// Get can be called from any goroutine to retrieve the chunk referenced by hash. If the chunk is not present, Get returns the empty Chunk.
func (p *orderedChunkCache) Get(hash hash.Hash) chunks.Chunk {
// Don't use defer p.mu.RUnlock() here, because I want reading from orderedChunks NOT to be guarded by the lock. LevelDB handles its own goroutine-safety.
p.mu.RLock()
dbKey, ok := p.chunkIndex[hash]
p.mu.RUnlock()
if !ok {
return chunks.EmptyChunk
}
compressed, err := p.orderedChunks.Get(dbKey, nil)
d.Chk.NoError(err)
data, err := snappy.Decode(nil, compressed)
d.Chk.NoError(err)
return chunks.NewChunkWithHash(hash, data)
}
// ExtractChunks can be called from any goroutine to write Chunks referenced by the given hashes to w. The chunks are ordered by ref-height. Chunks of the same height are written in an unspecified order, relative to one another.
func (p *orderedChunkCache) ExtractChunks(hashes hash.HashSet, chunkChan chan *chunks.Chunk) error {
iter := p.orderedChunks.NewIterator(nil, nil)
defer iter.Release()
for iter.Next() {
_, hash := fromDbKey(iter.Key())
if !hashes.Has(hash) {
continue
}
compressed := iter.Value()
data, err := snappy.Decode(nil, compressed)
d.Chk.NoError(err)
c := chunks.NewChunkWithHash(hash, data)
chunkChan <- &c
}
return nil
}