core, eth/filters, miner, xeth: Optimised log filtering

Log filtering is now using a MIPmap like approach where addresses of
logs are added to a mapped bloom bin. The current levels for the MIP are
in ranges of 1.000.000, 500.000, 100.000, 50.000, 1.000. Logs are
therefor filtered in batches of 1.000.

eth/backend_test.go

@@ -0,0 +1,67 @@
+package eth
+
+import (
+	"math/big"
+	"testing"
+
+	"github.com/ethereum/go-ethereum/common"
+	"github.com/ethereum/go-ethereum/core"
+	"github.com/ethereum/go-ethereum/core/types"
+	"github.com/ethereum/go-ethereum/core/vm"
+	"github.com/ethereum/go-ethereum/ethdb"
+)
+
+func TestMipmapUpgrade(t *testing.T) {
+	db, _ := ethdb.NewMemDatabase()
+	addr := common.BytesToAddress([]byte("jeff"))
+	genesis := core.WriteGenesisBlockForTesting(db)
+
+	chain := core.GenerateChain(genesis, db, 10, func(i int, gen *core.BlockGen) {
+		var receipts types.Receipts
+		switch i {
+		case 1:
+			receipt := types.NewReceipt(nil, new(big.Int))
+			receipt.SetLogs(vm.Logs{&vm.Log{Address: addr}})
+			gen.AddUncheckedReceipt(receipt)
+			receipts = types.Receipts{receipt}
+		case 2:
+			receipt := types.NewReceipt(nil, new(big.Int))
+			receipt.SetLogs(vm.Logs{&vm.Log{Address: addr}})
+			gen.AddUncheckedReceipt(receipt)
+			receipts = types.Receipts{receipt}
+		}
+
+		// store the receipts
+		err := core.PutReceipts(db, receipts)
+		if err != nil {
+			t.Fatal(err)
+		}
+	})
+	for _, block := range chain {
+		core.WriteBlock(db, block)
+		if err := core.WriteCanonicalHash(db, block.Hash(), block.NumberU64()); err != nil {
+			t.Fatalf("failed to insert block number: %v", err)
+		}
+		if err := core.WriteHeadBlockHash(db, block.Hash()); err != nil {
+			t.Fatalf("failed to insert block number: %v", err)
+		}
+		if err := core.PutBlockReceipts(db, block, block.Receipts()); err != nil {
+			t.Fatal("error writing block receipts:", err)
+		}
+	}
+
+	err := addMipmapBloomBins(db)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	bloom := core.GetMipmapBloom(db, 1, core.MIPMapLevels[0])
+	if (bloom == types.Bloom{}) {
+		t.Error("got empty bloom filter")
+	}
+
+	data, _ := db.Get([]byte("setting-mipmap-version"))
+	if len(data) == 0 {
+		t.Error("setting-mipmap-version not written to database")
+	}
+}