James Tucker
e7415e6393
Brings Subscriber[T] in line with the same non-generic-core pattern already
applied to SubscriberFunc[T] and Publisher[T]:
- Renames subscriberFuncCore to subscriberCore and shares it between
Subscriber[T] and SubscriberFunc[T]. Both typed facades hold a
*subscriberCore plus their respective per-T delivery state
(Subscriber: chan T; SubscriberFunc: nothing, the user callback is
captured in the dispatch closure).
- The bus's outputs map and subscriber-interface itab key on
*subscriberCore for both subscriber kinds, so adding a new Subscribe[T]
call site no longer pays a per-T itab, dictionary, or equality function
for the subscriber-interface side.
- Subscribe[T] now hoists the non-generic constructor portion into
newSubscriberCore (timer setup, core allocation, cached type/typeName,
unregister method-value), matching SubscribeFunc.
The dispatch loop is intentionally NOT extracted to a non-generic helper for
Subscriber[T], unlike SubscriberFunc[T]. The reason is the typed channel send
'case s.read <- t:' must appear lexically inside the select; the only way to
lift it into a non-generic loop is to bridge typed and untyped via a per-event
goroutine, which costs ~2.7x throughput on BenchmarkBasicThroughput. We keep
dispatchTyped on the generic facade and accept the per-shape stencil cost as
the cheaper alternative.
Symbol-level effect on tailscaled (linux/amd64, measured via
`go tool nm -size`):
Before:
(*Subscriber[T]).dispatch
2 shape stencils: 1,682 + 1,549 = 3,231 B
3 thin per-T wrappers: 124 B each = 372 B
2 deferwrap1 helpers: 62 B each = 124 B
total: 3,727 B
After:
(*Subscriber[T]).dispatchTyped
2 shape stencils: 1,678 + 1,582 = 3,260 B
0 per-T wrappers (replaced by closure stored on core)
2 deferwrap1 helpers: 62 B each = 124 B
total: 3,384 B
dispatch path .text delta: -343 B (-9.2%)
Per-shape stencils are ~1,600 B (.text body) + ~1,100 B (pclntab) =
~2,700 B each on production tailscaled. The shape count matches before/after
(two distinct GC shapes for the Subscriber[T] event types in this binary).
What changes is that the per-T thin wrappers are eliminated because
Subscriber[T] no longer implements the subscriber interface directly.
Whole-binary section deltas:
.text: -2,304 B (includes the dispatch savings plus other
small downstream effects)
.rodata: +512 B (additional closure-type metadata)
.gopclntab: -2,981 B (fewer per-T compiled functions => less metadata)
Stripped tailscaled (linux/amd64): no change at the file level (the savings
fall below the linker's section-alignment boundary). Unstripped builds shrink
by ~2,900 B.
Behavior is unchanged:
BenchmarkBasicThroughput: 2,161 ns/op, 0 B/op, 0 allocs/op
BenchmarkBasicFuncThroughput: 2,493 ns/op, 144 B/op, 2 allocs/op
BenchmarkSubsThroughput: 3,727 ns/op, 0 B/op, 0 allocs/op
Updates #12614
Change-Id: I97918ec68bd2cdb15958bbfd7687592b39663efe
Signed-off-by: James Tucker <james@tailscale.com>
Tailscale
Private WireGuard® networks made easy
Overview
This repository contains the majority of Tailscale's open source code.
Notably, it includes the tailscaled daemon and
the tailscale CLI tool. The tailscaled daemon runs on Linux, Windows,
macOS, and to varying degrees
on FreeBSD and OpenBSD. The Tailscale iOS and Android apps use this repo's
code, but this repo doesn't contain the mobile GUI code.
Other Tailscale repos of note:
- the Android app is at https://github.com/tailscale/tailscale-android
- the Synology package is at https://github.com/tailscale/tailscale-synology
- the QNAP package is at https://github.com/tailscale/tailscale-qpkg
- the Chocolatey packaging is at https://github.com/tailscale/tailscale-chocolatey
For background on which parts of Tailscale are open source and why, see https://tailscale.com/opensource/.
Using
We serve packages for a variety of distros and platforms at https://pkgs.tailscale.com.
Other clients
The macOS, iOS, and Windows clients use the code in this repository but additionally include small GUI wrappers. The GUI wrappers on non-open source platforms are themselves not open source.
Building
We always require the latest Go release, currently Go 1.26. (While we build releases with our Go fork, its use is not required.)
go install tailscale.com/cmd/tailscale{,d}
If you're packaging Tailscale for distribution, use build_dist.sh
instead, to burn commit IDs and version info into the binaries:
./build_dist.sh tailscale.com/cmd/tailscale
./build_dist.sh tailscale.com/cmd/tailscaled
If your distro has conventions that preclude the use of
build_dist.sh, please do the equivalent of what it does in your
distro's way, so that bug reports contain useful version information.
Bugs
Please file any issues about this code or the hosted service on the issue tracker.
Contributing
PRs welcome! But please file bugs. Commit messages should reference bugs.
We require Developer Certificate of
Origin
Signed-off-by lines in commits.
See commit-messages.md (or skim git log) for our commit message style.
About Us
Tailscale is primarily developed by the people at https://github.com/orgs/tailscale/people. For other contributors, see:
- https://github.com/tailscale/tailscale/graphs/contributors
- https://github.com/tailscale/tailscale-android/graphs/contributors
Legal
WireGuard is a registered trademark of Jason A. Donenfeld.