ] of Object.entries(engineInfos)) {
+      // maxRecords of -1 means "any number", so we can skip asking the server.
+      // Used for tests.
+      if (maxRecords >= 0 && recordCount > maxRecords) {
+        log.debug(
+          `Skipping validation for ${engineName} because ` +
+            `the number of records (${recordCount}) is greater ` +
+            `than the maximum allowed (${maxRecords}).`
+        );
+        continue;
+      }
+      let validator = engine.getValidator();
+      if (!validator) {
+        // This is probably only possible in profile downgrade cases.
+        log.warn(
+          `engine.getValidator returned null for ${engineName} but the pref that controls validation is enabled.`
+        );
+        continue;
+      }
+
+      if (!(await validator.canValidate())) {
+        log.debug(
+          `Skipping validation for ${engineName} because validator.canValidate() is false`
+        );
+        continue;
+      }
+
+      // Let's do it!
+      Services.console.logStringMessage(
+        `Sync is about to run a consistency check of ${engine.name}. This may be slow, and ` +
+          `can be controlled using the pref "services.sync.${engine.name}.validation.enabled".\n` +
+          `If you encounter any problems because of this, please file a bug.`
+      );
+
+      try {
+        log.info(`Running validator for ${engine.name}`);
+        let result = await validator.validate(engine);
+        let { problems, version, duration, recordCount } = result;
+        Observers.notify(
+          "weave:engine:validate:finish",
+          {
+            version,
+            checked: recordCount,
+            took: duration,
+            problems: problems ? problems.getSummary(true) : null,
+          },
+          engine.name
+        );
+      } catch (ex) {
+        if (Async.isShutdownException(ex)) {
+          throw ex;
+        }
+        log.error(`Failed to run validation on ${engine.name}!`, ex);
+        Observers.notify("weave:engine:validate:error", ex, engine.name);
+        // Keep validating -- there's no reason to think that a failure for one
+        // validator would mean the others will fail.
+      }
+    }
+  },
+
+  // mainly for mocking.
+  async _fetchCollectionCounts() {
+    let collectionCountsURL = Service.userBaseURL + "info/collection_counts";
+    try {
+      let infoResp = await Service._fetchInfo(collectionCountsURL);
+      if (!infoResp.success) {
+        log.error(
+          "Can't fetch collection counts: request to info/collection_counts responded with " +
+            infoResp.status
+        );
+        return {};
+      }
+      return infoResp.obj; // might throw because obj is a getter which parses json.
+    } catch (ex) {
+      if (Async.isShutdownException(ex)) {
+        throw ex;
+      }
+      // Not running validation is totally fine, so we just write an error log and return.
+      log.error("Caught error when fetching counts", ex);
+      return {};
+    }
+  },
+
+  // functions used so tests can mock them
+  _now() {
+    // We use the server time, which is SECONDS
+    return Resource.serverTime;
+  },
+};