@Override
public synchronized int readLob(
long lobId, byte[] hmac, long offset, byte[] buff, int off, int length) {
for (int i = 0, count = 0; i < transferList.size(); i++) {
Transfer transfer = transferList.get(i);
try {
traceOperation("LOB_READ", (int) lobId);
transfer.writeInt(SessionRemote.LOB_READ);
transfer.writeLong(lobId);
if (clientVersion >= Constants.TCP_PROTOCOL_VERSION_12) {
transfer.writeBytes(hmac);
}
transfer.writeLong(offset);
transfer.writeInt(length);
done(transfer);
length = transfer.readInt();
if (length <= 0) {
return length;
}
transfer.readBytes(buff, off, length);
return length;
} catch (IOException e) {
removeServer(e, i--, ++count);
}
}
return 1;
}
@Override
public void run() {
try {
transfer.init();
trace("Connect");
// TODO server: should support a list of allowed databases
// and a list of allowed clients
try {
// 如果没有加-tcpAllowOthers参数，那么只接受本地连接
if (!server.allow(transfer.getSocket())) {
throw DbException.get(ErrorCode.REMOTE_CONNECTION_NOT_ALLOWED);
}
int minClientVersion = transfer.readInt();
if (minClientVersion < Constants.TCP_PROTOCOL_VERSION_6) {
throw DbException.get(
ErrorCode.DRIVER_VERSION_ERROR_2,
"" + clientVersion,
"" + Constants.TCP_PROTOCOL_VERSION_6);
} else if (minClientVersion > Constants.TCP_PROTOCOL_VERSION_12) {
throw DbException.get(
ErrorCode.DRIVER_VERSION_ERROR_2,
"" + clientVersion,
"" + Constants.TCP_PROTOCOL_VERSION_12);
}
int maxClientVersion = transfer.readInt();
if (maxClientVersion >= Constants.TCP_PROTOCOL_VERSION_12) {
clientVersion = Constants.TCP_PROTOCOL_VERSION_12;
} else {
clientVersion = minClientVersion;
}
transfer.setVersion(clientVersion);
String db = transfer.readString();
String originalURL = transfer.readString();
if (db == null && originalURL == null) {
String targetSessionId = transfer.readString();
int command = transfer.readInt();
stop = true;
if (command == SessionRemote.SESSION_CANCEL_STATEMENT) {
// cancel a running statement
int statementId = transfer.readInt();
server.cancelStatement(targetSessionId, statementId);
} else if (command == SessionRemote.SESSION_CHECK_KEY) {
// check if this is the correct server
db = server.checkKeyAndGetDatabaseName(targetSessionId);
if (!targetSessionId.equals(db)) {
transfer.writeInt(SessionRemote.STATUS_OK);
} else {
transfer.writeInt(SessionRemote.STATUS_ERROR);
}
}
}
// 启动TcpServer时加"-baseDir"或者像这样System.setProperty("h2.baseDir", "E:\\H2\\baseDir")
String baseDir = server.getBaseDir();
if (baseDir == null) {
baseDir = SysProperties.getBaseDir();
}
// 例如启动TcpServer时，指定了"-key mydb mydatabase"，
// 如果db变量是mydb，那么实际上就是mydatabase，相当于做一次映射
// 如果db变量不是mydb，那么抛错: org.h2.jdbc.JdbcSQLException: Wrong user name or password [28000-170]
db = server.checkKeyAndGetDatabaseName(db);
ConnectionInfo ci = new ConnectionInfo(db);
ci.setOriginalURL(originalURL);
ci.setUserName(transfer.readString());
// password参数的值已经转换成userPasswordHash和filePasswordHash了，
// 不能由userPasswordHash和filePasswordHash得到原始的password
ci.setUserPasswordHash(transfer.readBytes());
ci.setFilePasswordHash(transfer.readBytes()); // 只有指定"CIPHER"参数时filePasswordHash才是非null的
int len = transfer.readInt();
for (int i = 0; i < len; i++) {
ci.setProperty(transfer.readString(), transfer.readString());
}
// override client's requested properties with server settings
if (baseDir != null) {
ci.setBaseDir(baseDir);
}
if (server.getIfExists()) {
// 启动TcpServer时加"-ifExists"，限制只有数据库存在时客户端才能连接，也就是不允许在客户端创建数据库
ci.setProperty("IFEXISTS", "TRUE");
}
session = Engine.getInstance().createSession(ci);
transfer.setSession(session);
transfer.writeInt(SessionRemote.STATUS_OK);
transfer.writeInt(clientVersion);
transfer.flush();
// 每建立一个新的Session对象时，把它保存到内存数据库management_db_9092的SESSIONS表
server.addConnection(threadId, originalURL, ci.getUserName());
trace("Connected");
} catch (Throwable e) {
sendError(e);
stop = true;
}
while (!stop) {
try {
process();
} catch (Throwable e) {
sendError(e);
}
}
trace("Disconnect");
} catch (Throwable e) {
server.traceError(e);
} finally {
close();
}
}
// 总共18条命令，这里包含16条
// 下面这两条在run方法中特殊处理
// SESSION_CANCEL_STATEMENT
// SESSION_CHECK_KEY
// 分三种级别，从大到小: SESSION级、COMMAND级、RESULT级
private void process() throws IOException {
int operation = transfer.readInt();
switch (operation) {
case SessionRemote.SESSION_PREPARE_READ_PARAMS:
case SessionRemote.SESSION_PREPARE:
{
int id = transfer.readInt();
String sql = transfer.readString();
int old = session.getModificationId();
Command command = session.prepareLocal(sql);
boolean readonly = command.isReadOnly();
cache.addObject(id, command);
boolean isQuery = command.isQuery();
ArrayList<? extends ParameterInterface> params = command.getParameters();
transfer
.writeInt(getState(old))
.writeBoolean(isQuery)
.writeBoolean(readonly)
.writeInt(params.size());
if (operation == SessionRemote.SESSION_PREPARE_READ_PARAMS) {
for (ParameterInterface p : params) {
ParameterRemote.writeMetaData(transfer, p);
}
}
transfer.flush();
break;
}
case SessionRemote.SESSION_CLOSE:
{
stop = true;
closeSession();
transfer.writeInt(SessionRemote.STATUS_OK).flush();
close();
break;
}
case SessionRemote.COMMAND_COMMIT:
{
// 并不是通过org.h2.jdbc.JdbcConnection.commit()触发，此方法是通过发送COMMIT SQL触发
// 触发SessionRemote.COMMAND_COMMIT的是在集群环境下，通过org.h2.engine.SessionRemote.autoCommitIfCluster()触发
if (commit == null) {
commit = session.prepareLocal("COMMIT");
}
int old = session.getModificationId();
commit.executeUpdate();
transfer.writeInt(getState(old)).flush();
break;
}
case SessionRemote.COMMAND_GET_META_DATA:
{
int id = transfer.readInt();
int objectId = transfer.readInt();
Command command = (Command) cache.getObject(id, false);
ResultInterface result = command.getMetaData();
cache.addObject(objectId, result);
int columnCount = result.getVisibleColumnCount();
transfer.writeInt(SessionRemote.STATUS_OK).writeInt(columnCount).writeInt(0);
for (int i = 0; i < columnCount; i++) {
ResultColumn.writeColumn(transfer, result, i);
}
transfer.flush();
break;
}
case SessionRemote.COMMAND_EXECUTE_QUERY:
{
int id = transfer.readInt();
int objectId = transfer.readInt();
int maxRows = transfer.readInt();
int fetchSize = transfer.readInt();
Command command = (Command) cache.getObject(id, false);
setParameters(command);
int old = session.getModificationId();
ResultInterface result;
synchronized (session) {
result = command.executeQuery(maxRows, false);
}
cache.addObject(objectId, result);
int columnCount = result.getVisibleColumnCount();
int state = getState(old);
transfer.writeInt(state).writeInt(columnCount);
int rowCount = result.getRowCount();
transfer.writeInt(rowCount);
for (int i = 0; i < columnCount; i++) {
ResultColumn.writeColumn(transfer, result, i);
}
int fetch = Math.min(rowCount, fetchSize);
for (int i = 0; i < fetch; i++) {
sendRow(result);
}
transfer.flush();
break;
}
case SessionRemote.COMMAND_EXECUTE_UPDATE:
{
int id = transfer.readInt();
Command command = (Command) cache.getObject(id, false);
// if(command!=null)throw new Error();
setParameters(command);
int old = session.getModificationId();
int updateCount;
synchronized (session) {
updateCount = command.executeUpdate();
}
int status;
if (session.isClosed()) {
status = SessionRemote.STATUS_CLOSED;
} else {
status = getState(old);
}
transfer.writeInt(status).writeInt(updateCount).writeBoolean(session.getAutoCommit());
transfer.flush();
break;
}
case SessionRemote.COMMAND_CLOSE:
{
int id = transfer.readInt();
Command command = (Command) cache.getObject(id, true);
if (command != null) {
command.close();
cache.freeObject(id);
}
break;
}
case SessionRemote.RESULT_FETCH_ROWS:
{
int id = transfer.readInt();
int count = transfer.readInt();
ResultInterface result = (ResultInterface) cache.getObject(id, false);
transfer.writeInt(SessionRemote.STATUS_OK);
for (int i = 0; i < count; i++) {
sendRow(result);
}
transfer.flush();
break;
}
case SessionRemote.RESULT_RESET:
{
int id = transfer.readInt();
ResultInterface result = (ResultInterface) cache.getObject(id, false);
result.reset();
break;
}
case SessionRemote.RESULT_CLOSE:
{
int id = transfer.readInt();
ResultInterface result = (ResultInterface) cache.getObject(id, true);
if (result != null) {
result.close();
cache.freeObject(id);
}
break;
}
case SessionRemote.CHANGE_ID:
{
int oldId = transfer.readInt();
int newId = transfer.readInt();
Object obj = cache.getObject(oldId, false);
cache.freeObject(oldId);
cache.addObject(newId, obj);
break;
}
case SessionRemote.SESSION_SET_ID:
{
sessionId = transfer.readString();
transfer.writeInt(SessionRemote.STATUS_OK).flush();
break;
}
case SessionRemote.SESSION_SET_AUTOCOMMIT:
{
boolean autoCommit = transfer.readBoolean();
session.setAutoCommit(autoCommit);
transfer.writeInt(SessionRemote.STATUS_OK).flush();
break;
}
case SessionRemote.SESSION_HAS_PENDING_TRANSACTION:
{
transfer
.writeInt(SessionRemote.STATUS_OK)
.writeInt(session.hasPendingTransaction() ? 1 : 0)
.flush();
break;
}
case SessionRemote.LOB_READ:
{
long lobId = transfer.readLong();
byte[] hmac;
CachedInputStream in;
boolean verifyMac;
if (clientVersion >= Constants.TCP_PROTOCOL_VERSION_11) {
if (clientVersion >= Constants.TCP_PROTOCOL_VERSION_12) {
hmac = transfer.readBytes();
verifyMac = true;
} else {
hmac = null;
verifyMac = false;
}
in = lobs.get(lobId);
if (in == null && verifyMac) {
in = new CachedInputStream(null);
lobs.put(lobId, in);
}
} else {
verifyMac = false;
hmac = null;
in = lobs.get(lobId);
}
long offset = transfer.readLong();
int length = transfer.readInt();
if (verifyMac) {
transfer.verifyLobMac(hmac, lobId);
}
if (in == null) {
throw DbException.get(ErrorCode.OBJECT_CLOSED);
}
if (in.getPos() != offset) {
LobStorageInterface lobStorage = session.getDataHandler().getLobStorage();
InputStream lobIn = lobStorage.getInputStream(lobId, hmac, -1);
in = new CachedInputStream(lobIn);
lobs.put(lobId, in);
lobIn.skip(offset);
}
// limit the buffer size
length = Math.min(16 * Constants.IO_BUFFER_SIZE, length);
byte[] buff = new byte[length];
length = IOUtils.readFully(in, buff, 0, length);
transfer.writeInt(SessionRemote.STATUS_OK);
transfer.writeInt(length);
transfer.writeBytes(buff, 0, length);
transfer.flush();
break;
}
default:
trace("Unknown operation: " + operation);
closeSession();
close();
}
}