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();

bramble-core/src/test/java/org/briarproject/bramble/mailbox/MailboxApiTest.java

@@ -630,6 +630,7 @@ public class MailboxApiTest extends BrambleTestCase {
 		server.enqueue(new MockResponse().setBody(invalidResponse3));
 		server.enqueue(new MockResponse().setBody(invalidResponse4));
 		server.enqueue(new MockResponse().setResponseCode(401));
+		server.enqueue(new MockResponse().setResponseCode(404));
 		server.enqueue(new MockResponse().setResponseCode(500));
 		server.start();
 		String baseUrl = getBaseUrl(server);
@@ -706,13 +707,21 @@ public class MailboxApiTest extends BrambleTestCase {
 		assertEquals("GET", request8.getMethod());
 		assertToken(request8, token);
 
-		// 500 internal server error
-		assertThrows(ApiException.class,
-				() -> api.getFiles(properties, contactInboxId));
+		// 404 not found
+		assertThrows(TolerableFailureException.class, () ->
+				api.getFiles(properties, contactInboxId));
 		RecordedRequest request9 = server.takeRequest();
 		assertEquals("/files/" + contactInboxId, request9.getPath());
 		assertEquals("GET", request9.getMethod());
 		assertToken(request9, token);
+
+		// 500 internal server error
+		assertThrows(ApiException.class,
+				() -> api.getFiles(properties, contactInboxId));
+		RecordedRequest request10 = server.takeRequest();
+		assertEquals("/files/" + contactInboxId, request10.getPath());
+		assertEquals("GET", request10.getMethod());
+		assertToken(request10, token);
 	}
 
 	@Test

bramble-core/src/test/java/org/briarproject/bramble/mailbox/MailboxIntegrationTest.java

@@ -186,7 +186,7 @@ public class MailboxIntegrationTest extends BrambleTestCase {
 		MailboxFileId fileName1 = files1.get(0).name;
 
 		// owner can't check files
-		assertThrows(ApiException.class, () ->
+		assertThrows(TolerableFailureException.class, () ->
 				api.getFiles(ownerProperties, contact.inboxId));
 
 		// contact downloads file
@@ -197,12 +197,13 @@ public class MailboxIntegrationTest extends BrambleTestCase {
 
 		// owner can't download file, even if knowing name
 		File file1forbidden = folder.newFile();
-		assertThrows(ApiException.class, () -> api.getFile(ownerProperties,
-				contact.inboxId, fileName1, file1forbidden));
+		assertThrows(TolerableFailureException.class, () ->
+				api.getFile(ownerProperties, contact.inboxId, fileName1,
+						file1forbidden));
 		assertEquals(0, file1forbidden.length());
 
 		// owner can't delete file
-		assertThrows(ApiException.class, () ->
+		assertThrows(TolerableFailureException.class, () ->
 				api.deleteFile(ownerProperties, contact.inboxId, fileName1));
 
 		// contact deletes file
@@ -232,7 +233,7 @@ public class MailboxIntegrationTest extends BrambleTestCase {
 		MailboxFileId file3name = files2.get(1).name;
 
 		// contact can't list files in contact's outbox
-		assertThrows(ApiException.class, () ->
+		assertThrows(TolerableFailureException.class, () ->
 				api.getFiles(contactProperties, contact.outboxId));
 
 		// owner downloads both files from contact's outbox
@@ -252,17 +253,19 @@ public class MailboxIntegrationTest extends BrambleTestCase {
 		// contact can't download files again, even if knowing name
 		File file2forbidden = folder.newFile();
 		File file3forbidden = folder.newFile();
-		assertThrows(ApiException.class, () -> api.getFile(contactProperties,
-				contact.outboxId, file2name, file2forbidden));
-		assertThrows(ApiException.class, () -> api.getFile(contactProperties,
-				contact.outboxId, file3name, file3forbidden));
+		assertThrows(TolerableFailureException.class, () ->
+				api.getFile(contactProperties, contact.outboxId, file2name,
+						file2forbidden));
+		assertThrows(TolerableFailureException.class, () ->
+				api.getFile(contactProperties, contact.outboxId, file3name,
+						file3forbidden));
 		assertEquals(0, file1forbidden.length());
 		assertEquals(0, file2forbidden.length());
 
 		// contact can't delete files in outbox
-		assertThrows(ApiException.class, () ->
+		assertThrows(TolerableFailureException.class, () ->
 				api.deleteFile(contactProperties, contact.outboxId, file2name));
-		assertThrows(ApiException.class, () ->
+		assertThrows(TolerableFailureException.class, () ->
 				api.deleteFile(contactProperties, contact.outboxId, file3name));
 
 		// owner deletes files