James Tucker d72cde1a6b util/eventbus: move SubscriberFunc subscriber-interface impl to a non-generic core
Splits SubscriberFunc[T] into:

  - SubscriberFunc[T]: a thin user-facing facade that holds only a
    pointer to a non-generic core. It exposes Close() to user code,
    which forwards to the core.
  - subscriberFuncCore: a non-generic struct that owns all the
    subscriber state (stop flag, unregister, logf, slow timer,
    cached reflect.Type) and implements the bus's package-private
    subscriber interface. Its dispatch() invokes a closure
    captured at construction time that performs the
    vals.Peek().Event.(T) type assertion and runs the user
    callback on the unboxed value.

The bus's outputs map and subscriber-interface itab are
parameterized only by *subscriberFuncCore, not by T, eliminating
both the per-T itab and the per-T generic dictionary that
previously scaled with the number of subscribed event types.

Measured impact (util/eventbus/sizetest):

  total per-flow binary cost:
    linux/amd64:  3039.2 B/flow -> 2252.8 B/flow  (-786.4 B / -25.9%)
    linux/arm64:  3145.7 B/flow -> 2228.2 B/flow  (-917.5 B / -29.2%)

  SubscriberFunc per-receiver attribution:
    linux/amd64:   840.8 B/flow ->  300.8 B/flow  (-540.0 B / -64.2%)
    linux/arm64:   849.9 B/flow ->  303.8 B/flow  (-546.1 B / -64.3%)

Dropped per-T symbols (200-flow eventbus binary):

  - (*SubscriberFunc[T]).dispatch     was 26,639 B total (130 B/T)
  - (*SubscriberFunc[T]).subscribeType was  3,600 B total ( 18 B/T)
  - .dict.SubscriberFunc[T]            was 14,400 B total ( 72 B/T)
  - go:itab.*SubscriberFunc[T],...     was  9,600 B total ( 48 B/T)

Of the original 913 B/flow attributed to SubscriberFunc, 540 B/flow
is now gone, dropping the receiver to 300 B/flow.

Behavior is unchanged: BenchmarkBasicThroughput is within noise
(1955 -> 1941 ns/op on the test box) and all eventbus tests pass.

Updates #12614

Change-Id: I646b3b05fd8d95f9afead59bfd0f69cd18b7a709
Signed-off-by: James Tucker <james@tailscale.com>
2026-05-11 12:14:05 -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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