diff --git a/path.go b/path.go index d1f5962..a6bac7b 100644 --- a/path.go +++ b/path.go @@ -5,6 +5,8 @@ package gin +const stackBufSize = 128 + // cleanPath is the URL version of path.Clean, it returns a canonical URL path // for p, eliminating . and .. elements. // @@ -24,8 +26,11 @@ func cleanPath(p string) string { return "/" } + // Reasonably sized buffer on stack to avoid allocations in the common case. + // If a larger buffer is required, it gets allocated dynamically. + buf := make([]byte, 0, stackBufSize) + n := len(p) - var buf []byte // Invariants: // reading from path; r is index of next byte to process. @@ -37,7 +42,12 @@ func cleanPath(p string) string { if p[0] != '/' { r = 0 - buf = make([]byte, n+1) + + if n+1 > stackBufSize { + buf = make([]byte, n+1) + } else { + buf = buf[:n+1] + } buf[0] = '/' } @@ -69,7 +79,7 @@ func cleanPath(p string) string { // can backtrack w-- - if buf == nil { + if len(buf) == 0 { for w > 1 && p[w] != '/' { w-- } @@ -103,7 +113,7 @@ func cleanPath(p string) string { w++ } - if buf == nil { + if len(buf) == 0 { return p[:w] } return string(buf[:w]) @@ -111,13 +121,20 @@ func cleanPath(p string) string { // internal helper to lazily create a buffer if necessary. func bufApp(buf *[]byte, s string, w int, c byte) { - if *buf == nil { + b := *buf + if len(b) == 0 { if s[w] == c { return } - *buf = make([]byte, len(s)) - copy(*buf, s[:w]) + if l := len(s); l > cap(b) { + *buf = make([]byte, len(s)) + } else { + *buf = (*buf)[:l] + } + b = *buf + + copy(b, s[:w]) } - (*buf)[w] = c + b[w] = c } diff --git a/path_test.go b/path_test.go index c1e6ed4..caefd63 100644 --- a/path_test.go +++ b/path_test.go @@ -6,15 +6,17 @@ package gin import ( - "runtime" + "strings" "testing" "github.com/stretchr/testify/assert" ) -var cleanTests = []struct { +type cleanPathTest struct { path, result string -}{ +} + +var cleanTests = []cleanPathTest{ // Already clean {"/", "/"}, {"/abc", "/abc"}, @@ -77,13 +79,62 @@ func TestPathCleanMallocs(t *testing.T) { if testing.Short() { t.Skip("skipping malloc count in short mode") } - if runtime.GOMAXPROCS(0) > 1 { - t.Log("skipping AllocsPerRun checks; GOMAXPROCS>1") - return - } for _, test := range cleanTests { allocs := testing.AllocsPerRun(100, func() { cleanPath(test.result) }) assert.EqualValues(t, allocs, 0) } } + +func BenchmarkPathClean(b *testing.B) { + b.ReportAllocs() + + for i := 0; i < b.N; i++ { + for _, test := range cleanTests { + cleanPath(test.path) + } + } +} + +func genLongPaths() (testPaths []cleanPathTest) { + for i := 1; i <= 1234; i++ { + ss := strings.Repeat("a", i) + + correctPath := "/" + ss + testPaths = append(testPaths, cleanPathTest{ + path: correctPath, + result: correctPath, + }, cleanPathTest{ + path: ss, + result: correctPath, + }, cleanPathTest{ + path: "//" + ss, + result: correctPath, + }, cleanPathTest{ + path: "/" + ss + "/b/..", + result: correctPath, + }) + } + return +} + +func TestPathCleanLong(t *testing.T) { + cleanTests := genLongPaths() + + for _, test := range cleanTests { + assert.Equal(t, test.result, cleanPath(test.path)) + assert.Equal(t, test.result, cleanPath(test.result)) + } +} + +func BenchmarkPathCleanLong(b *testing.B) { + cleanTests := genLongPaths() + b.ResetTimer() + b.ReportAllocs() + + for i := 0; i < b.N; i++ { + for _, test := range cleanTests { + cleanPath(test.path) + } + } +}