increment failures atomically

Author: David Cavazos

.github/workflows/samples-tools/README.md

@@ -30,7 +30,7 @@ For example:
 
   // Skip these packages, these could be handled by a different config.
   // Defaults to not exclude anything.
-  "exclude-packages": ["path/to/slow-to-test", "special-config-package"]
+  "exclude-packages": ["path/to/slow-to-test", "special-config-package"],
 }
 ```
 
@@ -60,6 +60,7 @@ git --no-pager diff --name-only HEAD origin/main | tee /tmp/diffs.txt
 ```
 
 Now we can check which packages have been affected.
+We pass the config file and the diffs file as positional arguments.
 
 ```sh
 /tmp/tools affected .github/config/nodejs.jsonc /tmp/diffs.txt
@@ -68,3 +69,12 @@ Now we can check which packages have been affected.
 ## Running on all packages
 
 > This must run at the repository root directory.
+
+We pass the config file and a bash script to run as positional arguments.
+The script must receive a single positional argument in `$1` as the package name.
+For example, the script should be called like `bash path/to/my-script.sh path/to/package`.
+
+```sh
+# To run all the Node.js tests.
+/tmp/tools run-all ./github/config/nodejs.jsonc ./github/scripts/nodejs-test.sh
+```

.github/workflows/samples-tools/cmd/runAll.go

@@ -21,33 +21,27 @@ import (
 	"os"
 	"os/exec"
 	"strings"
+	"sync/atomic"
 )
 
 // runAll runs all the commands in parallel.
-func runAll(packages []string, script string, maxGoroutines int) int {
-	failures := make([]string, len(packages))
+func runAll(packages []string, script string, maxGoroutines int) int64 {
+	var failures int64
 	guard := make(chan struct{}, maxGoroutines)
-	for i, pkg := range packages {
+	for _, pkg := range packages {
 		guard <- struct{}{} // block if channel is filled
 		go func() {
 			output, err := exec.Command("bash", script, pkg).CombinedOutput()
 			if err != nil {
 				printError(os.Stderr, pkg, err, string(output))
-				failures[i] = pkg
+				atomic.AddInt64(&failures, 1)
 			} else {
 				fmt.Printf("✅ %v\n", pkg)
 			}
 			<-guard
 		}()
 	}
-
-	failed := 0
-	for _, failure := range failures {
-		if failure != "" {
-			failed++
-		}
-	}
-	return failed
+	return failures
 }
 
 func printError(f *os.File, pkg string, err error, output string) {