Planning of libuv v2. Slides from the meeting which took place in Node Inteactive 2016 in Amsterdam.

1. Planning libuv v2
Node Interactive 2016 — Amsterdam

2. Present
• Ben Noordhuis (@bnoordhuis)
• Bert Belder (@piscisaureus)
• Fedor Indutny (@indutny)
• Saul Ibarra Corretge (@saghul)
• Observers: Felix, Rob and Anna

3. Current status (v1.x)
• New release is imminent: 1.10.0
• 7 maintainers, 5 active
• 12 new APIs since 1.0.0
• ABI remains stable!
• Release cadence: when enough fixes / features
pile up

4. Current status (master)
• Supported platforms cleanup
• ABI compatibility hacks removed
• Some PRs pending review

5. The 10k ft view
• Internal cleanups / improvements
• Add new APIs which could’t land on v1.x
• Evolutionary, not too many breaking changes
• More approachable -> more & better docs

6. Open PRs for v2
• Timer wheels
• uv_fs_{open,read,close}dir
• Changes to uv_interface_addresses / uv_cpu_info
• uv_device_t (stalled)

7. Pain points
• Documentation
• Multi-threaded applications
• TLS support
• Serial port access

8. Documentation
• Improve existing API docs
• Merge in the uvbook (author agreed to help!)
• Add sample applications (ex. simple HTTP client)

9. Multi-threading
• We need a better story for our thread pool
• Easier way for sending handles from one loop to
another
• (long term) Thread-safe APIs?

10. Actionable Items

11. libuv-extras
• Inaugurate libuv-extras with uv_ssl_t + uv_link_t
(@indutny)
• Different support guarantees
• A serial port support module could land there,
needs a champion

12. Timers
• Use a timer wheel?
• Linux removed them! Worst case scenario is far worse. Complex
implementation.
• Repeating timers are weird for some, get rid of them
• Use sub-millisecond precision where possible: use a double
• int uv_timeout(uv_timeout_t* req, double timeout, uv_timeout_cb
cb)
• uv_timer_t remains, built on top of uv_timeout
• @saghul

13. uv_read()
• New API functions
• uv_pollin: Poll for readability
• uv_pollin(uv_poolin_t*req, uv_stream_t* stream, uv_pollin_cb cb)
• uv_read: Read into a pre-allocated buffer
• uv_read(uv_read_t* req, const uv_buf_t[] bufs, unsigned nbufs, uv_read_cb cb)
• uv_try_read: Read inline
• uv_try_read(uv_stream_t* stream, const uv_buf_t[] bufs, unsigned nbufs);
• @piscisaureus will kickstart the work

14. Reentrant uv_run
• Very complex.
• Not for now.

15. uv_pipefds
• Simplify the master process + multiple workers
scenario
• int uv_pipefds(uv_file[2], int flags)
• Problem: pipe mode on Windows: overlapped vs
blocking
• @saghul

16. Threadpool
• Hooks for running tasks in a thread pool
• Pluggable
• Default implementation
• @bnoordhuis will write a LEP

17. LEP cleanup
• Deal with stalled LEPs
• Break the big one into smaller pieces
• @saghul

18. Task list
• Merge timers
• uv_timeout
• Start uv_read
• Threadpool rework
• Docs
• uv_read

19. Schedule
• When It’s Ready (R)