protectedstorage(protectedstorage)

前沿拓展：

序

本文主要研究一下rocketmq-streams的ILeaseService

ILeaseService/**
* 通过db实现租约和锁，可以更轻量级，减少其他中间件的依赖使用主备场景，只有一个实例运行，当当前实例挂掉，在一定时间内，会被其他实例接手也可以用于全局锁
*/
public interface ILeaseService {

/**
* 默认锁定时间
*/
static final int DE**T_LOCK_TIME = 60 * 5;

/**
* 检查某用户当前时间是否具有租约。这个方法是纯内存**作，无性能开销
*
* @return true，租约有效；false，租约无效
*/
boolean hasLease(String name);

/**
* 申请租约，会启动一个线程，不停申请租约，直到申请成功。申请成功后，每租期/2 续约。如果目前被其他租户获取租约，只有在对方租约失效，后才允许新的租户获取租约
*
* @param name 租约名称，无特殊要求，相同名称会竞争租约
*/
void startLeaseTask(String name);

/**
* 申请租约，会启动一个线程，不停申请租约，直到申请成功。申请成功后，每租期/2 续约。如果目前被其他租户获取租约，只有在对方租约失效，后才允许新的租户获取租约
*
* @param name 租约名称，无特殊要求，相同名称会竞争租约
* @param callback 当第一获取租约时，回调此函数
*/
void startLeaseTask(final String name, ILeaseGetCallback callback);

/**
* 申请租约，会启动一个线程，不停申请租约，直到申请成功。申请成功后，每租期/2 续约。如果目前被其他租户获取租约，只有在对方租约失效，后才允许新的租户获取租约
*
* @param name 租约名称，无特殊要求，相同名称会竞争租约
* @param leaseTermSecond 租期，在租期内可以做业务处理，单位是秒
* @param callback 当第一获取租约时，回调此函数
*/
void startLeaseTask(final String name, int leaseTermSecond, ILeaseGetCallback callback);

/**
* 申请锁,无论成功与否，立刻返回。如果不释放，最大锁定时间是5分钟
*
* @param name 业务名称
* @param lockerName 锁名称
* @return 是否枷锁成功
*/
boolean lock(String name, String lockerName);

/**
* 申请锁,无论成功与否，立刻返回。默认锁定时间是5分钟
*
* @param name 业务名称
* @param lockerName 锁名称
* @param lockTimeSecond 如果不释放，锁定的最大时间，单位是秒
* @return 是否枷锁成功
* @return
*/
boolean lock(String name, String lockerName, int lockTimeSecond);

/**
* 申请锁，如果没有则等待，等待时间可以指定，如果是－1 则无限等待。如果不释放，最大锁定时间是5分钟
*
* @param name 业务名称
* @param lockerName 锁名称
* @param waitTime 没获取锁时，最大等待多长时间，如果是－1 则无限等待
* @return 是否枷锁成功
*/
boolean tryLocker(String name, String lockerName, long waitTime);

/**
* 申请锁，如果没有则等待，等待时间可以指定，如果是－1 则无限等待。如果不释放，最大锁定时间是lockTimeSecond
*
* @param name 业务名称
* @param lockerName 锁名称
* @param waitTime 没获取锁时，最大等待多长时间，如果是－1 则无限等待
* @param lockTimeSecond 如果不释放，锁定的最大时间，单位是秒
* @return 是否枷锁成功
*/
boolean tryLocker(String name, String lockerName, long waitTime, int lockTimeSecond);

/**
* 释放锁
*
* @param name
* @param lockerName
* @return
*/
boolean unlock(String name, String lockerName);

/**
* 对于已经获取锁的，可以通过这个方法，一直持有锁。和租约的区别是，当释放锁后，无其他实例抢占。无法实现主备模式
*
* @param name 业务名称
* @param lockerName 锁名称
* @param lockTimeSecond 租期，这个方**自动续约，如果不主动释放，会一直持有锁
* @return 是否成功获取锁
*/
boolean holdLock(String name, String lockerName, int lockTimeSecond);

/**
* 是否持有锁，不会申请锁。如果以前申请过，且未过期，返回true，否则返回false
*
* @param name 业务名称
* @param lockerName 锁名称
* @return
*/
boolean hasHoldLock(String name, String lockerName);

List<LeaseInfo> queryLockedInstanceByNamePrefix(String name, String lockerNamePrefix);

}
ILeaseService接口定义了hasLease、startLeaseTask、lock、tryLocker、unlock、holdLock、hasHoldLock、queryLockedInstanceByNamePrefix方法BasedLesaseImplpublic abstract class BasedLesaseImpl implements ILeaseService {
private static final Log LOG = LogFactory.getLog(BasedLesaseImpl.class);

private static final String CONSISTENT_HASH_PREFIX = "consistent_hash_";
private static final AtomicBoolean syncStart = new AtomicBoolean(false);
private static final int synTime = 120; // 5分钟的一致性hash同步时间太久了，改为2分钟
protected ScheduledExecutorService taskExecutor = null;
protected int leaseTerm = 300 * 2; // 租约时间

// protected transient JDBCDriver jdbcDataSource = null;
protected ILeaseStorage leaseStorage;
protected volatile Map<String, Date> leaseName2Date = new ConcurrentHashMap<>(); // 每个lease name对应的租约到期时间

public BasedLesaseImpl() {

taskExecutor = new ScheduledThreadPoolExecutor(10);
}

/**
* lease_name: consistent_hash_ip, lease_user_ip: ip,定时刷新lease_info表，检查一致性hash环的节点情况
*
* @param name
* @return
*/
@Override
public boolean hasLease(String name) {
// 内存中没有租约信息则表示没有租约
Date leaseEndTime = leaseName2Date.get(name);
if (leaseEndTime == null) {
// LOG.info("内存中根据 " + name + "没有查询到租约信息，表示没有租约");
return false;
}
// LOG.info("查询是否有租约 name:" + name + " ,当前时间：" + new SimpleDateFormat("yyyy-MM-dd HH:mm:ss").format(new Date())
// + " 租约到期时间 " + new SimpleDateFormat("yyyy-MM-dd HH:mm:ss").format(leaseEndTime));
// 有租约时间，并且租约时间大于当前时间，表示有租约信息
if (new Date().before(leaseEndTime)) {
return true;
}

return false;
}

private final Map<String, AtomicBoolean> startLeaseMap = new HashMap<>();

@Override
public void startLeaseTask(final String name) {
startLeaseTask(name, this.leaseTerm, null);
}

@Override
public void startLeaseTask(final String name, ILeaseGetCallback callback) {
startLeaseTask(name, this.leaseTerm, callback);
}

@Override
public void startLeaseTask(final String name, int leaseTerm, ILeaseGetCallback callback) {
ApplyTask applyTask = new ApplyTask(leaseTerm, name, callback);
startLeaseTask(name, applyTask, leaseTerm / 2, true);
}

/**
* 启动定时器，定时执行任务，确保任务可重入
*
* @param name
* @param runnable 具体任务
* @param scheduleTime 调度时间
* @param startNow 是否立刻启动一次
*/
protected void startLeaseTask(final String name, Runnable runnable, int scheduleTime, boolean startNow) {
AtomicBoolean isStartLease = startLeaseMap.get(name);//多次调用，只启动一次定时任务
if (isStartLease == null) {
synchronized (this) {
isStartLease = startLeaseMap.get(name);
if (isStartLease == null) {
isStartLease = new AtomicBoolean(false);
startLeaseMap.put(name, isStartLease);
}
}
}
if (isStartLease.compareAndSet(false, true)) {
if (startNow) {
runnable.run();
}
taskExecutor.scheduleWithFixedDelay(runnable, 0, scheduleTime, TimeUnit.SECONDS);
}
}

//……
}
BasedLesaseImpl声明实现了ILeaseService，它依赖ILeaseStorage，startLeaseTask方**创建ApplyTask，第二以固定间隔调度执行ApplyTask /**
* 续约任务
*/
protected class ApplyTask implements Runnable {

protected String name;
protected int leaseTerm;
protected ILeaseGetCallback callback;

public ApplyTask(int leaseTerm, String name) {
this(leaseTerm, name, null);
}

public ApplyTask(int leaseTerm, String name, ILeaseGetCallback callback) {
this.name = name;
this.leaseTerm = leaseTerm;
this.callback = callback;
}

@Override
public void run() {
try {
// LOG.info("LeaseServiceImpl name: " + name + "开始获取租约…");
AtomicBoolean newApplyLease = new AtomicBoolean(false);
Date leaseDate = applyLeaseTask(leaseTerm, name, newApplyLease);
if (leaseDate != null) {
leaseName2Date.put(name, leaseDate);
LOG.info("LeaseServiceImpl, name: " + name + " " + getSelfUser() + " 获取租约成功, 租约到期时间为 "
+ new SimpleDateFormat("yyyy-MM-dd HH:mm:ss").format(leaseDate));
} else {
// fix.2020.08.13 这时name对应的租约可能还在有效期内,或者本机还持有租约，需要remove
// leaseName2Date.remove(name);
LOG.info("LeaseServiceImpl name: " + name + " " + getSelfUser() + " 获取租约失败 ");
}
if (newApplyLease.get() && callback != null) {
callback.callback(leaseDate);
}
} catch (Exception e) {
LOG.error(" LeaseServiceImpl name: " + name + " " + getSelfUser() + " 获取租约出现异常 ", e);
}

}
}

/**
* 申请租约，如果当期租约有效，直接更新一个租约周期，如果当前租约无效，先查询是否有有效的租约，如果有申请失败，否则直接申请租约
*/
protected Date applyLeaseTask(int leaseTerm, String name, AtomicBoolean newApplyLease) {

// 计算下一次租约时间 = 当前时间 + 租约时长
Date nextLeaseDate = DateUtil.addSecond(new Date(), leaseTerm);

// 1 如果已经有租约，则更新租约时间(内存和数据库)即可
if (hasLease(name)) {
// LOG.info("用户已有租约，更新数据库和内存中的租约信息");
// 更新数据库
LeaseInfo leaseInfo = queryValidateLease(name);
if (leaseInfo == null) {
LOG.error("LeaseServiceImpl applyLeaseTask leaseInfo is null");
return null;
}
// fix.2020.08.13,与本机ip相等且满足一致性hash分配策略，才续约，其他情况为null
String leaseUserIp = leaseInfo.getLeaseUserIp();
if (!leaseUserIp.equals(getSelfUser())) {
return null;
}
leaseInfo.setLeaseEndDate(nextLeaseDate);
updateLeaseInfo(leaseInfo);
return nextLeaseDate;
}

// 2 没有租约情况判断是否可以获取租约，只要租约没有被其他人获取，则说明有有效租约
boolean success = canGetLease(name);
if (!success) { // 表示被其他机器获取到了有效的租约
// LOG.info("其他机器获取到了有效的租约");
return null;
}

// 3 没有租约而且可以获取租约的情况，则尝试使用数据库原子更新的方式获取租约，保证只有一台机器成功获取租约，而且可以运行
boolean flag = tryGetLease(name, nextLeaseDate);
if (flag) { // 获取租约成功
newApplyLease.set(true);
return nextLeaseDate;
}
return null;

}
ApplyTask内部调用applyLeaseTask，如果已有租约则更新租约时间，没有租约则判断是否可以获取租约，可以则执行tryGetLeasetryGetLease /**
* 更新数据库，占用租期并更新租期时间
*
* @param time
*/
protected boolean tryGetLease(String name, Date time) {
// LOG.info("尝试获取租约 lease name is : " + name + " 下次到期时间: "
// + new SimpleDateFormat("yyyy-MM-dd HH:mm:ss").format(time));
LeaseInfo validateLeaseInfo = queryValidateLease(name);

if (validateLeaseInfo == null) {// 这里有两种情况 1 数据库里面没有租约信息 2 数据库里面有租约信息但是已经过期
Integer count = countLeaseInfo(name);
if (count == null || count == 0) {// 表示现在数据库里面没有任何租约信息，插入租约成功则表示获取成功，失败表示在这一时刻其他机器获取了租约
// LOG.info("数据库中暂时没有租约信息，尝试原子插入租约:" + name);
// fix.2020.08.13,经过一致性hash计算，该名字的任务不应该在本机执行，直接返回，无需插入。只有分配到hash执行权限的机器才可以插入并获取租约
if (!getSelfUser().equals(getConsistentHashHost(name))) {
return false;
}
validateLeaseInfo = new LeaseInfo();
validateLeaseInfo.setLeaseName(name);
validateLeaseInfo.setLeaseUserIp(getSelfUser());
validateLeaseInfo.setLeaseEndDate(time);
validateLeaseInfo.setStatus(1);
validateLeaseInfo.setVersion(1);
if (insert(validateLeaseInfo)) {
LOG.info("数据库中暂时没有租约信息，原子插入成功，获取租约成功:" + name);
return true;
} else {
LOG.info("数据库中暂时没有租约信息，原子插入失败，已经被其他机器获取租约:" + name);
return false;
}
} else { // 表示数据库里面有一条但是无效，这里需要两台机器按照version进行原子更新，更新成功的获取租约
// LOG.info("数据库中有一条无效的租约信息，尝试根据版本号去原子更新租约信息:" + name);
LeaseInfo inValidateLeaseInfo = queryInValidateLease(name);
if (inValidateLeaseInfo == null) {// 说明这个时候另外一台机器获取成功了
LOG.info("另外一台机器获取成功了租约:" + name);
return false;
}
// fix.2020.08.13,机器重启之后，该名字的任务已经不分配在此机器上执行，直接返回，无需更新数据库
if (!getSelfUser().equals(getConsistentHashHost(name))) {
return false;
}
inValidateLeaseInfo.setLeaseName(name);
inValidateLeaseInfo.setLeaseUserIp(getSelfUser());
inValidateLeaseInfo.setLeaseEndDate(time);
inValidateLeaseInfo.setStatus(1);
boolean success = updateDBLeaseInfo(inValidateLeaseInfo);
if (success) {
LOG.info("LeaseServiceImpl 原子更新租约成功，当前机器获取到了租约信息:" + name);
} else {
LOG.info("LeaseServiceImpl 原子更新租约失败，租约被其他机器获取:" + name);
}
return success;
}

} else { // 判断是否是自己获取了租约，如果是自己获取了租约则更新时间（内存和数据库），
// 这里是为了解决机器重启的情况，机器重启，内存中没有租约信息，但是实际上该用户是有租约权限的
// fix.2020.08.13,租约的ip与本机ip相等，且满足一致性hash策略，才会被本机执行
String leaseUserIp = validateLeaseInfo.getLeaseUserIp();
if (leaseUserIp.equals(getSelfUser())) {
// 如果当期用户有租约信息，则更新数据库
validateLeaseInfo.setLeaseEndDate(time);
boolean hasUpdate = updateLeaseInfo(validateLeaseInfo);
if (hasUpdate) {
LOG.info(
"LeaseServiceImpl机器重启情况，当前用户有租约信息，并且更新数据库成功，租约信息为 name :" + validateLeaseInfo.getLeaseName()
+ " ip : " + validateLeaseInfo.getLeaseUserIp() + " 到期时间 : " + new SimpleDateFormat(
"yyyy-MM-dd HH:mm:ss").format(validateLeaseInfo.getLeaseEndDate()));
return true;
} else {
LOG.info("LeaseServiceImpl 机器重启情况，当前用户有租约信息，并且更新数据库失败，表示失去租约:" + name);
return false;
}
}
// LOG.info("LeaseServiceImpl 租约被其他机器获取，租约信息为 name :" + validateLeaseInfo.getLeaseName() + " ip : "
// + validateLeaseInfo.getLeaseUserIp() + " 到期时间 : "
// + new SimpleDateFormat("yyyy-MM-dd HH:mm:ss").format(validateLeaseInfo.getLeaseEndDate()));
return false;
}

}

protected LeaseInfo queryValidateLease(String name) {
//String sql = "SELECT * FROM lease_info WHERE lease_name ='" + name + "' and status=1 and lease_end_time>now()";
//// LOG.info("LeaseServiceImpl query validate lease sql:" + sql);
//return queryLease(name, sql);
return leaseStorage.queryValidateLease(name);
}
tryGetLease先通过queryValidateLease查询租约信息，若没有租约则插入，若过期则根据版本号更新，若已有租约则判断是否是自己获取了租约，是则更新租约信息LeaseServiceImplpublic class LeaseServiceImpl extends BasedLesaseImpl {

private static final Log LOG = LogFactory.getLog(LeaseServiceImpl.class);

private transient ConcurrentHashMap<String, HoldLockTask> holdLockTasks = new ConcurrentHashMap();

protected ConcurrentHashMap<String, HoldLockFunture> seizeLockingFuntures = new ConcurrentHashMap<>();
//如果是抢占锁状态中，则不允许申请锁

public LeaseServiceImpl() {
super();
}

/**
* 尝试获取锁，可以等待waitTime，如果到点未返回，则直接返回。如果是-1，则一直等待
*
* @param name 业务名称
* @param lockerName 锁名称
* @param waitTime 等待时间，是微秒单位
* @return
*/
@Override
public boolean tryLocker(String name, String lockerName, long waitTime) {
return tryLocker(name, lockerName, waitTime, ILeaseService.DE**T_LOCK_TIME);
}

@Override
public boolean tryLocker(String name, String lockerName, long waitTime, int lockTimeSecond) {
long now = System.currentTimeMillis();
boolean success = lock(name, lockerName, lockTimeSecond);
while (!success) {
if (waitTime > -1 && (System.currentTimeMillis() – now > waitTime)) {
break;
}
success = lock(name, lockerName, lockTimeSecond);
if (success) {
return success;
}
try {
Thread.sleep(100);
} catch (InterruptedException e) {
LOG.error("LeaseServiceImpl try locker error", e);
}
}
return success;

}

@Override
public boolean lock(String name, String lockerName) {
return lock(name, lockerName, ILeaseService.DE**T_LOCK_TIME);
}

@Override
public boolean lock(String name, String lockerName, int leaseSecond) {
lockerName = createLockName(name, lockerName);
Future future = seizeLockingFuntures.get(lockerName);
if (future != null && ((HoldLockFunture)future).isDone == false) {
return false;
}
Date nextLeaseDate =
DateUtil.addSecond(new Date(), leaseSecond);// 默认锁定5分钟，用完需要立刻释放.如果时间不同步，可能导致锁失败
return tryGetLease(lockerName, nextLeaseDate);
}

@Override
public boolean unlock(String name, String lockerName) {
// LOG.info("LeaseServiceImpl unlock,name:" + name);
lockerName = createLockName(name, lockerName);
LeaseInfo validateLeaseInfo = queryValidateLease(lockerName);
if (validateLeaseInfo == null) {
LOG.warn("LeaseServiceImpl unlock,validateLeaseInfo is null,lockerName:" + lockerName);
}
if (validateLeaseInfo != null && validateLeaseInfo.getLeaseUserIp().equals(getSelfUser())) {
validateLeaseInfo.setStatus(0);
updateDBLeaseInfo(validateLeaseInfo);
}
HoldLockTask holdLockTask = holdLockTasks.remove(lockerName);
if (holdLockTask != null) {
holdLockTask.close();
}
leaseName2Date.remove(lockerName);
return false;
}

/**
* 如果有锁，则一直持有，如果不能获取，则结束。和租约不同，租约是没有也会尝试重试，一备对方挂机，自己可以接手工作
*
* @param name
* @param secondeName
* @param lockTimeSecond 获取锁的时间
* @return
*/
@Override
public boolean holdLock(String name, String secondeName, int lockTimeSecond) {
if (hasHoldLock(name, secondeName)) {
return true;
}
synchronized (this) {
if (hasHoldLock(name, secondeName)) {
return true;
}
String lockerName = createLockName(name, secondeName);
Date nextLeaseDate =
DateUtil.addSecond(new Date(), lockTimeSecond);
boolean success = tryGetLease(lockerName, nextLeaseDate);// 申请锁，锁的时间是leaseTerm
if (!success) {
return false;
}
leaseName2Date.put(lockerName, nextLeaseDate);

if (!holdLockTasks.containsKey(lockerName)) {
HoldLockTask holdLockTask = new HoldLockTask(lockTimeSecond, lockerName, this);
holdLockTask.start();
holdLockTasks.putIfAbsent(lockerName, holdLockTask);
}
}

return true;
}

/**
* 是否持有锁，不访问数据库，直接看本地
*
* @param name
* @param secondeName
* @return
*/
@Override
public boolean hasHoldLock(String name, String secondeName) {
String lockerName = createLockName(name, secondeName);
return hasLease(lockerName);
}

@Override
public List<LeaseInfo> queryLockedInstanceByNamePrefix(String name, String lockerNamePrefix) {
String leaseNamePrefix = MapKeyUtil.createKey(name, lockerNamePrefix);
return queryValidateLeaseByNamePrefix(leaseNamePrefix);
}

//……
}
LeaseServiceImpl继承了BasedLesaseImpl，tryLocker方**根据等待时间循环执行lock，lock方法则执行tryGetLease，unlock方法则更新租约信息，同时移除内存记录；holdLock则通过hasHoldLock判断是否持有锁，若有则返回，没有则执行tryGetLeaseILeaseStoragepublic interface ILeaseStorage {

/**
* 更新lease info，需要是原子**作，存储保障多线程**作的原子性
*
* @param leaseInfo 租约表数据
* @return
*/
boolean updateLeaseInfo(LeaseInfo leaseInfo);

/**
* 统计这个租约名称下，LeaseInfo对象个数
*
* @param leaseName 租约名称，无特殊要求，相同名称会竞争租约
* @return
*/
Integer countLeaseInfo(String leaseName);

/**
* 查询无效的的租约
*
* @param leaseName 租约名称，无特殊要求，相同名称会竞争租约
* @return
*/
LeaseInfo queryInValidateLease(String leaseName);

/**
* 查询有效的的租约
*
* @param leaseName 租约名称，无特殊要求，相同名称会竞争租约
* @return
*/
LeaseInfo queryValidateLease(String leaseName);

/**
* 按前缀查询有效的租约信息
*
* @param namePrefix
* @return
*/
List<LeaseInfo> queryValidateLeaseByNamePrefix(String namePrefix);

/**
* 增加租约
*
* @param leaseInfo 租约名称，无特殊要求，相同名称会竞争租约
*/
void addLeaseInfo(LeaseInfo leaseInfo);

}
ILeaseStorage接口定义了updateLeaseInfo、countLeaseInfo、queryInValidateLease、queryValidateLease、queryValidateLeaseByNamePrefix、addLeaseInfo方法DBLeaseStoragepublic class DBLeaseStorage implements ILeaseStorage {
private static final Log LOG = LogFactory.getLog(DBLeaseStorage.class);
protected JDBCDriver jdbcDataSource;
private String url;
protected String userName;
protected String password;
protected String jdbc;

public DBLeaseStorage(String jdbc, String url, String userName, String password) {
this.jdbc = jdbc;
this.url = url;
this.userName = userName;
this.password = password;
jdbcDataSource = DriverBuilder.createDriver(jdbc, url, userName, password);
}

@Override
public boolean updateLeaseInfo(LeaseInfo leaseInfo) {
String sql = "UPDATE lease_info SET version=version+1,status=#{status},gmt_modified=now()";
String whereSQL = " WHERE id=#{id} and version=#{version}";

if (StringUtil.isNotEmpty(leaseInfo.getLeaseName())) {
sql += ",lease_name=#{leaseName}";
}
if (StringUtil.isNotEmpty(leaseInfo.getLeaseUserIp())) {
sql += ",lease_user_ip=#{leaseUserIp}";
}
if (leaseInfo.getLeaseEndDate() != null) {
sql += ",lease_end_time=#{leaseEndDate}";
}
sql += whereSQL;
sql = SQLUtil.parseIbatisSQL(leaseInfo, sql);
try {
int count = getOrCreateJDBCDataSource().update(sql);
boolean success = count > 0;
if (success) {
synchronized (this) {
leaseInfo.setVersion(leaseInfo.getVersion() + 1);
}
} else {
System.out.println(count);
}
return success;
} catch (Exception e) {
LOG.error("LeaseServiceImpl updateLeaseInfo excuteUpdate error", e);
throw new RuntimeException("execute sql error " + sql, e);
}
}

@Override
public Integer countLeaseInfo(String leaseName) {
String sql = "SELECT count(*) as c FROM lease_info WHERE lease_name = '" + leaseName + "' and status = 1";
try {

List<Map<String, Object>> rows = getOrCreateJDBCDataSource().queryForList(sql);
if (rows == null || rows.size() == 0) {
return null;
}
Long value = (Long) rows.get(0).get("c");
return value.intValue();
} catch (Exception e) {
throw new RuntimeException("execute sql error " + sql, e);
}
}

@Override
public LeaseInfo queryInValidateLease(String leaseName) {
String sql = "SELECT * FROM lease_info WHERE lease_name ='" + leaseName + "' and status=1 and lease_end_time<'" + DateUtil.getCurrentTimeString() + "'";
LOG.info("LeaseServiceImpl queryInValidateLease builder:" + sql);
return queryLease(leaseName, sql);
}

@Override
public LeaseInfo queryValidateLease(String leaseName) {
String sql = "SELECT * FROM lease_info WHERE lease_name ='" + leaseName + "' and status=1 and lease_end_time>now()";
return queryLease(leaseName, sql);
}

@Override
public List<LeaseInfo> queryValidateLeaseByNamePrefix(String namePrefix) {
String sql = "SELECT * FROM lease_info WHERE lease_name like '" + namePrefix + "%' and status=1 and lease_end_time>now()";
try {
List<LeaseInfo> leaseInfos = new ArrayList<>();
List<Map<String, Object>> rows = getOrCreateJDBCDataSource().queryForList(sql);
if (rows == null || rows.size() == 0) {
return null;
}
for (Map<String, Object> row : rows) {
LeaseInfo leaseInfo = convert(row);
leaseInfos.add(leaseInfo);
}

return leaseInfos;
} catch (Exception e) {
throw new RuntimeException("execute sql error " + sql, e);
}
}

@Override
public void addLeaseInfo(LeaseInfo leaseInfo) {
String sql =
" REPLACE INTO lease_info(lease_name,lease_user_ip,lease_end_time,status,version,gmt_create,gmt_modified)"
+ " VALUES (#{leaseName},#{leaseUserIp},#{leaseEndDate},#{status},#{version},now(),now())";
sql = SQLUtil.parseIbatisSQL(leaseInfo, sql);
try {

getOrCreateJDBCDataSource().execute(sql);
} catch (Exception e) {
LOG.error("LeaseServiceImpl execute sql error,sql:" + sql, e);
throw new RuntimeException("execute sql error " + sql, e);
}
}

protected JDBCDriver getOrCreateJDBCDataSource() {
if (this.jdbcDataSource == null || !this.jdbcDataSource.isValidate()) {
synchronized (this) {
if (this.jdbcDataSource == null || !this.jdbcDataSource.isValidate()) {
this.jdbcDataSource =
DriverBuilder.createDriver(this.jdbc, this.url, this.userName, this.password);
}
}
}
return jdbcDataSource;
}

protected LeaseInfo queryLease(String name, String sql) {
try {
List<Map<String, Object>> rows = getOrCreateJDBCDataSource().queryForList(sql);
if (rows == null || rows.size() == 0) {
return null;
}
return convert(rows.get(0));
} catch (Exception e) {
throw new RuntimeException("execute sql error " + sql, e);
}
}

protected LeaseInfo convert(Map<String, Object> map) {
LeaseInfo leaseInfo = new LeaseInfo();
leaseInfo.setId(getMapLongValue("id", map));
leaseInfo.setCreateTime(getMapDateValue("gmt_create", map));
leaseInfo.setLeaseEndDate(getMapDateValue("lease_end_time", map));
leaseInfo.setLeaseName(getMapValue("lease_name", map, String.class));
leaseInfo.setLeaseUserIp(getMapValue("lease_user_ip", map, String.class));
Integer status = getMapValue("status", map, Integer.class);
if (status != null) {
leaseInfo.setStatus(status);
}
leaseInfo.setUpdateTime(getMapDateValue("gmt_modified", map));
Long version = getMapLongValue("version", map);
if (version != null) {
leaseInfo.setVersion(version);
}
return leaseInfo;
}

@SuppressWarnings("unchecked")
private <T> T getMapValue(String fieldName, Map<String, Object> map, Class<T> integerClass) {
Object value = map.get(fieldName);
if (value == null) {
return null;
}
return (T) value;
}

private Long getMapLongValue(String fieldName, Map<String, Object> map) {
Object value = map.get(fieldName);
if (value == null) {
return null;
}
if (value instanceof Long) {
return (Long) value;
}
if (value instanceof BigInteger) {
return ((BigInteger) value).longValue();
}
return null;
}

private Date getMapDateValue(String fieldName, Map<String, Object> map) {
Object value = map.get(fieldName);
if (value == null) {
return null;
}
if (value instanceof Date) {
return (Date) value;
}
if (value instanceof String) {
return DateUtil.parseTime(((String) value));
}
return null;

}

}
DBLeaseStorage实现了ILeaseStorage接口，使用jdbc实现了其方法小结

rocketmq-streams的LeaseService基于db实现了租约和锁，可用于主备场景切换。

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