Vegeta as a library

* Slicker API
* Privatises a bunch of stuff
* More tests
* More documentation

lib/attack.go

@@ -0,0 +1,68 @@
+package vegeta
+
+import (
+	"errors"
+	"io/ioutil"
+	"net/http"
+	"time"
+)
+
+// Attack hits the passed Targets (http.Requests) at the rate specified for
+// duration time and then waits for all the requests to come back.
+// The results of the attack are put into the rep Reporter.
+func Attack(targets Targets, rate uint64, duration time.Duration, rep Reporter) {
+	hits := make(chan *http.Request, rate*uint64((duration).Seconds()))
+	defer close(hits)
+	responses := make(chan *result, cap(hits))
+	defer close(responses)
+	go drill(rate, hits, responses) // Attack!
+	for i := 0; i < cap(hits); i++ {
+		hits <- targets[i%len(targets)]
+	}
+	// Wait for all requests to finish
+	for i := 0; i < cap(responses); i++ {
+		rep.add(<-responses)
+	}
+}
+
+// result represents the metrics we want out of an http.Response
+type result struct {
+	code      uint64
+	timestamp time.Time
+	timing    time.Duration
+	bytesOut  uint64
+	bytesIn   uint64
+	err       error
+}
+
+// drill loops over the passed reqs channel and executes each request.
+// It is throttled to the rate specified.
+func drill(rate uint64, reqs chan *http.Request, res chan *result) {
+	throttle := time.Tick(time.Duration(1e9 / rate))
+	for req := range reqs {
+		<-throttle
+		go hit(req, res)
+	}
+}
+
+// hit executes the passed http.Request and puts a generated *result into res.
+// Both transport errors and unsucessfull requests (non {2xx,3xx}) are
+// considered errors which are set in the Response.
+func hit(req *http.Request, res chan *result) {
+	began := time.Now()
+	r, err := http.DefaultClient.Do(req)
+	result := &result{
+		timestamp: began,
+		timing:    time.Since(began),
+		bytesOut:  uint64(req.ContentLength),
+		err:       err,
+	}
+	if err == nil {
+		result.bytesIn, result.code = uint64(r.ContentLength), uint64(r.StatusCode)
+		if body, err := ioutil.ReadAll(r.Body); err != nil && result.code < 200 || result.code >= 300 {
+			result.err = errors.New(string(body))
+		}
+	}
+
+	res <- result
+}