Tolerate 404 responses due to missing folders.

This prevents our own mailbox's download worker from getting stuck trying to list a folder that has been removed. Instead, the worker will move on to the next folder.

bramble-core/src/main/java/org/briarproject/bramble/mailbox/ContactMailboxDownloadWorker.java

@@ -5,6 +5,7 @@ import org.briarproject.bramble.api.mailbox.MailboxProperties;
 import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
 import org.briarproject.bramble.mailbox.MailboxApi.ApiException;
 import org.briarproject.bramble.mailbox.MailboxApi.MailboxFile;
+import org.briarproject.bramble.mailbox.MailboxApi.TolerableFailureException;
 
 import java.io.IOException;
 import java.util.LinkedList;
@@ -13,6 +14,7 @@ import java.util.Queue;
 
 import javax.annotation.concurrent.ThreadSafe;
 
+import static java.util.Collections.emptyList;
 import static org.briarproject.bramble.api.nullsafety.NullSafety.requireNonNull;
 
 @ThreadSafe
@@ -43,8 +45,13 @@ class ContactMailboxDownloadWorker extends MailboxDownloadWorker {
 		LOG.info("Listing inbox");
 		MailboxFolderId folderId =
 				requireNonNull(mailboxProperties.getInboxId());
-		List<MailboxFile> files =
-				mailboxApi.getFiles(mailboxProperties, folderId);
+		List<MailboxFile> files;
+		try {
+			files = mailboxApi.getFiles(mailboxProperties, folderId);
+		} catch (TolerableFailureException e) {
+			LOG.warning("Inbox folder does not exist");
+			files = emptyList();
+		}
 		if (files.isEmpty()) {
 			onDownloadCycleFinished();
 		} else {

bramble-core/src/main/java/org/briarproject/bramble/mailbox/MailboxApi.java

@@ -91,9 +91,13 @@ interface MailboxApi {
 	 * Used by owner and contacts to list their files to retrieve.
 	 * <p>
 	 * Returns 200 OK with the list of files in JSON.
+	 *
+	 * @throws TolerableFailureException if response code is 404 (folder does
+	 * not exist or client is not authorised to download from it)
 	 */
 	List<MailboxFile> getFiles(MailboxProperties properties,
-			MailboxFolderId folderId) throws IOException, ApiException;
+			MailboxFolderId folderId)
+			throws IOException, ApiException, TolerableFailureException;
 
 	/**
 	 * Used by owner and contacts to retrieve a file.
@@ -102,17 +106,22 @@ interface MailboxApi {
 	 * in the response body.
 	 *
 	 * @param file the empty file the response bytes will be written into.
+	 * @throws TolerableFailureException if response code is 404 (folder does
+	 * not exist, client is not authorised to download from folder, or file
+	 * does not exist)
 	 */
 	void getFile(MailboxProperties properties, MailboxFolderId folderId,
-			MailboxFileId fileId, File file) throws IOException, ApiException;
+			MailboxFileId fileId, File file)
+			throws IOException, ApiException, TolerableFailureException;
 
 	/**
 	 * Used by owner and contacts to delete files.
 	 * <p>
 	 * Returns 200 OK (no exception) if deletion was successful.
 	 *
-	 * @throws TolerableFailureException on 404 response,
-	 * because file was most likely deleted already.
+	 * @throws TolerableFailureException if response code is 404 (folder does
+	 * not exist, client is not authorised to download from folder, or file
+	 * does not exist)
 	 */
 	void deleteFile(MailboxProperties properties, MailboxFolderId folderId,
 			MailboxFileId fileId)

bramble-core/src/main/java/org/briarproject/bramble/mailbox/MailboxApiImpl.java

@@ -216,9 +216,11 @@ class MailboxApiImpl implements MailboxApi {
 
 	@Override
 	public List<MailboxFile> getFiles(MailboxProperties properties,
-			MailboxFolderId folderId) throws IOException, ApiException {
+			MailboxFolderId folderId)
+			throws IOException, ApiException, TolerableFailureException {
 		String path = "/files/" + folderId;
 		Response response = sendGetRequest(properties, path);
+		if (response.code() == 404) throw new TolerableFailureException();
 		if (response.code() != 200) throw new ApiException();
 
 		ResponseBody body = response.body();
@@ -252,9 +254,11 @@ class MailboxApiImpl implements MailboxApi {
 
 	@Override
 	public void getFile(MailboxProperties properties, MailboxFolderId folderId,
-			MailboxFileId fileId, File file) throws IOException, ApiException {
+			MailboxFileId fileId, File file)
+			throws IOException, ApiException, TolerableFailureException {
 		String path = "/files/" + folderId + "/" + fileId;
 		Response response = sendGetRequest(properties, path);
+		if (response.code() == 404) throw new TolerableFailureException();
 		if (response.code() != 200) throw new ApiException();
 
 		ResponseBody body = response.body();

bramble-core/src/main/java/org/briarproject/bramble/mailbox/MailboxDownloadWorker.java

@@ -19,9 +19,7 @@ import javax.annotation.Nullable;
 import javax.annotation.concurrent.GuardedBy;
 import javax.annotation.concurrent.ThreadSafe;
 
-import static java.util.logging.Level.INFO;
 import static java.util.logging.Logger.getLogger;
-import static org.briarproject.bramble.util.LogUtils.logException;
 
 @ThreadSafe
 @NotNullByDefault
@@ -161,9 +159,17 @@ abstract class MailboxDownloadWorker implements MailboxWorker,
 	void downloadNextFile(Queue<FolderFile> queue) {
 		synchronized (lock) {
 			if (state == State.DESTROYED) return;
-			FolderFile file = queue.remove();
-			apiCall = mailboxApiCaller.retryWithBackoff(
-					new SimpleApiCall(() -> apiCallDownloadFile(file, queue)));
+			if (queue.isEmpty()) {
+				// Check for files again, as new files may have arrived while
+				// we were downloading
+				apiCall = mailboxApiCaller.retryWithBackoff(
+						createApiCallForDownloadCycle());
+			} else {
+				FolderFile file = queue.remove();
+				apiCall = mailboxApiCaller.retryWithBackoff(
+						new SimpleApiCall(() ->
+								apiCallDownloadFile(file, queue)));
+			}
 		}
 	}
 
@@ -182,6 +188,14 @@ abstract class MailboxDownloadWorker implements MailboxWorker,
 				LOG.warning("Failed to delete temporary file");
 			}
 			throw e;
+		} catch (TolerableFailureException e) {
+			// File not found - continue to the next file
+			LOG.warning("File does not exist");
+			if (!tempFile.delete()) {
+				LOG.warning("Failed to delete temporary file");
+			}
+			downloadNextFile(queue);
+			return;
 		}
 		mailboxFileManager.handleDownloadedFile(tempFile);
 		deleteFile(file, queue);
@@ -204,20 +218,10 @@ abstract class MailboxDownloadWorker implements MailboxWorker,
 			mailboxApi.deleteFile(mailboxProperties, file.folderId,
 					file.fileId);
 		} catch (TolerableFailureException e) {
-			// Catch this so we can continue to the next file
-			logException(LOG, INFO, e);
-		}
-		if (queue.isEmpty()) {
-			// Check for files again, as new files may have arrived while we
-			// were downloading
-			synchronized (lock) {
-				if (state == State.DESTROYED) return;
-				apiCall = mailboxApiCaller.retryWithBackoff(
-						createApiCallForDownloadCycle());
-			}
-		} else {
-			downloadNextFile(queue);
+			// File not found - continue to the next file
+			LOG.warning("File does not exist");
 		}
+		downloadNextFile(queue);
 	}
 
 	@Override

bramble-core/src/main/java/org/briarproject/bramble/mailbox/OwnMailboxContactListWorker.java

@@ -303,7 +303,7 @@ class OwnMailboxContactListWorker
 			mailboxApi.deleteContact(mailboxProperties, c);
 		} catch (TolerableFailureException e) {
 			// Catch this so we can continue to the next update
-			logException(LOG, INFO, e);
+			LOG.warning("Contact does not exist");
 		}
 		updateContactList();
 	}

bramble-core/src/main/java/org/briarproject/bramble/mailbox/OwnMailboxDownloadWorker.java

@@ -5,6 +5,7 @@ import org.briarproject.bramble.api.mailbox.MailboxProperties;
 import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
 import org.briarproject.bramble.mailbox.MailboxApi.ApiException;
 import org.briarproject.bramble.mailbox.MailboxApi.MailboxFile;
+import org.briarproject.bramble.mailbox.MailboxApi.TolerableFailureException;
 
 import java.io.IOException;
 import java.util.ArrayList;
@@ -85,9 +86,15 @@ class OwnMailboxDownloadWorker extends MailboxDownloadWorker {
 			if (state == State.DESTROYED) return;
 		}
 		LOG.info("Listing folder");
-		List<MailboxFile> files =
-				mailboxApi.getFiles(mailboxProperties, folder);
-		if (!files.isEmpty()) available.put(folder, new LinkedList<>(files));
+		try {
+			List<MailboxFile> files =
+					mailboxApi.getFiles(mailboxProperties, folder);
+			if (!files.isEmpty()) {
+				available.put(folder, new LinkedList<>(files));
+			}
+		} catch (TolerableFailureException e) {
+			LOG.warning("Folder does not exist");
+		}
 		if (queue.isEmpty()) {
 			LOG.info("Finished listing folders");
 			if (available.isEmpty()) onDownloadCycleFinished();