feat: support multiple dev servers by using random temp directories

[meteorlxy]

Current global vuepress does not support multiple instances.

In other words, we cannot open multiple dev server using global installed vuepress.

The reason is we are now using a fixed/single temp directory, i.e. lib/app/.temp. Each project will overwrite the same temp directory, which will cause collision.

For enhancement, I introduce tmp module, which is widely used by many projects.

[meteorlxy]

#355

[ulivz]

Since VuePress is still in the early iterations, I still think that the temp dirs should be in placed in local package's directory.

To support multiple temp dirs, you can simply suffixed the temp dir with a hash or timestamp for each instance.

[ulivz]

This change shouldn't be included here.

[meteorlxy]

Oh, forget to add -g when change the registry

[meteorlxy]

@ulivz

Changed to local package's dir.

[ycmjason]

I wonder why would we need to spawn multiple dev servers?

[ulivz]

Same question, why would we need to spawn multiple dev servers?

[meteorlxy]

Good question, why hexo & jekyll support multiple dev servers?

[ulivz]

Hmmm, do you mean that we must support others' support? Where is the actual meaning?

[meteorlxy]

LOL, don't mind my word.

Users may have different requirements. For me, I'm deving the official repo and my own custom theme in the mean time, so I have to restart and restart.

Or I have another question: why we restrict users to open only one dev server?

[hmatalonga]

@meteorlxy

While it is not strictly necessary... I agree it can be handy to have that possibility 😃

[ulivz]

Shouldn't it be a feature request first? If you just submitted a PR and hoped to be merged as soon as possible, then we will discuss whether we need to do it. Will you put the cart before the horse?

BTW, I don't want and DON'T have time to argue with you at all. If you want to support a feature, please submit a feature request first.

[meteorlxy]

I did, sir #355... And you tagged it as enhancement 😓

[ulivz]

@meteorlxy

We just want to know why we need to support this feature. in my opinion, this makes core a little more complex and create a unpleasant directory, and 99% users will only need one instance. so if you can give us a convincing reason, I will support you. But as a reviewer, you just kept asking me.

I tagged a enhancementto #355 is that the description doesn't look like a feature request but also not bug.

I think we should follow such a process: Why need it => How to do it.

[ulivz]

And, can you confirm that will the old temp file be deleted when reboot?

[meteorlxy]

@ulivz They will be deleted immediately after the process exits.

However, there may be some exceptions that make the process interrupt unexpectedly, or the machine shutdown accidently, then the temp files will remain there.

If we use system tmp directory as my first commit, we don't have to worry about it.

If we use local package directory as you suggested, it could be a potential problem that we should delete them manually.

[ulivz]

We can simply implement it with native node.js. since we didn't need tmp's other features.

And delete the .temp-* dirs before prepare.

[meteorlxy]

After discussion on slack, so far we (@ulivz , @ycmjason and I) have some conclusion:

• Multiple dev servers is necessary in these possible scenarios:
  • Developing multiple vuepress projects in the mean time, or trying to campare some changes with each other.
  • Multiple users access to one remote machine, and start vuepress dev server in the mean time.
• Although tmp module can cleanup the tempfile after the process exits, if the vuepress process was killed by accident, the temp files will still remain there. So we would prefer to store the temp files to OS's temp dir. (But we cannot determine if this is a good solution. cc @yyx990803 )