Initial implementation of DEXON consensus algorithm

2 files changed, 144 insertions, 0 deletions

diff --git a/blockdb/interfaces.go b/blockdb/interfaces.go
new file mode 100644
index 0000000..4d35e2e
--- /dev/null
+++ b/blockdb/interfaces.go
@@ -0,0 +1,59 @@
+// Copyright 2018 The dexon-consensus-core Authors
+// This file is part of the dexon-consensus-core library.
+//
+// The dexon-consensus-core library is free software: you can redistribute it
+// and/or modify it under the terms of the GNU Lesser General Public License as
+// published by the Free Software Foundation, either version 3 of the License,
+// or (at your option) any later version.
+//
+// The dexon-consensus-core library is distributed in the hope that it will be
+// useful, but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser
+// General Public License for more details.
+//
+// You should have received a copy of the GNU Lesser General Public License
+// along with the dexon-consensus-core library. If not, see
+// <http://www.gnu.org/licenses/>.
+
+package blockdb
+
+import (
+	"errors"
+
+	"github.com/dexon-foundation/dexon-consensus-core/common"
+	"github.com/dexon-foundation/dexon-consensus-core/core/types"
+)
+
+var (
+	// ErrBlockExists is the error when block eixsts.
+	ErrBlockExists = errors.New("block exists")
+	// ErrBlockDoesNotExist is the error when block does not eixsts.
+	ErrBlockDoesNotExist = errors.New("block does not exist")
+	// ErrValidatorDoesNotExist is the error when validator does not eixsts.
+	ErrValidatorDoesNotExist = errors.New("validator does not exist")
+)
+
+// BlockDatabase is the interface for a BlockDatabse.
+type BlockDatabase interface {
+	Reader
+	Writer
+	Deleter
+}
+
+// Reader defines the interface for reading blocks into DB.
+type Reader interface {
+	Has(hash common.Hash) bool
+	Get(hash common.Hash) (types.Block, error)
+	GetByValidatorAndHeight(vID types.ValidatorID, height uint64) (types.Block, error)
+}
+
+// Writer defines the interface for writing blocks into DB.
+type Writer interface {
+	Update(block types.Block) error
+	Put(block types.Block) error
+}
+
+// Deleter defines the interface for deleting blocks in the DB.
+type Deleter interface {
+	Delete(hash common.Hash)
+}
diff --git a/blockdb/memory.go b/blockdb/memory.go
new file mode 100644
index 0000000..fd62b71
--- /dev/null
+++ b/blockdb/memory.go
@@ -0,0 +1,85 @@
+// Copyright 2018 The dexon-consensus-core Authors
+// This file is part of the dexon-consensus-core library.
+//
+// The dexon-consensus-core library is free software: you can redistribute it
+// and/or modify it under the terms of the GNU Lesser General Public License as
+// published by the Free Software Foundation, either version 3 of the License,
+// or (at your option) any later version.
+//
+// The dexon-consensus-core library is distributed in the hope that it will be
+// useful, but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser
+// General Public License for more details.
+//
+// You should have received a copy of the GNU Lesser General Public License
+// along with the dexon-consensus-core library. If not, see
+// <http://www.gnu.org/licenses/>.
+
+package blockdb
+
+import (
+	"github.com/dexon-foundation/dexon-consensus-core/common"
+	"github.com/dexon-foundation/dexon-consensus-core/core/types"
+)
+
+// MemBackendBlockDB is a memory bakcend BlockDB implementation.
+type MemBackendBlockDB struct {
+	blocksByHash      map[common.Hash]*types.Block
+	blocksByValidator map[types.ValidatorID]map[uint64]*types.Block
+}
+
+// NewMemBackedBlockDB initialize a memory-backed block database.
+func NewMemBackedBlockDB() *MemBackendBlockDB {
+	return &MemBackendBlockDB{
+		blocksByHash:      make(map[common.Hash]*types.Block),
+		blocksByValidator: make(map[types.ValidatorID]map[uint64]*types.Block),
+	}
+}
+
+// Has returns wheter or not the DB has a block identified with the hash.
+func (m *MemBackendBlockDB) Has(hash common.Hash) bool {
+	_, ok := m.blocksByHash[hash]
+	return ok
+}
+
+// Get returns a block given a hash.
+func (m *MemBackendBlockDB) Get(hash common.Hash) (types.Block, error) {
+	b, ok := m.blocksByHash[hash]
+	if !ok {
+		return types.Block{}, ErrBlockDoesNotExist
+	}
+	return *b, nil
+}
+
+// GetByValidatorAndHeight returns a block given validator ID and hash.
+func (m *MemBackendBlockDB) GetByValidatorAndHeight(
+	vID types.ValidatorID, height uint64) (types.Block, error) {
+	validatorBlocks, ok := m.blocksByValidator[vID]
+	if !ok {
+		return types.Block{}, ErrValidatorDoesNotExist
+	}
+	block, ok2 := validatorBlocks[height]
+	if !ok2 {
+		return types.Block{}, ErrBlockDoesNotExist
+	}
+	return *block, nil
+}
+
+// Put inserts a new block into the database.
+func (m *MemBackendBlockDB) Put(block types.Block) error {
+	if m.Has(block.Hash) {
+		return ErrBlockExists
+	}
+	return m.Update(block)
+}
+
+// Update updates a block in the database.
+func (m *MemBackendBlockDB) Update(block types.Block) error {
+	m.blocksByHash[block.Hash] = &block
+	return nil
+}
+
+// Delete deletes a block in the database.
+func (m *MemBackendBlockDB) Delete(hash common.Hash) {
+	delete(m.blocksByHash, hash)
+}