forked from mirror/gin
Reuse bytes when cleaning the URL paths (#2179)
* path: use stack buffer in CleanPath to avoid allocs in common case
Sync from 8222db13db
* path: sync test code from httprouter
* path: update path_test.go to the latest code
Co-authored-by: Bo-Yi Wu <appleboy.tw@gmail.com>
This commit is contained in:
parent
fd8a65b252
commit
025950afe9
33
path.go
33
path.go
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@ -5,6 +5,8 @@
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package gin
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package gin
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const stackBufSize = 128
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// cleanPath is the URL version of path.Clean, it returns a canonical URL path
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// cleanPath is the URL version of path.Clean, it returns a canonical URL path
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// for p, eliminating . and .. elements.
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// for p, eliminating . and .. elements.
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//
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//
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@ -24,8 +26,11 @@ func cleanPath(p string) string {
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return "/"
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return "/"
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}
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}
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// Reasonably sized buffer on stack to avoid allocations in the common case.
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// If a larger buffer is required, it gets allocated dynamically.
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buf := make([]byte, 0, stackBufSize)
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n := len(p)
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n := len(p)
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var buf []byte
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// Invariants:
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// Invariants:
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// reading from path; r is index of next byte to process.
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// reading from path; r is index of next byte to process.
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@ -37,7 +42,12 @@ func cleanPath(p string) string {
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if p[0] != '/' {
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if p[0] != '/' {
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r = 0
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r = 0
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buf = make([]byte, n+1)
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if n+1 > stackBufSize {
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buf = make([]byte, n+1)
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} else {
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buf = buf[:n+1]
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}
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buf[0] = '/'
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buf[0] = '/'
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}
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}
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@ -69,7 +79,7 @@ func cleanPath(p string) string {
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// can backtrack
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// can backtrack
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w--
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w--
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if buf == nil {
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if len(buf) == 0 {
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for w > 1 && p[w] != '/' {
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for w > 1 && p[w] != '/' {
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w--
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w--
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}
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}
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@ -103,7 +113,7 @@ func cleanPath(p string) string {
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w++
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w++
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}
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}
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if buf == nil {
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if len(buf) == 0 {
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return p[:w]
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return p[:w]
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}
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}
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return string(buf[:w])
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return string(buf[:w])
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@ -111,13 +121,20 @@ func cleanPath(p string) string {
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// internal helper to lazily create a buffer if necessary.
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// internal helper to lazily create a buffer if necessary.
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func bufApp(buf *[]byte, s string, w int, c byte) {
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func bufApp(buf *[]byte, s string, w int, c byte) {
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if *buf == nil {
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b := *buf
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if len(b) == 0 {
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if s[w] == c {
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if s[w] == c {
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return
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return
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}
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}
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*buf = make([]byte, len(s))
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if l := len(s); l > cap(b) {
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copy(*buf, s[:w])
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*buf = make([]byte, len(s))
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} else {
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*buf = (*buf)[:l]
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}
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b = *buf
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copy(b, s[:w])
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}
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}
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(*buf)[w] = c
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b[w] = c
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}
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}
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65
path_test.go
65
path_test.go
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@ -6,15 +6,17 @@
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package gin
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package gin
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import (
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import (
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"runtime"
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"strings"
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"testing"
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"testing"
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"github.com/stretchr/testify/assert"
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"github.com/stretchr/testify/assert"
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)
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)
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var cleanTests = []struct {
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type cleanPathTest struct {
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path, result string
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path, result string
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}{
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}
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var cleanTests = []cleanPathTest{
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// Already clean
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// Already clean
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{"/", "/"},
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{"/", "/"},
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{"/abc", "/abc"},
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{"/abc", "/abc"},
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@ -77,13 +79,62 @@ func TestPathCleanMallocs(t *testing.T) {
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if testing.Short() {
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if testing.Short() {
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t.Skip("skipping malloc count in short mode")
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t.Skip("skipping malloc count in short mode")
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}
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}
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if runtime.GOMAXPROCS(0) > 1 {
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t.Log("skipping AllocsPerRun checks; GOMAXPROCS>1")
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return
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}
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for _, test := range cleanTests {
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for _, test := range cleanTests {
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allocs := testing.AllocsPerRun(100, func() { cleanPath(test.result) })
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allocs := testing.AllocsPerRun(100, func() { cleanPath(test.result) })
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assert.EqualValues(t, allocs, 0)
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assert.EqualValues(t, allocs, 0)
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}
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}
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}
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}
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func BenchmarkPathClean(b *testing.B) {
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b.ReportAllocs()
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for i := 0; i < b.N; i++ {
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for _, test := range cleanTests {
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cleanPath(test.path)
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}
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}
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}
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func genLongPaths() (testPaths []cleanPathTest) {
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for i := 1; i <= 1234; i++ {
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ss := strings.Repeat("a", i)
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correctPath := "/" + ss
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testPaths = append(testPaths, cleanPathTest{
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path: correctPath,
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result: correctPath,
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}, cleanPathTest{
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path: ss,
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result: correctPath,
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}, cleanPathTest{
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path: "//" + ss,
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result: correctPath,
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}, cleanPathTest{
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path: "/" + ss + "/b/..",
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result: correctPath,
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})
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}
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return
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}
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func TestPathCleanLong(t *testing.T) {
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cleanTests := genLongPaths()
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for _, test := range cleanTests {
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assert.Equal(t, test.result, cleanPath(test.path))
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assert.Equal(t, test.result, cleanPath(test.result))
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}
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}
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func BenchmarkPathCleanLong(b *testing.B) {
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cleanTests := genLongPaths()
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b.ResetTimer()
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b.ReportAllocs()
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for i := 0; i < b.N; i++ {
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for _, test := range cleanTests {
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cleanPath(test.path)
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}
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}
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}
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