(1). 先聊一下Spring
GlobalTransactionalInterceptor在什么时候创建的?
GlobalTransactionalInterceptor是在GlobalTransactionScanner.wrapIfNecessary方法构建的.
GlobalTransactionScanner.wrapIfNecessary的业务逻辑功能请参考该链接
GlobalTransactionScanner会判断Bean上是否有相应的注解,如果有注解,就会对Bean织入业务逻辑(我们简称AOP),而织入的业务逻辑就在:GlobalTransactionalInterceptor,Spring要求织入的类需要实现:org.aopalliance.intercept.MethodInterceptor
(2). GlobalTransactionalInterceptor构造器
构造器主要是获得配置中的参数,并记录在实例的属性上.部份属性是什么意思,请参考官网.
// domain
private static final FailureHandler DEFAULT_FAIL_HANDLER = new DefaultFailureHandlerImpl();
private static int defaultGlobalTransactionTimeout = 0;
// **********************************************************************
// 需要关注下这几个属性
// **********************************************************************
private static final FailureHandler DEFAULT_FAIL_HANDLER = new DefaultFailureHandlerImpl();
private final TransactionalTemplate transactionalTemplate = new TransactionalTemplate();
private final GlobalLockTemplate globalLockTemplate = new GlobalLockTemplate();
private final FailureHandler failureHandler;
// methods
public GlobalTransactionalInterceptor(FailureHandler failureHandler) {
// 如果failureHandler为空,则指定默认的:FailureHandler
this.failureHandler = failureHandler == null ? DEFAULT_FAIL_HANDLER : failureHandler;
// service.disableGlobalTransaction = false
this.disable = ConfigurationFactory.getInstance().getBoolean(ConfigurationKeys.DISABLE_GLOBAL_TRANSACTION,
DEFAULT_DISABLE_GLOBAL_TRANSACTION);
// client.tm.degradeCheck = false
degradeCheck = ConfigurationFactory.getInstance().getBoolean(ConfigurationKeys.CLIENT_DEGRADE_CHECK,
DEFAULT_TM_DEGRADE_CHECK);
if (degradeCheck) {
ConfigurationCache.addConfigListener(ConfigurationKeys.CLIENT_DEGRADE_CHECK, this);
degradeCheckPeriod = ConfigurationFactory.getInstance().getInt(
ConfigurationKeys.CLIENT_DEGRADE_CHECK_PERIOD, DEFAULT_TM_DEGRADE_CHECK_PERIOD);
degradeCheckAllowTimes = ConfigurationFactory.getInstance().getInt(
ConfigurationKeys.CLIENT_DEGRADE_CHECK_ALLOW_TIMES, DEFAULT_TM_DEGRADE_CHECK_ALLOW_TIMES);
EVENT_BUS.register(this);
if (degradeCheckPeriod > 0 && degradeCheckAllowTimes > 0) {
startDegradeCheck();
}
}
this.initDefaultGlobalTransactionTimeout();
} // end
private void initDefaultGlobalTransactionTimeout() {
// true
if (GlobalTransactionalInterceptor.defaultGlobalTransactionTimeout <= 0) {
int defaultGlobalTransactionTimeout;
try {
// 60000
defaultGlobalTransactionTimeout = ConfigurationFactory.getInstance().getInt(
ConfigurationKeys.DEFAULT_GLOBAL_TRANSACTION_TIMEOUT, DEFAULT_GLOBAL_TRANSACTION_TIMEOUT);
} catch (Exception e) {
LOGGER.error("Illegal global transaction timeout value: " + e.getMessage());
defaultGlobalTransactionTimeout = DEFAULT_GLOBAL_TRANSACTION_TIMEOUT;
}
if (defaultGlobalTransactionTimeout <= 0) {
LOGGER.warn("Global transaction timeout value '{}' is illegal, and has been reset to the default value '{}'",
defaultGlobalTransactionTimeout, DEFAULT_GLOBAL_TRANSACTION_TIMEOUT);
defaultGlobalTransactionTimeout = DEFAULT_GLOBAL_TRANSACTION_TIMEOUT;
}
GlobalTransactionalInterceptor.defaultGlobalTransactionTimeout = defaultGlobalTransactionTimeout;
}
} //end initDefaultGlobalTransactionTimeout
(3). GlobalTransactionalInterceptor.invoke
注意:只有有标注于相应的注解的类,才会进入该invoke方法.
public Object invoke(final MethodInvocation methodInvocation) throws Throwable {
// 获得目标类
Class<?> targetClass =
methodInvocation.getThis() != null ? AopUtils.getTargetClass(methodInvocation.getThis()) : null;
// 获得方法
Method specificMethod = ClassUtils.getMostSpecificMethod(methodInvocation.getMethod(), targetClass);
// 方法的签名不是Object
if (specificMethod != null && !specificMethod.getDeclaringClass().equals(Object.class)) {
// 获得方法信息
final Method method = BridgeMethodResolver.findBridgedMethod(specificMethod);
// 获得方法上是否有: @GlobalTransactional 注解
final GlobalTransactional globalTransactionalAnnotation =
getAnnotation(method, targetClass, GlobalTransactional.class);
// 获得方法上是否有: @GlobalLock 注解
final GlobalLock globalLockAnnotation = getAnnotation(method, targetClass, GlobalLock.class);
// false
boolean localDisable = disable || (degradeCheck && degradeNum >= degradeCheckAllowTimes);
if (!localDisable) { // !false
if (globalTransactionalAnnotation != null) { // @GlobalTransactional注解处理逻辑
// 实际就是methodInvocation.proceed()方法的前后做拦截处理
return handleGlobalTransaction(methodInvocation, globalTransactionalAnnotation);
} else if (globalLockAnnotation != null) { // @GlobalLock注解处理逻辑
// 实际就是methodInvocation.proceed()方法的前后做拦截处理
return handleGlobalLock(methodInvocation, globalLockAnnotation);
}
}
}
// 直接放过
return methodInvocation.proceed();
}
(4). GlobalTransactionalInterceptor.handleGlobalTransaction
// domain
// 事务模板,是不是感觉和Spring很像?
private final TransactionalTemplate transactionalTemplate = new TransactionalTemplate();
private final GlobalLockTemplate globalLockTemplate = new GlobalLockTemplate();
// method
Object handleGlobalTransaction(final MethodInvocation methodInvocation,
final GlobalTransactional globalTrxAnno) throws Throwable {
boolean succeed = true;
try {
// *********************************************************
// 调用:TransactionalTemplate.execute方法,执行事务
// TransactionalExecutor transactionalExecutor = new TransactionalExecutor(){...}
// TransactionalTemplate transactionalTemplate = new TransactionalTemplate();
// transactionalTemplate.execute(transactionalExecutor);
// *********************************************************
return transactionalTemplate.execute(new TransactionalExecutor() {
// **************************************************
//
// **************************************************
@Override
public Object execute() throws Throwable {
return methodInvocation.proceed();
}
// **************************************************
// 获得:注解@GlobalTransactional(name="xxx")
// 如果没有配置,就用方法签名
// **************************************************
public String name() {
String name = globalTrxAnno.name();
if (!StringUtils.isNullOrEmpty(name)) {
return name;
}
return formatMethod(methodInvocation.getMethod());
}
// **************************************************
// 把注解@GlobalTransactional解析成业务模型对象:TransactionInfo
// **************************************************
@Override
public TransactionInfo getTransactionInfo() {
// reset the value of timeout
int timeout = globalTrxAnno.timeoutMills();
if (timeout <= 0 || timeout == DEFAULT_GLOBAL_TRANSACTION_TIMEOUT) {
timeout = defaultGlobalTransactionTimeout;
}
TransactionInfo transactionInfo = new TransactionInfo();
transactionInfo.setTimeOut(timeout);
transactionInfo.setName(name());
transactionInfo.setPropagation(globalTrxAnno.propagation());
transactionInfo.setLockRetryInternal(globalTrxAnno.lockRetryInternal());
transactionInfo.setLockRetryTimes(globalTrxAnno.lockRetryTimes());
Set<RollbackRule> rollbackRules = new LinkedHashSet<>();
for (Class<?> rbRule : globalTrxAnno.rollbackFor()) {
rollbackRules.add(new RollbackRule(rbRule));
}
for (String rbRule : globalTrxAnno.rollbackForClassName()) {
rollbackRules.add(new RollbackRule(rbRule));
}
for (Class<?> rbRule : globalTrxAnno.noRollbackFor()) {
rollbackRules.add(new NoRollbackRule(rbRule));
}
for (String rbRule : globalTrxAnno.noRollbackForClassName()) {
rollbackRules.add(new NoRollbackRule(rbRule));
}
transactionInfo.setRollbackRules(rollbackRules);
return transactionInfo;
}
});
} catch (TransactionalExecutor.ExecutionException e) {
TransactionalExecutor.Code code = e.getCode();
switch (code) {
case RollbackDone:
throw e.getOriginalException();
case BeginFailure:
succeed = false;
failureHandler.onBeginFailure(e.getTransaction(), e.getCause());
throw e.getCause();
case CommitFailure:
succeed = false;
failureHandler.onCommitFailure(e.getTransaction(), e.getCause());
throw e.getCause();
case RollbackFailure:
failureHandler.onRollbackFailure(e.getTransaction(), e.getOriginalException());
throw e.getOriginalException();
case RollbackRetrying:
failureHandler.onRollbackRetrying(e.getTransaction(), e.getOriginalException());
throw e.getOriginalException();
default:
throw new ShouldNeverHappenException(String.format("Unknown TransactionalExecutor.Code: %s", code));
}
} finally {
if (degradeCheck) {
EVENT_BUS.post(new DegradeCheckEvent(succeed));
}
}
}
(5). 总结
GlobalTransactionalInterceptor的职责如下:
- 拦截方法上的注解(@GlobalTransactional),委托给:TransactionalTemplate处理.
- 拦堆方法上的注解(@GlobalLock),委托给:GlobalLockTemplate处理.
- TransactionalTemplate和GlobalLockTemplate的业务逻辑,后面会再详解.
