Remove the reuse for UNIX stream DNS lookup.

[madeye]

Our UNIX stream based DNS lookup doesn't support connection reuse.

[Mygod]

My compiler complains that this commit cannot be found: https://github.com/zonyitoo/tokio/commit/47b76a5a

[madeye]

I got the compilation error as well, you may have to rebase to an old commit.

[zonyitoo]

My compiler complains that this commit cannot be found: zonyitoo/tokio@47b76a5

Just ignore it. I will fix it until tokio's PR was merged.

[Mygod]

Can confirm this fixes everything. (I thought I was going to implement a DNS cache in shadowsocks-android for a moment so thank god!)

[zonyitoo]

The UNIX stream should report errors if the endpoint have been closed. Hmm.. Why it is the cause of shadowsocks/shadowsocks-android#2751 ?

[zonyitoo]

LGTM. But why?

[madeye]

Our android UNIX stream resolver doesn't support connection reuse yet.

I will use this PR to create a new release of shadowsocks-android as a hotfix. But for now, I think it's okay to keep it open for shadowsocks-rust.

[Mygod]

There is no reason to support connection reuse on local sockets since the delay is negligible. Currently, shadowsocks-android should close the socket (syscall close) after the response is written.

EDIT: Holding a local socket open also wastes system resources methinks.

[zonyitoo]

Well, you are right about the cost of creating unix local stream is negligible. I am Ok with this PR, but I still cannot understand why it cause that issue.

Currently the implementation will open a new client if the connection have been lost due to for _ in 0..self.retry_count.

[Mygod]

Maybe we merge this and figure out the retry later? 😛

[zonyitoo]

I am worrying about if there are any issues in this connection management strategy, then it will also affect TCP and UDP DNS clients.

[zonyitoo]

Will shadowsocks-android implement connection reuse in the future? @madeye @Mygod

• If NO, then I will merge this PR and only checks TCP and UDP connections;
• If YES, then I will prefer another solution that checks the status of connection before actually write to it

[Mygod]

There is no reason to support connection reuse on local sockets since the delay is negligible. Currently, shadowsocks-android should close the socket (syscall close) after the response is written.

EDIT: Holding a local socket open also wastes system resources methinks.

^