How to measure time in private network and to control mining process?

Question

I am using private network with geth 1.7, and have some questions

1- To get the time of executing a function, i found some discussion about use of Data.getTime(), but i am wondering if anyone was successfully able to implement other methods such as performance.now() to measure time in geth commandlines? I tried but seems not defined function!!

2- how can i get the timestamp for a specific block if i knew the block number?

3- how can i mine only one block. For example, i send one transaction to the private network and then only mine one block containing that transaction. I found here some suggest to use while loop to check if there is no pending transactions and then stop mining. But i do not want this method, i would rather prefer to only mine one block.

Thanks in advance,

Answer 1

1：You could get the time of executing a function by updating source on jsre.go file,as follows:

func (self *JSRE) Evaluate(code string, w io.Writer) error {
    var fail error

    self.Do(func(vm *otto.Otto) {
        var startTime = time.Now();
        fmt.Println("jsre function ",code," start")
        val, err := vm.Run(code)
        if err != nil {
            prettyError(vm, err, w)
        } else {
            prettyPrint(vm, val, w)
        }
        fmt.Fprintln(w)
        fmt.Println("jsre function ",code," end ,consume time " ,(time.Now().UnixNano() - startTime.UnixNano()))
    })
    return fail
}

and then, deploy contract to test.

2: there is no way to obtain block timestamp by number, block.timestamp or now just is current block timestamp as seconds since unix epoch.

3:miner.start(1);admin.sleepBlocks(1);miner.stop(); just mines one block and then will stop mine. Please notice executing by together.