xboard
85 lines
2.1 KiB
Go
85 lines
2.1 KiB
Go
package limiter
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import (
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"sync"
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"sync/atomic"
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"github.com/cedar2025/xboard-node/internal/panel"
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)
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// Limiter enforces per-user device limits and detects removed users.
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type Limiter struct {
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mu sync.RWMutex
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users map[int]panel.User
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// uuidDeviceLimit provides O(1) UUID→device-limit lookup for the
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// kernel gate-keeping hot path (called per new connection).
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uuidDeviceLimit map[string]int
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deviceLimitEvents atomic.Uint64
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}
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func New() *Limiter {
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return &Limiter{
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users: make(map[int]panel.User),
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uuidDeviceLimit: make(map[string]int),
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}
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}
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// UpdateUsers refreshes the user limit configuration and returns
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// the IDs of users that were present before but are now removed.
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func (l *Limiter) UpdateUsers(users []panel.User) []int {
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l.mu.Lock()
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defer l.mu.Unlock()
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newUsers := make(map[int]panel.User, len(users))
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for _, u := range users {
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newUsers[u.ID] = u
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}
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// Find removed users
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var removed []int
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for id := range l.users {
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if _, ok := newUsers[id]; !ok {
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removed = append(removed, id)
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}
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}
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l.users = newUsers
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// Rebuild UUID→device-limit index for O(1) lookups.
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idx := make(map[string]int, len(newUsers))
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for _, u := range newUsers {
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if u.DeviceLimit > 0 {
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idx[u.UUID] = u.DeviceLimit
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}
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}
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l.uuidDeviceLimit = idx
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return removed
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}
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// LimiterMetrics holds aggregated limiter statistics.
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type LimiterMetrics struct {
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// DeviceLimitEvents is the total number of times a user exceeded
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// the configured device limit (since process start).
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DeviceLimitEvents uint64
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}
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// SnapshotMetrics returns a snapshot of limiter metrics.
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func (l *Limiter) SnapshotMetrics() LimiterMetrics {
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return LimiterMetrics{
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DeviceLimitEvents: l.deviceLimitEvents.Load(),
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}
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}
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// GetDeviceLimitByUUID returns the device limit for a user identified by UUID.
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// Returns (limit, true) if a device limit is set, (0, false) otherwise.
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// This is designed to be passed as a function reference to kernel.SetDeviceLimitFunc.
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func (l *Limiter) GetDeviceLimitByUUID(uuid string) (int, bool) {
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l.mu.RLock()
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defer l.mu.RUnlock()
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limit, ok := l.uuidDeviceLimit[uuid]
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return limit, ok
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}
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