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Microsoft JDBC Driver for SQL Server.
/*
* Microsoft JDBC Driver for SQL Server Copyright(c) Microsoft Corporation All rights reserved. This program is made
* available under the terms of the MIT License. See the LICENSE file in the project root for more information.
*/
package com.microsoft.sqlserver.jdbc;
import java.util.concurrent.atomic.AtomicInteger;
class IdleConnectionResiliency {
private boolean connectionRecoveryNegotiated;
private int connectRetryCount;
private SQLServerConnection connection;
private SessionStateTable sessionStateTable;
private ReconnectThread reconnectThread;
private AtomicInteger unprocessedResponseCount = new AtomicInteger();
private boolean connectionRecoveryPossible;
/*
* Variables needed to perform a reconnect, these are not necessarily determined from just the connection string
*/
private String loginInstanceValue;
private int loginNPort;
private FailoverInfo loginFailoverInfo;
private int loginLoginTimeoutSeconds;
IdleConnectionResiliency(SQLServerConnection connection) {
this.connection = connection;
reconnectThread = new ReconnectThread(connection);
}
boolean isConnectionRecoveryNegotiated() {
return connectionRecoveryNegotiated;
}
void setConnectionRecoveryNegotiated(boolean connectionRecoveryNegotiated) {
this.connectionRecoveryNegotiated = connectionRecoveryNegotiated;
}
int getConnectRetryCount() {
return connectRetryCount;
}
void setConnectRetryCount(int connectRetryCount) {
this.connectRetryCount = connectRetryCount;
}
SQLServerConnection getConnection() {
return connection;
}
void setConnection(SQLServerConnection connection) {
this.connection = connection;
}
ReconnectThread getReconnectThread() {
return reconnectThread;
}
SessionStateTable getSessionStateTable() {
return sessionStateTable;
}
void setSessionStateTable(SessionStateTable sessionStateTable) {
this.sessionStateTable = sessionStateTable;
}
boolean isConnectionRecoveryPossible() {
return connectionRecoveryPossible;
}
void setConnectionRecoveryPossible(boolean connectionRecoveryPossible) {
this.connectionRecoveryPossible = connectionRecoveryPossible;
}
int getUnprocessedResponseCount() {
return unprocessedResponseCount.get();
}
void resetUnprocessedResponseCount() {
this.unprocessedResponseCount.set(0);
}
void parseInitialSessionStateData(byte[] data, byte[][] sessionStateInitial) throws SQLServerException {
int bytesRead = 0;
// Contains StateId, StateLen, StateValue
while (bytesRead < data.length) {
short sessionStateId = (short) (data[bytesRead] & 0xFF);
bytesRead++;
int sessionStateLength;
byte byteLength = data[bytesRead];
bytesRead++;
if (byteLength == 0xFF) {
sessionStateLength = (int) (Util.readInt(data, bytesRead) & 0xFFFFFFFFL);
bytesRead += 4;
} else {
sessionStateLength = byteLength;
}
sessionStateInitial[sessionStateId] = new byte[sessionStateLength];
System.arraycopy(data, bytesRead, sessionStateInitial[sessionStateId], 0, sessionStateLength);
bytesRead += sessionStateLength;
}
}
void incrementUnprocessedResponseCount() {
if (connection.getRetryCount() > 0 && !getReconnectThread().isAlive()) {
if (unprocessedResponseCount.incrementAndGet() < 0)
/*
* When this number rolls over, connection recovery is disabled for the rest of the life of the
* connection.
*/
setConnectionRecoveryPossible(false);
}
}
void decrementUnprocessedResponseCount() {
if (connection.getRetryCount() > 0 && !getReconnectThread().isAlive()) {
if (unprocessedResponseCount.decrementAndGet() < 0)
/*
* When this number rolls over, connection recovery is disabled for the rest of the life of the
* connection.
*/
setConnectionRecoveryPossible(false);
}
}
void setLoginParameters(String instanceValue, int nPort, FailoverInfo fo, int loginTimeoutSeconds) {
this.loginInstanceValue = instanceValue;
this.loginNPort = nPort;
this.loginFailoverInfo = fo;
this.loginLoginTimeoutSeconds = loginTimeoutSeconds;
}
String getInstanceValue() {
return loginInstanceValue;
}
int getNPort() {
return loginNPort;
}
FailoverInfo getFailoverInfo() {
return loginFailoverInfo;
}
int getLoginTimeoutSeconds() {
return loginLoginTimeoutSeconds;
}
}
class SessionStateValue {
private boolean isRecoverable;
private int sequenceNumber;
private int dataLength;
private byte[] data;
boolean isSequenceNumberGreater(int sequenceNumberToBeCompared) {
// Illustration using 8 bit number
// Initial assignment takes care of following scenarios:
// toBeCompared= 2 benchmark = 1 (both positive) ..true
// toBeCompared=-1(255) benchmark = -2(254) (both negative) ..true
// toBeCompared=-1(255) benchmark = 1 ..true
// toBeCompared=-1(255) benchmark = 0 ..true
boolean greater = true;
if (sequenceNumberToBeCompared > sequenceNumber) {
// Following if condition takes care of these scenarios:
// toBeCompared = 0 benchmark = -1(255)
// toBeCompared = 1 benchmark = -1(255)
if ((sequenceNumberToBeCompared >= 0) && (sequenceNumber < 0))
greater = false;
}
// This else takes care of these scenarios where result is false:
// toBeCompared= 1 benchmark = 2 (both positive) ..false
// toBeCompared=-2(254) benchmark = -1(255) (both negative) ..false
else
// Following if condition to not set return to false for these scenarios:
// toBeCompared=-1(255) benchmark = 1 ..true
// toBeCompared=-1(255) benchmark = 0 ..true
if ((sequenceNumberToBeCompared > 0) || (sequenceNumber < 0))
greater = false;
return greater;
}
boolean isRecoverable() {
return isRecoverable;
}
void setRecoverable(boolean isRecoverable) {
this.isRecoverable = isRecoverable;
}
int getSequenceNumber() {
return sequenceNumber;
}
void setSequenceNumber(int sequenceNumber) {
this.sequenceNumber = sequenceNumber;
}
int getDataLength() {
return dataLength;
}
void setDataLengh(int dataLength) {
this.dataLength = dataLength;
}
byte[] getData() {
return data;
}
void setData(byte[] data) {
this.data = data;
}
}
class SessionStateTable {
static final int SESSION_STATE_ID_MAX = 256;
static final long MASTER_RECOVERY_DISABLE_SEQ_NUMBER = 0XFFFFFFFF;
private boolean masterRecoveryDisabled;
private byte[][] sessionStateInitial;
private SessionStateValue sessionStateDelta[];
private AtomicInteger unRecoverableSessionStateCount = new AtomicInteger(0);
private String originalCatalog;
private String originalLanguage;
private SQLCollation originalCollation;
private byte originalNegotiatedEncryptionLevel = TDS.ENCRYPT_INVALID;
private boolean resetCalled = false;
SessionStateTable() {
this.sessionStateDelta = new SessionStateValue[SESSION_STATE_ID_MAX];
this.sessionStateInitial = new byte[SessionStateTable.SESSION_STATE_ID_MAX][];
}
void updateSessionState(TDSReader tdsReader, short sessionStateId, int sessionStateLength, int sequenceNumber,
boolean fRecoverable) throws SQLServerException {
sessionStateDelta[sessionStateId].setSequenceNumber(sequenceNumber);
sessionStateDelta[sessionStateId].setDataLengh(sessionStateLength);
if ((sessionStateDelta[sessionStateId].getData() == null)
|| (sessionStateDelta[sessionStateId].getData().length < sessionStateLength)) {
sessionStateDelta[sessionStateId].setData(new byte[sessionStateLength]);
// First time state update and value is not recoverable, hence count is incremented.
if (!fRecoverable) {
unRecoverableSessionStateCount.incrementAndGet();
}
} else {
// Not a first time state update hence if only there is a transition in state do we update the count.
if (fRecoverable != sessionStateDelta[sessionStateId].isRecoverable()) {
if(fRecoverable)
unRecoverableSessionStateCount.decrementAndGet();
else
unRecoverableSessionStateCount.incrementAndGet();
}
}
tdsReader.readBytes(sessionStateDelta[sessionStateId].getData(), 0, sessionStateLength);
sessionStateDelta[sessionStateId].setRecoverable(fRecoverable);
}
/**
* @return length of initial session state data.
*/
int getInitialLength() {
int length = 0;
for (int i = 0; i < SESSION_STATE_ID_MAX; i++) {
if (sessionStateInitial[i] != null) {
length += (1/* state id */ + (sessionStateInitial[i].length < 0xFF ? 1 : 5)/* Data length */
+ sessionStateInitial[i].length);
}
}
return length;
}
/**
* @return length of delta session state data.
*/
int getDeltaLength() {
int length = 0;
for (int i = 0; i < SESSION_STATE_ID_MAX; i++) {
if (sessionStateDelta[i] != null && sessionStateDelta[i].getData() != null) {
length += (1/* state id */ + (sessionStateDelta[i].getDataLength() < 0xFF ? 1 : 5)/* Data length */
+ sessionStateDelta[i].getDataLength());
}
}
return length;
}
boolean isSessionRecoverable() {
return (!isMasterRecoveryDisabled() && (0 == unRecoverableSessionStateCount.get()));
}
boolean isMasterRecoveryDisabled() {
return masterRecoveryDisabled;
}
void setMasterRecoveryDisabled(boolean masterRecoveryDisabled) {
this.masterRecoveryDisabled = masterRecoveryDisabled;
}
byte[][] getSessionStateInitial() {
return sessionStateInitial;
}
void setSessionStateInitial(byte[][] sessionStateInitial) {
this.sessionStateInitial = sessionStateInitial;
}
SessionStateValue[] getSessionStateDelta() {
return sessionStateDelta;
}
void setSessionStateDelta(SessionStateValue[] sessionStateDelta) {
this.sessionStateDelta = sessionStateDelta;
}
String getOriginalCatalog() {
return originalCatalog;
}
void setOriginalCatalog(String catalog) {
this.originalCatalog = catalog;
}
String getOriginalLanguage() {
return originalLanguage;
}
void setOriginalLanguage(String language) {
this.originalLanguage = language;
}
SQLCollation getOriginalCollation() {
return originalCollation;
}
void setOriginalCollation(SQLCollation collation) {
this.originalCollation = collation;
}
byte getOriginalNegotiatedEncryptionLevel() {
return originalNegotiatedEncryptionLevel;
}
void setOriginalNegotiatedEncryptionLevel(byte originalNegotiatedEncryptionLevel) {
this.originalNegotiatedEncryptionLevel = originalNegotiatedEncryptionLevel;
}
boolean spResetCalled() {
return resetCalled;
}
void setspResetCalled(boolean status) {
this.resetCalled = status;
}
public void reset() {
resetCalled = true;
sessionStateDelta = new SessionStateValue[SESSION_STATE_ID_MAX];
unRecoverableSessionStateCount = new AtomicInteger(0);
}
}
final class ReconnectThread extends Thread {
private SQLServerConnection con = null;
private SQLServerException eReceived = null;
private TDSCommand command = null;
private volatile boolean stopRequested = false;
private int connectRetryCount = 0;
/*
* This class is only meant to be used by a Connection object to reconnect in the background. Don't allow default
* instantiation as it doesn't make sense.
*/
@SuppressWarnings("unused")
private ReconnectThread() {};
ReconnectThread(SQLServerConnection sqlC) {
this.con = sqlC;
}
// Resets the thread
void init(TDSCommand cmd) {
this.command = cmd;
connectRetryCount = con.getRetryCount();
eReceived = null;
stopRequested = false;
}
public void run() {
boolean interruptsEnabled = command.getInterruptsEnabled();
/*
* All TDSCommands are not interruptible before execution, and all the commands passed to here won't have been
* executed. We need to be able to interrupt these commands so the TimeoutPoller can tell us when a query has
* timed out.
*/
command.setInterruptsEnabled(true);
command.attachThread(this);
command.addToPoller();
boolean keepRetrying = true;
while ((connectRetryCount != 0) && (!stopRequested) && keepRetrying) {
try {
eReceived = null;
con.connect(null, con.getPooledConnectionParent());
keepRetrying = false;
} catch (SQLServerException e) {
if (!stopRequested) {
eReceived = e;
if (con.isFatalError(e)) {
keepRetrying = false;
} else {
try {
if (connectRetryCount > 1) {
Thread.sleep(con.getRetryInterval() * 1000);
}
} catch (InterruptedException ie) {
this.eReceived = new SQLServerException(SQLServerException.getErrString("R_queryTimedOut"),
SQLState.STATEMENT_CANCELED, DriverError.NOT_SET, null);
keepRetrying = false;
}
}
}
} finally {
connectRetryCount--;
try {
command.checkForInterrupt();
} catch (SQLServerException e) {
// Interrupted, timeout occurred. Stop retrying.
keepRetrying = false;
eReceived = e;
}
}
}
if ((connectRetryCount == 0) && (keepRetrying)) {
eReceived = new SQLServerException(SQLServerException.getErrString("R_crClientAllRecoveryAttemptsFailed"),
eReceived);
}
command.setInterruptsEnabled(interruptsEnabled);
return;
}
void stop(boolean blocking) {
stopRequested = true;
if (blocking && this.isAlive()) {
while (this.getState() != State.TERMINATED) {
// wait until thread terminates
}
}
}
/*
* Run method can not be implemented to return an exception hence statement execution thread that called
* reconnection will get exception through this function as soon as reconnection thread execution is over.
*/
SQLServerException getException() {
return eReceived;
}
}