From b75184ec8e3436200bacdcd832e3324702553d20 Mon Sep 17 00:00:00 2001
From: syuilo <Syuilotan@yahoo.co.jp>
Date: Sun, 18 Sep 2022 03:27:08 +0900
Subject: なんかもうめっちゃ変えた
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---
 packages/backend/src/core/MetaService.ts | 63 ++++++++++++++++++++++++++++++++
 1 file changed, 63 insertions(+)
 create mode 100644 packages/backend/src/core/MetaService.ts

(limited to 'packages/backend/src/core/MetaService.ts')

diff --git a/packages/backend/src/core/MetaService.ts b/packages/backend/src/core/MetaService.ts
new file mode 100644
index 0000000000..b5bd423765
--- /dev/null
+++ b/packages/backend/src/core/MetaService.ts
@@ -0,0 +1,63 @@
+import { Inject, Injectable } from '@nestjs/common';
+import { DataSource } from 'typeorm';
+import type { UsersRepository } from '@/models/index.js';
+import { DI } from '@/di-symbols.js';
+import { Meta } from '@/models/entities/Meta.js';
+import type { OnApplicationShutdown } from '@nestjs/common';
+
+@Injectable()
+export class MetaService implements OnApplicationShutdown {
+	#cache: Meta | undefined;
+	#intervalId: NodeJS.Timer;
+
+	constructor(
+		@Inject(DI.db)
+		private db: DataSource,
+	) {
+		if (process.env.NODE_ENV !== 'test') {
+			this.#intervalId = setInterval(() => {
+				this.fetch(true).then(meta => {
+					this.#cache = meta;
+				});
+			}, 1000 * 10);
+		}
+	}
+
+	async fetch(noCache = false): Promise<Meta> {
+		if (!noCache && this.#cache) return this.#cache;
+	
+		return await this.db.transaction(async transactionalEntityManager => {
+			// 過去のバグでレコードが複数出来てしまっている可能性があるので新しいIDを優先する
+			const metas = await transactionalEntityManager.find(Meta, {
+				order: {
+					id: 'DESC',
+				},
+			});
+	
+			const meta = metas[0];
+	
+			if (meta) {
+				this.#cache = meta;
+				return meta;
+			} else {
+				// metaが空のときfetchMetaが同時に呼ばれるとここが同時に呼ばれてしまうことがあるのでフェイルセーフなupsertを使う
+				const saved = await transactionalEntityManager
+					.upsert(
+						Meta,
+						{
+							id: 'x',
+						},
+						['id'],
+					)
+					.then((x) => transactionalEntityManager.findOneByOrFail(Meta, x.identifiers[0]));
+	
+				this.#cache = saved;
+				return saved;
+			}
+		});
+	}
+	
+	public onApplicationShutdown(signal?: string | undefined) {
+		clearInterval(this.#intervalId);
+	}
+}
-- 
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