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package stm
import (
"sync"
"sync/atomic"
)
// Holds an STM variable.
type Var struct {
value atomic.Value
watchers sync.Map
mu sync.Mutex
}
func (v *Var) changeValue(new interface{}) {
v.value.Store(v.value.Load().(VarValue).Set(new))
v.wakeWatchers()
}
func (v *Var) wakeWatchers() {
v.watchers.Range(func(k, _ interface{}) bool {
tx := k.(*Tx)
tx.mu.Lock()
tx.cond.Broadcast()
tx.mu.Unlock()
return true
})
}
type varSnapshot struct {
val interface{}
version uint64
}
// Returns a new STM variable.
func NewVar(val interface{}) *Var {
v := &Var{}
v.value.Store(versionedValue{
value: val,
})
return v
}
func NewCustomVar(val interface{}, changed func(interface{}, interface{}) bool) *Var {
v := &Var{}
v.value.Store(customVarValue{
value: val,
changed: changed,
})
return v
}
func NewBuiltinEqVar(val interface{}) *Var {
return NewCustomVar(val, func(a, b interface{}) bool {
return a != b
})
}
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