tailscale/types
Brad Fitzpatrick aa5da2e5f2 ipn/ipnlocal, control/controlclient: process node adds/removes in constant time
For large tailnets (~50k+ nodes) with frequent peer churn (ephemeral
GitHub Actions workers etc.), tailscaled used to rebuild the full
netmap and fan it out on the IPN bus on every MapResponse that
added or removed a peer. There were two O(N) costs per delta: the
full netmap rebuild + every Notify.NetMap encode to every bus watcher.

This change tackles both:

  1. Plumb O(1) peer add/remove through the delta path. PeersChanged
     and PeersRemoved no longer prevent the delta happy path; instead,
     they mutate the per-node-backend peer map in place.

  2. Restrict ipn.Notify.NetMap emission to the platforms whose host
     GUIs still depend on it (Windows, macOS, iOS) and migrate
     in-tree consumers off it everywhere else:

     - Migrate reactive consumers (containerboot, kube agents,
       sniproxy, tsconsensus, etc.) off Notify.NetMap to the
       previously-added Notify.SelfChange signal so they no longer
       have to subscribe to the full netmap.
     - Add ipn.NotifyNoNetMap so GUI clients on "legacy-emit" platforms
       that have already migrated can opt out of the per-watcher
       NetMap encode.
     - Gate Notify.NetMap emission on the producer side by a compile-
       time GOOS check, so the supporting code is dead-code-eliminated
       on Linux and other geese where no GUI consumer needs it.

Re-running BenchmarkGiantTailnet from tstest/largetailnet, which was
added along with baseline numbers on unmodified main in ad5436af0d,
the per-delta cost (one peer add+remove pair) is now ~O(1) regardless
of tailnet size N:

    N         no-watcher (ms/op)            bus-watcher (ms/op)
              before    now     factor      before    now     factor
     10000        32   0.11       300x         166   0.13      1300x
     50000       222   0.11      2000x         865   0.13      6700x
    100000       504   0.12      4100x        1765   0.13     13400x
    250000      1551   0.12     12500x        4696   0.15     32400x

Updates #12542

Change-Id: I94e34b37331d1a8ec74c299deffadf4d061fda9e
Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>
2026-05-21 09:26:19 -07:00
..
appctype feature/conn25: add IPv6 support 2026-04-07 11:00:04 -07:00
bools all: remove AUTHORS file and references to it 2026-01-23 15:49:45 -08:00
dnstype cmd/vet: add subtestnames analyzer; fix all existing violations 2026-04-05 15:52:51 -07:00
empty all: remove AUTHORS file and references to it 2026-01-23 15:49:45 -08:00
events wgengine/magicsock,control/controlclient: do not overwrite discokey with old key (#18606) 2026-03-20 08:56:27 -04:00
flagtype all: remove AUTHORS file and references to it 2026-01-23 15:49:45 -08:00
geo types/geo: fix floating point bug causing NaN returns in SphericalAngleTo (#18777) 2026-03-02 17:33:57 -08:00
iox all: remove AUTHORS file and references to it 2026-01-23 15:49:45 -08:00
ipproto all: use Go 1.26 things, run most gofix modernizers 2026-03-06 13:32:03 -08:00
jsonx types/ptr: deprecate ptr.To, use Go 1.26 new 2026-03-05 20:13:18 -08:00
key all: update more references to Tailnet/Network Lock 2026-05-15 16:23:50 +01:00
lazy all: use Go 1.26 things, run most gofix modernizers 2026-03-06 13:32:03 -08:00
logger all: remove AUTHORS file and references to it 2026-01-23 15:49:45 -08:00
logid all: remove AUTHORS file and references to it 2026-01-23 15:49:45 -08:00
mapx all: remove AUTHORS file and references to it 2026-01-23 15:49:45 -08:00
netlogfunc all: remove AUTHORS file and references to it 2026-01-23 15:49:45 -08:00
netlogtype all: remove AUTHORS file and references to it 2026-01-23 15:49:45 -08:00
netmap ipn/ipnlocal, control/controlclient: process node adds/removes in constant time 2026-05-21 09:26:19 -07:00
nettype all: remove AUTHORS file and references to it 2026-01-23 15:49:45 -08:00
opt all: remove AUTHORS file and references to it 2026-01-23 15:49:45 -08:00
persist tailcfg: reintroduce UserProfile.Groups 2026-03-09 11:08:45 +00:00
prefs types/ptr: deprecate ptr.To, use Go 1.26 new 2026-03-05 20:13:18 -08:00
preftype all: remove AUTHORS file and references to it 2026-01-23 15:49:45 -08:00
ptr types/ptr: deprecate ptr.To, use Go 1.26 new 2026-03-05 20:13:18 -08:00
result all: remove AUTHORS file and references to it 2026-01-23 15:49:45 -08:00
structs all: remove AUTHORS file and references to it 2026-01-23 15:49:45 -08:00
tkatype all: remove AUTHORS file and references to it 2026-01-23 15:49:45 -08:00
views all: use Go 1.26 things, run most gofix modernizers 2026-03-06 13:32:03 -08:00