Jan Novak
8ec926bbcd
Add probe.Summarize to aggregate N Results into per-phase min/avg/max stats. Wire up -n/--count flag in main to repeat each URL N times and display an aligned three-column table. Single-sample output (n=1) is unchanged. URLs are grouped with a blank line between them. Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
80 lines
2.4 KiB
Markdown
80 lines
2.4 KiB
Markdown
# Step 3 — Multiple URLs + Sampling
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## What this step delivers
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- Multiple URLs accepted as positional arguments; each is measured in turn.
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- `-n`/`--count` flag repeats each URL N times and reports **min / avg / max**
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per phase instead of a single value.
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- With `n=1` (the default) the output is identical to Step 2.
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## Build
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```sh
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cd go
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go build -o latprobe .
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```
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## Usage
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```sh
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latprobe [flags] <url> [url ...]
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-n, --count int Number of requests per URL (default 1)
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```
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## Examples
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### Default (single sample, unchanged from Step 2)
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```sh
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$ ./latprobe https://example.com
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https://example.com (200)
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DNS lookup : 13.74 ms
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TCP connect : 11.20 ms
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TLS handshake : 22.92 ms
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Server (TTFB) : 14.88 ms
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Transfer : 0.11 ms
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─────────────────────────────
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Total : 63.97 ms
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```
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### Multiple samples (`-n`)
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```sh
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$ ./latprobe -n 5 https://example.com
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https://example.com (200, 5 samples)
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min avg max
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DNS lookup : 1.50 ms 1.60 ms 1.70 ms
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TCP connect : 10.20 ms 10.80 ms 11.50 ms
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TLS handshake : 21.00 ms 22.10 ms 23.40 ms
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Server (TTFB) : 12.00 ms 13.50 ms 15.20 ms
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Transfer : 0.07 ms 0.09 ms 0.12 ms
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─────────────────────────────────────────────────
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Total : 45.00 ms 48.10 ms 52.00 ms
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```
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### Multiple URLs
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```sh
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$ ./latprobe -n 3 https://example.com https://www.google.com
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https://example.com (200, 3 samples)
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min avg max
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...
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─────────────────────────────────────────────────
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Total : ...
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https://www.google.com (200, 3 samples)
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min avg max
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...
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```
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## Notes
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- **DNS and connect on repeated requests**: after the first request the OS
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DNS cache and HTTP keep-alive may eliminate those phases in subsequent
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samples. The spread in TCP connect and DNS between min and max shows the
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true variance when caches are cold.
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- **Partial failure**: if a sample fails mid-run, that URL is skipped and
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the exit code is 1. Successful samples already collected are discarded for
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that URL.
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