Perform thread list core access within a single transaction

briar-api/src/main/java/org/briarproject/briar/api/forum/ForumManager.java

@@ -11,6 +11,7 @@ import org.briarproject.bramble.api.sync.MessageId;
 import org.briarproject.briar.api.client.MessageTracker.GroupCount;
 
 import java.util.Collection;
+import java.util.List;
 
 import javax.annotation.Nullable;
 
@@ -84,11 +85,22 @@ public interface ForumManager {
 	 */
 	String getPostText(MessageId m) throws DbException;
 
+	/**
+	 * Returns the text of the forum post with the given ID.
+	 */
+	String getPostText(Transaction txn, MessageId m) throws DbException;
+
 	/**
 	 * Returns the headers of all posts in the given forum.
 	 */
 	Collection<ForumPostHeader> getPostHeaders(GroupId g) throws DbException;
 
+	/**
+	 * Returns the headers of all posts in the given forum.
+	 */
+	List<ForumPostHeader> getPostHeaders(Transaction txn, GroupId g)
+			throws DbException;
+
 	/**
 	 * Registers a hook to be called whenever a forum is removed.
 	 */

briar-api/src/main/java/org/briarproject/briar/api/privategroup/PrivateGroupManager.java

@@ -12,6 +12,7 @@ import org.briarproject.bramble.api.sync.MessageId;
 import org.briarproject.briar.api.client.MessageTracker.GroupCount;
 
 import java.util.Collection;
+import java.util.List;
 
 @NotNullByDefault
 public interface PrivateGroupManager {
@@ -107,11 +108,22 @@ public interface PrivateGroupManager {
 	 */
 	String getMessageText(MessageId m) throws DbException;
 
+	/**
+	 * Returns the text of the private group message with the given ID.
+	 */
+	String getMessageText(Transaction txn, MessageId m) throws DbException;
+
 	/**
 	 * Returns the headers of all messages in the given private group.
 	 */
 	Collection<GroupMessageHeader> getHeaders(GroupId g) throws DbException;
 
+	/**
+	 * Returns the headers of all messages in the given private group.
+	 */
+	List<GroupMessageHeader> getHeaders(Transaction txn, GroupId g)
+			throws DbException;
+
 	/**
 	 * Returns all members of the given private group.
 	 */

briar-core/src/main/java/org/briarproject/briar/forum/ForumManagerImpl.java

@@ -192,6 +192,15 @@ class ForumManagerImpl extends BdfIncomingMessageHook implements ForumManager {
 		}
 	}
 
+	@Override
+	public String getPostText(Transaction txn, MessageId m) throws DbException {
+		try {
+			return getPostText(clientHelper.getMessageAsList(txn, m));
+		} catch (FormatException e) {
+			throw new DbException(e);
+		}
+	}
+
 	private String getPostText(BdfList body) throws FormatException {
 		// Parent ID, author, text, signature
 		return body.getString(2);
@@ -200,33 +209,35 @@ class ForumManagerImpl extends BdfIncomingMessageHook implements ForumManager {
 	@Override
 	public Collection<ForumPostHeader> getPostHeaders(GroupId g)
 			throws DbException {
+		return db.transactionWithResult(true, txn -> getPostHeaders(txn, g));
+	}
+
+	@Override
+	public List<ForumPostHeader> getPostHeaders(Transaction txn, GroupId g)
+			throws DbException {
 		try {
-			return db.transactionWithResult(true, txn -> {
+			List<ForumPostHeader> headers = new ArrayList<>();
-				Collection<ForumPostHeader> headers = new ArrayList<>();
+			Map<MessageId, BdfDictionary> metadata =
-				Map<MessageId, BdfDictionary> metadata =
+					clientHelper.getMessageMetadataAsDictionary(txn, g);
-						clientHelper.getMessageMetadataAsDictionary(txn, g);
+			// get all authors we need to get the info for
-				// get all authors we need to get the info for
+			Set<AuthorId> authors = new HashSet<>();
-				Set<AuthorId> authors = new HashSet<>();
+			for (Entry<MessageId, BdfDictionary> entry : metadata.entrySet()) {
-				for (Entry<MessageId, BdfDictionary> entry :
+				BdfList authorList = entry.getValue().getList(KEY_AUTHOR);
-						metadata.entrySet()) {
+				Author a = clientHelper.parseAndValidateAuthor(authorList);
-					BdfList authorList = entry.getValue().getList(KEY_AUTHOR);
+				authors.add(a.getId());
-					Author a = clientHelper.parseAndValidateAuthor(authorList);
+			}
-					authors.add(a.getId());
+			// get information for all authors
-				}
+			Map<AuthorId, AuthorInfo> authorInfos = new HashMap<>();
-				// get information for all authors
+			for (AuthorId id : authors) {
-				Map<AuthorId, AuthorInfo> authorInfos = new HashMap<>();
+				authorInfos.put(id, authorManager.getAuthorInfo(txn, id));
-				for (AuthorId id : authors) {
+			}
-					authorInfos.put(id, authorManager.getAuthorInfo(txn, id));
+			// Parse the metadata
-				}
+			for (Entry<MessageId, BdfDictionary> entry : metadata.entrySet()) {
-				// Parse the metadata
+				BdfDictionary meta = entry.getValue();
-				for (Entry<MessageId, BdfDictionary> entry :
+				headers.add(getForumPostHeader(txn, entry.getKey(), meta,
-						metadata.entrySet()) {
+						authorInfos));
-					BdfDictionary meta = entry.getValue();
+			}
-					headers.add(getForumPostHeader(txn, entry.getKey(), meta,
+			return headers;
-							authorInfos));
-				}
-				return headers;
-			});
 		} catch (FormatException e) {
 			throw new DbException(e);
 		}

briar-core/src/main/java/org/briarproject/briar/privategroup/PrivateGroupManagerImpl.java

@@ -315,6 +315,16 @@ class PrivateGroupManagerImpl extends BdfIncomingMessageHook
 		}
 	}
 
+	@Override
+	public String getMessageText(Transaction txn, MessageId m)
+			throws DbException {
+		try {
+			return getMessageText(clientHelper.getMessageAsList(txn, m));
+		} catch (FormatException e) {
+			throw new DbException(e);
+		}
+	}
+
 	private String getMessageText(BdfList body) throws FormatException {
 		// Message type (0), member (1), parent ID (2), previous message ID (3),
 		// text (4), signature (5)
@@ -324,8 +334,13 @@ class PrivateGroupManagerImpl extends BdfIncomingMessageHook
 	@Override
 	public Collection<GroupMessageHeader> getHeaders(GroupId g)
 			throws DbException {
-		Collection<GroupMessageHeader> headers = new ArrayList<>();
+		return db.transactionWithResult(true, txn -> getHeaders(txn, g));
-		Transaction txn = db.startTransaction(true);
+	}
+
+	@Override
+	public List<GroupMessageHeader> getHeaders(Transaction txn, GroupId g)
+			throws DbException {
+		List<GroupMessageHeader> headers = new ArrayList<>();
 		try {
 			Map<MessageId, BdfDictionary> metadata =
 					clientHelper.getMessageMetadataAsDictionary(txn, g);
@@ -354,12 +369,9 @@ class PrivateGroupManagerImpl extends BdfIncomingMessageHook
 							meta, authorInfos));
 				}
 			}
-			db.commitTransaction(txn);
 			return headers;
 		} catch (FormatException e) {
 			throw new DbException(e);
-		} finally {
-			db.endTransaction(txn);
 		}
 	}