Reserve the prefix name range when a ReservedPackage.name ends with _

app/lib/admin/actions/package_reservation_create.dart

@@ -5,6 +5,7 @@
 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/shared/redis_cache.dart';
 
 import 'actions.dart';
 
@@ -52,6 +53,8 @@ able to claim it.
       return entry;
     });
 
+    await cache.reservedPackagePrefixes().purge();
+
     return {
       'ReservedPackage': {
         'name': entry.name,

app/lib/admin/actions/package_reservation_delete.dart

@@ -4,6 +4,7 @@
 
 import 'package:pub_dev/package/backend.dart';
 import 'package:pub_dev/shared/datastore.dart';
+import 'package:pub_dev/shared/redis_cache.dart';
 
 import 'actions.dart';
 
@@ -27,6 +28,7 @@ Deletes a ReservedPackage entity, allowing the package name use by any user.
     }
 
     await dbService.commit(deletes: [rp.key]);
+    await cache.reservedPackagePrefixes().purge();
 
     return {
       'ReservedPackage': {

app/lib/package/backend.dart

@@ -198,6 +198,30 @@ class PackageBackend {
     return await db.lookupOrNull<ReservedPackage>(packageKey);
   }
 
+  /// Lists the currently reserved package names. A reserved package prefix is a regular name
+  /// that ends with `_` (underscore).
+  ///
+  /// List the prefixes in descending length for easier matching.
+  Future<List<String>> listReservedPackagePrefixes() async {
+    return await cache.reservedPackagePrefixes().get(() async {
+          final list = <String>[];
+          await for (final p in db.query<ReservedPackage>().run()) {
+            final name = p.name;
+            if (name != null && name.endsWith('_')) {
+              list.add(name);
+            }
+          }
+          list.sort((a, b) {
+            if (a.length != b.length) {
+              return -a.length.compareTo(b.length);
+            }
+            return a.compareTo(b);
+          });
+          return list;
+        })
+        as List<String>;
+  }
+
   /// Looks up a package by name.
   Future<List<Package>> lookupPackages(Iterable<String> packageNames) async {
     return (await db.lookup(
@@ -1191,7 +1215,18 @@ class PackageBackend {
     required String name,
     required AuthenticatedAgent agent,
   }) async {
-    final reservedPackage = await lookupReservedPackage(name);
+    // Apply either the exact-name reserved package lookup, or the closest prefix (ending with '_').
+    var reservedPackage = await lookupReservedPackage(name);
+    if (reservedPackage == null) {
+      // lookup prefixes
+      final prefixes = await listReservedPackagePrefixes();
+      for (final prefix in prefixes) {
+        if (name.startsWith(prefix)) {
+          reservedPackage = await lookupReservedPackage(prefix);
+          break;
+        }
+      }
+    }
 
     bool isAllowedUser = false;
     if (agent is AuthenticatedUser) {

app/lib/shared/redis_cache.dart

@@ -500,6 +500,17 @@ class CachePatterns {
                   PlaylistItemListResponse.fromJson(v as Map<String, dynamic>),
             ),
           )[pageToken];
+
+  Entry<List<String>> reservedPackagePrefixes() => _cache
+      .withPrefix('reserved-package-prefixes/')
+      .withTTL(Duration(hours: 1))
+      .withCodec(utf8)
+      .withCodec(
+        wrapAsCodec(
+          encode: (List<String> v) => json.encode(v),
+          decode: (v) => (json.decode(v) as List).cast<String>(),
+        ),
+      )[''];
 }
 
 /// The active cache.

app/test/admin/package_reservation_test.dart

@@ -134,6 +134,24 @@ void main() {
       },
     );
 
+    testWithProfile(
+      'prefix reserve',
+      fn: () async {
+        await _reserve('pkg_');
+
+        final pubspecContent = generatePubspecYaml('pkg_foo', '1.0.0');
+        final bytes = await packageArchiveBytes(pubspecContent: pubspecContent);
+        await expectApiException(
+          createPubApiClient(
+            authToken: userClientToken,
+          ).uploadPackageBytes(bytes),
+          code: 'PackageRejected',
+          status: 400,
+          message: 'Package name pkg_foo is reserved.',
+        );
+      },
+    );
+
     testWithProfile(
       'list and delete',
       fn: () async {