async_flush不会触发结束事件

我刚刚意识到我忘了更新这个问题。

这是一个工作版本,只有在调用_flush回调函数后,以及在结束事件被消耗后,才会触发结束事件(请参见 https://github.com/nodejs/node/issues/34520#issuecomment-664646155 )

const { Transform } = require('stream')

async function main() {
    let resolveFlush
    const flush = new Promise(resolve => {
        resolveFlush = resolve
    })

    class Pipe extends Transform {
        _transform(data, encoding, callback) {
            console.log('_transform', data.toString())
            this.push(data)
            callback()
        }

        _flush(callback) {
            process.nextTick(() => {
                console.log('flush callback')
                callback()
                resolveFlush()
            })
        }
    }

    const pipe = new Pipe()

    pipe.on('finish', () => {
        console.log('on finish')
    })

    pipe.on('end', () => {
        console.log('on end')
    })

    pipe.write('foo')

    console.log('pipe.end()')
    pipe.end()

    console.log('read 1', pipe.read().toString())
    console.log('read 2', pipe.read())

    await flush
    console.log('read 3', pipe.read())
}

main()

输出

_transform foo
pipe.end()
read 1 foo
read 2 null
on finish
flush callback
read 3  null
on end