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package core
import (
"sync"
"github.com/ethereum/go-ethereum/common"
"github.com/ethereum/go-ethereum/core/types"
)
// BlockCache implements a caching mechanism specifically for blocks and uses FILO to pop
type BlockCache struct {
size int
hashes []common.Hash
blocks map[common.Hash]*types.Block
mu sync.RWMutex
}
// Creates and returns a `BlockCache` with `size`. If `size` is smaller than 1 it will panic
func NewBlockCache(size int) *BlockCache {
if size < 1 {
panic("block cache size not allowed to be smaller than 1")
}
bc := &BlockCache{size: size}
bc.Clear()
return bc
}
func (bc *BlockCache) Clear() {
bc.blocks = make(map[common.Hash]*types.Block)
bc.hashes = nil
}
func (bc *BlockCache) Push(block *types.Block) {
bc.mu.Lock()
defer bc.mu.Unlock()
if len(bc.hashes) == bc.size {
delete(bc.blocks, bc.hashes[0])
// XXX There are a few other options on solving this
// 1) use a poller / GC like mechanism to clean up untracked objects
// 2) copy as below
// re-use the slice and remove the reference to bc.hashes[0]
// this will allow the element to be garbage collected.
copy(bc.hashes, bc.hashes[1:])
} else {
bc.hashes = append(bc.hashes, common.Hash{})
}
hash := block.Hash()
bc.blocks[hash] = block
bc.hashes[len(bc.hashes)-1] = hash
}
func (bc *BlockCache) Delete(hash common.Hash) {
bc.mu.Lock()
defer bc.mu.Unlock()
if _, ok := bc.blocks[hash]; ok {
delete(bc.blocks, hash)
for i, h := range bc.hashes {
if hash == h {
bc.hashes = bc.hashes[:i+copy(bc.hashes[i:], bc.hashes[i+1:])]
// or ? => bc.hashes = append(bc.hashes[:i], bc.hashes[i+1]...)
break
}
}
}
}
func (bc *BlockCache) Get(hash common.Hash) *types.Block {
bc.mu.RLock()
defer bc.mu.RUnlock()
if block, haz := bc.blocks[hash]; haz {
return block
}
return nil
}
func (bc *BlockCache) Has(hash common.Hash) bool {
bc.mu.RLock()
defer bc.mu.RUnlock()
_, ok := bc.blocks[hash]
return ok
}
func (bc *BlockCache) Each(cb func(int, *types.Block)) {
bc.mu.Lock()
defer bc.mu.Unlock()
i := 0
for _, block := range bc.blocks {
cb(i, block)
i++
}
}
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