libs: Call Flush() before rename #2428 (#2439)

* fix Group.RotateFile need call Flush() before rename. #2428
* fix some review issue. #2428
 refactor Group's config: replace  setting member with initial option
* fix a handwriting mistake
* fix a time window error between rename and write.
* fix a syntax mistake.
* change option name Get_ to With_
* fix review issue
* fix review issue

consensus/wal_test.go

@@ -4,11 +4,16 @@ import (
 	"bytes"
 	"crypto/rand"
 	"fmt"
+	"io/ioutil"
+	"os"
+	"path/filepath"
+
 	// "sync"
 	"testing"
 	"time"
 
 	"github.com/tendermint/tendermint/consensus/types"
+	"github.com/tendermint/tendermint/libs/autofile"
 	tmtypes "github.com/tendermint/tendermint/types"
 	tmtime "github.com/tendermint/tendermint/types/time"
 
@@ -16,6 +21,51 @@ import (
 	"github.com/stretchr/testify/require"
 )
 
+func TestWALTruncate(t *testing.T) {
+	walDir, err := ioutil.TempDir("", "wal")
+	if err != nil {
+		panic(fmt.Errorf("failed to create temp WAL file: %v", err))
+	}
+	defer os.RemoveAll(walDir)
+
+	walFile := filepath.Join(walDir, "wal")
+
+	//this magic number 4K can truncate the content when RotateFile. defaultHeadSizeLimit(10M) is hard to simulate.
+	//this magic number 1 * time.Millisecond make RotateFile check frequently. defaultGroupCheckDuration(5s) is hard to simulate.
+	wal, err := NewWAL(walFile, autofile.GroupHeadSizeLimit(4096), autofile.GroupCheckDuration(1*time.Millisecond))
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	wal.Start()
+	defer wal.Stop()
+
+	//60 block's size nearly 70K, greater than group's headBuf size(4096 * 10), when headBuf is full, truncate content will Flush to the file.
+	//at this time, RotateFile is called, truncate content exist in each file.
+	err = WALGenerateNBlocks(wal.Group(), 60)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	time.Sleep(1 * time.Millisecond) //wait groupCheckDuration, make sure RotateFile run
+
+	wal.Group().Flush()
+
+	h := int64(50)
+	gr, found, err := wal.SearchForEndHeight(h, &WALSearchOptions{})
+	assert.NoError(t, err, fmt.Sprintf("expected not to err on height %d", h))
+	assert.True(t, found, fmt.Sprintf("expected to find end height for %d", h))
+	assert.NotNil(t, gr, "expected group not to be nil")
+	defer gr.Close()
+
+	dec := NewWALDecoder(gr)
+	msg, err := dec.Decode()
+	assert.NoError(t, err, "expected to decode a message")
+	rs, ok := msg.Msg.(tmtypes.EventDataRoundState)
+	assert.True(t, ok, "expected message of type EventDataRoundState")
+	assert.Equal(t, rs.Height, h+1, fmt.Sprintf("wrong height"))
+}
+
 func TestWALEncoderDecoder(t *testing.T) {
 	now := tmtime.Now()
 	msgs := []TimedWALMessage{