Sorted autocomplete (#1918)

Users, groups, repositories and repository roles have been sorted in the rest layer by default if no other sort option was given. In the layers "below" (aka the manager classes or the dao), the collections have been unsorted. This led to the effect, that the autocomplete resource, which did not sort all values beforehand, returned unsorted results. As a sideeffect, direct matches for an input could occur at a random position or not at all (as reported in #1695), when there were enough other matches.

With this pull request the databases for users, groups, repositories and repository roles will use instances of TreeMap instead of LinkedHashMap internally, so that these values are sorted implicitly (by id respectively name for users, groups and repository roles and namespace/name for repositories).

Due to this change the default sort applied in the rest layer could be removed.

gradle/changelog/autocomplete_sorted.yaml

@@ -0,0 +1,2 @@
+- type: fixed
+  description: Autocompletion has sorted suggestions ([#1918](https://github.com/scm-manager/scm-manager/pull/1918))

scm-dao-xml/src/main/java/sonia/scm/group/xml/XmlGroupDatabase.java

@@ -24,22 +24,17 @@
 
 package sonia.scm.group.xml;
 
-//~--- non-JDK imports --------------------------------------------------------
-
 import sonia.scm.group.Group;
 import sonia.scm.xml.XmlDatabase;
 
-//~--- JDK imports ------------------------------------------------------------
-
-import java.util.Collection;
-import java.util.LinkedHashMap;
-import java.util.Map;
-
 import javax.xml.bind.annotation.XmlAccessType;
 import javax.xml.bind.annotation.XmlAccessorType;
 import javax.xml.bind.annotation.XmlElement;
 import javax.xml.bind.annotation.XmlRootElement;
 import javax.xml.bind.annotation.adapters.XmlJavaTypeAdapter;
+import java.util.Collection;
+import java.util.Map;
+import java.util.TreeMap;
 
 /**
  *
@@ -190,7 +185,7 @@ public class XmlGroupDatabase implements XmlDatabase<Group>
   /** Field description */
   @XmlJavaTypeAdapter(XmlGroupMapAdapter.class)
   @XmlElement(name = "groups")
-  private Map<String, Group> groupMap = new LinkedHashMap<>();
+  private Map<String, Group> groupMap = new TreeMap<>();
 
   /** Field description */
   private Long lastModified;

scm-dao-xml/src/main/java/sonia/scm/group/xml/XmlGroupMapAdapter.java

@@ -24,16 +24,11 @@
 
 package sonia.scm.group.xml;
 
-//~--- non-JDK imports --------------------------------------------------------
-
 import sonia.scm.group.Group;
 
-//~--- JDK imports ------------------------------------------------------------
-
-import java.util.LinkedHashMap;
-import java.util.Map;
-
 import javax.xml.bind.annotation.adapters.XmlAdapter;
+import java.util.Map;
+import java.util.TreeMap;
 
 /**
  *
@@ -72,7 +67,7 @@ public class XmlGroupMapAdapter
   @Override
   public Map<String, Group> unmarshal(XmlGroupList groups) throws Exception
   {
-    Map<String, Group> groupMap = new LinkedHashMap<>();
+    Map<String, Group> groupMap = new TreeMap<>();
 
     for (Group group : groups)
     {

scm-dao-xml/src/main/java/sonia/scm/repository/xml/XmlRepositoryDAO.java

@@ -41,8 +41,13 @@ import javax.inject.Inject;
 import java.io.IOException;
 import java.nio.file.Path;
 import java.util.Collection;
+import java.util.HashMap;
 import java.util.Map;
-import java.util.concurrent.ConcurrentHashMap;
+import java.util.TreeMap;
+import java.util.concurrent.locks.Lock;
+import java.util.concurrent.locks.ReadWriteLock;
+import java.util.concurrent.locks.ReentrantReadWriteLock;
+import java.util.function.Supplier;
 
 /**
  * @author Sebastian Sdorra
@@ -50,7 +55,6 @@ import java.util.concurrent.ConcurrentHashMap;
 @Singleton
 public class XmlRepositoryDAO implements RepositoryDAO {
 
-
   private final MetadataStore metadataStore = new MetadataStore();
 
   private final PathBasedRepositoryLocationResolver repositoryLocationResolver;
@@ -59,6 +63,7 @@ public class XmlRepositoryDAO implements RepositoryDAO {
 
   private final Map<String, Repository> byId;
   private final Map<NamespaceAndName, Repository> byNamespaceAndName;
+  private final ReadWriteLock byNamespaceLock = new ReentrantReadWriteLock();
 
   @Inject
   public XmlRepositoryDAO(PathBasedRepositoryLocationResolver repositoryLocationResolver, FileSystem fileSystem, RepositoryExportingCheck repositoryExportingCheck) {
@@ -66,19 +71,21 @@ public class XmlRepositoryDAO implements RepositoryDAO {
     this.fileSystem = fileSystem;
     this.repositoryExportingCheck = repositoryExportingCheck;
 
-    this.byId = new ConcurrentHashMap<>();
-    this.byNamespaceAndName = new ConcurrentHashMap<>();
+    this.byId = new HashMap<>();
+    this.byNamespaceAndName = new TreeMap<>();
 
     init();
   }
 
   private void init() {
+    withWriteLockedMaps(() -> {
       RepositoryLocationResolver.RepositoryLocationResolverInstance<Path> pathRepositoryLocationResolverInstance = repositoryLocationResolver.create(Path.class);
       pathRepositoryLocationResolverInstance.forAllLocations((repositoryId, repositoryPath) -> {
         Repository repository = metadataStore.read(repositoryPath);
         byNamespaceAndName.put(repository.getNamespaceAndName(), repository);
         byId.put(repositoryId, repository);
       });
+    });
   }
 
   @Override
@@ -106,38 +113,40 @@ public class XmlRepositoryDAO implements RepositoryDAO {
       throw new InternalRepositoryException(repository, "failed to create filesystem", e);
     }
 
+    withWriteLockedMaps(() -> {
       byId.put(repository.getId(), clone);
       byNamespaceAndName.put(repository.getNamespaceAndName(), clone);
+    });
   }
 
   @Override
   public boolean contains(Repository repository) {
-    return byId.containsKey(repository.getId());
+    return withReadLockedMaps(() -> byId.containsKey(repository.getId()));
   }
 
   @Override
   public boolean contains(NamespaceAndName namespaceAndName) {
-    return byNamespaceAndName.containsKey(namespaceAndName);
+    return withReadLockedMaps(() -> byNamespaceAndName.containsKey(namespaceAndName));
   }
 
   @Override
   public boolean contains(String id) {
-    return byId.containsKey(id);
+    return withReadLockedMaps(() -> byId.containsKey(id));
   }
 
   @Override
   public Repository get(NamespaceAndName namespaceAndName) {
-    return byNamespaceAndName.get(namespaceAndName);
+    return withReadLockedMaps(() -> byNamespaceAndName.get(namespaceAndName));
   }
 
   @Override
   public Repository get(String id) {
-    return byId.get(id);
+    return withReadLockedMaps(() -> byId.get(id));
   }
 
   @Override
   public Collection<Repository> getAll() {
-    return ImmutableList.copyOf(byNamespaceAndName.values());
+    return withReadLockedMaps(() -> ImmutableList.copyOf(byNamespaceAndName.values()));
   }
 
   @Override
@@ -147,14 +156,14 @@ public class XmlRepositoryDAO implements RepositoryDAO {
       throw new StoreReadOnlyException(repository);
     }
 
-    synchronized (this) {
+    withWriteLockedMaps(() -> {
       // remove old namespaceAndName from map, in case of rename
       Repository prev = byId.put(clone.getId(), clone);
       if (prev != null) {
         byNamespaceAndName.remove(prev.getNamespaceAndName());
       }
       byNamespaceAndName.put(clone.getNamespaceAndName(), clone);
-    }
+    });
 
     Path repositoryPath = repositoryLocationResolver
       .create(Path.class)
@@ -164,8 +173,10 @@ public class XmlRepositoryDAO implements RepositoryDAO {
   }
 
   private boolean mustNotModifyRepository(Repository clone) {
-    return clone.isArchived() && byId.get(clone.getId()).isArchived()
-      || repositoryExportingCheck.isExporting(clone);
+    return withReadLockedMaps(() ->
+      clone.isArchived() && byId.get(clone.getId()).isArchived()
+        || repositoryExportingCheck.isExporting(clone)
+    );
   }
 
   @Override
@@ -173,14 +184,13 @@ public class XmlRepositoryDAO implements RepositoryDAO {
     if (repository.isArchived() || repositoryExportingCheck.isExporting(repository)) {
       throw new StoreReadOnlyException(repository);
     }
-    Path path;
-    synchronized (this) {
+    Path path = withWriteLockedMaps(() -> {
       Repository prev = byId.remove(repository.getId());
       if (prev != null) {
         byNamespaceAndName.remove(prev.getNamespaceAndName());
       }
-      path = repositoryLocationResolver.remove(repository.getId());
-    }
+      return repositoryLocationResolver.remove(repository.getId());
+    });
 
     try {
       fileSystem.destroy(path.toFile());
@@ -201,8 +211,40 @@ public class XmlRepositoryDAO implements RepositoryDAO {
 
   public void refresh() {
     repositoryLocationResolver.refresh();
+    withWriteLockedMaps(() -> {
       byNamespaceAndName.clear();
       byId.clear();
+    });
     init();
   }
+
+  private void withWriteLockedMaps(Runnable runnable) {
+    Lock lock = byNamespaceLock.writeLock();
+    lock.lock();
+    try {
+      runnable.run();
+    } finally {
+      lock.unlock();
+    }
+  }
+
+  private <T> T withWriteLockedMaps(Supplier<T> runnable) {
+    Lock lock = byNamespaceLock.writeLock();
+    lock.lock();
+    try {
+      return runnable.get();
+    } finally {
+      lock.unlock();
+    }
+  }
+
+  private <T> T withReadLockedMaps(Supplier<T> runnable) {
+    Lock lock = byNamespaceLock.readLock();
+    lock.lock();
+    try {
+      return runnable.get();
+    } finally {
+      lock.unlock();
+    }
+  }
 }

scm-dao-xml/src/main/java/sonia/scm/repository/xml/XmlRepositoryRoleDatabase.java

@@ -33,8 +33,8 @@ import javax.xml.bind.annotation.XmlElement;
 import javax.xml.bind.annotation.XmlRootElement;
 import javax.xml.bind.annotation.adapters.XmlJavaTypeAdapter;
 import java.util.Collection;
-import java.util.LinkedHashMap;
 import java.util.Map;
+import java.util.TreeMap;
 
 @XmlRootElement(name = "user-db")
 @XmlAccessorType(XmlAccessType.FIELD)
@@ -45,7 +45,7 @@ public class XmlRepositoryRoleDatabase implements XmlDatabase<RepositoryRole> {
 
   @XmlJavaTypeAdapter(XmlRepositoryRoleMapAdapter.class)
   @XmlElement(name = "roles")
-  private Map<String, RepositoryRole> roleMap = new LinkedHashMap<>();
+  private Map<String, RepositoryRole> roleMap = new TreeMap<>();
 
   public XmlRepositoryRoleDatabase() {
     long c = System.currentTimeMillis();

scm-dao-xml/src/main/java/sonia/scm/repository/xml/XmlRepositoryRoleMapAdapter.java

@@ -27,8 +27,8 @@ package sonia.scm.repository.xml;
 import sonia.scm.repository.RepositoryRole;
 
 import javax.xml.bind.annotation.adapters.XmlAdapter;
-import java.util.LinkedHashMap;
 import java.util.Map;
+import java.util.TreeMap;
 
 public class XmlRepositoryRoleMapAdapter
         extends XmlAdapter<XmlRepositoryRoleList, Map<String, RepositoryRole>> {
@@ -40,7 +40,7 @@ public class XmlRepositoryRoleMapAdapter
 
   @Override
   public Map<String, RepositoryRole> unmarshal(XmlRepositoryRoleList roles) {
-    Map<String, RepositoryRole> roleMap = new LinkedHashMap<>();
+    Map<String, RepositoryRole> roleMap = new TreeMap<>();
 
     for (RepositoryRole role : roles) {
       roleMap.put(role.getName(), role);

scm-dao-xml/src/main/java/sonia/scm/user/xml/XmlUserDatabase.java

@@ -24,22 +24,17 @@
 
 package sonia.scm.user.xml;
 
-//~--- non-JDK imports --------------------------------------------------------
-
 import sonia.scm.user.User;
 import sonia.scm.xml.XmlDatabase;
 
-//~--- JDK imports ------------------------------------------------------------
-
-import java.util.Collection;
-import java.util.LinkedHashMap;
-import java.util.Map;
-
 import javax.xml.bind.annotation.XmlAccessType;
 import javax.xml.bind.annotation.XmlAccessorType;
 import javax.xml.bind.annotation.XmlElement;
 import javax.xml.bind.annotation.XmlRootElement;
 import javax.xml.bind.annotation.adapters.XmlJavaTypeAdapter;
+import java.util.Collection;
+import java.util.Map;
+import java.util.TreeMap;
 
 /**
  *
@@ -193,5 +188,5 @@ public class XmlUserDatabase implements XmlDatabase<User>
   /** Field description */
   @XmlJavaTypeAdapter(XmlUserMapAdapter.class)
   @XmlElement(name = "users")
-  private Map<String, User> userMap = new LinkedHashMap<>();
+  private Map<String, User> userMap = new TreeMap<>();
 }

scm-dao-xml/src/main/java/sonia/scm/user/xml/XmlUserMapAdapter.java

@@ -24,16 +24,11 @@
 
 package sonia.scm.user.xml;
 
-//~--- non-JDK imports --------------------------------------------------------
-
 import sonia.scm.user.User;
 
-//~--- JDK imports ------------------------------------------------------------
-
-import java.util.LinkedHashMap;
-import java.util.Map;
-
 import javax.xml.bind.annotation.adapters.XmlAdapter;
+import java.util.Map;
+import java.util.TreeMap;
 
 /**
  *
@@ -72,7 +67,7 @@ public class XmlUserMapAdapter
   @Override
   public Map<String, User> unmarshal(XmlUserList users) throws Exception
   {
-    Map<String, User> userMap = new LinkedHashMap<>();
+    Map<String, User> userMap = new TreeMap<>();
 
     for (User user : users)
     {

scm-dao-xml/src/main/java/sonia/scm/xml/AbstractXmlDAO.java

@@ -45,7 +45,7 @@ import java.util.Collection;
  * @param <T>
  */
 public abstract class AbstractXmlDAO<I extends ModelObject,
-      T extends XmlDatabase> implements GenericDAO<I>
+      T extends XmlDatabase<I>> implements GenericDAO<I>
 {
 
   /** Field description */

scm-ui/ui-api/src/repositories.test.ts

@@ -89,11 +89,7 @@ describe("Test repository hooks", () => {
     it("should return repositories", async () => {
       const queryClient = createInfiniteCachingClient();
       setIndexLink(queryClient, "repositories", "/repos");
-      fetchMock.get("/api/v2/repos", repositoryCollection, {
-        query: {
-          sortBy: "namespaceAndName"
-        }
-      });
+      fetchMock.get("/api/v2/repos", repositoryCollection);
 
       await expectCollection(queryClient);
     });
@@ -103,7 +99,6 @@ describe("Test repository hooks", () => {
       setIndexLink(queryClient, "repositories", "/repos");
       fetchMock.get("/api/v2/repos", repositoryCollection, {
         query: {
-          sortBy: "namespaceAndName",
           page: "42"
         }
       });
@@ -116,11 +111,7 @@ describe("Test repository hooks", () => {
     it("should use repository from namespace", async () => {
       const queryClient = createInfiniteCachingClient();
       setIndexLink(queryClient, "repositories", "/repos");
-      fetchMock.get("/api/v2/spaceships", repositoryCollection, {
-        query: {
-          sortBy: "namespaceAndName"
-        }
-      });
+      fetchMock.get("/api/v2/spaceships", repositoryCollection);
 
       await expectCollection(queryClient, {
         namespace: {
@@ -139,7 +130,6 @@ describe("Test repository hooks", () => {
       setIndexLink(queryClient, "repositories", "/repos");
       fetchMock.get("/api/v2/repos", repositoryCollection, {
         query: {
-          sortBy: "namespaceAndName",
           q: "heart"
         }
       });
@@ -152,11 +142,7 @@ describe("Test repository hooks", () => {
     it("should update repository cache", async () => {
       const queryClient = createInfiniteCachingClient();
       setIndexLink(queryClient, "repositories", "/repos");
-      fetchMock.get("/api/v2/repos", repositoryCollection, {
-        query: {
-          sortBy: "namespaceAndName"
-        }
-      });
+      fetchMock.get("/api/v2/repos", repositoryCollection);
 
       await expectCollection(queryClient);
 

scm-ui/ui-api/src/repositories.ts

@@ -30,7 +30,7 @@ import {
   Repository,
   RepositoryCollection,
   RepositoryCreation,
-  RepositoryTypeCollection,
+  RepositoryTypeCollection
 } from "@scm-manager/ui-types";
 import { useMutation, useQuery, useQueryClient } from "react-query";
 import { apiClient } from "./apiclient";
@@ -55,9 +55,7 @@ export const useRepositories = (request?: UseRepositoriesRequest): ApiResult<Rep
   const namespaceLink = (request?.namespace?._links.repositories as Link)?.href;
   const link = namespaceLink || indexLink;
 
-  const queryParams: Record<string, string> = {
-    sortBy: "namespaceAndName",
-  };
+  const queryParams: Record<string, string> = {};
   if (request?.search) {
     queryParams.q = request.search;
   }
@@ -66,7 +64,7 @@ export const useRepositories = (request?: UseRepositoriesRequest): ApiResult<Rep
   }
   return useQuery<RepositoryCollection, Error>(
     ["repositories", request?.namespace?.namespace, request?.search || "", request?.page || 0],
-    () => apiClient.get(`${link}?${createQueryString(queryParams)}`).then((response) => response.json()),
+    () => apiClient.get(`${link}?${createQueryString(queryParams)}`).then(response => response.json()),
     {
       enabled: !request?.disabled,
       onSuccess: (repositories: RepositoryCollection) => {
@@ -74,7 +72,7 @@ export const useRepositories = (request?: UseRepositoriesRequest): ApiResult<Rep
         repositories._embedded?.repositories.forEach((repository: Repository) => {
           queryClient.setQueryData(["repository", repository.namespace, repository.name], repository);
         });
-      },
+      }
     }
   );
 };
@@ -92,14 +90,14 @@ const createRepository = (link: string) => {
     }
     return apiClient
       .post(createLink, request.repository, "application/vnd.scmm-repository+json;v=2")
-      .then((response) => {
+      .then(response => {
         const location = response.headers.get("Location");
         if (!location) {
           throw new Error("Server does not return required Location header");
         }
         return apiClient.get(location);
       })
-      .then((response) => response.json());
+      .then(response => response.json());
   };
 };
 
@@ -111,10 +109,10 @@ export const useCreateRepository = () => {
   const { mutate, data, isLoading, error } = useMutation<Repository, Error, CreateRepositoryRequest>(
     createRepository(link),
     {
-      onSuccess: (repository) => {
+      onSuccess: repository => {
         queryClient.setQueryData(["repository", repository.namespace, repository.name], repository);
         return queryClient.invalidateQueries(["repositories"]);
-      },
+      }
     }
   );
   return {
@@ -123,7 +121,7 @@ export const useCreateRepository = () => {
     },
     isLoading,
     error,
-    repository: data,
+    repository: data
   };
 };
 
@@ -133,7 +131,7 @@ export const useRepositoryTypes = () => useIndexJsonResource<RepositoryTypeColle
 export const useRepository = (namespace: string, name: string): ApiResult<Repository> => {
   const link = useRequiredIndexLink("repositories");
   return useQuery<Repository, Error>(["repository", namespace, name], () =>
-    apiClient.get(concat(link, namespace, name)).then((response) => response.json())
+    apiClient.get(concat(link, namespace, name)).then(response => response.json())
   );
 };
 
@@ -144,7 +142,7 @@ export type UseDeleteRepositoryOptions = {
 export const useDeleteRepository = (options?: UseDeleteRepositoryOptions) => {
   const queryClient = useQueryClient();
   const { mutate, isLoading, error, data } = useMutation<unknown, Error, Repository>(
-    (repository) => {
+    repository => {
       const link = requiredLink(repository, "delete");
       return apiClient.delete(link);
     },
@@ -153,23 +151,23 @@ export const useDeleteRepository = (options?: UseDeleteRepositoryOptions) => {
         if (options?.onSuccess) {
           options.onSuccess(repository);
         }
-        await queryClient.removeQueries(repoQueryKey(repository));
+        queryClient.removeQueries(repoQueryKey(repository));
         await queryClient.invalidateQueries(["repositories"]);
-      },
+      }
     }
   );
   return {
     remove: (repository: Repository) => mutate(repository),
     isLoading,
     error,
-    isDeleted: !!data,
+    isDeleted: !!data
   };
 };
 
 export const useUpdateRepository = () => {
   const queryClient = useQueryClient();
   const { mutate, isLoading, error, data } = useMutation<unknown, Error, Repository>(
-    (repository) => {
+    repository => {
       const link = requiredLink(repository, "update");
       return apiClient.put(link, repository, "application/vnd.scmm-repository+json;v=2");
     },
@@ -177,21 +175,21 @@ export const useUpdateRepository = () => {
       onSuccess: async (_, repository) => {
         await queryClient.invalidateQueries(repoQueryKey(repository));
         await queryClient.invalidateQueries(["repositories"]);
-      },
+      }
     }
   );
   return {
     update: (repository: Repository) => mutate(repository),
     isLoading,
     error,
-    isUpdated: !!data,
+    isUpdated: !!data
   };
 };
 
 export const useArchiveRepository = () => {
   const queryClient = useQueryClient();
   const { mutate, isLoading, error, data } = useMutation<unknown, Error, Repository>(
-    (repository) => {
+    repository => {
       const link = requiredLink(repository, "archive");
       return apiClient.post(link);
     },
@@ -199,21 +197,21 @@ export const useArchiveRepository = () => {
       onSuccess: async (_, repository) => {
         await queryClient.invalidateQueries(repoQueryKey(repository));
         await queryClient.invalidateQueries(["repositories"]);
-      },
+      }
     }
   );
   return {
     archive: (repository: Repository) => mutate(repository),
     isLoading,
     error,
-    isArchived: !!data,
+    isArchived: !!data
   };
 };
 
 export const useUnarchiveRepository = () => {
   const queryClient = useQueryClient();
   const { mutate, isLoading, error, data } = useMutation<unknown, Error, Repository>(
-    (repository) => {
+    repository => {
       const link = requiredLink(repository, "unarchive");
       return apiClient.post(link);
     },
@@ -221,35 +219,35 @@ export const useUnarchiveRepository = () => {
       onSuccess: async (_, repository) => {
         await queryClient.invalidateQueries(repoQueryKey(repository));
         await queryClient.invalidateQueries(["repositories"]);
-      },
+      }
     }
   );
   return {
     unarchive: (repository: Repository) => mutate(repository),
     isLoading,
     error,
-    isUnarchived: !!data,
+    isUnarchived: !!data
   };
 };
 
 export const useRunHealthCheck = () => {
   const queryClient = useQueryClient();
   const { mutate, isLoading, error, data } = useMutation<unknown, Error, Repository>(
-    (repository) => {
+    repository => {
       const link = requiredLink(repository, "runHealthCheck");
       return apiClient.post(link);
     },
     {
       onSuccess: async (_, repository) => {
         await queryClient.invalidateQueries(repoQueryKey(repository));
-      },
+      }
     }
   );
   return {
     runHealthCheck: (repository: Repository) => mutate(repository),
     isLoading,
     error,
-    isRunning: !!data,
+    isRunning: !!data
   };
 };
 
@@ -258,7 +256,7 @@ export const useExportInfo = (repository: Repository): ApiResultWithFetching<Exp
   //TODO Refetch while exporting to update the page
   const { isLoading, isFetching, error, data } = useQuery<ExportInfo, Error>(
     ["repository", repository.namespace, repository.name, "exportInfo"],
-    () => apiClient.get(link).then((response) => response.json()),
+    () => apiClient.get(link).then(response => response.json()),
     {}
   );
 
@@ -266,7 +264,7 @@ export const useExportInfo = (repository: Repository): ApiResultWithFetching<Exp
     isLoading,
     isFetching,
     error: error instanceof NotFoundError ? null : error,
-    data,
+    data
   };
 };
 
@@ -309,14 +307,14 @@ export const useExportRepository = () => {
             const id = setInterval(() => {
               apiClient
                 .get(infolink)
-                .then((r) => r.json())
+                .then(r => r.json())
                 .then((info: ExportInfo) => {
                   if (info._links.download) {
                     clearInterval(id);
                     resolve(info);
                   }
                 })
-                .catch((e) => {
+                .catch(e => {
                   clearInterval(id);
                   reject(e);
                 });
@@ -329,21 +327,21 @@ export const useExportRepository = () => {
       onSuccess: async (_, { repository }) => {
         await queryClient.invalidateQueries(repoQueryKey(repository));
         await queryClient.invalidateQueries(["repositories"]);
-      },
+      }
     }
   );
   return {
     exportRepository: (repository: Repository, options: ExportOptions) => mutate({ repository, options }),
     isLoading,
     error,
-    data,
+    data
   };
 };
 
 export const usePaths = (repository: Repository, revision: string): ApiResult<Paths> => {
   const link = requiredLink(repository, "paths").replace("{revision}", revision);
   return useQuery<Paths, Error>(repoQueryKey(repository, "paths", revision), () =>
-    apiClient.get(link).then((response) => response.json())
+    apiClient.get(link).then(response => response.json())
   );
 };
 
@@ -364,7 +362,7 @@ export const useRenameRepository = (repository: Repository) => {
   const { mutate, isLoading, error, data } = useMutation<unknown, Error, RenameRepositoryRequest>(
     ({ name, namespace }) => apiClient.post(url, { namespace, name }, "application/vnd.scmm-repository+json;v=2"),
     {
-      onSuccess: () => queryClient.removeQueries(repoQueryKey(repository)),
+      onSuccess: () => queryClient.removeQueries(repoQueryKey(repository))
     }
   );
 
@@ -372,6 +370,6 @@ export const useRenameRepository = (repository: Repository) => {
     renameRepository: (namespace: string, name: string) => mutate({ namespace, name }),
     isLoading,
     error,
-    isRenamed: !!data,
+    isRenamed: !!data
   };
 };

scm-ui/ui-components/src/repositories.test.ts

@@ -35,10 +35,10 @@ describe("getProtocolLinkByType tests", () => {
         protocol: [
           {
             name: "http",
-            href: "http://scm.scm-manager.org/repo/scm/core",
-          },
-        ],
-      },
+            href: "http://scm.scm-manager.org/repo/scm/core"
+          }
+        ]
+      }
     };
 
     const link = getProtocolLinkByType(repository, "http");
@@ -54,14 +54,14 @@ describe("getProtocolLinkByType tests", () => {
         protocol: [
           {
             name: "http",
-            href: "http://scm.scm-manager.org/repo/scm/core",
+            href: "http://scm.scm-manager.org/repo/scm/core"
           },
           {
             name: "ssh",
-            href: "git@scm.scm-manager.org:scm/core",
-          },
-        ],
-      },
+            href: "git@scm.scm-manager.org:scm/core"
+          }
+        ]
+      }
     };
 
     const link = getProtocolLinkByType(repository, "http");
@@ -76,9 +76,9 @@ describe("getProtocolLinkByType tests", () => {
       _links: {
         protocol: {
           name: "http",
-          href: "http://scm.scm-manager.org/repo/scm/core",
-        },
-      },
+          href: "http://scm.scm-manager.org/repo/scm/core"
+        }
+      }
     };
 
     const link = getProtocolLinkByType(repository, "http");
@@ -94,14 +94,14 @@ describe("getProtocolLinkByType tests", () => {
         protocol: [
           {
             name: "http",
-            href: "http://scm.scm-manager.org/repo/scm/core",
+            href: "http://scm.scm-manager.org/repo/scm/core"
           },
           {
             name: "ssh",
-            href: "git@scm.scm-manager.org:scm/core",
-          },
-        ],
-      },
+            href: "git@scm.scm-manager.org:scm/core"
+          }
+        ]
+      }
     };
 
     const link = getProtocolLinkByType(repository, "awesome");
@@ -113,7 +113,7 @@ describe("getProtocolLinkByType tests", () => {
       namespace: "scm",
       name: "core",
       type: "git",
-      _links: {},
+      _links: {}
     };
 
     const link = getProtocolLinkByType(repository, "http");

scm-webapp/src/main/java/sonia/scm/GenericDisplayManager.java

@@ -31,6 +31,7 @@ import java.util.Collection;
 import java.util.Optional;
 import java.util.function.Function;
 
+import static java.util.Optional.empty;
 import static java.util.Optional.ofNullable;
 
 public abstract class GenericDisplayManager<D, T extends ReducedModelObject> implements DisplayManager<T> {
@@ -60,6 +61,9 @@ public abstract class GenericDisplayManager<D, T extends ReducedModelObject> imp
 
   @Override
   public Optional<T> get(String id) {
+    if (id == null) {
+      return empty();
+    }
     return ofNullable(dao.get(id)).map(transform);
   }
 }

scm-webapp/src/main/java/sonia/scm/api/v2/resources/CollectionResourceManagerAdapter.java

@@ -77,12 +77,12 @@ class CollectionResourceManagerAdapter<MODEL_OBJECT extends ModelObject,
     AssertUtil.assertPositive(pageNumber);
     AssertUtil.assertPositive(pageSize);
 
-    if (Util.isEmpty(sortBy)) {
-      // replace with something useful
-      sortBy = "id";
+    Comparator<MODEL_OBJECT> comparator = null;
+    if (!Util.isEmpty(sortBy)) {
+      comparator = createComparator(sortBy, desc);
     }
 
-    return manager.getPage(filter, createComparator(sortBy, desc), pageNumber, pageSize);
+    return manager.getPage(filter, comparator, pageNumber, pageSize);
   }
 
   private Comparator<MODEL_OBJECT> createComparator(String sortBy, boolean desc) {

scm-webapp/src/main/java/sonia/scm/repository/DefaultRepositoryManager.java

@@ -41,7 +41,6 @@ import sonia.scm.event.ScmEventBus;
 import sonia.scm.security.AuthorizationChangedEvent;
 import sonia.scm.security.KeyGenerator;
 import sonia.scm.util.AssertUtil;
-import sonia.scm.util.CollectionAppender;
 import sonia.scm.util.IOUtil;
 import sonia.scm.util.Util;
 
@@ -51,13 +50,19 @@ import java.util.Collections;
 import java.util.Comparator;
 import java.util.HashMap;
 import java.util.HashSet;
+import java.util.LinkedHashSet;
 import java.util.List;
 import java.util.Map;
 import java.util.Set;
+import java.util.function.BiConsumer;
+import java.util.function.BinaryOperator;
 import java.util.function.Consumer;
+import java.util.function.Function;
 import java.util.function.Predicate;
+import java.util.function.Supplier;
+import java.util.stream.Collector;
 
-import static java.util.stream.Collectors.toSet;
+import static java.util.Collections.emptySet;
 import static sonia.scm.AlreadyExistsException.alreadyExists;
 import static sonia.scm.ContextEntry.ContextBuilder.entity;
 import static sonia.scm.NotFoundException.notFound;
@@ -70,6 +75,33 @@ import static sonia.scm.NotFoundException.notFound;
 @Singleton
 public class DefaultRepositoryManager extends AbstractRepositoryManager {
 
+  @SuppressWarnings("unchecked")
+  public static final Collector<String, Object, Collection<String>> LINKED_HASH_SET_COLLECTOR = new Collector<String, Object, Collection<String>>() {
+    @Override
+    public Supplier<Object> supplier() {
+      return LinkedHashSet::new;
+    }
+
+    @Override
+    public BiConsumer<Object, String> accumulator() {
+      return (collection, value) -> ((Collection<String>) collection).add(value);
+    }
+
+    @Override
+    public BinaryOperator<Object> combiner() {
+      return (c1, c2) -> ((Collection<String>) c1).addAll((Collection<String>) c2);
+    }
+
+    @Override
+    public Function<Object, Collection<String>> finisher() {
+      return collection -> (Collection<String>) collection;
+    }
+
+    @Override
+    public Set<Characteristics> characteristics() {
+      return emptySet();
+    }
+  };
   private static final Logger logger = LoggerFactory.getLogger(DefaultRepositoryManager.class);
   private final Map<String, RepositoryHandler> handlerMap;
   private final KeyGenerator keyGenerator;
@@ -340,13 +372,10 @@ public class DefaultRepositoryManager extends AbstractRepositoryManager {
                                        int start, int limit) {
 
     return Util.createSubCollection(repositoryDAO.getAll(), comparator,
-      new CollectionAppender<Repository>() {
-        @Override
-        public void append(Collection<Repository> collection, Repository item) {
+      (collection, item) -> {
         if (RepositoryPermissions.read().isPermitted(item)) {
           collection.add(postProcess(item));
         }
-        }
       }, start, limit);
   }
 
@@ -363,7 +392,7 @@ public class DefaultRepositoryManager extends AbstractRepositoryManager {
   public Collection<String> getAllNamespaces() {
     return getAll().stream()
       .map(Repository::getNamespace)
-      .collect(toSet());
+      .collect(LINKED_HASH_SET_COLLECTOR);
   }
 
   @Override

scm-webapp/src/test/java/sonia/scm/api/v2/resources/CollectionResourceManagerAdapterTest.java

@@ -38,6 +38,7 @@ import sonia.scm.api.rest.resources.Simple;
 import java.util.Comparator;
 import java.util.function.Predicate;
 
+import static org.junit.Assert.assertNull;
 import static org.junit.Assert.assertTrue;
 import static org.mockito.ArgumentMatchers.eq;
 import static org.mockito.Mockito.when;
@@ -61,11 +62,11 @@ public class CollectionResourceManagerAdapterTest {
   }
 
   @Test
-  public void shouldAcceptDefaultSortByParameter() {
+  public void shouldNotSortByDefault() {
     abstractManagerResource.getAll(0, 1, x -> true, null, true, r -> null);
 
     Comparator<Simple> comparator = comparatorCaptor.getValue();
-    assertTrue(comparator.compare(new Simple("1", null), new Simple("2", null)) > 0);
+    assertNull(comparator);
   }
 
   @Test