kacerrandClaude Fable 5
7219eb5a23
Includes solved 02-worker-pool and 09-safe-counter (mutex, atomic, sharded). Co-Authored-By: Claude Fable 5 <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_01GbnJj9ZqEx9nUvzkjdwfMq
54 lines
1.6 KiB
Go
54 lines
1.6 KiB
Go
// Exercise 01 — Concurrent URL Health Checker
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//
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// ASSIGNMENT
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// ----------
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// Implement CheckAll so that it:
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//
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// 1. Checks every URL in `urls` with an HTTP GET.
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// 2. Runs AT MOST `limit` checks concurrently (bounded concurrency).
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// 3. Uses a per-request timeout of 5s AND respects the global `ctx`
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// (if ctx is cancelled, pending/unstarted checks must return ctx.Err()).
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// 4. Returns one Result per URL, at the SAME index as the input URL.
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// 5. Reuses a single http.Client and properly drains+closes response bodies
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// so connections are reused.
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//
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// Run the tests: go test -race ./01-url-health-checker/
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// Run the demo: go run ./01-url-health-checker/
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package main
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import (
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"context"
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"fmt"
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"time"
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)
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type Result struct {
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URL string
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Status int
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Latency time.Duration
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Err error
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}
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// CheckAll checks all URLs with at most `limit` in flight at once.
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// TODO: implement me.
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func CheckAll(ctx context.Context, urls []string, limit int) []Result {
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results := make([]Result, len(urls))
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// TODO:
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// - semaphore (buffered channel) or worker pool for the concurrency limit
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// - sync.WaitGroup to wait for completion
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// - http.NewRequestWithContext for cancellation
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// - write results[i] from goroutine i (why is this safe without a mutex?)
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_ = ctx
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_ = limit
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return results
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}
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func main() {
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ctx, cancel := context.WithTimeout(context.Background(), 10*time.Second)
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defer cancel()
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urls := []string{"https://example.com", "https://httpbin.org/status/500", "https://nope.invalid"}
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for _, r := range CheckAll(ctx, urls, 2) {
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fmt.Printf("%-40s status=%d latency=%v err=%v\n", r.URL, r.Status, r.Latency, r.Err)
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}
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}
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