use reader interface insteead of string copies (decreases memory footprint)

bird/bird.go

@@ -1,7 +1,9 @@
 package bird
 
 import (
+	"bytes"
 	"fmt"
+	"io"
 	"reflect"
 	"strings"
 	"sync"
@@ -53,10 +55,16 @@ func toCache(key string, val Parsed) {
 	Cache.Unlock()
 }
 
-func Run(args string) ([]byte, error) {
+func Run(args string) (io.Reader, error) {
 	args = "show " + args
 	argsList := strings.Split(args, " ")
-	return exec.Command(ClientConf.BirdCmd, argsList...).Output()
+
+	out, err := exec.Command(ClientConf.BirdCmd, argsList...).Output()
+	if err != nil {
+		return nil, err
+	}
+
+	return bytes.NewReader(out), nil
 }
 
 func InstallRateLimitReset() {
@@ -93,7 +101,7 @@ func checkRateLimit() bool {
 	return true
 }
 
-func RunAndParse(cmd string, parser func([]byte) Parsed) (Parsed, bool) {
+func RunAndParse(cmd string, parser func(io.Reader) Parsed) (Parsed, bool) {
 	if val, ok := fromCache(cmd); ok {
 		return val, true
 	}

bird/parser.go

@@ -2,6 +2,7 @@ package bird
 
 import (
 	"bufio"
+	"io"
 	"regexp"
 	"strconv"
 	"strings"
@@ -93,44 +94,32 @@ func emptyLine(line string) bool {
 	return len(strings.TrimSpace(line)) == 0
 }
 
-func getLinesUnfiltered(input string) []string {
-	lines := make([]string, 0)
+func getLines(reader io.Reader, excludeFilter func(string) bool) []string {
+	lines := []string{}
 
-	reader := strings.NewReader(input)
 	scanner := bufio.NewScanner(reader)
-
 	for scanner.Scan() {
+		if excludeFilter != nil && excludeFilter(scanner.Text()) {
+			continue
+		}
+
 		lines = append(lines, scanner.Text())
 	}
 
 	return lines
 }
 
-func getLinesFromString(input string) []string {
-	lines := getLinesUnfiltered(input)
-
-	var filtered []string
-
-	for _, line := range lines {
-		if !emptyLine(line) {
-			filtered = append(filtered, line)
-		}
-	}
-
-	return filtered
-}
-
-func getLines(input []byte) []string {
-	return getLinesFromString(string(input))
+func getNonEmptyLines(reader io.Reader) []string {
+	return getLines(reader, emptyLine)
 }
 
 func specialLine(line string) bool {
 	return (strings.HasPrefix(line, "BIRD") || strings.HasPrefix(line, "Access restricted"))
 }
 
-func parseStatus(input []byte) Parsed {
+func parseStatus(reader io.Reader) Parsed {
 	res := Parsed{}
-	lines := getLines(input)
+	lines := getNonEmptyLines(reader)
 
 	for _, line := range lines {
 		if regex.status.startLine.MatchString(line) {
@@ -157,10 +146,10 @@ func parseStatus(input []byte) Parsed {
 	return Parsed{"status": res}
 }
 
-func parseProtocols(input []byte) Parsed {
+func parseProtocols(reader io.Reader) Parsed {
 	res := Parsed{}
 	protocols := []string{}
-	lines := getLinesUnfiltered(string(input))
+	lines := getLines(reader, nil)
 
 	proto := ""
 	for _, line := range lines {
@@ -178,9 +167,9 @@ func parseProtocols(input []byte) Parsed {
 	return res
 }
 
-func parseSymbols(input []byte) Parsed {
+func parseSymbols(reader io.Reader) Parsed {
 	res := Parsed{}
-	lines := getLines(input)
+	lines := getNonEmptyLines(reader)
 
 	for _, line := range lines {
 		if specialLine(line) {
@@ -196,9 +185,9 @@ func parseSymbols(input []byte) Parsed {
 	return Parsed{"symbols": res}
 }
 
-func parseRoutes(input []byte) Parsed {
+func parseRoutes(reader io.Reader) Parsed {
 	res := Parsed{}
-	lines := getLines(input)
+	lines := getNonEmptyLines(reader)
 
 	routes := []Parsed{}
 	route := Parsed{}
@@ -325,9 +314,9 @@ func parseRoutesLargeCommunities(groups []string, res Parsed) {
 	res["large_communities"] = communities
 }
 
-func parseRoutesCount(input []byte) Parsed {
+func parseRoutesCount(reader io.Reader) Parsed {
 	res := Parsed{}
-	lines := getLines(input)
+	lines := getNonEmptyLines(reader)
 
 	for _, line := range lines {
 		if specialLine(line) {
@@ -351,7 +340,7 @@ func isCorrectChannel(currentIPVersion string) bool {
 	return currentIPVersion == IPVersion
 }
 
-func parseBgp(input string) Parsed {
+func parseBgp(lines string) Parsed {
 	res := Parsed{}
 	routeChanges := Parsed{}
 
@@ -366,9 +355,13 @@ func parseBgp(input string) Parsed {
 		func(l string) bool { return parseBgpStringValuesRx(l, res) },
 	}
 
-	lines := getLinesFromString(input)
 	ipVersion := ""
-	for _, line := range lines {
+
+	reader := strings.NewReader(lines)
+	scanner := bufio.NewScanner(reader)
+	for scanner.Scan() {
+		line := scanner.Text()
+
 		if m := regex.bgp.channel.FindStringSubmatch(line); len(m) > 0 {
 			ipVersion = m[1]
 		}

bird/parser_test.go

@@ -1,15 +1,14 @@
 package bird
 
 import (
-	"fmt"
-	"io/ioutil"
+	"os"
 	"reflect"
 	"testing"
 )
 
-func readSampleData(filename string) ([]byte, error) {
+func openFile(filename string) (*os.File, error) {
 	sample := "../test/" + filename
-	return ioutil.ReadFile(sample)
+	return os.Open(sample)
 }
 
 func TestParseBgpRoutes(t *testing.T) {
@@ -42,12 +41,13 @@ func TestParseBgpRoutes(t *testing.T) {
 }
 
 func TestParseRoutesAll(t *testing.T) {
-	sample, err := readSampleData("routes_bird1_ipv4.sample")
+	f, err := openFile("routes_bird1_ipv4.sample")
 	if err != nil {
 		t.Error(err)
 	}
+	defer f.Close()
 
-	result := parseRoutes(sample)
+	result := parseRoutes(f)
 	routes, ok := result["routes"].([]Parsed)
 	if !ok {
 		t.Error("Error getting routes")
@@ -135,13 +135,14 @@ func TestParseRoutesAllBird2(t *testing.T) {
 	runTestForIpv6WithTemplate("routes_bird2_ipv6.sample", t)
 }
 
-func runTestForIpv6WithTemplate(template string, t *testing.T) {
-	sample, err := readSampleData(template)
+func runTestForIpv6WithTemplate(file string, t *testing.T) {
+	f, err := openFile(file)
 	if err != nil {
 		t.Error(err)
 	}
+	defer f.Close()
 
-	result := parseRoutes(sample)
+	result := parseRoutes(f)
 	routes, ok := result["routes"].([]Parsed)
 	if !ok {
 		t.Fatal("Error getting routes")
@@ -151,8 +152,6 @@ func runTestForIpv6WithTemplate(template string, t *testing.T) {
 		t.Fatal("Expected 3 routes but got ", len(routes))
 	}
 
-	fmt.Println(routes[1])
-
 	assertRouteIsEqual(expectedRoute{
 		network: "2001:4860::/32",
 		gateway: "fe80:ffff:ffff::1",