From 66aaedf32c59d82f172daf80db5e2391bdef301a Mon Sep 17 00:00:00 2001
From: Will McCutchen <will@mccutch.org>
Date: Wed, 28 Jun 2023 23:21:19 -0400
Subject: [PATCH] Update /drip endpoint:
- Add Server-Timing trailers to record each component of the overall
response time
- Switch Content-Type from application/octet-stream to text/plain to
make the endpoint a bit easier to work with in a browser
- Eliminate unnecessary pause after writing final byte to response
---
Makefile | 2 +-
httpbin/handlers.go | 41 ++++++++++++----
httpbin/handlers_test.go | 79 ++++++++++++++++++++++++++++---
httpbin/helpers.go | 41 ++++++++++++++++
httpbin/static/index.html | 2 +-
internal/testing/assert/assert.go | 24 ++++++++--
6 files changed, 167 insertions(+), 22 deletions(-)
diff --git a/Makefile b/Makefile
index 9a10cbe..bbcd4ae 100644
--- a/Makefile
+++ b/Makefile
@@ -70,7 +70,7 @@ lint:
# run locally
# =============================================================================
run: build
- $(DIST_PATH)/go-httpbin
+ $(DIST_PATH)/go-httpbin -host 127.0.0.1 -port 8080
.PHONY: run
watch:
diff --git a/httpbin/handlers.go b/httpbin/handlers.go
index 9dc7888..b696589 100644
--- a/httpbin/handlers.go
+++ b/httpbin/handlers.go
@@ -584,6 +584,7 @@ func (h *HTTPBin) Delay(w http.ResponseWriter, r *http.Request) {
// Drip returns data over a duration after an optional initial delay, then
// (optionally) returns with the given status code.
func (h *HTTPBin) Drip(w http.ResponseWriter, r *http.Request) {
+ start := time.Now()
q := r.URL.Query()
var (
@@ -639,21 +640,42 @@ func (h *HTTPBin) Drip(w http.ResponseWriter, r *http.Request) {
pause = duration / time.Duration(numBytes-1)
}
- w.Header().Set("Content-Type", "application/octet-stream")
- w.Header().Set("Content-Length", fmt.Sprintf("%d", numBytes))
+ w.Header().Add("Trailer", "Server-Timing")
+ defer func() {
+ w.Header().Add("Server-Timing", encodeServerTimings([]serverTiming{
+ {"total", time.Since(start), "total request duration"},
+ {"delay", delay, "requested initial delay"},
+ {"duration", duration, "requested duration"},
+ {"pause", pause, "computed pause between writes"},
+ }))
+ }()
+
+ w.Header().Set("Content-Type", "text/plain")
w.WriteHeader(code)
flusher := w.(http.Flusher)
flusher.Flush()
- // wait for initial delay before writing response body
- select {
- case <-r.Context().Done():
+ if delay > 0 {
+ select {
+ case <-time.After(delay):
+ // ok
+ case <-r.Context().Done():
+ return
+ }
+ }
+
+ // special case when we do not need to pause between each write
+ if pause == 0 {
+ b := bytes.Repeat([]byte{'*'}, int(numBytes))
+ w.Write(b)
return
- case <-time.After(delay):
}
- // write response body byte-by-byte, pausing between each write
+ // otherwise, write response body byte-by-byte
+ ticker := time.NewTicker(pause)
+ defer ticker.Stop()
+
b := []byte{'*'}
for i := int64(0); i < numBytes; i++ {
w.Write(b)
@@ -661,13 +683,14 @@ func (h *HTTPBin) Drip(w http.ResponseWriter, r *http.Request) {
// don't pause after last byte
if i == numBytes-1 {
- break
+ return
}
select {
+ case <-ticker.C:
+ // ok
case <-r.Context().Done():
return
- case <-time.After(pause):
}
}
}
diff --git a/httpbin/handlers_test.go b/httpbin/handlers_test.go
index ebdce3e..4453a65 100644
--- a/httpbin/handlers_test.go
+++ b/httpbin/handlers_test.go
@@ -1690,8 +1690,16 @@ func TestDrip(t *testing.T) {
elapsed := time.Since(start)
assert.StatusCode(t, resp, test.code)
- assert.Header(t, resp, "Content-Type", "application/octet-stream")
- assert.Header(t, resp, "Content-Length", strconv.Itoa(test.numbytes))
+ assert.Header(t, resp, "Content-Type", "text/plain")
+ assert.Header(t, resp, "Content-Length", "")
+ assert.DeepEqual(t, resp.TransferEncoding, []string{"chunked"}, "incorrect Transfer-Encoding header")
+
+ timings := decodeServerTimings(resp.Trailer.Get("Server-Timing"))
+ for _, k := range []string{"duration", "delay", "pause", "total"} {
+ if _, ok := timings[k]; !ok {
+ t.Fatalf("expected %q timing, got %v", k, timings)
+ }
+ }
if len(body) != test.numbytes {
t.Fatalf("expected %d bytes, got %d", test.numbytes, len(body))
@@ -1735,9 +1743,12 @@ func TestDrip(t *testing.T) {
t.Parallel()
var (
- duration = 100 * time.Millisecond
- numBytes = 3
- wantDelay = duration / time.Duration(numBytes)
+ duration = 100 * time.Millisecond
+ numBytes = 3
+ // compute initial delay using the same logic the endpoint will use
+ // to compute the pause between writes, to simplify the read loop
+ // below
+ wantDelay = duration / time.Duration(numBytes-1)
endpoint = fmt.Sprintf("/drip?duration=%s&delay=%s&numbytes=%d", duration, wantDelay, numBytes)
)
req := newTestRequest(t, "GET", endpoint)
@@ -1750,6 +1761,7 @@ func TestDrip(t *testing.T) {
// wait between writes so that even the first iteration of this loop
// expects to wait the same amount of time for a read.
buf := make([]byte, 1024)
+ gotBody := make([]byte, 0, numBytes)
for {
start := time.Now()
n, err := resp.Body.Read(buf)
@@ -1762,9 +1774,62 @@ func TestDrip(t *testing.T) {
assert.NilError(t, err)
assert.Equal(t, n, 1, "incorrect number of bytes read")
assert.DeepEqual(t, buf[:n], []byte{'*'}, "unexpected bytes read")
- if gotDelay < wantDelay {
- t.Fatalf("to wait at least %s between reads, waited %s", wantDelay, gotDelay)
+
+ // allow for minor mismatch in local timers and server timers
+ assert.RoughDuration(t, gotDelay, wantDelay, 3*time.Millisecond)
+
+ gotBody = append(gotBody, buf[:n]...)
+ }
+
+ wantBody := bytes.Repeat([]byte{'*'}, numBytes)
+ assert.DeepEqual(t, gotBody, wantBody, "incorrect body")
+ })
+
+ t.Run("Server-Timings trailers", func(t *testing.T) {
+ t.Parallel()
+
+ var (
+ duration = 512 * time.Millisecond
+ delay = 250 * time.Millisecond
+ numBytes = 256
+ params = url.Values{
+ "duration": {duration.String()},
+ "delay": {delay.String()},
+ "numbytes": {strconv.Itoa(numBytes)},
}
+ )
+
+ req := newTestRequest(t, "GET", "/drip?"+params.Encode())
+ resp := must.DoReq(t, client, req)
+
+ // need to fully consume body for Server-Timing trailers to arrive
+ body := must.ReadAll(t, resp.Body)
+ assert.Equal(t, body, strings.Repeat("*", numBytes), "incorrect body")
+
+ rawTimings := resp.Trailer.Get("Server-Timing")
+ t.Logf("Server-Timing: %s", rawTimings)
+
+ timings := decodeServerTimings(rawTimings)
+
+ // Ensure total server time makes sense based on duration and delay
+ total := timings["total"]
+ assert.DurationRange(t, total.dur, duration+delay, duration+delay+25*time.Millisecond)
+
+ // Ensure computed pause time makes sense based on duration, delay, and
+ // numbytes (should be exact, but we're re-parsing a truncated float in
+ // the header value)
+ pause := timings["pause"]
+ assert.RoughDuration(t, pause.dur, duration/time.Duration(numBytes-1), 1*time.Millisecond)
+
+ // remaining timings should exactly match request parameters, no need
+ // to adjust for per-run variations
+ wantTimings := map[string]serverTiming{
+ "duration": {"duration", duration, "requested duration"},
+ "delay": {"delay", delay, "requested initial delay"},
+ }
+ for k, want := range wantTimings {
+ got := timings[k]
+ assert.DeepEqual(t, got, want, "incorrect timing for key %q", k)
}
})
diff --git a/httpbin/helpers.go b/httpbin/helpers.go
index 9eca145..5b44171 100644
--- a/httpbin/helpers.go
+++ b/httpbin/helpers.go
@@ -415,3 +415,44 @@ func (b *base64Helper) Encode() ([]byte, error) {
func (b *base64Helper) Decode() ([]byte, error) {
return base64.URLEncoding.DecodeString(b.data)
}
+
+type serverTiming struct {
+ name string
+ dur time.Duration
+ desc string
+}
+
+func encodeServerTimings(timings []serverTiming) string {
+ var entries []string
+ for _, t := range timings {
+ ms := float64(t.dur) / float64(time.Millisecond)
+ entries = append(entries, fmt.Sprintf("%s;dur=%0.2f;desc=\"%s\"", t.name, ms, t.desc))
+ }
+ return strings.Join(entries, ", ")
+}
+
+func decodeServerTimings(headerVal string) map[string]serverTiming {
+ if headerVal == "" {
+ return nil
+ }
+ timings := map[string]serverTiming{}
+ for _, entry := range strings.Split(headerVal, ",") {
+ var t serverTiming
+ for _, kv := range strings.Split(entry, ";") {
+ kv = strings.TrimSpace(kv)
+ key, val, _ := strings.Cut(kv, "=")
+ switch key {
+ case "dur":
+ t.dur, _ = time.ParseDuration(val + "ms")
+ case "desc":
+ t.desc = strings.Trim(val, "\"")
+ default:
+ t.name = key
+ }
+ }
+ if t.name != "" {
+ timings[t.name] = t
+ }
+ }
+ return timings
+}
diff --git a/httpbin/static/index.html b/httpbin/static/index.html
index 4d94d0b..71790b7 100644
--- a/httpbin/static/index.html
+++ b/httpbin/static/index.html
@@ -79,7 +79,7 @@
<li><a href="/deny"><code>/deny</code></a> Denied by robots.txt file.</li>
<li><a href="/digest-auth/auth/user/passwd/MD5"><code>/digest-auth/:qop/:user/:passwd/:algorithm</code></a> Challenges HTTP Digest Auth.</li>
<li><a href="/digest-auth/auth/user/passwd/MD5"><code>/digest-auth/:qop/:user/:passwd</code></a> Challenges HTTP Digest Auth.</li>
-<li><a href="/drip?code=200&numbytes=5&duration=5"><code>/drip?numbytes=n&duration=s&delay=s&code=code</code></a> Drips data over a duration after an optional initial delay, then (optionally) returns with the given status code.</li>
+<li><a href="/drip?code=200&numbytes=5&duration=5"><code>/drip?numbytes=n&duration=s&delay=s&code=code</code></a> Drips data over a duration after an optional initial delay, using <code>chunked</code> transfer-encoding, and (optionally) returns with the given status code.</li>
<li><a href="/dump/request"><code>/dump/request</code></a> Returns the given request in its HTTP/1.x wire approximate representation.</li>
<li><a href="/encoding/utf8"><code>/encoding/utf8</code></a> Returns page containing UTF-8 data.</li>
<li><a href="/etag/etag"><code>/etag/:etag</code></a> Assumes the resource has the given etag and responds to If-None-Match header with a 200 or 304 and If-Match with a 200 or 412 as appropriate.</li>
diff --git a/internal/testing/assert/assert.go b/internal/testing/assert/assert.go
index 112be3a..96efe65 100644
--- a/internal/testing/assert/assert.go
+++ b/internal/testing/assert/assert.go
@@ -6,14 +6,15 @@ import (
"reflect"
"strings"
"testing"
+ "time"
"github.com/mccutchen/go-httpbin/v2/internal/testing/must"
)
// Equal asserts that two values are equal.
-func Equal[T comparable](t *testing.T, want, got T, msg string, arg ...any) {
+func Equal[T comparable](t *testing.T, got, want T, msg string, arg ...any) {
t.Helper()
- if want != got {
+ if got != want {
if msg == "" {
msg = "expected values to match"
}
@@ -23,9 +24,9 @@ func Equal[T comparable](t *testing.T, want, got T, msg string, arg ...any) {
}
// DeepEqual asserts that two values are deeply equal.
-func DeepEqual[T any](t *testing.T, want, got T, msg string, arg ...any) {
+func DeepEqual[T any](t *testing.T, got, want T, msg string, arg ...any) {
t.Helper()
- if !reflect.DeepEqual(want, got) {
+ if !reflect.DeepEqual(got, want) {
if msg == "" {
msg = "expected values to match"
}
@@ -89,3 +90,18 @@ func BodyEquals(t *testing.T, resp *http.Response, want string) {
got := must.ReadAll(t, resp.Body)
Equal(t, got, want, "incorrect response body")
}
+
+// DurationRange asserts that a duration is within a specific range.
+func DurationRange(t *testing.T, got, min, max time.Duration) {
+ t.Helper()
+ if got < min || got > max {
+ t.Fatalf("expected duration between %s and %s, got %s", min, max, got)
+ }
+}
+
+// RoughDuration asserts that a duration is within a certain tolerance of a
+// given value.
+func RoughDuration(t *testing.T, got, want time.Duration, tolerance time.Duration) {
+ t.Helper()
+ DurationRange(t, got, want-tolerance, want+tolerance)
+}
--
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