Jan Novak
0ecfb9bb1a
Instruments HTTP requests with net/http/httptrace.ClientTrace to capture timestamps for DNS, TCP connect, TLS handshake, TTFB, and body transfer. TLS row is omitted automatically for plain http:// URLs. Output is an aligned text table with a separator before the Total row. Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
92 lines
1.8 KiB
Go
92 lines
1.8 KiB
Go
package main
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import (
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"flag"
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"fmt"
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"os"
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"strings"
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"latprobe/internal/probe"
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)
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const usageText = `latprobe — measure per-phase HTTP request latency
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Usage:
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latprobe [flags] <url> [url ...]
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Flags:
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-n, --count int Number of requests per URL (default 1)
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--json Output results as JSON instead of text
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-h, --help Show this help
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Examples:
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latprobe https://example.com
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latprobe -n 5 https://example.com https://www.google.com
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latprobe --json https://example.com | jq .
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`
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func main() {
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count := flag.Int("count", 1, "number of requests per URL")
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flag.IntVar(count, "n", 1, "number of requests per URL (shorthand)")
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jsonOut := flag.Bool("json", false, "output results as JSON")
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flag.Usage = func() { fmt.Fprint(os.Stderr, usageText) }
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flag.Parse()
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urls := flag.Args()
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if len(urls) == 0 {
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fmt.Fprint(os.Stderr, usageText)
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os.Exit(1)
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}
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// --json and -n are parsed but not yet functional (wired in Steps 3–4).
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_ = jsonOut
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_ = count
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failed := false
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for i, url := range urls {
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if i > 0 {
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fmt.Println()
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}
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r := probe.Measure(url)
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if r.Err != nil {
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fmt.Fprintf(os.Stderr, "error %s: %v\n", r.URL, r.Err)
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failed = true
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continue
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}
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printResult(r)
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}
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if failed {
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os.Exit(1)
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}
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}
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func printResult(r probe.Result) {
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fmt.Printf("%s (%d)\n", r.URL, r.StatusCode)
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phases := []struct {
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label string
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p probe.Phase
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}{
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{"DNS lookup ", r.DNS},
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{"TCP connect ", r.Connect},
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{"TLS handshake ", r.TLS},
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{"Server (TTFB) ", r.TTFB},
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{"Transfer ", r.Transfer},
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}
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for _, ph := range phases {
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if ph.p.Present {
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fmt.Printf(" %s : %8.2f ms\n", ph.label, msec(ph.p))
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}
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}
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fmt.Println(" " + strings.Repeat("─", 29))
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fmt.Printf(" %s : %8.2f ms\n", "Total ", msec(r.Total))
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}
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func msec(p probe.Phase) float64 {
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return float64(p.Duration.Microseconds()) / 1000
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}
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