场景描述

RM二阶段发生异常时，TC是会进行不断的重试。直到成功为止
那么，问题就来了。一直重试虽然在一定程度上可能成功，但大部分情况下一直重试是不会成功的
这个时候，是需要作出一定的告警措施，比如发邮件，发钉钉之类的

比较幸运的是，seata提供了SPI，这样可以比较方便的实现。经过一番研究尝试，终于找到比较好的实现方式。如下，enjoy!

Step One

注入自己实现的SPI
新建文件: src/main/resources/META-INF/services/io.seata.core.model.ResourceManager
文件内容如下。注意，是实现类的全路径来的，不懂SPI机制可先自行谷歌

com.xxx.MyTCCResourceManager

Step Two

com.xxx.MyTCCResourceManager类代码。大部分抄官方的io.seata.rm.tcc.TCCResourceManager代码即可，这里只列出关键代码

@Override
    public BranchStatus branchCommit(BranchType branchType, String xid, long branchId, String resourceId,
                                     String applicationData) throws TransactionException {
        TCCResource tccResource = (TCCResource)tccResourceCache.get(resourceId);
        if (tccResource == null) {
            throw new ShouldNeverHappenException(String.format("TCC resource is not exist, resourceId: %s", resourceId));
        }
        Object targetTCCBean = tccResource.getTargetBean();
        Method commitMethod = tccResource.getCommitMethod();
        if (targetTCCBean == null || commitMethod == null) {
            throw new ShouldNeverHappenException(String.format("TCC resource is not available, resourceId: %s", resourceId));
        }
        try {
            //BusinessActionContext
            BusinessActionContext businessActionContext = getBusinessActionContext(xid, branchId, resourceId,
                applicationData);
            Object[] args = this.getTwoPhaseCommitArgs(tccResource, businessActionContext);
            Object ret;
            boolean result;
            // add idempotent and anti hanging
            if (Boolean.TRUE.equals(businessActionContext.getActionContext(Constants.USE_TCC_FENCE))) {
                try {
                    result = TCCFenceHandler.commitFence(commitMethod, targetTCCBean, xid, branchId, args);
                } catch (SkipCallbackWrapperException | UndeclaredThrowableException e) {
                    throw e.getCause();
                }
            } else {
                ret = commitMethod.invoke(targetTCCBean, args);
                if (ret != null) {
                    if (ret instanceof TwoPhaseResult) {
                        result = ((TwoPhaseResult)ret).isSuccess();
                    } else {
                        result = (boolean)ret;
                    }
                } else {
                    result = true;
                }
            }
            LOGGER.info("TCC resource commit result : {}, xid: {}, branchId: {}, resourceId: {}", result, xid, branchId, resourceId);
            if (!result) {
                // !!!FBI WARNING!!! 关键地方。把你做告警的代码放这里就可以了！！！
            }
            return result ? BranchStatus.PhaseTwo_Committed : BranchStatus.PhaseTwo_CommitFailed_Retryable;
        } catch (Throwable t) {
            String msg = String.format("commit TCC resource error, resourceId: %s, xid: %s.", resourceId, xid);
            LOGGER.error(msg, t);
            // !!!FBI WARNING!!! 关键地方。把你做告警的代码放这里就可以了！！！
            return BranchStatus.PhaseTwo_CommitFailed_Retryable;
        }
    }

    @Override
    public BranchStatus branchRollback(BranchType branchType, String xid, long branchId, String resourceId,
                                       String applicationData) throws TransactionException {
        TCCResource tccResource = (TCCResource)tccResourceCache.get(resourceId);
        if (tccResource == null) {
            throw new ShouldNeverHappenException(String.format("TCC resource is not exist, resourceId: %s", resourceId));
        }
        Object targetTCCBean = tccResource.getTargetBean();
        Method rollbackMethod = tccResource.getRollbackMethod();
        if (targetTCCBean == null || rollbackMethod == null) {
            throw new ShouldNeverHappenException(String.format("TCC resource is not available, resourceId: %s", resourceId));
        }
        try {
            //BusinessActionContext
            BusinessActionContext businessActionContext = getBusinessActionContext(xid, branchId, resourceId,
                applicationData);
            Object[] args = this.getTwoPhaseRollbackArgs(tccResource, businessActionContext);
            Object ret;
            boolean result;
            // add idempotent and anti hanging
            if (Boolean.TRUE.equals(businessActionContext.getActionContext(Constants.USE_TCC_FENCE))) {
                try {
                    result = TCCFenceHandler.rollbackFence(rollbackMethod, targetTCCBean, xid, branchId,
                            args, tccResource.getActionName());
                } catch (SkipCallbackWrapperException | UndeclaredThrowableException e) {
                    throw e.getCause();
                }
            } else {
                ret = rollbackMethod.invoke(targetTCCBean, args);
                if (ret != null) {
                    if (ret instanceof TwoPhaseResult) {
                        result = ((TwoPhaseResult)ret).isSuccess();
                    } else {
                        result = (boolean)ret;
                    }
                } else {
                    result = true;
                }
            }
            LOGGER.info("TCC resource rollback result : {}, xid: {}, branchId: {}, resourceId: {}", result, xid, branchId, resourceId);
            if (!result) {
                // !!!FBI WARNING!!! 关键地方。把你做告警的代码放这里就可以了！！！
            }
            return result ? BranchStatus.PhaseTwo_Rollbacked : BranchStatus.PhaseTwo_RollbackFailed_Retryable;
        } catch (Throwable t) {
            String msg = String.format("rollback TCC resource error, resourceId: %s, xid: %s.", resourceId, xid);
            LOGGER.error(msg, t);
            // !!!FBI WARNING!!! 关键地方。把你做告警的代码放这里就可以了！！！
            return BranchStatus.PhaseTwo_RollbackFailed_Retryable;
        }
    }