lnd.xprv/blockcache/blockcache.go

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package blockcache
import (
"github.com/btcsuite/btcd/chaincfg/chainhash"
"github.com/btcsuite/btcd/wire"
"github.com/btcsuite/btcutil"
"github.com/lightninglabs/neutrino/cache"
"github.com/lightninglabs/neutrino/cache/lru"
"github.com/lightningnetwork/lnd/lntypes"
"github.com/lightningnetwork/lnd/multimutex"
)
// BlockCache is an lru cache for blocks.
type BlockCache struct {
Cache *lru.Cache
HashMutex *multimutex.HashMutex
}
// NewBlockCache creates a new BlockCache with the given maximum capacity.
func NewBlockCache(capacity uint64) *BlockCache {
return &BlockCache{
Cache: lru.NewCache(capacity),
HashMutex: multimutex.NewHashMutex(),
}
}
// GetBlock first checks to see if the BlockCache already contains the block
// with the given hash. If it does then the block is fetched from the cache and
// returned. Otherwise the getBlockImpl function is used in order to fetch the
// new block and then it is stored in the block cache and returned.
func (bc *BlockCache) GetBlock(hash *chainhash.Hash,
getBlockImpl func(hash *chainhash.Hash) (*wire.MsgBlock,
error)) (*wire.MsgBlock, error) {
bc.HashMutex.Lock(lntypes.Hash(*hash))
defer bc.HashMutex.Unlock(lntypes.Hash(*hash))
// Create an inv vector for getting the block.
inv := wire.NewInvVect(wire.InvTypeWitnessBlock, hash)
// Check if the block corresponding to the given hash is already
// stored in the blockCache and return it if it is.
cacheBlock, err := bc.Cache.Get(*inv)
if err != nil && err != cache.ErrElementNotFound {
return nil, err
}
if cacheBlock != nil {
return cacheBlock.(*cache.CacheableBlock).MsgBlock(), nil
}
// Fetch the block from the chain backends.
block, err := getBlockImpl(hash)
if err != nil {
return nil, err
}
// Add the new block to blockCache. If the Cache is at its maximum
// capacity then the LFU item will be evicted in favour of this new
// block.
_, err = bc.Cache.Put(
*inv, &cache.CacheableBlock{
Block: btcutil.NewBlock(block),
},
)
if err != nil {
return nil, err
}
return block, nil
}