/*
* Copyright 2004-2023 H2 Group. Multiple-Licensed under the MPL 2.0,
* and the EPL 1.0 (https://h2database.com/html/license.html).
* Initial Developer: H2 Group
*/
package org.h2.engine;
import java.util.ArrayList;
import org.h2.command.CommandInterface;
import org.h2.jdbc.meta.DatabaseMeta;
import org.h2.message.Trace;
import org.h2.result.ResultInterface;
import org.h2.store.DataHandler;
import org.h2.util.NetworkConnectionInfo;
import org.h2.util.TimeZoneProvider;
import org.h2.util.Utils;
import org.h2.value.ValueLob;
/**
* A local or remote session. A session represents a database connection.
*/
public abstract class Session implements CastDataProvider, AutoCloseable {
/**
* Static settings.
*/
public static final class StaticSettings {
/**
* Whether unquoted identifiers are converted to upper case.
*/
public final boolean databaseToUpper;
/**
* Whether unquoted identifiers are converted to lower case.
*/
public final boolean databaseToLower;
/**
* Whether all identifiers are case insensitive.
*/
public final boolean caseInsensitiveIdentifiers;
/**
* Creates new instance of static settings.
*
* @param databaseToUpper
* whether unquoted identifiers are converted to upper case
* @param databaseToLower
* whether unquoted identifiers are converted to lower case
* @param caseInsensitiveIdentifiers
* whether all identifiers are case insensitive
*/
public StaticSettings(boolean databaseToUpper, boolean databaseToLower, boolean caseInsensitiveIdentifiers) {
this.databaseToUpper = databaseToUpper;
this.databaseToLower = databaseToLower;
this.caseInsensitiveIdentifiers = caseInsensitiveIdentifiers;
}
}
/**
* Dynamic settings.
*/
public static final class DynamicSettings {
/**
* The database mode.
*/
public final Mode mode;
/**
* The current time zone.
*/
public final TimeZoneProvider timeZone;
/**
* Creates new instance of dynamic settings.
*
* @param mode
* the database mode
* @param timeZone
* the current time zone
*/
public DynamicSettings(Mode mode, TimeZoneProvider timeZone) {
this.mode = mode;
this.timeZone = timeZone;
}
}
private ArrayList<String> sessionState;
boolean sessionStateChanged;
private boolean sessionStateUpdating;
volatile StaticSettings staticSettings;
Session() {
}
/**
* Get the list of the cluster servers for this session.
*
* @return A list of "ip:port" strings for the cluster servers in this
* session.
*/
public abstract ArrayList<String> getClusterServers();
/**
* Parse a command and prepare it for execution.
*
* @param sql the SQL statement
* @param fetchSize the number of rows to fetch in one step
* @return the prepared command
*/
public abstract CommandInterface prepareCommand(String sql, int fetchSize);
/**
* Roll back pending transactions and close the session.
*/
@Override
public abstract void close();
/**
* Get the trace object
*
* @return the trace object
*/
public abstract Trace getTrace();
/**
* Check if close was called.
*
* @return if the session has been closed
*/
public abstract boolean isClosed();
/**
* Get the data handler object.
*
* @return the data handler
*/
public abstract DataHandler getDataHandler();
/**
* Check whether this session has a pending transaction.
*
* @return true if it has
*/
public abstract boolean hasPendingTransaction();
/**
* Cancel the current or next command (called when closing a connection).
*/
public abstract void cancel();
/**
* Check if this session is in auto-commit mode.
*
* @return true if the session is in auto-commit mode
*/
public abstract boolean getAutoCommit();
/**
* Set the auto-commit mode. This call doesn't commit the current
* transaction.
*
* @param autoCommit the new value
*/
public abstract void setAutoCommit(boolean autoCommit);
/**
* Add a temporary LOB, which is closed when the session commits.
*
* @param v the value
* @return the specified value
*/
public abstract ValueLob addTemporaryLob(ValueLob v);
/**
* Check if this session is remote or embedded.
*
* @return true if this session is remote
*/
public abstract boolean isRemote();
/**
* Set current schema.
*
* @param schema the schema name
*/
public abstract void setCurrentSchemaName(String schema);
/**
* Get current schema.
*
* @return the current schema name
*/
public abstract String getCurrentSchemaName();
/**
* Sets the network connection information if possible.
*
* @param networkConnectionInfo the network connection information
*/
public abstract void setNetworkConnectionInfo(NetworkConnectionInfo networkConnectionInfo);
/**
* Returns the isolation level.
*
* @return the isolation level
*/
public abstract IsolationLevel getIsolationLevel();
/**
* Sets the isolation level.
*
* @param isolationLevel the isolation level to set
*/
public abstract void setIsolationLevel(IsolationLevel isolationLevel);
/**
* Returns static settings. These settings cannot be changed during
* lifecycle of session.
*
* @return static settings
*/
public abstract StaticSettings getStaticSettings();
/**
* Returns dynamic settings. These settings can be changed during lifecycle
* of session.
*
* @return dynamic settings
*/
public abstract DynamicSettings getDynamicSettings();
/**
* Returns database meta information.
*
* @return database meta information
*/
public abstract DatabaseMeta getDatabaseMeta();
/**
* Returns whether INFORMATION_SCHEMA contains old-style tables.
*
* @return whether INFORMATION_SCHEMA contains old-style tables
*/
public abstract boolean isOldInformationSchema();
/**
* Re-create the session state using the stored sessionState list.
*/
void recreateSessionState() {
if (sessionState != null && !sessionState.isEmpty()) {
sessionStateUpdating = true;
try {
for (String sql : sessionState) {
CommandInterface ci = prepareCommand(sql, Integer.MAX_VALUE);
ci.executeUpdate(null);
}
} finally {
sessionStateUpdating = false;
sessionStateChanged = false;
}
}
}
/**
* Read the session state if necessary.
*/
public void readSessionState() {
if (!sessionStateChanged || sessionStateUpdating) {
return;
}
sessionStateChanged = false;
sessionState = Utils.newSmallArrayList();
CommandInterface ci = prepareCommand(!isOldInformationSchema()
? "SELECT STATE_COMMAND FROM INFORMATION_SCHEMA.SESSION_STATE"
: "SELECT SQL FROM INFORMATION_SCHEMA.SESSION_STATE", Integer.MAX_VALUE);
ResultInterface result = ci.executeQuery(0, false);
while (result.next()) {
sessionState.add(result.currentRow()[0].getString());
}
}
/**
* Sets this session as thread local session, if this session is a local
* session.
*
* @return old thread local session, or {@code null}
*/
public Session setThreadLocalSession() {
return null;
}
/**
* Resets old thread local session.
*
* @param oldSession
* the old thread local session, or {@code null}
*/
public void resetThreadLocalSession(Session oldSession) {
}
}