/**
* Parse and prepare the given SQL statement. This method also checks if the connection has been
* closed.
*
* @param sql the SQL statement
* @return the prepared statement
*/
public Command prepareLocal(String sql) {
if (closed) {
throw DbException.get(ErrorCode.CONNECTION_BROKEN_1, "session closed");
}
Command command;
if (queryCacheSize > 0) {
if (queryCache == null) {
queryCache = SmallLRUCache.newInstance(queryCacheSize);
modificationMetaID = database.getModificationMetaId();
} else {
long newModificationMetaID = database.getModificationMetaId();
if (newModificationMetaID != modificationMetaID) {
queryCache.clear();
modificationMetaID = newModificationMetaID;
}
command = queryCache.get(sql);
if (command != null && command.canReuse()) {
command.reuse();
return command;
}
}
}
Parser parser = new Parser(this);
command = parser.prepareCommand(sql);
if (queryCache != null) {
if (command.isCacheable()) {
queryCache.put(sql, command);
}
}
return command;
}
/**
* Get or create a trace object for this module.
*
* @param module the module name
* @return the trace object
*/
public synchronized Trace getTrace(String module) {
Trace t = traces.get(module);
if (t == null) {
t = new Trace(writer, module);
traces.put(module, t);
}
return t;
}
private void writeValue(Value v) throws IOException {
if (v.getType() == Value.CLOB || v.getType() == Value.BLOB) {
if (v instanceof ValueLobDb) {
ValueLobDb lob = (ValueLobDb) v;
if (lob.isStored()) {
long id = lob.getLobId();
lobs.put(id, new CachedInputStream(null));
}
}
}
transfer.writeValue(v);
}
public PlanItem getBestPlanItem(Session session, int[] masks) {
PlanItem item = new PlanItem();
item.cost = index.getCost(session, masks);
IntArray masksArray = new IntArray(masks == null ? Utils.EMPTY_INT_ARRAY : masks);
ViewIndex i2 = indexCache.get(masksArray);
if (i2 == null || i2.getSession() != session) {
i2 = new ViewIndex(this, index, session, masks);
indexCache.put(masksArray, i2);
}
item.setIndex(i2);
return item;
}
public double getCost(Session session, int[] masks) {
if (recursive) {
return 1000;
}
IntArray masksArray = new IntArray(masks == null ? Utils.EMPTY_INT_ARRAY : masks);
CostElement cachedCost = costCache.get(masksArray);
if (cachedCost != null) {
long time = System.currentTimeMillis();
if (time < cachedCost.evaluatedAt + Constants.VIEW_COST_CACHE_MAX_AGE) {
return cachedCost.cost;
}
}
Query q = (Query) session.prepare(querySQL, true);
if (masks != null) {
IntArray paramIndex = new IntArray();
for (int i = 0; i < masks.length; i++) {
int mask = masks[i];
if (mask == 0) {
continue;
}
paramIndex.add(i);
}
int len = paramIndex.size();
for (int i = 0; i < len; i++) {
int idx = paramIndex.get(i);
int mask = masks[idx];
int nextParamIndex = q.getParameters().size() + view.getParameterOffset();
if ((mask & IndexCondition.EQUALITY) != 0) {
Parameter param = new Parameter(nextParamIndex);
q.addGlobalCondition(param, idx, Comparison.EQUAL_NULL_SAFE);
} else {
if ((mask & IndexCondition.START) != 0) {
Parameter param = new Parameter(nextParamIndex);
q.addGlobalCondition(param, idx, Comparison.BIGGER_EQUAL);
}
if ((mask & IndexCondition.END) != 0) {
Parameter param = new Parameter(nextParamIndex);
q.addGlobalCondition(param, idx, Comparison.SMALLER_EQUAL);
}
}
}
String sql = q.getPlanSQL();
q = (Query) session.prepare(sql, true);
}
double cost = q.getCost();
cachedCost = new CostElement();
cachedCost.evaluatedAt = System.currentTimeMillis();
cachedCost.cost = cost;
costCache.put(masksArray, cachedCost);
return cost;
}
// 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();
}
}
