currently when you use go mod to manage you dependencies,new packages are added and old ones are not removed.
So can we maintain a global gomod.stats file to keep reference counter of every package? It can only be modified when executing `go mod download/init/tidy` and when running `go mod clean`, it will traverse gomod.stats and find packages who's refcount is 0 then delete them.
This is similar to simplified GC using reference counting and I think customizing digraph may deal with it.
2020/07/02 周四 19:36 <DIR> tools
2020/01/09 周四 23:02 <DIR> to...@v0.0.0-20180824175216-6c1c5e93cdc1
2020/01/09 周四 23:03 <DIR> to...@v0.0.0-20181130195746-895048a75ecf
2019/11/12 周二 15:00 <DIR> to...@v0.0.0-20190312170243-e65039ee4138
2020/01/09 周四 23:02 <DIR> to...@v0.0.0-20190408220357-e5b8258f4918
2020/04/24 周五 14:47 <DIR> to...@v0.0.0-20190611222205-d73e1c7e250b
2019/11/20 周三 15:46 <DIR> to...@v0.0.0-20190809145639-6d4652c779c4
2019/12/13 周五 17:16 <DIR> to...@v0.0.0-20191012152004-8de300cfc20a
2020/01/09 周四 23:03 <DIR> to...@v0.0.0-20191030062658-86caa796c7ab
2019/11/19 周二 14:59 <DIR> to...@v0.0.0-20191108194844-46f05828f2fe
2019/11/19 周二 14:59 <DIR> to...@v0.0.0-20191118222007-07fc4c7f2b98
2020/01/09 周四 23:03 <DIR> to...@v0.0.0-20191125144606-a911d9008d1f
2019/12/11 周三 16:41 <DIR> to...@v0.0.0-20191206201009-952e2c076240
2019/12/11 周三 16:41 <DIR> to...@v0.0.0-20191210221141-98df12377212
2020/01/09 周四 23:02 <DIR> to...@v0.0.0-20200108203644-89082a384178
2020/02/28 周五 10:24 <DIR> to...@v0.0.0-20200130002326-2f3ba24bd6e7
2020/02/18 周二 16:59 <DIR> to...@v0.0.0-20200212213342-7a21e308cf6c
2020/02/18 周二 16:59 <DIR> to...@v0.0.0-20200216192241-b320d3a0f5a2
2020/04/30 周四 15:41 <DIR> to...@v0.0.0-20200226224502-204d844ad48d
2020/03/03 周二 12:29 <DIR> to...@v0.0.0-20200227200655-6862ededa516
2020/02/28 周五 10:23 <DIR> to...@v0.0.0-20200227222343-706bc42d1f0d
2020/03/03 周二 12:29 <DIR> to...@v0.0.0-20200302225559-9b52d559c609
2020/06/15 周一 22:39 <DIR> to...@v0.0.0-20200304193943-95d2e580d8eb
2020/03/25 周三 16:50 <DIR> to...@v0.0.0-20200316194252-fafb6e2e8a4a
2020/03/25 周三 16:50 <DIR> to...@v0.0.0-20200325010219-a49f79bcc224
2020/04/10 周五 17:48 <DIR> to...@v0.0.0-20200407041343-bf15fae40dea
2020/04/10 周五 17:48 <DIR> to...@v0.0.0-20200410040751-3bd20875a2eb
2020/04/30 周四 15:40 <DIR> to...@v0.0.0-20200430040329-4b814e061378
2020/05/11 周一 21:46 <DIR> to...@v0.0.0-20200509030707-2212a7e161a5
2020/05/15 周五 09:43 <DIR> to...@v0.0.0-20200513154647-78b527d18275
2020/05/15 周五 09:43 <DIR> to...@v0.0.0-20200515010526-7d3b6ebf133d
2020/07/02 周四 19:36 <DIR> to...@v0.0.0-20200701133321-6ddc6be4d35f
2020/07/02 周四 19:36 <DIR> to...@v0.0.0-20200702044944-0cc1aa72b347
Thanks.