lotus/paychmgr/accessorcache.go

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package paychmgr
import "github.com/filecoin-project/go-address"
// accessorByFromTo gets a channel accessor for a given from / to pair.
// The channel accessor facilitates locking a channel so that operations
// must be performed sequentially on a channel (but can be performed at
// the same time on different channels).
func (pm *Manager) accessorByFromTo(from address.Address, to address.Address) (*channelAccessor, error) {
key := pm.accessorCacheKey(from, to)
// First take a read lock and check the cache
pm.lk.RLock()
ca, ok := pm.channels[key]
pm.lk.RUnlock()
if ok {
return ca, nil
}
// Not in cache, so take a write lock
pm.lk.Lock()
defer pm.lk.Unlock()
// Need to check cache again in case it was updated between releasing read
// lock and taking write lock
ca, ok = pm.channels[key]
if !ok {
// Not in cache, so create a new one and store in cache
ca = pm.addAccessorToCache(from, to)
}
return ca, nil
}
// accessorByAddress gets a channel accessor for a given channel address.
// The channel accessor facilitates locking a channel so that operations
// must be performed sequentially on a channel (but can be performed at
// the same time on different channels).
func (pm *Manager) accessorByAddress(ch address.Address) (*channelAccessor, error) {
// Get the channel from / to
pm.lk.RLock()
channelInfo, err := pm.store.ByAddress(ch)
pm.lk.RUnlock()
if err != nil {
return nil, err
}
// TODO: cache by channel address so we can get by address instead of using from / to
return pm.accessorByFromTo(channelInfo.Control, channelInfo.Target)
}
// accessorCacheKey returns the cache key use to reference a channel accessor
func (pm *Manager) accessorCacheKey(from address.Address, to address.Address) string {
return from.String() + "->" + to.String()
}
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// addAccessorToCache adds a channel accessor to the cache. Note that the
// channel may not have been created yet, but we still want to reference
// the same channel accessor for a given from/to, so that all attempts to
// access a channel use the same lock (the lock on the accessor)
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func (pm *Manager) addAccessorToCache(from address.Address, to address.Address) *channelAccessor {
key := pm.accessorCacheKey(from, to)
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ca := newChannelAccessor(pm, from, to)
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// TODO: Use LRU
pm.channels[key] = ca
return ca
}