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package memory
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import (
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	"context"
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	"time"
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	"go.miragespace.co/specter/spec/chord"
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)
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var _ chord.LeaseKV = (*MemoryKV)(nil)
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func durationGuard(t time.Duration) (time.Duration, bool) {
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	td := t.Truncate(time.Second)
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	if td < time.Second {
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		return 0, false
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	}
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	return td, true
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}
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func (m *MemoryKV) Acquire(ctx context.Context, lease []byte, ttl time.Duration) (token uint64, err error) {
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	ttl, ok := durationGuard(ttl)
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	if !ok {
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		return 0, chord.ErrKVLeaseInvalidTTL
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	}
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	v, _ := m.fetchVal(lease)
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	curr := v.lease.Load()
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	ref := time.Now() // questionable
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	if curr > uint64(ref.UnixNano()) {
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		return 0, chord.ErrKVLeaseConflict
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	}
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	next := uint64(ref.Add(ttl).UnixNano())
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	if !v.lease.CompareAndSwap(curr, next) {
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		return 0, chord.ErrKVLeaseConflict
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	}
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	return next, nil
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}
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func (m *MemoryKV) Renew(ctx context.Context, lease []byte, ttl time.Duration, prevToken uint64) (newToken uint64, err error) {
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	ttl, ok := durationGuard(ttl)
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	if !ok {
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		return 0, chord.ErrKVLeaseInvalidTTL
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	}
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	v, _ := m.fetchVal(lease)
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	curr := v.lease.Load()
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	if curr == 0 {
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		return 0, chord.ErrKVLeaseExpired
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	}
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	if time.Now().UnixNano() > int64(curr) {
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		return 0, chord.ErrKVLeaseExpired
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	}
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	if curr != prevToken {
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		return 0, chord.ErrKVLeaseExpired
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	}
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	next := uint64(time.Now().Add(ttl).UnixNano())
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	if !v.lease.CompareAndSwap(curr, next) {
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		return 0, chord.ErrKVLeaseExpired
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	}
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	return next, nil
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}
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func (m *MemoryKV) Release(ctx context.Context, lease []byte, token uint64) error {
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	v, _ := m.fetchVal(lease)
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	if !v.lease.CompareAndSwap(token, 0) {
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		return chord.ErrKVLeaseExpired
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	}
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	return nil
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}