Enhance tenant migration command to support parallel execution

- Added a `--parallel` option to the Migrate command for concurrent tenant migrations.
- Introduced a `parallel-batch-size` option to control the number of concurrent migrations.
- Implemented a new method `runParallel` to handle parallel migrations.
- Updated the `handle` method to initiate parallel migrations when the option is set.
- Added tests to verify the functionality of the parallel migration option.

src/Commands/Migrate.php

@@ -10,12 +10,18 @@ use Illuminate\Database\Migrations\Migrator;
 use Stancl\Tenancy\Concerns\DealsWithMigrations;
 use Stancl\Tenancy\Concerns\ExtendsLaravelCommand;
 use Stancl\Tenancy\Concerns\HasATenantsOption;
+use Stancl\Tenancy\Concerns\ParallelTenantMigrator;
+use Stancl\Tenancy\Contracts\Tenant;
 use Stancl\Tenancy\Events\DatabaseMigrated;
 use Stancl\Tenancy\Events\MigratingDatabase;
+use Symfony\Component\Console\Input\InputOption;
 
 class Migrate extends MigrateCommand
 {
-    use HasATenantsOption, DealsWithMigrations, ExtendsLaravelCommand;
+    use HasATenantsOption {
+        getOptions as private tenantsCommandOptions;
+    }
+    use DealsWithMigrations, ExtendsLaravelCommand, ParallelTenantMigrator;
 
     protected $description = 'Run migrations for tenant(s)';
 
@@ -31,12 +37,20 @@ class Migrate extends MigrateCommand
         $this->specifyParameters();
     }
 
-    /**
-     * Execute the console command.
-     *
-     * @return mixed
-     */
-    public function handle()
+    protected function getOptions()
+    {
+        return array_merge([
+            [
+                'parallel-batch-size',
+                null,
+                InputOption::VALUE_OPTIONAL,
+                'Maximum concurrent tenant migrations per batch when using --parallel',
+                '10',
+            ],
+        ], $this->tenantsCommandOptions());
+    }
+
+    public function handle(): int
     {
         foreach (config('tenancy.migration_parameters') as $parameter => $value) {
             if (! $this->input->hasParameterOption($parameter)) {
@@ -45,15 +59,73 @@ class Migrate extends MigrateCommand
         }
 
         if (! $this->confirmToProceed()) {
-            return;
+            return static::FAILURE;
         }
 
-        tenancy()->runForMultiple($this->option('tenants'), function ($tenant) {
+        if ($this->option('parallel')) {
+            return $this->runParallel();
+        }
+
+        $this->runMigrationForTenants($this->option('tenants'));
+
+        return static::SUCCESS;
+    }
+
+    private function runParallel(): int
+    {
+        if (! class_exists(\Illuminate\Support\Facades\Concurrency::class)) {
+            $this->error('Parallel tenant migrations require Laravel 11 or newer (Concurrency facade).');
+
+            return static::FAILURE;
+        }
+
+        $keys = $this->tenantKeys();
+        if ($keys === []) {
+            $this->info('No tenants to migrate.');
+
+            return static::SUCCESS;
+        }
+
+        $this->info('Running migrations in parallel');
+
+        $this->runParallelTenantBatches(
+            $keys,
+            max(1, (int) $this->option('parallel-batch-size')),
+            function (int $batchIndex, int $batchTotal, array $batch): void {
+                $n = count($batch);
+                $this->line(sprintf(
+                    'Parallel batch %d/%d (%d tenant%s)',
+                    $batchIndex + 1,
+                    $batchTotal,
+                    $n,
+                    $n === 1 ? '' : 's'
+                ));
+            }
+        );
+
+        return static::SUCCESS;
+    }
+
+    /**
+     * @return list<string|int>
+     */
+    private function tenantKeys(): array
+    {
+        $keys = [];
+        foreach ($this->getTenants() as $tenant) {
+            $keys[] = $tenant instanceof Tenant ? $tenant->getTenantKey() : $tenant;
+        }
+
+        return $keys;
+    }
+
+    protected function runMigrationForTenants(?array $tenants = []): void
+    {
+        tenancy()->runForMultiple($tenants, function ($tenant) {
             $this->line("Tenant: {$tenant->getTenantKey()}");
 
             event(new MigratingDatabase($tenant));
 
-            // Migrate
             parent::handle();
 
             event(new DatabaseMigrated($tenant));

src/Concerns/ParallelTenantMigrator.php

@@ -0,0 +1,108 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Stancl\Tenancy\Concerns;
+
+use Illuminate\Support\Facades\Artisan;
+use Illuminate\Support\Facades\Concurrency;
+use RuntimeException;
+
+/**
+ * Parallel `tenants:migrate` via {@see Concurrency} and option forwarding for nested Artisan calls.
+ */
+trait ParallelTenantMigrator
+{
+    /**
+     * Options for nested `tenants:migrate` (parallel workers). Omits `--parallel`.
+     *
+     * @return array<string, mixed>
+     */
+    protected function optionsForNestedMigrateCall(): array
+    {
+        $options = [];
+
+        if ($database = $this->option('database')) {
+            $options['--database'] = $database;
+        }
+
+        if ($this->option('force')) {
+            $options['--force'] = true;
+        }
+
+        if ($paths = $this->option('path')) {
+            $options['--path'] = $paths;
+        }
+
+        if ($this->option('realpath')) {
+            $options['--realpath'] = true;
+        }
+
+        if ($schemaPath = $this->option('schema-path')) {
+            $options['--schema-path'] = $schemaPath;
+        }
+
+        if ($this->option('pretend')) {
+            $options['--pretend'] = true;
+        }
+
+        if ($this->option('seed')) {
+            $options['--seed'] = true;
+        }
+
+        if ($seeder = $this->option('seeder')) {
+            $options['--seeder'] = $seeder;
+        }
+
+        if ($this->option('step')) {
+            $options['--step'] = true;
+        }
+
+        if ($this->option('graceful')) {
+            $options['--graceful'] = true;
+        }
+
+        if ($this->option('no-interaction')) {
+            $options['--no-interaction'] = true;
+        }
+
+        return $options;
+    }
+
+    /**
+     * @param  list<string|int>  $keys
+     * @param  callable(int $batchIndex, int $batchTotal, list<string|int> $batchKeys): void  $beforeBatch
+     */
+    protected function runParallelTenantBatches(array $keys, int $batchSize, callable $beforeBatch): void
+    {
+        $forward = $this->optionsForNestedMigrateCall();
+        $batches = array_chunk($keys, max(1, $batchSize));
+        $total = count($batches);
+
+        foreach ($batches as $i => $batch) {
+            $beforeBatch($i, $total, $batch);
+
+            $tasks = [];
+            foreach ($batch as $key) {
+                $tasks[] = static fn () => self::migrateOneTenantViaArtisan($key, $forward);
+            }
+
+            Concurrency::run($tasks);
+        }
+    }
+
+    /**
+     * @param  array<string, mixed>  $forwardOptions
+     */
+    private static function migrateOneTenantViaArtisan(string|int $key, array $forwardOptions): void
+    {
+        $code = Artisan::call('tenants:migrate', array_merge($forwardOptions, [
+            '--tenants' => [$key],
+            '--force' => true,
+        ]));
+
+        if ($code !== 0) {
+            throw new RuntimeException("Tenant migration failed for [{$key}] with exit code {$code}.");
+        }
+    }
+}

tests/CommandsTest.php

@@ -5,6 +5,7 @@ declare(strict_types=1);
 namespace Stancl\Tenancy\Tests;
 
 use Illuminate\Support\Facades\Artisan;
+use Illuminate\Support\Facades\Concurrency;
 use Illuminate\Support\Facades\DB;
 use Illuminate\Support\Facades\Event;
 use Illuminate\Support\Facades\Schema;
@@ -92,6 +93,34 @@ class CommandsTest extends TestCase
         $this->assertTrue(Schema::hasTable('users'));
     }
 
+    #[Test]
+    public function migrate_command_works_with_parallel_option()
+    {
+        if (! class_exists(Concurrency::class)) {
+            $this->markTestSkipped('Parallel tenant migrations require the Concurrency facade (Laravel 11+).');
+        }
+
+        config(['concurrency.default' => 'sync']);
+
+        $tenant1 = Tenant::create();
+        $tenant2 = Tenant::create();
+
+        $this->assertFalse(Schema::hasTable('users'));
+
+        Artisan::call('tenants:migrate', [
+            '--parallel' => true,
+        ]);
+
+        $this->assertFalse(Schema::hasTable('users'));
+
+        tenancy()->initialize($tenant1);
+        $this->assertTrue(Schema::hasTable('users'));
+        tenancy()->end();
+
+        tenancy()->initialize($tenant2);
+        $this->assertTrue(Schema::hasTable('users'));
+    }
+
     #[Test]
     public function rollback_command_works()
     {