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caching.go
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caching.go
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package blockstore
import (
"errors"
context "gx/ipfs/QmZy2y8t9zQH2a1b8q2ZSLKp17ATuJoCNxxyMFG5qFExpt/go-net/context"
)
// Next to each option is it aproximate memory usage per unit
type CacheOpts struct {
HasBloomFilterSize int // 1 byte
HasBloomFilterHashes int // No size, 7 is usually best, consult bloom papers
HasARCCacheSize int // 32 bytes
}
func DefaultCacheOpts() CacheOpts {
return CacheOpts{
HasBloomFilterSize: 512 << 10,
HasBloomFilterHashes: 7,
HasARCCacheSize: 64 << 10,
}
}
func CachedBlockstore(bs GCBlockstore,
ctx context.Context, opts CacheOpts) (cbs GCBlockstore, err error) {
cbs = bs
if opts.HasBloomFilterSize < 0 || opts.HasBloomFilterHashes < 0 ||
opts.HasARCCacheSize < 0 {
return nil, errors.New("all options for cache need to be greater than zero")
}
if opts.HasBloomFilterSize != 0 && opts.HasBloomFilterHashes == 0 {
return nil, errors.New("bloom filter hash count can't be 0 when there is size set")
}
if opts.HasBloomFilterSize != 0 {
// *8 because of bytes to bits conversion
cbs, err = bloomCached(cbs, ctx, opts.HasBloomFilterSize*8, opts.HasBloomFilterHashes)
}
if opts.HasARCCacheSize > 0 {
cbs, err = arcCached(cbs, opts.HasARCCacheSize)
}
return cbs, err
}