test: add transport layer (#97)

The purpose of transport layer is to abstract the way to send messages and setup connections between peers in a p2p network. The peer discovery is simulated by a hosted server: every peer sends its address to a known server. Once collecting enough peers, respond the whole peers lists to all peers.

Changes:
- Add test.Trasnport interface
- Add test.Transport implementation by golang channel.
- Add test.transport implementation by TCP connection.
- Move LatencyModel to core/test package
- Add Marshaller interface

1 files changed, 54 insertions, 0 deletions

diff --git a/core/test/latency.go b/core/test/latency.go
new file mode 100644
index 0000000..0fe9277
--- /dev/null
+++ b/core/test/latency.go
@@ -0,0 +1,54 @@
+// 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 test
+
+import (
+	"math/rand"
+	"time"
+)
+
+// LatencyModel defines an interface to randomly decide latency
+// for one operation.
+type LatencyModel interface {
+	Delay() time.Duration
+}
+
+// NormalLatencyModel would return latencies in normal distribution.
+type NormalLatencyModel struct {
+	Sigma float64
+	Mean  float64
+}
+
+// Delay implements LatencyModel interface.
+func (m *NormalLatencyModel) Delay() time.Duration {
+	delay := rand.NormFloat64()*m.Sigma + m.Mean
+	if delay < 0 {
+		delay = m.Sigma / 2
+	}
+	return time.Duration(delay) * time.Millisecond
+}
+
+// FixedLatencyModel return fixed latencies.
+type FixedLatencyModel struct {
+	Latency float64
+}
+
+// Delay implements LatencyModel interface.
+func (m *FixedLatencyModel) Delay() time.Duration {
+	return time.Duration(m.Latency) * time.Millisecond
+}