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spend_set.go
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spend_set.go
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package spenddagv1
import (
"github.com/iotaledger/hive.go/ds"
"github.com/iotaledger/hive.go/ds/reactive"
"github.com/iotaledger/hive.go/ierrors"
"github.com/iotaledger/hive.go/runtime/syncutils"
"github.com/iotaledger/iota-core/pkg/protocol/engine/mempool/spenddag"
)
// SpendSet represents a set of Spenders of a Resource.
// If there's more than 1 spender in a SpendSet, they are conflicting with each other over the shared Resource.
type SpendSet[SpenderID, ResourceID spenddag.IDType, VoteRank spenddag.VoteRankType[VoteRank]] struct {
// ID is the ID of the Resource being spent.
ID ResourceID
// spenders is the set of spenders (e.g. transactions) that spend the resource (e.g. a utxo).
spenders ds.Set[*Spender[SpenderID, ResourceID, VoteRank]]
allMembersEvicted reactive.Variable[bool]
mutex syncutils.RWMutex
}
// NewSpendSet creates a new SpendSet containing spenders (e.g. a transaction) of a common resource (e.g. a utxo).
func NewSpendSet[SpenderID, ResourceID spenddag.IDType, VoteRank spenddag.VoteRankType[VoteRank]](id ResourceID) *SpendSet[SpenderID, ResourceID, VoteRank] {
return &SpendSet[SpenderID, ResourceID, VoteRank]{
ID: id,
allMembersEvicted: reactive.NewVariable[bool](),
spenders: ds.NewSet[*Spender[SpenderID, ResourceID, VoteRank]](),
}
}
// Add adds a Spender to the SpendSet and returns all other members of the set.
func (c *SpendSet[SpenderID, ResourceID, VoteRank]) Add(addedSpender *Spender[SpenderID, ResourceID, VoteRank]) (otherMembers ds.Set[*Spender[SpenderID, ResourceID, VoteRank]], err error) {
c.mutex.Lock()
defer c.mutex.Unlock()
if c.allMembersEvicted.Get() {
return nil, ierrors.New("cannot join a SpendSet whose all members are evicted")
}
if otherMembers = c.spenders.Clone(); !c.spenders.Add(addedSpender) {
return nil, spenddag.ErrAlreadyPartOfSpendSet
}
return otherMembers, nil
}
// Remove removes a Spender from the SpendSet and returns all remaining members of the set.
func (c *SpendSet[SpenderID, ResourceID, VoteRank]) Remove(removedSpender *Spender[SpenderID, ResourceID, VoteRank]) (removed bool) {
c.mutex.Lock()
defer c.mutex.Unlock()
if removed = c.spenders.Delete(removedSpender); removed && c.spenders.IsEmpty() {
c.allMembersEvicted.Set(true)
}
return removed
}
func (c *SpendSet[SpenderID, ResourceID, VoteRank]) ForEach(callback func(parent *Spender[SpenderID, ResourceID, VoteRank]) error) error {
c.mutex.RLock()
defer c.mutex.RUnlock()
return c.spenders.ForEach(callback)
}
// OnAllMembersEvicted executes a callback when all members of the SpendSet are evicted and the SpendSet itself can be evicted.
func (c *SpendSet[SpenderID, ResourceID, VoteRank]) OnAllMembersEvicted(callback func(prevValue, newValue bool)) {
c.allMembersEvicted.OnUpdate(callback)
}