[FAB-798] Factor out block cutting logic

This changeset removes the block cutting logic from solo and pushes it
into a common package to be reused by other components.

It is designed specifically to support applications which cannot utilize
a batch timer (Kafka) as well as applications for which cutting a block
does not imply committing it (SBFT).

Change-Id: Iea14eb1c4a030406cfe4a19f691464c2805b23ee
Signed-off-by: Jason Yellick <jyellick@us.ibm.com>

orderer/common/blockcutter/blockcutter.go

@@ -0,0 +1,131 @@
+/*
+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 blockcutter
+
+import (
+	"github.com/hyperledger/fabric/orderer/common/broadcastfilter"
+	"github.com/hyperledger/fabric/orderer/common/configtx"
+	cb "github.com/hyperledger/fabric/protos/common"
+
+	"github.com/golang/protobuf/proto"
+	"github.com/op/go-logging"
+)
+
+var logger = logging.MustGetLogger("orderer/common/blockcutter")
+
+func init() {
+	logging.SetLevel(logging.DEBUG, "")
+}
+
+// Target defines a sink for the ordered broadcast messages
+type Receiver interface {
+	// Ordered should be invoked sequentially as messages are ordered
+	// If the message is a valid normal message and does not fill the batch, nil, true is returned
+	// If the message is a valid normal message and fills a batch, the batch, true is returned
+	// If the message is a valid special message (like a config message) it terminates the current batch
+	// and returns the current batch (if it is not empty), plus a second batch containing the special transaction and true
+	// If the ordered message is determined to be invalid, then nil, false is returned
+	Ordered(msg *cb.Envelope) ([][]*cb.Envelope, bool)
+
+	// Cut returns the current batch and starts a new one
+	Cut() []*cb.Envelope
+}
+
+type receiver struct {
+	batchSize     int
+	filters       *broadcastfilter.RuleSet
+	configManager configtx.Manager
+	curBatch      []*cb.Envelope
+}
+
+func NewReceiverImpl(batchSize int, filters *broadcastfilter.RuleSet, configManager configtx.Manager) Receiver {
+	return &receiver{
+		batchSize:     batchSize,
+		filters:       filters,
+		configManager: configManager,
+	}
+}
+
+// Ordered should be invoked sequentially as messages are ordered
+// If the message is a valid normal message and does not fill the batch, nil, true is returned
+// If the message is a valid normal message and fills a batch, the batch, true is returned
+// If the message is a valid special message (like a config message) it terminates the current batch
+// and returns the current batch (if it is not empty), plus a second batch containing the special transaction and true
+// If the ordered message is determined to be invalid, then nil, false is returned
+func (r *receiver) Ordered(msg *cb.Envelope) ([][]*cb.Envelope, bool) {
+	// The messages must be filtered a second time in case configuration has changed since the message was received
+	action, _ := r.filters.Apply(msg)
+	switch action {
+	case broadcastfilter.Accept:
+		logger.Debugf("Enqueuing message into batch")
+		r.curBatch = append(r.curBatch, msg)
+
+		if len(r.curBatch) < r.batchSize {
+			return nil, true
+		}
+
+		logger.Debugf("Batch size met, creating block")
+		newBatch := r.curBatch
+		r.curBatch = nil
+		return [][]*cb.Envelope{newBatch}, true
+	case broadcastfilter.Reconfigure:
+		// TODO, this is unmarshaling for a second time, we need a cleaner interface, maybe Apply returns a second arg with thing to put in the batch
+		payload := &cb.Payload{}
+		if err := proto.Unmarshal(msg.Payload, payload); err != nil {
+			logger.Errorf("A change was flagged as configuration, but could not be unmarshaled: %v", err)
+			return nil, false
+		}
+		newConfig := &cb.ConfigurationEnvelope{}
+		if err := proto.Unmarshal(payload.Data, newConfig); err != nil {
+			logger.Errorf("A change was flagged as configuration, but could not be unmarshaled: %v", err)
+			return nil, false
+		}
+		err := r.configManager.Validate(newConfig)
+		if err != nil {
+			logger.Warningf("A configuration change made it through the ingress filter but could not be included in a batch: %v", err)
+			return nil, false
+		}
+
+		logger.Debugf("Configuration change applied successfully, committing previous block and configuration block")
+		firstBatch := r.curBatch
+		r.curBatch = nil
+		secondBatch := []*cb.Envelope{msg}
+		if firstBatch == nil {
+			return [][]*cb.Envelope{secondBatch}, true
+		} else {
+			return [][]*cb.Envelope{firstBatch, secondBatch}, true
+		}
+	case broadcastfilter.Reject:
+		logger.Debugf("Rejecting message")
+		return nil, false
+	case broadcastfilter.Forward:
+		logger.Debugf("Ignoring message because it was not accepted by a filter")
+		return nil, false
+	default:
+		logger.Fatalf("Received an unknown rule response: %v", action)
+	}
+
+	return nil, false // Unreachable
+
+}
+
+// Cut returns the current batch and starts a new one
+func (r *receiver) Cut() []*cb.Envelope {
+	batch := r.curBatch
+	r.curBatch = nil
+	return batch
+}