James Tucker 120bfcf1cc util/eventbus: extract non-generic SubscriberFunc constructor body and cache type name
Two changes that share the same intent of reducing per-T duplication
in code that doesn't actually depend on T:

1. Hoist the non-generic portion of newSubscriberFunc[T] into a
   newSubscriberFuncCore() helper. The hoisted work is the time
   timer setup, the subscriberFuncCore allocation, and the
   unregister closure (which captures only the non-generic
   reflect.Type and *subscribeState). The generic body now does
   only the two T-bound things it has to: compute reflect.TypeFor[T]
   and create the dispatch closure.

   Effect on the per-shape-stencil body of newSubscriberFunc[T]:
     before: 523 B per shape (in synthetic test)
     after:  293 B per shape (-230 B per shape; -56% on this body)

2. Cache reflect.Type.String() once at construction (in core.typeName)
   instead of recomputing it every time the dispatch closure runs.
   The dispatch closure also now takes the *subscriberFuncCore directly
   rather than building an intermediate dispatchFuncState struct on
   every call.

   Effect on the dispatch closure body (newSubscriberFunc[T].func1):
     before: 581 B per shape
     after:  480 B per shape (-101 B per shape; -17%)

Combined effect on tailscaled (linux/amd64):
  named-symbol savings via symcost: ~7 KB
  stripped binary delta:            -8 KB (page-quantized)
  arm64 binary delta:                0 (page-quantized)

  cumulative reduction from baseline (5167ff412):
    linux/amd64:  -110,592 bytes (-0.391%)
    linux/arm64:  -131,072 bytes (-0.499%)

Throughput is also improved by the typeName cache: BenchmarkBasic
goes from 2018 ns/op to 1864 ns/op (-7.6%) because the dispatch hot
path no longer allocates a string on every event.

Updates #12614

Change-Id: Ib3a3d6796785e16506330ec034e1144580d467a3
Signed-off-by: James Tucker <james@tailscale.com>
2026-05-12 11:16:04 -07:00
2026-05-04 10:34:27 -07:00
2026-03-27 08:41:33 +00:00
2026-01-27 16:15:17 -08:00
2026-05-07 15:33:05 -07:00

Tailscale

https://tailscale.com

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:

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:

WireGuard is a registered trademark of Jason A. Donenfeld.

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