Merge "[FAB-702] - Add gossip node metastate object"

gossip/state/metastate.go

@@ -0,0 +1,72 @@
+/*
+Copyright IBM Corp. 2016 All Rights Reserved.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+		 http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package state
+
+import (
+	"bytes"
+	"encoding/binary"
+)
+
+// Metadata information to store the information about current
+// height of the ledger (last accepted block sequence number).
+type NodeMetastate struct {
+
+	// Actual ledger height
+	LedgerHeight uint64
+}
+
+// Create new meta data with given ledger height148.69
+func NewNodeMetastate(height uint64) *NodeMetastate {
+	return &NodeMetastate{height}
+}
+
+// Decodes meta state into byte array for serialization
+func (n *NodeMetastate) Bytes() ([]byte, error) {
+	buffer := new(bytes.Buffer)
+	// Explicitly specify byte order for write into the buffer
+	// to provide cross platform support, note the it consistent
+	// with FromBytes function
+	err := binary.Write(buffer, binary.BigEndian, *n)
+	if err != nil {
+		return nil, err
+	}
+	return buffer.Bytes(), nil
+}
+
+// Get ledger height from the state
+func (n *NodeMetastate) Height() uint64 {
+	return n.LedgerHeight
+}
+
+// Update state with new ledger height
+func (n *NodeMetastate) Update(height uint64) {
+	n.LedgerHeight = height
+}
+
+// Encode from byte array into meta data structure
+func FromBytes(buf []byte) (*NodeMetastate, error) {
+	state  := NodeMetastate{}
+	reader := bytes.NewReader(buf)
+	// As bytes are written in the big endian to keep supporting
+	// cross platforming and for consistency reasons read also
+	// done using same order
+	err := binary.Read(reader, binary.BigEndian, &state)
+	if err != nil {
+		return nil, err
+	}
+	return &state, nil
+}

gossip/state/metastate_test.go

@@ -0,0 +1,74 @@
+/*
+Copyright IBM Corp. 2016 All Rights Reserved.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+		 http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package state
+
+import (
+	"testing"
+	"github.com/docker/docker/pkg/testutil/assert"
+)
+
+func TestNewNodeMetastate(t *testing.T) {
+	metastate := NewNodeMetastate(0)
+	assert.Equal(t, metastate.Height(), uint64(0))
+}
+
+func TestNodeMetastateImpl_Update(t *testing.T) {
+	metastate := NewNodeMetastate(0)
+	assert.Equal(t, metastate.Height(), uint64(0))
+	metastate.Update(10)
+	assert.Equal(t, metastate.Height(), uint64(10))
+}
+
+// Test node metastate encoding
+func TestNodeMetastateImpl_Bytes(t *testing.T) {
+	metastate := NewNodeMetastate(0)
+	// Encode state into bytes and check there is no errors
+	_, err := metastate.Bytes()
+	assert.NilError(t, err)
+}
+
+// Check the deserialization of the meta stats structure
+func TestNodeMetastate_FromBytes(t *testing.T) {
+	metastate := NewNodeMetastate(0)
+	// Serialize into bytes array
+	bytes, err := metastate.Bytes()
+	assert.NilError(t, err)
+	if bytes == nil {
+		t.Fatal("Was not able to serialize meta state into byte array.")
+	}
+
+	// Deserialize back and check, that state still have same
+	// height value
+	state, err := FromBytes(bytes)
+	assert.NilError(t, err)
+
+	assert.Equal(t, state.Height(), uint64(0))
+
+	// Update state to the new height and serialize it again
+	state.Update(17)
+	bytes, err = state.Bytes()
+	assert.NilError(t, err)
+	if bytes == nil {
+		t.Fatal("Was not able to serialize meta state into byte array.")
+	}
+
+	// Restore state from byte array and validate
+	// that stored height is still the same
+	updatedState, err := FromBytes(bytes)
+	assert.NilError(t, err)
+	assert.Equal(t, updatedState.Height(), uint64(17))
+}