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tiennm99
cf620a257e
Correct comments that described the retired webhook transport, a removed /cron route, the old KV store and wrapper types, and behaviour that has since changed; drop plan and review labels; reword two startup log lines that overstated or misnamed what they report.
34 lines
1.4 KiB
Go
34 lines
1.4 KiB
Go
// Package keylock serialises compound operations that target the same key
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// (typically a chat / user / subject identifier) across goroutines.
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//
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// Why a separate package: several modules need a per-subject mutex to turn
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// the store's single-op atomicity into safe Get→mutate→Put. Telegram updates
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// are handled one at a time, but crons fire on scheduler goroutines alongside
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// them, so without explicit per-subject serialisation a cron and a handler
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// writing the same subject could race and drop a write.
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//
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// Trade-off: the underlying sync.Map grows unboundedly with distinct keys
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// (~32 B each). At the current bot scale, that is acceptable; add eviction if
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// production cardinality starts growing materially.
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package keylock
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import "sync"
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// Map gives each string key its own mutex, lazily created. Zero value is
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// usable; do not copy after first use (sync.Map is non-copyable).
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type Map struct {
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m sync.Map // key: string → val: *sync.Mutex
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}
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// Acquire locks the per-key mutex and returns its Unlock as a func so the
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// caller can `defer m.Acquire(key)()` at the top of a critical section.
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//
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// Distinct keys never block each other; same-key callers run one at a time.
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// Like sync.Mutex, it does not guarantee FIFO order among waiters.
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func (m *Map) Acquire(key string) func() {
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v, _ := m.m.LoadOrStore(key, &sync.Mutex{})
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mu := v.(*sync.Mutex)
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mu.Lock()
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return mu.Unlock
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}
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