Merge pull request #35 from overleaf/msw-refactor_24

#24 Part 3/6: refactor

services/git-bridge/src/main/java/uk/ac/ic/wlgitbridge/bridge/Bridge.java

@@ -1,7 +1,7 @@
 package uk.ac.ic.wlgitbridge.bridge;
 
 import com.google.api.client.auth.oauth2.Credential;
-import org.eclipse.jgit.transport.ServiceMayNotContinueException;
+import org.eclipse.jgit.errors.RepositoryNotFoundException;
 import uk.ac.ic.wlgitbridge.bridge.db.DBStore;
 import uk.ac.ic.wlgitbridge.bridge.db.ProjectState;
 import uk.ac.ic.wlgitbridge.bridge.db.sqlite.SqliteDBStore;
@@ -15,13 +15,14 @@ import uk.ac.ic.wlgitbridge.bridge.repo.ProjectRepo;
 import uk.ac.ic.wlgitbridge.bridge.repo.RepoStore;
 import uk.ac.ic.wlgitbridge.bridge.resource.ResourceCache;
 import uk.ac.ic.wlgitbridge.bridge.resource.UrlResourceCache;
-import uk.ac.ic.wlgitbridge.bridge.snapshot.NetSnapshotAPI;
-import uk.ac.ic.wlgitbridge.bridge.snapshot.SnapshotAPI;
+import uk.ac.ic.wlgitbridge.bridge.snapshot.NetSnapshotApi;
+import uk.ac.ic.wlgitbridge.bridge.snapshot.SnapshotApi;
 import uk.ac.ic.wlgitbridge.bridge.swap.job.SwapJob;
 import uk.ac.ic.wlgitbridge.bridge.swap.job.SwapJobConfig;
 import uk.ac.ic.wlgitbridge.bridge.swap.job.SwapJobImpl;
 import uk.ac.ic.wlgitbridge.bridge.swap.store.S3SwapStore;
 import uk.ac.ic.wlgitbridge.bridge.swap.store.SwapStore;
+import uk.ac.ic.wlgitbridge.bridge.snapshot.SnapshotApiFacade;
 import uk.ac.ic.wlgitbridge.data.CandidateSnapshot;
 import uk.ac.ic.wlgitbridge.data.ProjectLockImpl;
 import uk.ac.ic.wlgitbridge.data.filestore.GitDirectoryContents;
@@ -38,12 +39,9 @@ import uk.ac.ic.wlgitbridge.server.FileHandler;
 import uk.ac.ic.wlgitbridge.server.PostbackContents;
 import uk.ac.ic.wlgitbridge.server.PostbackHandler;
 import uk.ac.ic.wlgitbridge.snapshot.base.ForbiddenException;
-import uk.ac.ic.wlgitbridge.snapshot.getdoc.GetDocRequest;
-import uk.ac.ic.wlgitbridge.snapshot.getdoc.exception.InvalidProjectException;
 import uk.ac.ic.wlgitbridge.snapshot.getforversion.SnapshotAttachment;
 import uk.ac.ic.wlgitbridge.snapshot.push.PostbackManager;
 import uk.ac.ic.wlgitbridge.snapshot.push.PostbackPromise;
-import uk.ac.ic.wlgitbridge.snapshot.push.PushRequest;
 import uk.ac.ic.wlgitbridge.snapshot.push.PushResult;
 import uk.ac.ic.wlgitbridge.snapshot.push.exception.*;
 import uk.ac.ic.wlgitbridge.util.Log;
@@ -120,8 +118,8 @@ import java.util.*;
  *
  * 6. The Snapshot API, which provides data from the Overleaf app.
  *
- *    @see SnapshotAPI - the interface for the Snapshot API.
- *    @see NetSnapshotAPI - the default concrete implementation
+ *    @see SnapshotApi - the interface for the Snapshot API.
+ *    @see NetSnapshotApi - the default concrete implementation
  *
  * 7. The Resource Cache, which provides the data for attachment resources from
  *    URLs. It will generally fetch from the source on a cache miss.
@@ -149,7 +147,7 @@ public class Bridge {
     private final SwapJob swapJob;
     private final GcJob gcJob;
 
-    private final SnapshotAPI snapshotAPI;
+    private final SnapshotApiFacade snapshotAPI;
     private final ResourceCache resourceCache;
 
     private final PostbackManager postbackManager;
@@ -169,7 +167,8 @@ public class Bridge {
             RepoStore repoStore,
             DBStore dbStore,
             SwapStore swapStore,
-            Optional<SwapJobConfig> swapJobConfig
+            Optional<SwapJobConfig> swapJobConfig,
+            SnapshotApi snapshotApi
     ) {
         ProjectLock lock = new ProjectLockImpl((int threads) ->
                 Log.info("Waiting for " + threads + " projects...")
@@ -187,7 +186,7 @@ public class Bridge {
                         swapStore
                 ),
                 new GcJobImpl(repoStore, lock),
-                new NetSnapshotAPI(),
+                new SnapshotApiFacade(snapshotApi),
                 new UrlResourceCache(dbStore)
         );
     }
@@ -202,7 +201,7 @@ public class Bridge {
      * @param swapStore the {@link SwapStore} to use
      * @param swapJob the {@link SwapJob} to use
      * @param gcJob
-     * @param snapshotAPI the {@link SnapshotAPI} to use
+     * @param snapshotAPI the {@link SnapshotApi} to use
      * @param resourceCache the {@link ResourceCache} to use
      */
     Bridge(
@@ -212,7 +211,7 @@ public class Bridge {
             SwapStore swapStore,
             SwapJob swapJob,
             GcJob gcJob,
-            SnapshotAPI snapshotAPI,
+            SnapshotApiFacade snapshotAPI,
             ResourceCache resourceCache
     ) {
         this.lock = lock;
@@ -291,63 +290,26 @@ public class Bridge {
         }
     }
 
-    /**
-     * Checks if a project exists by asking the snapshot API.
-     *
-     * The snapshot API is the source of truth because we can't know by
-     * ourselves whether a project exists. If a user creates a project on the
-     * app, and clones, the project is not on the git bridge disk and must ask
-     * the snapshot API whether it exists.
-     *
-     * 1. Acquires the project lock.
-     * 2. Makes a docs request and tries to get the version ID.
-     * 3. If the version ID is valid, returns true.
-     * 4. Otherwise, the version ID is invalid, and throws
-     *    InvalidProjectException, returning false.
-     *
-     * @param oauth2 The oauth2 to use for the snapshot API
-     * @param projectName The project name
-     * @return true iff the project exists
-     * @throws ServiceMayNotContinueException if the connection fails
-     * @throws GitUserException if the user is not allowed access
-     */
-    public boolean projectExists(
-            Credential oauth2,
-            String projectName
-    ) throws ServiceMayNotContinueException,
-             GitUserException {
-        Log.info("[{}] Checking that project exists", projectName);
-        try (LockGuard __ = lock.lockGuard(projectName)) {
-            GetDocRequest getDocRequest = new GetDocRequest(
-                    oauth2,
-                    projectName
-            );
-            getDocRequest.request();
-            getDocRequest.getResult().getVersionID();
-            return true;
-        } catch (InvalidProjectException e) {
-            return false;
-        }
-    }
-
     /**
      * Synchronises the given repository with Overleaf.
      *
      * It acquires the project lock and calls
-     * {@link #updateRepositoryCritical(Credential, ProjectRepo)}
+     * {@link #getUpdatedRepoCritical(Optional, String)}.
      * @param oauth2 The oauth2 to use
-     * @param repo the repository to use
+     * @param projectName The name of the project
      * @throws IOException
      * @throws GitUserException
      */
-    public void updateRepository(
-            Credential oauth2,
-            ProjectRepo repo
+    public ProjectRepo getUpdatedRepo(
+            Optional<Credential> oauth2,
+            String projectName
     ) throws IOException, GitUserException {
-        String projectName = repo.getProjectName();
         try (LockGuard __ = lock.lockGuard(projectName)) {
+            if (!snapshotAPI.projectExists(oauth2, projectName)) {
+                throw new RepositoryNotFoundException(projectName);
+            }
             Log.info("[{}] Updating repository", projectName);
-            updateRepositoryCritical(oauth2, repo);
+            return getUpdatedRepoCritical(oauth2, projectName);
         }
     }
 
@@ -359,9 +321,7 @@ public class Bridge {
      * 1. Queries the project state for the given project name.
      *    a. NOT_PRESENT = We've never seen it before, and the row for the
      *                     project doesn't even exist. The project definitely
-     *                     exists because
-     *                     {@link #projectExists(Credential, String)} would
-     *                     have had to return true to get here.
+     *                     exists because we would have aborted otherwise.
      *    b. PRESENT = The project is on disk.
      *    c. SWAPPED = The project is in the {@link SwapStore}
      *
@@ -370,43 +330,44 @@ public class Bridge {
      * present.
      *
      * With the project present, snapshots are downloaded from the snapshot
-     * API with {@link #updateProject(Credential, ProjectRepo)}.
+     * API with {@link #updateProject(Optional, ProjectRepo)}.
      *
      * Then, the last accessed time of the project is set to the current time.
      * This is to support the LRU of the swap store.
      * @param oauth2
-     * @param repo
+     * @param projectName The name of the project
      * @throws IOException
      * @throws GitUserException
      */
-    private void updateRepositoryCritical(
-            Credential oauth2,
-            ProjectRepo repo
+    private ProjectRepo getUpdatedRepoCritical(
+            Optional<Credential> oauth2,
+            String projectName
     ) throws IOException, GitUserException {
-        String projectName = repo.getProjectName();
+        ProjectRepo repo;
         ProjectState state = dbStore.getProjectState(projectName);
         switch (state) {
         case NOT_PRESENT:
-            repo.initRepo(repoStore);
+            repo = repoStore.initRepo(projectName);
             break;
         case SWAPPED:
             swapJob.restore(projectName);
             /* Fallthrough */
         default:
-            repo.useExistingRepository(repoStore);
+            repo = repoStore.getExistingRepo(projectName);
         }
         updateProject(oauth2, repo);
         dbStore.setLastAccessedTime(
                 projectName,
                 Timestamp.valueOf(LocalDateTime.now())
         );
+        return repo;
     }
 
     /**
      * The public call to push a project.
      *
      * It acquires the lock and calls {@link #pushCritical(
-     *      Credential,
+     *      Optional,
      *      String,
      *      RawDirectory,
      *      RawDirectory
@@ -421,7 +382,7 @@ public class Bridge {
      * @throws ForbiddenException
      */
     public void push(
-            Credential oauth2,
+            Optional<Credential> oauth2,
             String projectName,
             RawDirectory directoryContents,
             RawDirectory oldDirectoryContents,
@@ -499,7 +460,7 @@ public class Bridge {
      * @throws SnapshotPostException
      */
     private void pushCritical(
-            Credential oauth2,
+            Optional<Credential> oauth2,
             String projectName,
             RawDirectory directoryContents,
             RawDirectory oldDirectoryContents
@@ -523,13 +484,8 @@ public class Bridge {
                     projectName,
                     candidate
             );
-            PushRequest pushRequest = new PushRequest(
-                    oauth2,
-                    candidate,
-                    postbackKey
-            );
-            pushRequest.request();
-            PushResult result = pushRequest.getResult();
+            PushResult result
+                    = snapshotAPI.push(oauth2, candidate, postbackKey);
             if (result.wasSuccessful()) {
                 Log.info(
                         "[{}] Push to Overleaf successful",
@@ -587,7 +543,7 @@ public class Bridge {
      * {@link PostbackContents#processPostback()}, i.e. once the Overleaf app
      * has fetched all the atts and has committed the push and is happy, it
      * calls back here, fulfilling the promise that the push
-     * {@link #push(Credential, String, RawDirectory, RawDirectory, String)}
+     * {@link #push(Optional, String, RawDirectory, RawDirectory, String)}
      * is waiting on.
      *
      * The Overleaf app will have invented a new version for the push, which is
@@ -642,7 +598,7 @@ public class Bridge {
     /* PRIVATE */
 
     /**
-     * Called by {@link #updateRepositoryCritical(Credential, ProjectRepo)}.
+     * Called by {@link #getUpdatedRepoCritical(Optional, String)}
      *
      * Does the actual work of getting the snapshots for a project from the
      * snapshot API and committing them to a repo.
@@ -655,16 +611,13 @@ public class Bridge {
      * @throws GitUserException
      */
     private void updateProject(
-            Credential oauth2,
+            Optional<Credential> oauth2,
             ProjectRepo repo
     ) throws IOException, GitUserException {
         String projectName = repo.getProjectName();
-        Deque<Snapshot> snapshots =
-                snapshotAPI.getSnapshotsForProjectAfterVersion(
-                        oauth2,
-                        projectName,
-                        dbStore.getLatestVersionForProject(projectName)
-                );
+        int latestVersionId = dbStore.getLatestVersionForProject(projectName);
+        Deque<Snapshot> snapshots = snapshotAPI.getSnapshots(
+                oauth2, projectName, latestVersionId);
 
         makeCommitsFromSnapshots(repo, snapshots);
 
@@ -677,7 +630,7 @@ public class Bridge {
     }
 
     /**
-     * Called by {@link #updateProject(Credential, ProjectRepo)}.
+     * Called by {@link #updateProject(Optional, ProjectRepo)}.
      *
      * Performs the actual Git commits on the disk.
      *
@@ -732,7 +685,7 @@ public class Bridge {
 
     /**
      * Called by
-     * {@link #pushCritical(Credential, String, RawDirectory, RawDirectory)}.
+     * {@link #pushCritical(Optional, String, RawDirectory, RawDirectory)}.
      *
      * This call consists of 2 things: Creating the candidate snapshot,
      * and writing the atts to the atts directory.
@@ -761,7 +714,7 @@ public class Bridge {
 
     /**
      * Called by
-     * {@link #pushCritical(Credential, String, RawDirectory, RawDirectory)}.
+     * {@link #pushCritical(Optional, String, RawDirectory, RawDirectory)}.
      *
      * This method approves a push by setting the latest version and removing
      * any deleted files from the db store (files were already added by the

services/git-bridge/src/main/java/uk/ac/ic/wlgitbridge/bridge/gc/GcJob.java

@@ -1,10 +1,10 @@
 package uk.ac.ic.wlgitbridge.bridge.gc;
 
-import com.google.api.client.auth.oauth2.Credential;
 import uk.ac.ic.wlgitbridge.bridge.Bridge;
 import uk.ac.ic.wlgitbridge.bridge.repo.ProjectRepo;
 import uk.ac.ic.wlgitbridge.data.filestore.RawDirectory;
 
+import java.util.Optional;
 import java.util.concurrent.CompletableFuture;
 
 /**
@@ -12,9 +12,9 @@ import java.util.concurrent.CompletableFuture;
  * GC which executes every hour or so.
  *
  * We don't queue it into a more immediate Executor because there is no way to
- * know if a call to {@link Bridge#updateProject(Credential, ProjectRepo)},
+ * know if a call to {@link Bridge#updateProject(Optional, ProjectRepo)},
  * which releases the lock, is going to call
- * {@link Bridge#push(Credential, String, RawDirectory, RawDirectory, String)}.
+ * {@link Bridge#push(Optional, String, RawDirectory, RawDirectory, String)}.
  *
  * We don't want the GC to run in between an update and a push.
  */

services/git-bridge/src/main/java/uk/ac/ic/wlgitbridge/bridge/repo/FSGitRepoStore.java

@@ -45,6 +45,13 @@ public class FSGitRepoStore implements RepoStore {
         return rootDirectory;
     }
 
+    @Override
+    public ProjectRepo initRepo(String project) throws IOException {
+        GitProjectRepo ret = new GitProjectRepo(project);
+        ret.initRepo(this);
+        return ret;
+    }
+
     @Override
     public ProjectRepo getExistingRepo(String project) throws IOException {
         GitProjectRepo ret = new GitProjectRepo(project);

services/git-bridge/src/main/java/uk/ac/ic/wlgitbridge/bridge/repo/GitProjectRepo.java

@@ -199,6 +199,7 @@ public class GitProjectRepo implements ProjectRepo {
         }
     }
 
+    @Override
     public Repository getJGitRepository() {
         return repository.get();
     }

services/git-bridge/src/main/java/uk/ac/ic/wlgitbridge/bridge/repo/ProjectRepo.java

@@ -1,5 +1,6 @@
 package uk.ac.ic.wlgitbridge.bridge.repo;
 
+import org.eclipse.jgit.lib.Repository;
 import uk.ac.ic.wlgitbridge.data.filestore.GitDirectoryContents;
 import uk.ac.ic.wlgitbridge.data.filestore.RawFile;
 import uk.ac.ic.wlgitbridge.git.exception.GitUserException;
@@ -37,4 +38,5 @@ public interface ProjectRepo {
 
     File getProjectDir();
 
+    Repository getJGitRepository();
 }

services/git-bridge/src/main/java/uk/ac/ic/wlgitbridge/bridge/repo/RepoStore.java

@@ -17,6 +17,8 @@ public interface RepoStore {
 
     File getRootDirectory();
 
+    ProjectRepo initRepo(String project) throws IOException;
+
     ProjectRepo getExistingRepo(String project) throws IOException;
 
     void purgeNonexistentProjects(

services/git-bridge/src/main/java/uk/ac/ic/wlgitbridge/bridge/snapshot/NetSnapshotApi.java

@@ -0,0 +1,55 @@
+package uk.ac.ic.wlgitbridge.bridge.snapshot;
+
+import com.google.api.client.auth.oauth2.Credential;
+import uk.ac.ic.wlgitbridge.data.CandidateSnapshot;
+import uk.ac.ic.wlgitbridge.snapshot.getdoc.GetDocRequest;
+import uk.ac.ic.wlgitbridge.snapshot.getdoc.GetDocResult;
+import uk.ac.ic.wlgitbridge.snapshot.getforversion.GetForVersionRequest;
+import uk.ac.ic.wlgitbridge.snapshot.getforversion.GetForVersionResult;
+import uk.ac.ic.wlgitbridge.snapshot.getsavedvers.GetSavedVersRequest;
+import uk.ac.ic.wlgitbridge.snapshot.getsavedvers.GetSavedVersResult;
+import uk.ac.ic.wlgitbridge.snapshot.push.PushRequest;
+import uk.ac.ic.wlgitbridge.snapshot.push.PushResult;
+
+import java.util.Optional;
+import java.util.concurrent.CompletableFuture;
+
+/**
+ * Created by winston on 20/08/2016.
+ */
+public class NetSnapshotApi implements SnapshotApi {
+
+    @Override
+    public CompletableFuture<GetDocResult> getDoc(
+            Optional<Credential> oauth2, String projectName) {
+        return new GetDocRequest(opt(oauth2), projectName).request();
+    }
+
+    @Override
+    public CompletableFuture<GetForVersionResult> getForVersion(
+            Optional<Credential> oauth2, String projectName, int versionId) {
+        return new GetForVersionRequest(
+                opt(oauth2), projectName, versionId).request();
+    }
+
+    @Override
+    public CompletableFuture<GetSavedVersResult> getSavedVers(
+            Optional<Credential> oauth2, String projectName) {
+        return new GetSavedVersRequest(opt(oauth2), projectName).request();
+    }
+
+    @Override
+    public CompletableFuture<PushResult> push(
+            Optional<Credential> oauth2,
+            CandidateSnapshot candidateSnapshot,
+            String postbackKey
+    ) {
+        return new PushRequest(
+                opt(oauth2), candidateSnapshot, postbackKey).request();
+    }
+
+    private static Credential opt(Optional<Credential> oauth2) {
+        return oauth2.orElse(null);
+    }
+
+}

services/git-bridge/src/main/java/uk/ac/ic/wlgitbridge/bridge/snapshot/SnapshotAPI.java

@@ -1,21 +0,0 @@
-package uk.ac.ic.wlgitbridge.bridge.snapshot;
-
-import com.google.api.client.auth.oauth2.Credential;
-import uk.ac.ic.wlgitbridge.data.model.Snapshot;
-import uk.ac.ic.wlgitbridge.git.exception.GitUserException;
-import uk.ac.ic.wlgitbridge.snapshot.exception.FailedConnectionException;
-
-import java.util.Deque;
-
-/**
- * Created by winston on 20/08/2016.
- */
-public interface SnapshotAPI {
-
-    Deque<Snapshot> getSnapshotsForProjectAfterVersion(
-            Credential oauth2,
-            String projectName,
-            int latestVersion
-    ) throws FailedConnectionException, GitUserException;
-
-}

services/git-bridge/src/main/java/uk/ac/ic/wlgitbridge/bridge/snapshot/SnapshotApi.java

@@ -0,0 +1,52 @@
+package uk.ac.ic.wlgitbridge.bridge.snapshot;
+
+import com.google.api.client.auth.oauth2.Credential;
+import uk.ac.ic.wlgitbridge.data.CandidateSnapshot;
+import uk.ac.ic.wlgitbridge.snapshot.base.ForbiddenException;
+import uk.ac.ic.wlgitbridge.snapshot.exception.FailedConnectionException;
+import uk.ac.ic.wlgitbridge.snapshot.getdoc.GetDocResult;
+import uk.ac.ic.wlgitbridge.snapshot.getforversion.GetForVersionResult;
+import uk.ac.ic.wlgitbridge.snapshot.getsavedvers.GetSavedVersResult;
+import uk.ac.ic.wlgitbridge.snapshot.push.PushResult;
+
+import java.util.Optional;
+import java.util.concurrent.CompletableFuture;
+import java.util.concurrent.CompletionException;
+
+/**
+ * Created by winston on 20/08/2016.
+ */
+public interface SnapshotApi {
+
+    CompletableFuture<GetDocResult> getDoc(
+            Optional<Credential> oauth2, String projectName);
+
+    CompletableFuture<GetForVersionResult> getForVersion(
+            Optional<Credential> oauth2, String projectName, int versionId);
+
+    CompletableFuture<GetSavedVersResult> getSavedVers(
+            Optional<Credential> oauth2, String projectName);
+
+    CompletableFuture<PushResult> push(
+            Optional<Credential> oauth2,
+            CandidateSnapshot candidateSnapshot,
+            String postbackKey);
+
+    static <T> T getResult(CompletableFuture<T> result)
+            throws FailedConnectionException, ForbiddenException {
+        try {
+            return result.join();
+        } catch (CompletionException e) {
+            try {
+                throw e.getCause();
+            } catch (FailedConnectionException
+                    | ForbiddenException
+                    | RuntimeException r) {
+                throw r;
+            } catch (Throwable __) {
+                throw e;
+            }
+        }
+    }
+
+}

services/git-bridge/src/main/java/uk/ac/ic/wlgitbridge/bridge/snapshot/NetSnapshotAPI.java → services/git-bridge/src/main/java/uk/ac/ic/wlgitbridge/bridge/snapshot/SnapshotApiFacade.java

@@ -1,34 +1,57 @@
 package uk.ac.ic.wlgitbridge.bridge.snapshot;
 
 import com.google.api.client.auth.oauth2.Credential;
+import uk.ac.ic.wlgitbridge.data.CandidateSnapshot;
 import uk.ac.ic.wlgitbridge.data.model.Snapshot;
 import uk.ac.ic.wlgitbridge.git.exception.GitUserException;
 import uk.ac.ic.wlgitbridge.snapshot.base.ForbiddenException;
 import uk.ac.ic.wlgitbridge.snapshot.exception.FailedConnectionException;
-import uk.ac.ic.wlgitbridge.snapshot.getdoc.GetDocRequest;
 import uk.ac.ic.wlgitbridge.snapshot.getdoc.GetDocResult;
-import uk.ac.ic.wlgitbridge.snapshot.getforversion.GetForVersionRequest;
+import uk.ac.ic.wlgitbridge.snapshot.getforversion.GetForVersionResult;
 import uk.ac.ic.wlgitbridge.snapshot.getforversion.SnapshotData;
-import uk.ac.ic.wlgitbridge.snapshot.getsavedvers.GetSavedVersRequest;
+import uk.ac.ic.wlgitbridge.snapshot.getsavedvers.GetSavedVersResult;
 import uk.ac.ic.wlgitbridge.snapshot.getsavedvers.SnapshotInfo;
+import uk.ac.ic.wlgitbridge.snapshot.push.PushResult;
+import uk.ac.ic.wlgitbridge.snapshot.push.exception.InvalidProjectException;
 
 import java.util.*;
+import java.util.concurrent.CompletableFuture;
+import java.util.stream.Collectors;
 
 /**
- * Created by winston on 20/08/2016.
+ * Created by winston on 02/07/2017.
  */
-public class NetSnapshotAPI implements SnapshotAPI {
+public class SnapshotApiFacade {
 
-    @Override
-    public Deque<Snapshot> getSnapshotsForProjectAfterVersion(
-            Credential oauth2,
-            String projectName,
-            int version
+    private final SnapshotApi api;
+
+    public SnapshotApiFacade(SnapshotApi api) {
+        this.api = api;
+    }
+
+    public boolean projectExists(
+            Optional<Credential> oauth2,
+            String projectName
     ) throws FailedConnectionException, GitUserException {
+        try {
+            SnapshotApi
+                    .getResult(api.getDoc(oauth2, projectName))
+                    .getVersionID();
+            return true;
+        } catch (InvalidProjectException e) {
+            return false;
+        }
+    }
+
+    public Deque<Snapshot> getSnapshots(
+            Optional<Credential> oauth2,
+            String projectName,
+            int afterVersionId
+    ) throws GitUserException, FailedConnectionException {
         List<SnapshotInfo> snapshotInfos = getSnapshotInfosAfterVersion(
                 oauth2,
                 projectName,
-                version
+                afterVersionId
         );
         List<SnapshotData> snapshotDatas = getMatchingSnapshotData(
                 oauth2,
@@ -38,25 +61,31 @@ public class NetSnapshotAPI implements SnapshotAPI {
         return combine(snapshotInfos, snapshotDatas);
     }
 
+    public PushResult push(
+            Optional<Credential> oauth2,
+            CandidateSnapshot candidateSnapshot,
+            String postbackKey
+    ) throws FailedConnectionException, ForbiddenException {
+        return SnapshotApi.getResult(api.push(
+                oauth2, candidateSnapshot, postbackKey));
+    }
+
     private List<SnapshotInfo> getSnapshotInfosAfterVersion(
-            Credential oauth2,
+            Optional<Credential> oauth2,
             String projectName,
             int version
     ) throws FailedConnectionException, GitUserException {
         SortedSet<SnapshotInfo> versions = new TreeSet<>();
-        GetDocRequest getDoc = new GetDocRequest(oauth2, projectName);
-        GetSavedVersRequest getSavedVers = new GetSavedVersRequest(
-                oauth2,
-                projectName
-        );
-        getDoc.request();
-        getSavedVers.request();
-        GetDocResult latestDoc = getDoc.getResult();
+        CompletableFuture<GetDocResult> getDoc
+                = api.getDoc(oauth2, projectName);
+        CompletableFuture<GetSavedVersResult> savedVers
+                = api.getSavedVers(oauth2, projectName);
+        GetDocResult latestDoc = SnapshotApi.getResult(getDoc);
         int latest = latestDoc.getVersionID();
         if (latest > version) {
             for (
                     SnapshotInfo snapshotInfo :
-                    getSavedVers.getResult().getSavedVers()
+                    SnapshotApi.getResult(savedVers).getSavedVers()
             ) {
                 if (snapshotInfo.getVersionId() > version) {
                     versions.add(snapshotInfo);
@@ -70,45 +99,36 @@ public class NetSnapshotAPI implements SnapshotAPI {
             ));
 
         }
-        return new LinkedList<SnapshotInfo>(versions);
+        return new ArrayList<>(versions);
     }
 
     private List<SnapshotData> getMatchingSnapshotData(
-            Credential oauth2,
+            Optional<Credential> oauth2,
             String projectName,
             List<SnapshotInfo> snapshotInfos
     ) throws FailedConnectionException, ForbiddenException {
-        List<GetForVersionRequest> firedRequests = fireDataRequests(
-                oauth2,
-                projectName,
-                snapshotInfos
-        );
+        List<CompletableFuture<GetForVersionResult>> firedRequests
+                = fireDataRequests(oauth2, projectName, snapshotInfos);
         List<SnapshotData> snapshotDataList = new ArrayList<>();
-        for (GetForVersionRequest fired : firedRequests) {
-            snapshotDataList.add(fired.getResult().getSnapshotData());
+        for (CompletableFuture<GetForVersionResult> fired : firedRequests) {
+            snapshotDataList.add(fired.join().getSnapshotData());
         }
         return snapshotDataList;
     }
 
-    private List<GetForVersionRequest> fireDataRequests(
-            Credential oauth2,
+    private List<CompletableFuture<GetForVersionResult>> fireDataRequests(
+            Optional<Credential> oauth2,
             String projectName,
             List<SnapshotInfo> snapshotInfos
     ) {
-        List<GetForVersionRequest> requests = new ArrayList<>();
-        for (SnapshotInfo snapshotInfo : snapshotInfos) {
-            GetForVersionRequest request = new GetForVersionRequest(
-                    oauth2,
-                    projectName,
-                    snapshotInfo.getVersionId()
-            );
-            requests.add(request);
-            request.request();
-        }
-        return requests;
+        return snapshotInfos
+                .stream()
+                .map(snap -> api.getForVersion(
+                        oauth2, projectName, snap.getVersionId()))
+                .collect(Collectors.toList());
     }
 
-    private Deque<Snapshot> combine(
+    private static Deque<Snapshot> combine(
             List<SnapshotInfo> snapshotInfos,
             List<SnapshotData> snapshotDatas
     ) {

services/git-bridge/src/main/java/uk/ac/ic/wlgitbridge/git/handler/WLReceivePackFactory.java

@@ -5,7 +5,7 @@ import org.eclipse.jgit.lib.Repository;
 import org.eclipse.jgit.transport.ReceivePack;
 import org.eclipse.jgit.transport.resolver.ReceivePackFactory;
 import uk.ac.ic.wlgitbridge.bridge.Bridge;
-import uk.ac.ic.wlgitbridge.bridge.snapshot.SnapshotAPI;
+import uk.ac.ic.wlgitbridge.bridge.snapshot.SnapshotApi;
 import uk.ac.ic.wlgitbridge.git.handler.hook.WriteLatexPutHook;
 import uk.ac.ic.wlgitbridge.git.servlet.WLGitServlet;
 import uk.ac.ic.wlgitbridge.server.Oauth2Filter;
@@ -13,6 +13,7 @@ import uk.ac.ic.wlgitbridge.util.Log;
 import uk.ac.ic.wlgitbridge.util.Util;
 
 import javax.servlet.http.HttpServletRequest;
+import java.util.Optional;
 
 /**
  * Created by Winston on 02/11/14.
@@ -38,7 +39,7 @@ public class WLReceivePackFactory
      *
      * The {@link WriteLatexPutHook} needs our hostname, which we get from the
      * original {@link HttpServletRequest}, used to provide a postback URL to
-     * the {@link SnapshotAPI}. We also give it the oauth2 that we injected in
+     * the {@link SnapshotApi}. We also give it the oauth2 that we injected in
      * the {@link Oauth2Filter}, and the {@link Bridge}.
      *
      * At this point, the repository will have been synced to the latest on
@@ -59,9 +60,9 @@ public class WLReceivePackFactory
                 "[{}] Creating receive-pack",
                 repository.getWorkTree().getName()
         );
-        Credential oauth2 = (Credential) httpServletRequest.getAttribute(
-                Oauth2Filter.ATTRIBUTE_KEY
-        );
+        Optional<Credential> oauth2 = Optional.ofNullable(
+                (Credential) httpServletRequest.getAttribute(
+                        Oauth2Filter.ATTRIBUTE_KEY));
         ReceivePack receivePack = new ReceivePack(repository);
         String hostname = Util.getPostbackURL();
         if (hostname == null) {

services/git-bridge/src/main/java/uk/ac/ic/wlgitbridge/git/handler/WLRepositoryResolver.java

@@ -7,7 +7,6 @@ import org.eclipse.jgit.transport.ServiceMayNotContinueException;
 import org.eclipse.jgit.transport.resolver.RepositoryResolver;
 import org.eclipse.jgit.transport.resolver.ServiceNotAuthorizedException;
 import uk.ac.ic.wlgitbridge.bridge.Bridge;
-import uk.ac.ic.wlgitbridge.bridge.repo.GitProjectRepo;
 import uk.ac.ic.wlgitbridge.git.exception.GitUserException;
 import uk.ac.ic.wlgitbridge.git.handler.hook.WriteLatexPutHook;
 import uk.ac.ic.wlgitbridge.git.servlet.WLGitServlet;
@@ -19,6 +18,7 @@ import uk.ac.ic.wlgitbridge.util.Util;
 
 import javax.servlet.http.HttpServletRequest;
 import java.io.IOException;
+import java.util.Optional;
 
 /**
  * Created by Winston on 02/11/14.
@@ -82,17 +82,12 @@ public class WLRepositoryResolver
              ServiceNotAuthorizedException,
              ServiceMayNotContinueException {
         Log.info("[{}] Request to open git repo", name);
-        Credential oauth2 = (Credential) httpServletRequest.getAttribute(
-                Oauth2Filter.ATTRIBUTE_KEY
-        );
+        Optional<Credential> oauth2 = Optional.ofNullable(
+                (Credential) httpServletRequest.getAttribute(
+                        Oauth2Filter.ATTRIBUTE_KEY));
         String projName = Util.removeAllSuffixes(name, "/", ".git");
         try {
-            if (!bridge.projectExists(oauth2, projName)) {
-                throw new RepositoryNotFoundException(projName);
-            }
-            GitProjectRepo repo = new GitProjectRepo(projName);
-            bridge.updateRepository(oauth2, repo);
-            return repo.getJGitRepository();
+            return bridge.getUpdatedRepo(oauth2, projName).getJGitRepository();
         } catch (RepositoryNotFoundException e) {
             Log.info("Repository not found: " + name);
             throw e;

services/git-bridge/src/main/java/uk/ac/ic/wlgitbridge/git/handler/WLUploadPackFactory.java

@@ -5,7 +5,6 @@ import org.eclipse.jgit.transport.UploadPack;
 import org.eclipse.jgit.transport.resolver.UploadPackFactory;
 import uk.ac.ic.wlgitbridge.git.servlet.WLGitServlet;
 import uk.ac.ic.wlgitbridge.util.Log;
-import uk.ac.ic.wlgitbridge.util.Util;
 
 import javax.servlet.http.HttpServletRequest;
 

services/git-bridge/src/main/java/uk/ac/ic/wlgitbridge/git/handler/hook/WriteLatexPutHook.java

@@ -21,6 +21,7 @@ import uk.ac.ic.wlgitbridge.util.Log;
 import java.io.IOException;
 import java.util.Collection;
 import java.util.Iterator;
+import java.util.Optional;
 
 /**
  * Created by Winston on 03/11/14.
@@ -34,7 +35,7 @@ public class WriteLatexPutHook implements PreReceiveHook {
 
     private final Bridge bridge;
     private final String hostname;
-    private final Credential oauth2;
+    private final Optional<Credential> oauth2;
 
     /**
      * The constructor to use, which provides the hook with the {@link Bridge},
@@ -47,7 +48,7 @@ public class WriteLatexPutHook implements PreReceiveHook {
     public WriteLatexPutHook(
             Bridge bridge,
             String hostname,
-            Credential oauth2
+            Optional<Credential> oauth2
     ) {
         this.bridge = bridge;
         this.hostname = hostname;
@@ -112,7 +113,7 @@ public class WriteLatexPutHook implements PreReceiveHook {
     }
 
     private void handleReceiveCommand(
-            Credential oauth2,
+            Optional<Credential> oauth2,
             Repository repository,
             ReceiveCommand receiveCommand
     ) throws IOException, GitUserException {

services/git-bridge/src/main/java/uk/ac/ic/wlgitbridge/git/util/RepositoryObjectTreeWalker.java

@@ -49,10 +49,17 @@ public class RepositoryObjectTreeWalker {
 
     public RawDirectory getDirectoryContents(
     ) throws IOException, SizeLimitExceededException, InvalidGitRepository {
-        return getDirectoryContents(50 * 1024 * 1024);
+        return getDirectoryContents(Optional.empty());
     }
 
-    private RawDirectory getDirectoryContents(long maxFileSize)
+    public RawDirectory getDirectoryContents(long maxFileSize)
+            throws InvalidGitRepository,
+                    SizeLimitExceededException,
+                    IOException {
+        return getDirectoryContents(Optional.of(maxFileSize));
+    }
+
+    private RawDirectory getDirectoryContents(Optional<Long> maxFileSize)
             throws IOException,
                     SizeLimitExceededException,
                     InvalidGitRepository {
@@ -73,7 +80,7 @@ public class RepositoryObjectTreeWalker {
         return treeWalk;
     }
 
-    private Map<String, RawFile> walkGitObjectTree(long maxFileSize)
+    private Map<String, RawFile> walkGitObjectTree(Optional<Long> maxFileSize)
             throws IOException,
                     SizeLimitExceededException,
                     InvalidGitRepository {
@@ -90,9 +97,9 @@ public class RepositoryObjectTreeWalker {
             }
             ObjectLoader obj = repository.open(objectId);
             long size = obj.getSize();
-            if (size > maxFileSize) {
+            if (maxFileSize.isPresent() && size > maxFileSize.get()) {
                 throw new SizeLimitExceededException(
-                        Optional.ofNullable(path), size, maxFileSize);
+                        Optional.ofNullable(path), size, maxFileSize.get());
             }
             try (ByteArrayOutputStream o = new ByteArrayOutputStream(
                     CastUtil.assumeInt(size))) {

services/git-bridge/src/main/java/uk/ac/ic/wlgitbridge/server/GitBridgeServer.java

@@ -13,6 +13,8 @@ import uk.ac.ic.wlgitbridge.bridge.db.DBStore;
 import uk.ac.ic.wlgitbridge.bridge.db.sqlite.SqliteDBStore;
 import uk.ac.ic.wlgitbridge.bridge.repo.FSGitRepoStore;
 import uk.ac.ic.wlgitbridge.bridge.repo.RepoStore;
+import uk.ac.ic.wlgitbridge.bridge.snapshot.NetSnapshotApi;
+import uk.ac.ic.wlgitbridge.bridge.snapshot.SnapshotApi;
 import uk.ac.ic.wlgitbridge.bridge.swap.store.SwapStore;
 import uk.ac.ic.wlgitbridge.git.servlet.WLGitServlet;
 import uk.ac.ic.wlgitbridge.snapshot.base.SnapshotAPIRequest;
@@ -57,14 +59,16 @@ public class GitBridgeServer {
                 ).resolve(".wlgb").resolve("wlgb.db").toFile()
         );
         SwapStore swapStore = SwapStore.fromConfig(config.getSwapStore());
+        SnapshotApi snapshotApi = new NetSnapshotApi();
         bridge = Bridge.make(
                 repoStore,
                 dbStore,
                 swapStore,
-                config.getSwapJob()
+                config.getSwapJob(),
+                snapshotApi
         );
         jettyServer = new Server(port);
-        configureJettyServer(config);
+        configureJettyServer(config, snapshotApi);
         SnapshotAPIRequest.setBasicAuth(
                 config.getUsername(),
                 config.getPassword()
@@ -105,11 +109,12 @@ public class GitBridgeServer {
     }
 
     private void configureJettyServer(
-            Config config
+            Config config,
+            SnapshotApi snapshotApi
     ) throws ServletException {
         HandlerCollection handlers = new HandlerList();
         handlers.addHandler(initApiHandler());
-        handlers.addHandler(initGitHandler(config));
+        handlers.addHandler(initGitHandler(config, snapshotApi));
         jettyServer.setHandler(handlers);
     }
 
@@ -130,12 +135,13 @@ public class GitBridgeServer {
     }
 
     private Handler initGitHandler(
-            Config config
+            Config config,
+            SnapshotApi snapshotApi
     ) throws ServletException {
         final ServletContextHandler servletContextHandler =
                 new ServletContextHandler(ServletContextHandler.SESSIONS);
         if (config.isUsingOauth2()) {
-            Filter filter = new Oauth2Filter(config.getOauth2());
+            Filter filter = new Oauth2Filter(snapshotApi, config.getOauth2());
             servletContextHandler.addFilter(
                     new FilterHolder(filter),
                     "/*",

services/git-bridge/src/main/java/uk/ac/ic/wlgitbridge/server/Oauth2Filter.java

@@ -5,6 +5,7 @@ import com.google.api.client.http.GenericUrl;
 import org.apache.commons.codec.binary.Base64;
 import org.eclipse.jetty.server.Request;
 import uk.ac.ic.wlgitbridge.application.config.Oauth2;
+import uk.ac.ic.wlgitbridge.bridge.snapshot.SnapshotApi;
 import uk.ac.ic.wlgitbridge.snapshot.base.ForbiddenException;
 import uk.ac.ic.wlgitbridge.snapshot.getdoc.GetDocRequest;
 import uk.ac.ic.wlgitbridge.util.Instance;
@@ -17,6 +18,7 @@ import javax.servlet.http.HttpServletResponse;
 import java.io.IOException;
 import java.io.PrintWriter;
 import java.io.UnsupportedEncodingException;
+import java.util.Optional;
 import java.util.StringTokenizer;
 
 /**
@@ -26,9 +28,12 @@ public class Oauth2Filter implements Filter {
 
     public static final String ATTRIBUTE_KEY = "oauth2";
 
+    private final SnapshotApi snapshotApi;
+
     private final Oauth2 oauth2;
 
-    public Oauth2Filter(Oauth2 oauth2) {
+    public Oauth2Filter(SnapshotApi snapshotApi, Oauth2 oauth2) {
+        this.snapshotApi = snapshotApi;
         this.oauth2 = oauth2;
     }
 
@@ -60,7 +65,8 @@ public class Oauth2Filter implements Filter {
         GetDocRequest doc = new GetDocRequest(project);
         doc.request();
         try {
-            doc.getResult();
+            SnapshotApi.getResult(
+                    snapshotApi.getDoc(Optional.empty(), project));
         } catch (ForbiddenException e) {
             Log.info("[{}] Auth needed", project);
             getAndInjectCredentials(

services/git-bridge/src/main/java/uk/ac/ic/wlgitbridge/snapshot/base/Request.java

@@ -9,8 +9,7 @@ import uk.ac.ic.wlgitbridge.util.Log;
 
 import javax.servlet.http.HttpServletResponse;
 import java.io.IOException;
-import java.util.concurrent.ExecutionException;
-import java.util.concurrent.Future;
+import java.util.concurrent.*;
 
 /**
  * Created by Winston on 06/11/14.
@@ -19,6 +18,8 @@ public abstract class Request<T extends Result> {
 
     public static final AsyncHttpClient httpClient = new AsyncHttpClient();
 
+    private static final Executor executor = Executors.newCachedThreadPool();
+
     private final String url;
 
     private Future<HttpResponse> future;
@@ -27,7 +28,7 @@ public abstract class Request<T extends Result> {
         this.url = url;
     }
 
-    public void request() {
+    public CompletableFuture<T> request() {
         switch (httpMethod()) {
             case GET:
                 performGetRequest();
@@ -38,9 +39,18 @@ public abstract class Request<T extends Result> {
             default:
                 break;
         }
+        CompletableFuture<T> ret = new CompletableFuture<>();
+        executor.execute(() -> {
+            try {
+                ret.complete(getResult());
+            } catch (Throwable t) {
+                ret.completeExceptionally(t);
+            }
+        });
+        return ret;
     }
 
-    public T getResult() throws FailedConnectionException, ForbiddenException {
+    private T getResult() throws FailedConnectionException, ForbiddenException {
         try {
             HttpResponse response = future.get();
             Log.info(

services/git-bridge/src/test/java/uk/ac/ic/wlgitbridge/bridge/BridgeTest.java

@@ -9,14 +9,14 @@ import uk.ac.ic.wlgitbridge.bridge.lock.ProjectLock;
 import uk.ac.ic.wlgitbridge.bridge.repo.ProjectRepo;
 import uk.ac.ic.wlgitbridge.bridge.repo.RepoStore;
 import uk.ac.ic.wlgitbridge.bridge.resource.ResourceCache;
-import uk.ac.ic.wlgitbridge.bridge.snapshot.SnapshotAPI;
+import uk.ac.ic.wlgitbridge.bridge.snapshot.SnapshotApiFacade;
 import uk.ac.ic.wlgitbridge.bridge.swap.job.SwapJob;
 import uk.ac.ic.wlgitbridge.bridge.swap.store.SwapStore;
-import uk.ac.ic.wlgitbridge.data.model.Snapshot;
 import uk.ac.ic.wlgitbridge.git.exception.GitUserException;
 
 import java.io.IOException;
 import java.util.ArrayDeque;
+import java.util.Optional;
 
 import static org.mockito.Matchers.any;
 import static org.mockito.Matchers.anyInt;
@@ -34,7 +34,7 @@ public class BridgeTest {
     private RepoStore repoStore;
     private DBStore dbStore;
     private SwapStore swapStore;
-    private SnapshotAPI snapshotAPI;
+    private SnapshotApiFacade snapshotAPI;
     private ResourceCache resourceCache;
     private SwapJob swapJob;
     private GcJob gcJob;
@@ -45,7 +45,7 @@ public class BridgeTest {
         repoStore = mock(RepoStore.class);
         dbStore = mock(DBStore.class);
         swapStore = mock(SwapStore.class);
-        snapshotAPI = mock(SnapshotAPI.class);
+        snapshotAPI = mock(SnapshotApiFacade.class);
         resourceCache = mock(ResourceCache.class);
         swapJob = mock(SwapJob.class);
         gcJob = mock(GcJob.class);
@@ -75,17 +75,18 @@ public class BridgeTest {
     public void updatingRepositorySetsLastAccessedTime(
     ) throws IOException, GitUserException {
         ProjectRepo repo = mock(ProjectRepo.class);
-        when(repo.getProjectName()).thenReturn("asdf");
+        when(repoStore.getExistingRepo("asdf")).thenReturn(repo);
         when(dbStore.getProjectState("asdf")).thenReturn(ProjectState.PRESENT);
+        when(snapshotAPI.projectExists(Optional.empty(), "asdf")).thenReturn(true);
         when(
-                snapshotAPI.getSnapshotsForProjectAfterVersion(
+                snapshotAPI.getSnapshots(
                         any(),
                         any(),
                         anyInt()
                 )
-        ).thenReturn(new ArrayDeque<Snapshot>());
-        bridge.updateRepository(null, repo);
+        ).thenReturn(new ArrayDeque<>());
+        bridge.getUpdatedRepo(Optional.empty(), "asdf");
         verify(dbStore).setLastAccessedTime(eq("asdf"), any());
     }
 
-}
+}

services/git-bridge/src/test/java/uk/ac/ic/wlgitbridge/data/model/ResourceFetcherTest.java

@@ -1,7 +1,5 @@
 package uk.ac.ic.wlgitbridge.data.model;
 
-import org.eclipse.jgit.lib.Repository;
-import org.eclipse.jgit.storage.file.FileRepositoryBuilder;
 import org.jmock.Expectations;
 import org.jmock.Mockery;
 import org.junit.Rule;
@@ -10,11 +8,14 @@ import org.junit.rules.TemporaryFolder;
 import org.mockserver.client.server.MockServerClient;
 import org.mockserver.junit.MockServerRule;
 import uk.ac.ic.wlgitbridge.bridge.db.DBStore;
+import uk.ac.ic.wlgitbridge.bridge.repo.FSGitRepoStore;
+import uk.ac.ic.wlgitbridge.bridge.repo.GitProjectRepo;
+import uk.ac.ic.wlgitbridge.bridge.repo.ProjectRepo;
+import uk.ac.ic.wlgitbridge.bridge.repo.RepoStore;
 import uk.ac.ic.wlgitbridge.bridge.resource.ResourceCache;
 import uk.ac.ic.wlgitbridge.bridge.resource.UrlResourceCache;
 import uk.ac.ic.wlgitbridge.data.filestore.RawFile;
 import uk.ac.ic.wlgitbridge.git.exception.GitUserException;
-import uk.ac.ic.wlgitbridge.git.util.RepositoryObjectTreeWalker;
 
 import java.io.IOException;
 import java.util.HashMap;
@@ -65,12 +66,15 @@ public class ResourceFetcherTest {
         ResourceCache resources = new UrlResourceCache(dbStore);
         TemporaryFolder repositoryFolder = new TemporaryFolder();
         repositoryFolder.create();
-        Repository repository = new FileRepositoryBuilder().setWorkTree(repositoryFolder.getRoot()).build();
-        Map<String, RawFile> fileTable = new RepositoryObjectTreeWalker(repository).getDirectoryContents().getFileTable();
+        String repoStorePath = repositoryFolder.getRoot().getAbsolutePath();
+        RepoStore repoStore = new FSGitRepoStore(repoStorePath);
+        ProjectRepo repo = new GitProjectRepo("repo");
+        repo.initRepo(repoStore);
+        Map<String, RawFile> fileTable = repo.getFiles();
         Map<String, byte[]> fetchedUrls = new HashMap<String, byte[]>();
         resources.get(testProjectName, testUrl, newTestPath, fileTable, fetchedUrls);
 
         // We don't bother caching in this case, at present.
         assertEquals(0, fetchedUrls.size());
     }
-}
+}