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aefb1531d1
tsdial.Dialer.SetNetMap rebuilt an O(n peers) map of MagicDNS names on every netmap change. As we move toward per-peer incremental deltas, this becomes quadratic. This removes it and replaces it with SetResolveMagicDNS, a callback into LocalBackend that looks up hostnames from nodeBackend's new nodeByName index (populated alongside nodeByAddr/nodeByKey on both full and delta paths). The index stores both FQDNs and short names as keys. This is the same treatment applied to netlog (8f210454d), wglog (988b0905b), and drive (1d6989408): stop pushing *netmap.NetworkMap into subsystems and instead have them pull from LocalBackend's live data via callbacks. Updates #12542 Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com> Change-Id: I24557ab0c8a27636e08e4779bcfd3ec633db0a78
29 lines
759 B
Go
29 lines
759 B
Go
// Copyright (c) Tailscale Inc & contributors
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// SPDX-License-Identifier: BSD-3-Clause
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package mapx
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// RepopulateNonzero re-uses an existing map (preserving its allocated
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// buckets) by zeroing all values, calling populate to re-fill it, and
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// then deleting any entries still at their zero value. If *m is nil it
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// is lazily initialized.
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//
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// This avoids the allocation cost of creating a new map on every call,
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// which matters for maps that are rebuilt frequently (e.g. on every
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// netmap update).
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func RepopulateNonzero[K comparable, V comparable](m *map[K]V, populate func()) {
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if *m == nil {
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*m = make(map[K]V)
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}
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var zero V
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for k := range *m {
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(*m)[k] = zero
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}
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populate()
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for k, v := range *m {
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if v == zero {
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delete(*m, k)
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}
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}
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}
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