Added caching for block chain. Currently set to 10k

1 files changed, 68 insertions, 0 deletions

diff --git a/core/block_cache.go b/core/block_cache.go
new file mode 100644
index 000000000..321021eb4
--- /dev/null
+++ b/core/block_cache.go
@@ -0,0 +1,68 @@
+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) Get(hash common.Hash) *types.Block {
+	bc.mu.RLock()
+	defer bc.mu.RUnlock()
+
+	if block, haz := bc.blocks[hash]; haz {
+		return block
+	}
+
+	return nil
+}