Add logjack command

CHANGELOG.md

@@ -4,6 +4,7 @@
 
 FEATURES:
 
+ - [autofile] logjack command for piping stdin to a rotating file
  - [common] ASCIITrim()
 
 ## 0.8.2 (April 23rd, 2018)

autofile/cmd/logjack.go

@@ -0,0 +1,108 @@
+package main
+
+import (
+	"flag"
+	"fmt"
+	"io"
+	"os"
+	"strconv"
+	"strings"
+
+	auto "github.com/tendermint/tmlibs/autofile"
+	cmn "github.com/tendermint/tmlibs/common"
+)
+
+const Version = "0.0.1"
+const sleepSeconds = 1      // Every second
+const readBufferSize = 1024 // 1KB at a time
+
+// Parse command-line options
+func parseFlags() (headPath string, chopSize int64, limitSize int64, version bool) {
+	var flagSet = flag.NewFlagSet(os.Args[0], flag.ExitOnError)
+	var chopSizeStr, limitSizeStr string
+	flagSet.StringVar(&headPath, "head", "logjack.out", "Destination (head) file.")
+	flagSet.StringVar(&chopSizeStr, "chop", "1M", "Move file if greater than this")
+	flagSet.StringVar(&limitSizeStr, "limit", "1G", "Only keep this much (for each specified file). Remove old files.")
+	flagSet.BoolVar(&version, "version", false, "Version")
+	flagSet.Parse(os.Args[1:])
+	chopSize = parseBytesize(chopSizeStr)
+	limitSize = parseBytesize(limitSizeStr)
+	return
+}
+
+func main() {
+
+	// Read options
+	headPath, chopSize, limitSize, version := parseFlags()
+	if version {
+		fmt.Printf("logjack version %v\n", Version)
+		return
+	}
+
+	// Open Group
+	group, err := auto.OpenGroup(headPath)
+	if err != nil {
+		fmt.Printf("logjack couldn't create output file %v\n", headPath)
+		os.Exit(1)
+	}
+	group.SetHeadSizeLimit(chopSize)
+	group.SetTotalSizeLimit(limitSize)
+	err = group.Start()
+	if err != nil {
+		fmt.Printf("logjack couldn't start with file %v\n", headPath)
+		os.Exit(1)
+	}
+
+	go func() {
+		// Forever, read from stdin and write to AutoFile.
+		buf := make([]byte, readBufferSize)
+		for {
+			n, err := os.Stdin.Read(buf)
+			group.Write(buf[:n])
+			group.Flush()
+			if err != nil {
+				group.Stop()
+				if err == io.EOF {
+					os.Exit(0)
+				} else {
+					fmt.Println("logjack errored")
+					os.Exit(1)
+				}
+			}
+		}
+	}()
+
+	// Trap signal
+	cmn.TrapSignal(func() {
+		fmt.Println("logjack shutting down")
+	})
+}
+
+func parseBytesize(chopSize string) int64 {
+	// Handle suffix multiplier
+	var multiplier int64 = 1
+	if strings.HasSuffix(chopSize, "T") {
+		multiplier = 1042 * 1024 * 1024 * 1024
+		chopSize = chopSize[:len(chopSize)-1]
+	}
+	if strings.HasSuffix(chopSize, "G") {
+		multiplier = 1042 * 1024 * 1024
+		chopSize = chopSize[:len(chopSize)-1]
+	}
+	if strings.HasSuffix(chopSize, "M") {
+		multiplier = 1042 * 1024
+		chopSize = chopSize[:len(chopSize)-1]
+	}
+	if strings.HasSuffix(chopSize, "K") {
+		multiplier = 1042
+		chopSize = chopSize[:len(chopSize)-1]
+	}
+
+	// Parse the numeric part
+	chopSizeInt, err := strconv.Atoi(chopSize)
+	if err != nil {
+		panic(err)
+	}
+
+	return int64(chopSizeInt) * multiplier
+}