Plugin helpers for v2

doc/articles/plugins.md

@@ -161,6 +161,14 @@ class AwsPlugin implements PluginInterface, EventSubscriberInterface
         $this->io = $io;
     }
 
+    public function deactivate(Composer $composer, IOInterface $io)
+    {
+    }
+
+    public function uninstall(Composer $composer, IOInterface $io)
+    {
+    }
+
     public static function getSubscribedEvents()
     {
         return array(
@@ -175,9 +183,7 @@ class AwsPlugin implements PluginInterface, EventSubscriberInterface
         $protocol = parse_url($event->getProcessedUrl(), PHP_URL_SCHEME);
 
         if ($protocol === 's3') {
-            $awsClient = new AwsClient($this->io, $this->composer->getConfig());
-            $s3Downloader = new S3Downloader($this->io, $event->getHttpDownloader()->getOptions(), $awsClient);
-            $event->setHttpdownloader($s3Downloader);
+            // ...
         }
     }
 }
@@ -263,7 +269,7 @@ Now the `custom-plugin-command` is available alongside Composer commands.
 
 ## Running plugins manually
 
-Plugins for an event can be run manually by the `run-script` command. This works the same way as 
+Plugins for an event can be run manually by the `run-script` command. This works the same way as
 [running scripts manually](scripts.md#running-scripts-manually).
 
 ## Using Plugins
@@ -278,6 +284,12 @@ local project plugins are loaded.
 > installed plugins. This may be particularly helpful if any of the plugins
 > causes errors and you wish to update or uninstall it.
 
+## Plugin Helpers
+
+As of Composer 2, due to the fact that DownloaderInterface can sometimes return Promises
+and have been split up in more steps than they used to, we provide a [SyncHelper][11]
+to make downloading and installing packages easier.
+
 [1]: ../04-schema.md#type
 [2]: ../04-schema.md#extra
 [3]: https://github.com/composer/composer/blob/master/src/Composer/Plugin/PluginInterface.php
@@ -288,3 +300,4 @@ local project plugins are loaded.
 [8]: https://github.com/composer/composer/blob/master/src/Composer/Plugin/Capable.php
 [9]: https://github.com/composer/composer/blob/master/src/Composer/Plugin/Capability/CommandProvider.php
 [10]: https://symfony.com/doc/current/components/console.html
+[11]: https://github.com/composer/composer/blob/master/src/Composer/Util/SyncHelper.php

src/Composer/Factory.php

@@ -591,6 +591,8 @@ public static function create(IOInterface $io, $config = null, $disablePlugins =
     }
 
     /**
+     * If you are calling this in a plugin, you probably should instead use $composer->getLoop()->getHttpDownloader()
+     *
      * @param  IOInterface      $io      IO instance
      * @param  Config           $config  Config instance
      * @param  array            $options Array of options passed directly to HttpDownloader constructor

src/Composer/Util/Loop.php

@@ -21,22 +21,40 @@
  */
 class Loop
 {
+    /** @var HttpDownloader */
     private $httpDownloader;
+    /** @var ProcessExecutor|null */
     private $processExecutor;
+    /** @var Promise[]|null */
     private $currentPromises;
 
-    public function __construct(HttpDownloader $httpDownloader = null, ProcessExecutor $processExecutor = null)
+    public function __construct(HttpDownloader $httpDownloader, ProcessExecutor $processExecutor = null)
     {
         $this->httpDownloader = $httpDownloader;
-        if ($this->httpDownloader) {
-            $this->httpDownloader->enableAsync();
-        }
+        $this->httpDownloader->enableAsync();
+
         $this->processExecutor = $processExecutor;
         if ($this->processExecutor) {
             $this->processExecutor->enableAsync();
         }
     }
 
+    /**
+     * @return HttpDownloader
+     */
+    public function getHttpDownloader()
+    {
+        return $this->httpDownloader;
+    }
+
+    /**
+     * @return ProcessExecutor|null
+     */
+    public function getProcessExecutor()
+    {
+        return $this->processExecutor;
+    }
+
     public function wait(array $promises, ProgressBar $progress = null)
     {
         /** @var \Exception|null */

src/Composer/Util/SyncHelper.php

@@ -0,0 +1,56 @@
+<?php
+
+namespace Composer\Util;
+
+use Composer\Downloader\DownloaderInterface;
+use Composer\Package\PackageInterface;
+use React\Promise\PromiseInterface;
+
+class SyncHelper
+{
+    /**
+     * Helps you download + install a single package in a synchronous way
+     *
+     * This executes all the required steps and waits for promises to complete
+     *
+     * @param Loop                  $loop        Loop instance which you can get from $composer->getLoop()
+     * @param DownloaderInterface   $downloader  Downloader instance you can get from $composer->getDownloadManager()->getDownloader('zip') for example
+     * @param string                $path        the installation path for the package
+     * @param PackageInterface      $package     the package to install
+     * @param PackageInterface|null $prevPackage the previous package if this is an update and not an initial installation
+     */
+    public static function downloadAndInstallPackageSync(Loop $loop, DownloaderInterface $downloader, $path, PackageInterface $package, PackageInterface $prevPackage = null)
+    {
+        $type = $prevPackage ? 'update' : 'install';
+
+        try {
+            self::await($loop, $downloader->download($package, $path, $prevPackage));
+
+            self::await($loop, $downloader->prepare($type, $package, $path, $prevPackage));
+
+            if ($type === 'update') {
+                self::await($loop, $downloader->update($package, $path, $prevPackage));
+            } else {
+                self::await($loop, $downloader->install($package, $path, $prevPackage));
+            }
+        } catch (\Exception $e) {
+            self::await($loop, $downloader->cleanup($type, $package, $path, $prevPackage));
+            throw $e;
+        }
+
+        self::await($loop, $downloader->cleanup($type, $package, $path, $prevPackage));
+    }
+
+    /**
+     * Waits for a promise to resolve
+     *
+     * @param Loop                  $loop    Loop instance which you can get from $composer->getLoop()
+     * @param PromiseInterface|null $promise
+     */
+    public static function await(Loop $loop, PromiseInterface $promise = null)
+    {
+        if ($promise) {
+            $loop->wait(array($promise));
+        }
+    }
+}