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