eth: add debug_accountRange rpc call

eth/api.go

@@ -17,6 +17,7 @@
 package eth
 
 import (
+	"bytes"
 	"compress/gzip"
 	"context"
 	"errors"
@@ -334,6 +335,70 @@ func (api *PrivateDebugAPI) GetBadBlocks(ctx context.Context) ([]*BadBlockArgs,
 	return results, nil
 }
 
+type AccountRangeResult struct {
+	Preimages []common.Hash               `json:"preimages"`
+	Next      common.Hash                 `json:"nextKey"`
+}
+
+func accountRange(st state.Trie, start *common.Hash, maxResults int) (AccountRangeResult, error) {
+	it := trie.NewIterator(st.NodeIterator(start[:]))
+	result := AccountRangeResult{Preimages: []common.Hash{}, Next: common.Hash{}}
+	zeros := make([]byte, common.HashLength)
+
+	if bytes.Equal(start.Bytes()[:], zeros) {
+		start = nil
+	}
+
+	if maxResults > 100 {
+		maxResults = 100
+	}
+
+	// dont return the first account preimage
+	if !it.Next() && start != &(common.Hash{}) {
+		return result, nil
+	}
+
+	for i := 0; i < maxResults-1 && it.Next(); i++ {
+		result.Preimages = append(result.Preimages, common.BytesToHash(it.Key))
+	}
+
+	if it.Next() {
+		result.Next = common.BytesToHash(it.Key)
+	}
+
+	return result, nil
+}
+
+//enumerate and return account preimages in the state at the current block
+func (api *PrivateDebugAPI) AccountRange(ctx context.Context, startAddr *common.Hash, maxResults int) (AccountRangeResult, error) {
+	var statedb *state.StateDB = nil
+	var err error = nil
+	var block = api.eth.blockchain.CurrentBlock()
+
+	if len(block.Transactions()) == 0 {
+		parent := api.eth.blockchain.GetBlock(block.ParentHash(), block.NumberU64()-1)
+		if parent == nil {
+			return AccountRangeResult{}, fmt.Errorf("parent %x not found", block.ParentHash())
+		}
+		statedb, err = api.computeStateDB(parent, defaultTraceReexec)
+		if err != nil {
+			return AccountRangeResult{}, err
+		}
+	} else {
+		_, _, statedb, err = api.computeTxEnv(block.Hash(), len(block.Transactions())-1, 0)
+		if err != nil {
+			return AccountRangeResult{}, err
+		}
+	}
+
+	trie, err := statedb.Database().OpenTrie(block.Header().Root)
+	if err != nil {
+		return AccountRangeResult{}, err
+	}
+
+	return accountRange(trie, startAddr, maxResults)
+}
+
 // StorageRangeResult is the result of a debug_storageRangeAt API call.
 type StorageRangeResult struct {
 	Storage storageMap   `json:"storage"`

eth/api_test.go

@@ -19,7 +19,9 @@ package eth
 import (
 	"reflect"
 	"testing"
+        "math/big"
 
+        "github.com/ethereum/go-ethereum/crypto"
 	"github.com/davecgh/go-spew/spew"
 	"github.com/ethereum/go-ethereum/common"
 	"github.com/ethereum/go-ethereum/core/rawdb"
@@ -28,6 +30,51 @@ import (
 
 var dumper = spew.ConfigState{Indent: "    "}
 
+func TestAccountRange(t *testing.T) {
+        state, _ := state.New(common.Hash{}, state.NewDatabase(ethdb.NewMemDatabase()))
+        expectedPreimages := make(map[common.Hash]interface{})
+
+        // create some accounts
+        for i := 0; i < 256; i++ {
+                address := common.Address{byte(i)}
+                obj := state.GetOrNewStateObject(address)
+                expectedPreimages[crypto.Keccak256Hash(address.Bytes())] = true
+                obj.AddBalance(big.NewInt(22))
+                obj.SetCode(crypto.Keccak256Hash([]byte{3, 3, 3, 3, 3, 3, 3}), []byte{3, 3, 3, 3, 3, 3, 3})
+
+                //root = state.Commit(false)
+        }
+
+        root, err := state.Commit(false)
+        if err != nil {
+                t.Fatalf("%s", err)
+        }
+
+        state.Finalise(false)
+
+        trie, err := state.Database().OpenTrie(root)
+        if err != nil {
+                t.Fatalf("%s", err)
+        }
+
+        zeroHash := crypto.Keccak256Hash(common.Hash{}.Bytes())
+        result, err := accountRange(trie, &zeroHash, 256)
+        if err != nil {
+                t.Fatalf("%s", err)
+        }
+
+        if len(result.Preimages) != 99 {
+                t.Fatalf("maximum number of results returned should be 99, returned %d", len(result.Preimages))
+        }
+
+        for _, v := range result.Preimages {
+                if _, ok := expectedPreimages[v]; !ok {
+                        t.Fatalf("expected to find preimage %s in result", v.String())
+                }
+        }
+
+}
+
 func TestStorageRangeAt(t *testing.T) {
 	// Create a state where account 0x010000... has a few storage entries.
 	var (