feat/never discard the callback task

[fengjiachun]

Motivation:

The bolt default callback task rejection policy is discard policy, we should ensure that never discard the callback task.

    /**
     * @see com.alipay.remoting.InvokeCallbackListener#onResponse(com.alipay.remoting.InvokeFuture)
     */
    @Override
    public void onResponse(InvokeFuture future) {
        InvokeCallback callback = future.getInvokeCallback();
        if (callback != null) {
            CallbackTask task = new CallbackTask(this.getRemoteAddress(), future);
            if (callback.getExecutor() != null) {
                // There is no need to switch classloader, because executor is provided by user.
                try {
                    callback.getExecutor().execute(task);
                } catch (RejectedExecutionException e) {
                    if (callback instanceof RejectionProcessableInvokeCallback) {
                        switch (((RejectionProcessableInvokeCallback) callback)
                            .rejectedExecutionPolicy()) {
                            case CALLER_RUNS:
                                task.run();
                                break;
                            case CALLER_HANDLE_EXCEPTION:
                                callback.onException(e);
                                break;
                            case DISCARD:
                            default:
                                logger.warn("Callback thread pool busy. discard the callback");
                                break;
                        }
                    } else {
                        logger.warn("Callback thread pool busy.");
                    }
                }
            } else {
                task.run();
            }
        }
    }

Modification:

Impl RejectionProcessableInvokeCallback

Result:

If there is no issue then describe the changes introduced by this PR.

[killme2008]

这有点坑了，得改下

[killme2008]

CALLER_HANDLE_EXCEPTION 策略是不是更好， calle run 会阻塞当前发送线程，宁愿 callback 里去处理异常

[fengjiachun]

CALLER_HANDLE_EXCEPTION 策略是不是更好， calle run 会阻塞当前发送线程，宁愿 callback 里去处理异常

默认选项改为 CALLER_HANDLE_EXCEPTION 并且配置化了