util: encapsulate FakeTimeSource better

Firstly, need to have *util.FakeTimeSource implementing the util.TimeSource
interface, rather than util.FakeTimeSource, so the FakeTime value can
be changed.

Also, make it thread-safe.

examples/ct/handlers_test.go

@@ -53,7 +53,7 @@ var fakeTimeMillis = uint64(fakeTime.UnixNano() / millisPerNano)
 
 // The deadline should be the above bumped by 500ms
 var fakeDeadlineTime = time.Date(2016, 7, 22, 11, 01, 13, 500*1000*1000, time.UTC)
-var fakeTimeSource = util.FakeTimeSource{FakeTime: fakeTime}
+var fakeTimeSource = util.NewFakeTimeSource(fakeTime)
 
 const caCertB64 string = `MIIC0DCCAjmgAwIBAgIBADANBgkqhkiG9w0BAQUFADBVMQswCQYDVQQGEwJHQjEk
 MCIGA1UEChMbQ2VydGlmaWNhdGUgVHJhbnNwYXJlbmN5IENBMQ4wDAYDVQQIEwVX

log/sequencer_test.go

@@ -238,7 +238,7 @@ func createTestContext(ctrl *gomock.Controller, params testParameters) (testCont
 	}
 
 	signer := crypto.NewSHA256Signer(params.signer)
-	sequencer := NewSequencer(testonly.Hasher, util.FakeTimeSource{FakeTime: fakeTimeForTest}, mockStorage, signer)
+	sequencer := NewSequencer(testonly.Hasher, util.NewFakeTimeSource(fakeTimeForTest), mockStorage, signer)
 
 	return testContext{mockTx: mockTx, mockStorage: mockStorage, signer: signer, sequencer: sequencer}, context.Background()
 }

server/sequencer_manager_test.go

@@ -35,7 +35,7 @@ import (
 
 // Arbitrary time for use in tests
 var fakeTime = time.Date(2016, 6, 28, 13, 40, 12, 45, time.UTC)
-var fakeTimeSource = util.FakeTimeSource{FakeTime: fakeTime}
+var fakeTimeSource = util.NewFakeTimeSource(fakeTime)
 
 // We use a size zero tree for testing, Merkle tree state restore is tested elsewhere
 var testLogID1 = int64(1)

util/timesource.go

@@ -15,6 +15,7 @@
 package util
 
 import (
+	"sync"
 	"time"
 )
 
@@ -36,14 +37,28 @@ func (s SystemTimeSource) Now() time.Time {
 // FakeTimeSource provides a time that can be any arbitrarily set value for use in tests.
 // It should not be used in production code.
 type FakeTimeSource struct {
-	// FakeTime is the value that this fake time source will return. It is public so
-	// tests can manipulate it.
-	FakeTime time.Time
+	// fakeTime is the value that this fake time source will return.
+	mu       sync.Mutex
+	fakeTime time.Time
+}
+
+// NewFakeTimeSource creates a FakeTimeSource instance
+func NewFakeTimeSource(t time.Time) *FakeTimeSource {
+	return &FakeTimeSource{fakeTime: t}
 }
 
 // Now returns the time value this instance contains
-func (f FakeTimeSource) Now() time.Time {
-	return f.FakeTime
+func (f *FakeTimeSource) Now() time.Time {
+	f.mu.Lock()
+	defer f.mu.Unlock()
+	return f.fakeTime
+}
+
+// Set gives the time that this instance will report
+func (f *FakeTimeSource) Set(t time.Time) {
+	f.mu.Lock()
+	defer f.mu.Unlock()
+	f.fakeTime = t
 }
 
 // IncrementingFakeTimeSource takes a base time and several increments, which will be applied to

util/timesource_test.go

@@ -0,0 +1,38 @@
+// Copyright 2016 Google Inc. 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 util
+
+import (
+	"testing"
+	"time"
+)
+
+func TestFakeTimeSource(t *testing.T) {
+	date1 := time.Date(1970, 9, 19, 12, 00, 00, 00, time.UTC)
+	date2 := time.Date(2007, 7, 7, 11, 35, 00, 00, time.UTC)
+	fake := NewFakeTimeSource(date1)
+
+	// Check that a FakeTimeSource can be used as a TimeSource.
+	var ts TimeSource
+	ts = fake
+	if got, want := ts.Now(), date1; got != want {
+		t.Errorf("ts.Now=%v; want %v", got, want)
+	}
+
+	fake.Set(date2)
+	if got, want := ts.Now(), date2; got != want {
+		t.Errorf("ts.Now=%v; want %v", got, want)
+	}
+}