Determine the number of cores and run make with --jobs option

Author: asgrim

src/Building/UnixBuild.php

@@ -52,7 +52,7 @@ public function __invoke(
         $optionsOutput = count($configureOptions) ? ' with options: ' . implode(' ', $configureOptions) : '.';
         $output->writeln('<info>Configure complete</info>' . $optionsOutput);
 
-        $makeOutput = $this->make($targetPlatform, $downloadedPackage);
+        $makeOutput = $this->make($targetPlatform, $downloadedPackage, $output);
         if ($output->isVeryVerbose()) {
             $output->writeln($makeOutput);
         }
@@ -93,10 +93,19 @@ private function configure(DownloadedPackage $downloadedPackage, array $configur
         );
     }
 
-    private function make(TargetPlatform $targetPlatform, DownloadedPackage $downloadedPackage): string
+    private function make(TargetPlatform $targetPlatform, DownloadedPackage $downloadedPackage, OutputInterface $output): string
     {
+        $makeCommand = ['make'];
+
+        if ($targetPlatform->makeParallelJobs === 1) {
+            $output->writeln('Running make without parallelization - try providing -jN to PIE where N is the number of cores you have.');
+        } else {
+            $makeCommand[] = '--jobs';
+            $makeCommand[] = $targetPlatform->makeParallelJobs;
+        }
+
         return Process::run(
-            ['make', '--jobs', $targetPlatform->makeParallelJobs],
+            $makeCommand,
             $downloadedPackage->extractedSourcePath,
             self::MAKE_TIMEOUT_SECS,
         );

src/Platform/TargetPlatform.php

@@ -6,6 +6,7 @@
 
 use Php\Pie\Platform\TargetPhp\PhpBinaryPath;
 
+use Php\Pie\Util\NumberOfCores;
 use function array_key_exists;
 use function curl_version;
 use function explode;
@@ -124,10 +125,9 @@ public static function fromPhpBinaryPath(PhpBinaryPath $phpBinaryPath, int|null
         }
 
         if ($makeParallelJobs === null) {
-            $makeParallelJobs = 16; // @todo detect
+            $makeParallelJobs = NumberOfCores::determine();
         }
 
-
         return new self(
             $os,
             $phpBinaryPath,

src/Util/NumberOfCores.php

@@ -0,0 +1,69 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Php\Pie\Util;
+
+use Symfony\Component\Process\Process;
+
+final class NumberOfCores
+{
+    /** @psalm-suppress UnusedConstructor */
+    private function __construct()
+    {
+    }
+
+    /**
+     * @param list<string> $params
+     *
+     * @return positive-int
+     */
+    private static function tryCommand(string $command, array $params): int|null
+    {
+        $whichProcess = new Process(['which', $command]);
+        if ($whichProcess->run() === 0) {
+            $commandPath = trim($whichProcess->getOutput());
+
+            $commandProcess = new Process([$commandPath, ...$params]);
+            if ($commandProcess->run() === 0) {
+                $commandResult = trim($commandProcess->getOutput());
+                if (is_numeric($commandResult)) {
+                    $commandNumericResult = (int) $commandResult;
+
+                    if ($commandNumericResult > 0) {
+                        return $commandNumericResult;
+                    }
+                }
+            }
+        }
+
+        return null;
+    }
+
+    /**
+     * Try a few different ways of determining number of CPUs. If we can't guess
+     * how many CPUs someone has, then default to 1 for safety.
+     *
+     * @return positive-int
+     */
+    public static function determine(): int
+    {
+        $nproc = self::tryCommand('nproc', ['--all']);
+        if ($nproc !== null) {
+            return $nproc;
+        }
+
+        $getconf = self::tryCommand('getconf', ['_NPROCESSORS_ONLN']);
+        if ($getconf !== null) {
+            return $getconf;
+        }
+
+        $sysctl = self::tryCommand('sysctl', ['-n', 'hw.ncpu']);
+        if ($sysctl !== null) {
+            return $sysctl;
+        }
+
+        // Default to 1 for safety
+        return 1;
+    }
+}