test: add test.Scheduler (#58)

When simulating execution of core.Consensus by passing packets through golang-channel or real-socket, we need to utilize time.Sleep and time.Now to simulate the required network/proposing latency. It's problematic when we try to test a simulation with long network latency.

Instead, Scheduler would try to execute the event with minimum timestamp, thus time.Sleep is replaced with Scheduler.nextTick, and time.Now is replaced with Event.Time.

Changes:
- Add test.Scheduler.
- Add test.Stopper interface to provide encapsulate different stop conditions for scheduler.
- Add a reference implementation for test.Stopper, it will stop scheduler when all validators confirmed X blocks proposed from themselves.
- Add a test scenario on core.Consensus that all validators are not byzantine.

1 files changed, 76 insertions, 0 deletions

diff --git a/core/test/scheduler-event.go b/core/test/scheduler-event.go
new file mode 100644
index 0000000..60411b4
--- /dev/null
+++ b/core/test/scheduler-event.go
@@ -0,0 +1,76 @@
+// 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 (
+	"time"
+
+	"github.com/dexon-foundation/dexon-consensus-core/core/types"
+)
+
+// Event defines a scheduler event.
+type Event struct {
+	// ValidatorID is the ID of handler that this event deginated to.
+	ValidatorID types.ValidatorID
+	// Time is the expected execution time of this event.
+	Time time.Time
+	// ExecError record the error when handling this event.
+	ExecError error
+	// Payload is application specific data carried by this event.
+	Payload interface{}
+	// ParentTime is the time of parent event, this field is essential when
+	// we need to calculate the latency the handler assigned.
+	ParentTime time.Time
+	// ExecInterval is the latency to execute this event
+	ExecInterval time.Duration
+}
+
+// eventQueue implements heap.Interface.
+type eventQueue []*Event
+
+func (eq eventQueue) Len() int { return len(eq) }
+
+func (eq eventQueue) Less(i, j int) bool {
+	return eq[i].Time.Before(eq[j].Time)
+}
+
+func (eq eventQueue) Swap(i, j int) {
+	eq[i], eq[j] = eq[j], eq[i]
+}
+
+func (eq *eventQueue) Push(x interface{}) {
+	*eq = append(*eq, x.(*Event))
+}
+
+func (eq *eventQueue) Pop() interface{} {
+	pos := len(*eq) - 1
+	item := (*eq)[pos]
+	*eq = (*eq)[0:pos]
+	return item
+}
+
+// NewEvent is the constructor for Event.
+func NewEvent(
+	vID types.ValidatorID, when time.Time, payload interface{}) *Event {
+
+	return &Event{
+		ValidatorID: vID,
+		Time:        when,
+		Payload:     payload,
+	}
+}