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5b53aa1108
Wiser coders than myself have come to the conclusion that a `switch` statement is almost always superior to a statement that includes any `else if`. The exceptions that I have found in our codebase are just these two: * The `if else` is followed by an additional statement before the next condition (separated by a `;`). * The whole thing is within a `for` loop and `break` statements are used. In this case, using `switch` would require tagging the `for` loop, which probably tips the balance. Why are `switch` statements more readable? For one, fewer curly braces. But more importantly, the conditions all have the same alignment, so the whole thing follows the natural flow of going down a list of conditions. With `else if`, in contrast, all conditions but the first are "hidden" behind `} else if `, harder to spot and (for no good reason) presented differently from the first condition. I'm sure the aforemention wise coders can list even more reasons. In any case, I like it so much that I have found myself recommending it in code reviews. I would like to make it a habit in our code base, without making it a hard requirement that we would test on the CI. But for that, there has to be a role model, so this commit eliminates all `if else` occurrences, unless it is autogenerated code or fits one of the exceptions above. Signed-off-by: beorn7 <beorn@grafana.com>
83 lines
2.3 KiB
Go
83 lines
2.3 KiB
Go
// Copyright 2020 The Prometheus Authors
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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//
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//go:build !windows
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// +build !windows
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package main
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import (
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"fmt"
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"net/http"
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"os"
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"os/exec"
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"testing"
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"time"
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"github.com/prometheus/prometheus/util/testutil"
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)
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// As soon as prometheus starts responding to http request it should be able to
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// accept Interrupt signals for a graceful shutdown.
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func TestStartupInterrupt(t *testing.T) {
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if testing.Short() {
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t.Skip("skipping test in short mode.")
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}
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port := fmt.Sprintf(":%d", testutil.RandomUnprivilegedPort(t))
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prom := exec.Command(promPath, "-test.main", "--config.file="+promConfig, "--storage.tsdb.path="+t.TempDir(), "--web.listen-address=0.0.0.0"+port)
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err := prom.Start()
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if err != nil {
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t.Fatalf("execution error: %v", err)
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}
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done := make(chan error, 1)
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go func() {
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done <- prom.Wait()
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}()
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var startedOk bool
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var stoppedErr error
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url := "http://localhost" + port + "/graph"
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Loop:
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for x := 0; x < 10; x++ {
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// error=nil means prometheus has started, so we can send the interrupt
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// signal and wait for the graceful shutdown.
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if _, err := http.Get(url); err == nil {
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startedOk = true
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prom.Process.Signal(os.Interrupt)
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select {
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case stoppedErr = <-done:
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break Loop
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case <-time.After(10 * time.Second):
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}
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break Loop
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}
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time.Sleep(500 * time.Millisecond)
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}
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if !startedOk {
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t.Fatal("prometheus didn't start in the specified timeout")
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}
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switch err := prom.Process.Kill(); {
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case err == nil:
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t.Errorf("prometheus didn't shutdown gracefully after sending the Interrupt signal")
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case stoppedErr != nil && stoppedErr.Error() != "signal: interrupt":
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// TODO: find a better way to detect when the process didn't exit as expected!
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t.Errorf("prometheus exited with an unexpected error: %v", stoppedErr)
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}
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}
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