Merge pull request #128 from rauljordan/database-mutex

Making In-Memory DB Concurrency Safe

Former-commit-id: b00313f451c42e8036a10f183e631e4fbefecbd7 [formerly ad726a9680547ce7249da09fda0fd1878cab0f0f]
Former-commit-id: aeaec82f64e64594282c4c18bd2151f4ab4b9c11

sharding/database/inmemory.go

@@ -5,13 +5,15 @@ package database
 
 import (
 	"fmt"
+	"sync"
 
 	"github.com/ethereum/go-ethereum/common"
 )
 
 // ShardKV is an in-memory mapping of hashes to RLP encoded values.
 type ShardKV struct {
-	kv map[common.Hash]*[]byte
+	kv   map[common.Hash]*[]byte
+	lock sync.RWMutex
 }
 
 // NewShardKV initializes a keyval store in memory.
@@ -21,6 +23,8 @@ func NewShardKV() *ShardKV {
 
 // Get fetches a val from the mappping by key.
 func (sb *ShardKV) Get(k common.Hash) (*[]byte, error) {
+	sb.lock.RLock()
+	defer sb.lock.RUnlock()
 	v, ok := sb.kv[k]
 	if !ok {
 		return nil, fmt.Errorf("key not found: %v", k)
@@ -30,12 +34,16 @@ func (sb *ShardKV) Get(k common.Hash) (*[]byte, error) {
 
 // Has checks if the key exists in the mapping.
 func (sb *ShardKV) Has(k common.Hash) bool {
+	sb.lock.RLock()
+	defer sb.lock.RUnlock()
 	v := sb.kv[k]
 	return v != nil
 }
 
 // Put updates a key's value in the mapping.
 func (sb *ShardKV) Put(k common.Hash, v []byte) error {
+	sb.lock.Lock()
+	defer sb.lock.Unlock()
 	// there is no error in a simple setting of a value in a go map.
 	sb.kv[k] = &v
 	return nil
@@ -43,6 +51,8 @@ func (sb *ShardKV) Put(k common.Hash, v []byte) error {
 
 // Delete removes the key and value from the mapping.
 func (sb *ShardKV) Delete(k common.Hash) error {
+	sb.lock.Lock()
+	defer sb.lock.Unlock()
 	// There is no return value for deleting a simple key in a go map.
 	delete(sb.kv, k)
 	return nil