Remove dependency tracker and replace analysis triggers (#6958)

* Remove old dependency tracker.

* Remove most of Job backend + remove entries unconditionally.

app/lib/admin/tools/package_discontinued.dart

@@ -5,10 +5,10 @@
 import 'package:args/args.dart';
 import 'package:clock/clock.dart';
 
-import 'package:pub_dev/job/backend.dart';
 import 'package:pub_dev/package/backend.dart';
 import 'package:pub_dev/package/models.dart';
 import 'package:pub_dev/shared/datastore.dart';
+import 'package:pub_dev/task/backend.dart';
 
 final _argParser = ArgParser()
   ..addOption('package', help: 'The package to update.')
@@ -50,7 +50,6 @@ Future<String> executeSetPackageDiscontinued(List<String> args) async {
     tx.insert(pkg);
   });
   await purgePackageCache(packageName);
-  await jobBackend.trigger(JobService.analyzer, packageName,
-      version: package.latestVersion);
+  await taskBackend.trackPackage(packageName);
   return 'Done.';
 }

app/lib/job/backend.dart

@@ -4,24 +4,14 @@
 
 import 'dart:async';
 
-import 'package:clock/clock.dart';
 import 'package:gcloud/service_scope.dart' as ss;
-import 'package:logging/logging.dart';
 
-import '../package/backend.dart';
-import '../package/models.dart';
 import '../shared/datastore.dart' as db;
-import '../shared/popularity_storage.dart';
-import '../shared/versions.dart' as versions;
 
 import 'model.dart';
 
 export 'model.dart';
 
-const _shortExtendDuration = Duration(hours: 12);
-
-final _logger = Logger('pub.job.backend');
-
 typedef ShouldProcess = Future<bool> Function(
     String package, String version, DateTime updated);
 
@@ -37,154 +27,8 @@ class JobBackend {
 
   JobBackend(this._db);
 
-  String _id(JobService service, String package, String version) => Uri(
-        pathSegments: [
-          versions.runtimeVersion,
-          service.toString().split('.').last,
-          package,
-          version,
-        ],
-      ).toString();
-
-  /// Triggers analysis job.
-  Future<void> triggerAnalysis(
-    String package,
-    String? version, {
-    bool isHighPriority = false,
-  }) async {
-    await jobBackend.trigger(
-      JobService.analyzer,
-      package,
-      version: version,
-      isHighPriority: isHighPriority,
-    );
-  }
-
-  /// Triggers analysis/dartdoc for [package]/[version] if older than [updated].
-  Future<void> trigger(
-    JobService service,
-    String package, {
-    String? version,
-    DateTime? updated,
-    bool? shouldProcess,
-    bool isHighPriority = false,
-  }) async {
-    final pKey = _db.emptyKey.append(Package, id: package);
-    final p = await _db.lookupOrNull<Package>(pKey);
-    if (p == null || p.isNotVisible) {
-      _logger.info("Couldn't trigger $service job: $package not found.");
-      return;
-    }
-    final latestReleases = await packageBackend.latestReleases(p);
-
-    version ??= latestReleases.stable.version;
-    final pvKey = pKey.append(PackageVersion, id: version);
-    final pv = await _db.lookupOrNull<PackageVersion>(pvKey);
-    if (pv == null) {
-      _logger
-          .info("Couldn't trigger $service job: $package $version not found.");
-      return;
-    }
-
-    final isLatestStable = p.latestVersion == version;
-    final isLatestPrerelease = latestReleases.showPrerelease &&
-        latestReleases.prerelease!.version == version;
-    final isLatestPreview = latestReleases.showPreview &&
-        latestReleases.preview!.version == version;
-    shouldProcess ??= updated == null || updated.isAfter(pv.created!);
-    shouldProcess |= isHighPriority;
-    await createOrUpdate(
-      service: service,
-      package: package,
-      version: version,
-      isLatestStable: isLatestStable,
-      isLatestPrerelease: isLatestPrerelease,
-      isLatestPreview: isLatestPreview,
-      packageVersionUpdated: pv.created,
-      shouldProcess: shouldProcess,
-      priority: isHighPriority ? 0 : null,
-    );
-  }
-
-  Future<void> createOrUpdate({
-    required JobService service,
-    required String package,
-    required String version,
-    required bool isLatestStable,
-    required bool isLatestPrerelease,
-    required bool isLatestPreview,
-    required DateTime? packageVersionUpdated,
-    required bool shouldProcess,
-    int? priority,
-  }) async {
-    packageVersionUpdated ??= clock.now().toUtc();
-    final id = _id(service, package, version);
-    final state = shouldProcess ? JobState.available : JobState.idle;
-    final lockedUntil =
-        shouldProcess ? null : clock.now().add(_shortExtendDuration);
-    await db.withRetryTransaction(_db, (tx) async {
-      final current =
-          await tx.lookupOrNull<Job>(_db.emptyKey.append(Job, id: id));
-      if (current != null) {
-        final hasNotChanged = current.isLatestStable == isLatestStable &&
-            current.isLatestPrerelease == isLatestPrerelease &&
-            current.isLatestPreview == isLatestPreview &&
-            !current.packageVersionUpdated!.isBefore(packageVersionUpdated!) &&
-            (priority == null || current.priority <= priority);
-        if (hasNotChanged && !shouldProcess) {
-          // no reason to re-schedule the job
-          return;
-        }
-        if (current.state == JobState.available &&
-            current.lockedUntil == null) {
-          // already scheduled for processing
-          return;
-        }
-        _logger.info('Updating job: $id ($state, $lockedUntil)');
-        current
-          ..isLatestStable = isLatestStable
-          ..isLatestPrerelease = isLatestPrerelease
-          ..isLatestPreview = isLatestPreview
-          ..packageVersionUpdated = packageVersionUpdated
-          ..state = state
-          ..lockedUntil = lockedUntil
-          ..processingKey = null // drops ongoing processing
-          ..updatePriority(
-            popularityStorage.lookup(package),
-            fixPriority: priority,
-          );
-        tx.insert(current);
-        return;
-      } else {
-        _logger.info('Creating job: $id');
-        final job = Job()
-          ..id = id
-          ..service = service
-          ..packageName = package
-          ..packageVersion = version
-          ..isLatestStable = isLatestStable
-          ..isLatestPrerelease = isLatestPrerelease
-          ..isLatestPreview = isLatestPreview
-          ..packageVersionUpdated = packageVersionUpdated
-          ..state = JobState.available
-          ..lockedUntil = null
-          ..lastStatus = JobStatus.none
-          ..runtimeVersion = versions.runtimeVersion
-          ..errorCount = 0
-          ..updatePriority(
-            popularityStorage.lookup(package),
-            fixPriority: priority,
-          );
-        tx.insert(job);
-        return;
-      }
-    });
-  }
-
-  /// Deletes the old entries that predate [versions.gcBeforeRuntimeVersion].
+  /// Deletes the old entries.
   Future<void> deleteOldEntries() async {
-    final query = _db.query<Job>()
-      ..filter('runtimeVersion <', versions.gcBeforeRuntimeVersion);
-    await _db.deleteWithQuery<Job>(query);
+    await _db.deleteWithQuery<Job>(_db.query<Job>());
   }
 }

app/lib/package/backend.dart

@@ -26,7 +26,6 @@ import '../account/backend.dart';
 import '../account/consent_backend.dart';
 import '../account/models.dart' show User;
 import '../audit/models.dart';
-import '../job/backend.dart';
 import '../publisher/backend.dart';
 import '../service/email/backend.dart';
 import '../service/email/models.dart';
@@ -378,10 +377,8 @@ class PackageBackend {
     }
 
     final pkg = await _requirePackageAdmin(package, user.userId);
-    String? latestVersion;
     await withRetryTransaction(db, (tx) async {
       final p = await tx.lookupValue<Package>(pkg.key);
-      latestVersion = p.latestVersion;
 
       final optionsChanges = <String>[];
       if (options.isDiscontinued != null &&
@@ -419,8 +416,7 @@ class PackageBackend {
       ));
     });
     await purgePackageCache(package);
-    await jobBackend.trigger(JobService.analyzer, package,
-        version: latestVersion);
+    await taskBackend.trackPackage(package);
   }
 
   /// Updates [options] on [package]/[version], assuming the current user