server: Make sync lazy

Use streams and generators to save memory. Useful when there is not much memory and the articles are huge.
fossar · Sep 12, 2020 · b3d8dd0 · b3d8dd0
1 parent f72114e
commit b3d8dd0
Show file tree

Hide file tree

Showing 4 changed files with 135 additions and 12 deletions.
diff --git a/composer.json b/composer.json
@@ -13,6 +13,7 @@
         "guzzlehttp/guzzle": "^6.3",
         "guzzlehttp/oauth-subscriber": "^0.4.0",
         "guzzlehttp/psr7": "^1.5",
+        "http-interop/response-sender": "^1.0",
         "j0k3r/graby": "2.0.0-alpha.0",
         "level-2/dice": "^2.0",
         "lordelph/icofileloader": "^2.0",
@@ -21,6 +22,7 @@
         "php-http/guzzle6-adapter": "^1.0",
         "simplepie/simplepie": "^1.3",
         "smottt/wideimage": "^1.1",
+        "violet/streaming-json-encoder": "^1.1",
         "willwashburn/phpamo": "^1.0"
     },
     "require-dev": {

diff --git a/composer.lock b/composer.lock
diff --git a/src/controllers/Items/Sync.php b/src/controllers/Items/Sync.php
@@ -4,6 +4,7 @@
 
 use Base;
 use helpers\Authentication;
+use function helpers\json_response;
 use helpers\View;
 use helpers\ViewHelper;
 
@@ -86,16 +87,14 @@ public function sync(Base $f3) {
                                         2 * $itemsHowMany);
                 }
 
-                $sync['newItems'] = [];
-                foreach ($this->itemsDao->sync($sinceId, $notBefore, $since, $itemsHowMany)
-                         as $newItem) {
-                    $sync['newItems'][] = ViewHelper::preprocessEntry($newItem, $this->tagsController);
-                }
-                if ($sync['newItems']) {
-                    $sync['lastId'] = $this->itemsDao->lastId();
-                } else {
-                    unset($sync['newItems']);
-                }
+                $sync['newItems'] = function() use ($sinceId, $notBefore, $since, $itemsHowMany) {
+                    foreach ($this->itemsDao->sync($sinceId, $notBefore, $since, $itemsHowMany)
+                             as $newItem) {
+                        yield ViewHelper::preprocessEntry($newItem, $this->tagsController);
+                    }
+                };
+
+                $sync['lastId'] = $this->itemsDao->lastId();
             }
         }
 
@@ -115,7 +114,7 @@ public function sync(Base $f3) {
             }
         }
 
-        $this->view->jsonSuccess($sync);
+        $this->view->sendResponse(json_response($sync));
     }
 
     /**

diff --git a/src/helpers/View.php b/src/helpers/View.php
@@ -2,6 +2,9 @@
 
 namespace helpers;
 
+use function Http\Response\send;
+use Psr\Http\Message\ResponseInterface;
+
 /**
  * Helper class for rendering template
  *
@@ -104,4 +107,32 @@ public function jsonSuccess($data) {
         header('Content-type: application/json');
         die(json_encode($data));
     }
+
+    /**
+     * Send a PSR-7 response.
+     *
+     * @return void
+     */
+    public function sendResponse(ResponseInterface $response) {
+        send($response);
+        die;
+    }
+}
+
+/**
+ * Create a PSR-7 response for given JSON-encodable data.
+ *
+ * @param mixed $data
+ *
+ * @return ResponseInterface
+ */
+function json_response($data) {
+    $encoder = new \Violet\StreamingJsonEncoder\BufferJsonEncoder($data);
+    $stream = new \Violet\StreamingJsonEncoder\JsonStream($encoder);
+
+    $response = new \GuzzleHttp\Psr7\Response();
+    $response = $response->withHeader('Content-type', 'application/json');
+    $response = $response->withBody($stream);
+
+    return $response;
 }