/**
* Opens a cursor for a given database, dup'ing an existing CDB cursor if one is open for the
* current thread.
*/
Cursor openCursor(Database db, CursorConfig cursorConfig, boolean writeCursor, Transaction txn)
throws DatabaseException {
if (cdbMode) {
CdbCursors cdbCursors = null;
WeakHashMap cdbCursorsMap = (WeakHashMap) localCdbCursors.get();
if (cdbCursorsMap == null) {
cdbCursorsMap = new WeakHashMap();
localCdbCursors.set(cdbCursorsMap);
} else {
cdbCursors = (CdbCursors) cdbCursorsMap.get(db);
}
if (cdbCursors == null) {
cdbCursors = new CdbCursors();
cdbCursorsMap.put(db, cdbCursors);
}
/*
* In CDB mode the cursorConfig specified by the user is ignored
* and only the writeCursor parameter is honored. This is the only
* meaningful cursor attribute for CDB, and here we count on
* writeCursor flag being set correctly by the caller.
*/
List cursors;
CursorConfig cdbConfig;
if (writeCursor) {
if (cdbCursors.readCursors.size() > 0) {
/*
* Although CDB allows opening a write cursor when a read
* cursor is open, a self-deadlock will occur if a write is
* attempted for a record that is read-locked; we should
* avoid self-deadlocks at all costs
*/
throw new IllegalStateException("cannot open CDB write cursor when read cursor is open");
}
cursors = cdbCursors.writeCursors;
cdbConfig = new CursorConfig();
DbCompat.setWriteCursor(cdbConfig, true);
} else {
cursors = cdbCursors.readCursors;
cdbConfig = null;
}
Cursor cursor;
if (cursors.size() > 0) {
Cursor other = ((Cursor) cursors.get(0));
cursor = other.dup(false);
} else {
cursor = db.openCursor(null, cdbConfig);
}
cursors.add(cursor);
return cursor;
} else {
return db.openCursor(txn, cursorConfig);
}
}
/**
* Inserts an entity and returns null, or updates it if the primary key already exists and returns
* the existing entity.
*
* <p>If a {@link PrimaryKey#sequence} is used and the primary key field of the given entity is
* null or zero, this method will assign the next value from the sequence to the primary key field
* of the given entity.
*
* @param txn the transaction used to protect this operation, null to use auto-commit, or null if
* the store is non-transactional.
* @param entity the entity to be inserted or updated.
* @return the existing entity that was updated, or null if the entity was inserted.
* @throws DatabaseException the base class for all BDB exceptions.
*/
public E put(Transaction txn, E entity) throws DatabaseException {
DatabaseEntry keyEntry = new DatabaseEntry();
DatabaseEntry dataEntry = new DatabaseEntry();
assignKey(entity, keyEntry);
boolean autoCommit = false;
Environment env = db.getEnvironment();
if (transactional && txn == null && DbCompat.getThreadTransaction(env) == null) {
txn = env.beginTransaction(null, getAutoCommitTransactionConfig());
autoCommit = true;
}
CursorConfig cursorConfig = null;
if (concurrentDB) {
cursorConfig = new CursorConfig();
DbCompat.setWriteCursor(cursorConfig, true);
}
boolean failed = true;
Cursor cursor = db.openCursor(txn, cursorConfig);
LockMode lockMode = locking ? LockMode.RMW : null;
try {
while (true) {
OperationStatus status = cursor.getSearchKey(keyEntry, dataEntry, lockMode);
if (status == OperationStatus.SUCCESS) {
E existing = entityBinding.entryToObject(keyEntry, dataEntry);
entityBinding.objectToData(entity, dataEntry);
cursor.put(keyEntry, dataEntry);
failed = false;
return existing;
} else {
entityBinding.objectToData(entity, dataEntry);
status = cursor.putNoOverwrite(keyEntry, dataEntry);
if (status != OperationStatus.KEYEXIST) {
failed = false;
return null;
}
}
}
} finally {
cursor.close();
if (autoCommit) {
if (failed) {
txn.abort();
} else {
txn.commit();
}
}
}
}
