Javascript 暂停、恢复、中止和解决长期运行的承诺

我的控制器能够暂停、恢复和解决长期运行的承诺。 当我的控制器中止承诺时，不知何故我的控制器递归循环被破坏了

几天前我就知道了承诺，所以也许我对拒绝或抓住有些不理解

首先，可以在承诺链的两个步骤之间检查的状态变量

var state = "idle"

可以插入以检查此状态变量的垫片

// insert this shim before each link of promise chain
function promise_to_check_pause_and_abort(x) {
    if (state == "running") {
        return Promise.resolve(x) // just keep going 
    } else if (state == "pause") {
        let P = new Promise((resolve, reject) => {
            let resume_cb = () => { resolve() }
            pause_cb_queue.push(resume_cb)
        });
        return P;
    } else if (state == "abort") {
        return Promise.reject("aborted at stage " + x)
    } else {
        return promise.reject("should not be executing in this invalid state = " + state)
    }
}

我真正的应用程序运行许多连锁承诺，可能需要15分钟以上才能完成。这不需要证明我的问题。所以这里有一个简单的假任务，它返回一个承诺

function promise_to_do_something_long_running(n) {
    if (isNaN(n)) {
        n = 0;
    }

    if (n == 100) {
        return Promise.resolve("done")

    } else {
        let P = new Promise((resolve, reject) => {
            setTimeout(() => {
                console.log("doing " + n);
                resolve();
            }, 100)
        })

        return P
            .then(() => { return promise_to_check_pause_and_abort(n) })
            .then(() => { return promise_to_do_something_long_running(n + 1) })
    }

}

现在有一个简单的文本控制器来启动、暂停、恢复和中止上述长期运行的承诺

// A recursive controller. 
//   Get response based on current running state.
//   Regardless of response, do it again.
function controller() {

    if (state == "running") {
        rl.question("abort or pause :", (answer) => {

            if (answer == "abort") {
                state = "abort"
            } else if (answer == "pause") {
                state = "pause"
            };

            controller(); // regardless of response or state, get input again
        })

    } else if (state == "pause") {
        rl.question("abort or resume :", (answer) => {

            if (answer == "abort") {
                state = "abort";
                pause_cb_queue.forEach((cb) => { cb() })
                pause_cb_queue = []
            } else if (answer == "resume") {
                state = "running"
                pause_cb_queue.forEach((cb) => { cb() })
                pause_cb_queue = []
            };

            controller(); // regardless of response or state, get input again
        })

    } else if (state == "idle") {

        rl.question("start :", (answer) => {

            if (answer == "start") {
                state = "running";

                // controller loop not dependent on resolution of this
                // only state is 
                promise_to_do_something_long_running()
                    .then((a) => {
                        console.log("completed task, response :" + a);
                        state = "idle"
                    })
                    .catch((b) => {
                        console.log("task rejected with response :" + b);
                        state = "idle"
                    });
            };

            controller(); // regardless of response or state, get input again
        })
    }

}


controller();

一切工作都很完美，除非我中止，否则控制器递归会中断，并且不再请求用户输入。如何执行

.catch((b) => {
                        console.log("task rejected with response :" + b);
                        state = "idle"
                    });

导致外部控制器递归停止？

在nodejs中运行的完整代码如下所示：

'use strict';


const readline = require('readline');

const rl = readline.createInterface({
    input: process.stdin,
    output: process.stdout
});

var state = "idle"
var pause_cb_queue = []


// insert this shim before each link of promise chain
function promise_to_check_pause_and_abort(x) {
    if (state == "running") {
        return Promise.resolve(x) // just keep going 
    } else if (state == "pause") {
        let P = new Promise((resolve, reject) => {
            let resume_cb = () => { resolve() }
            pause_cb_queue.push(resume_cb)
        });
        return P;
    } else if (state == "abort") {
        return Promise.reject("aborted at stage " + x)
    } else {
        return promise.reject("should not be executing in this invalid state = " + state)
    }
}

function promise_to_do_something_long_running(n) {
    if (isNaN(n)) {
        n = 0;
    }

    if (n == 100) {
        return Promise.resolve("done")

    } else {
        let P = new Promise((resolve, reject) => {
            setTimeout(() => {
                console.log("doing " + n);
                resolve();
            }, 100)
        })

        return P
            .then(() => { return promise_to_check_pause_and_abort(n) })
            .then(() => { return promise_to_do_something_long_running(n + 1) })
    }

}

// A recursive controller. 
//   Get response based on current running state.
//   Regardless of response, do it again.
function controller() {

    if (state == "running") {
        rl.question("abort or pause :", (answer) => {

            if (answer == "abort") {
                state = "abort"
            } else if (answer == "pause") {
                state = "pause"
            };

            controller(); // regardless of response or state, get input again
        })

    } else if (state == "pause") {
        rl.question("abort or resume :", (answer) => {

            if (answer == "abort") {
                state = "abort";
                pause_cb_queue.forEach((cb) => { cb() })
                pause_cb_queue = []
            } else if (answer == "resume") {
                state = "running"
                pause_cb_queue.forEach((cb) => { cb() })
                pause_cb_queue = []
            };

            controller(); // regardless of response or state, get input again
        })

    } else if (state == "idle") {

        rl.question("start :", (answer) => {

            if (answer == "start") {
                state = "running";

                // controller loop not dependent on resolution of this
                // only state is 
                promise_to_do_something_long_running()
                    .then((a) => {
                        console.log("completed task, response :" + a);
                        state = "idle"
                    })
                    .catch((b) => {
                        console.log("task rejected with response :" + b);
                        state = "idle"
                    });
            };

            controller(); // regardless of response or state, get input again
        })
    }

}


controller();

---

暂停和恢复承诺没有错。我的bug在处理控制器中的中止状态时丢失了

    } else if (state == "abort") {
        rl.question("in abort state, no valid input :", (answer) => {
            controller(); // regardless of response or state, get input again
        })

加上以上的功能，一切都可以完美地工作。我现在可以暂停承诺链了