From d417ea8a4bd895b9a9c8fc56d0069a870b26e150 Mon Sep 17 00:00:00 2001
From: zkldi <notzkldi@zkldi.com>
Date: Wed, 16 Jun 2021 13:25:52 +0100
Subject: [PATCH] Create Import Locks

---
 server/pnpm-lock.yaml                         |  6 ++--
 server/src/external/mongo/db.ts               |  2 ++
 .../framework/import-locks/lock.ts            | 32 +++++++++++++++++++
 .../framework/score-import-main.ts            | 19 +++++++++++
 .../src/test-utils/mock-db/import-locks.json  |  1 +
 5 files changed, 57 insertions(+), 3 deletions(-)
 create mode 100644 server/src/lib/score-import/framework/import-locks/lock.ts
 create mode 100644 server/src/test-utils/mock-db/import-locks.json

diff --git a/server/pnpm-lock.yaml b/server/pnpm-lock.yaml
index 225a3b5d5..ad75a17b2 100644
--- a/server/pnpm-lock.yaml
+++ b/server/pnpm-lock.yaml
@@ -80,7 +80,7 @@ dependencies:
   rate-limit-redis: 2.1.0
   redis: 3.1.2
   rimraf: 3.0.2
-  tachi-common: github.com/zkldi/tachi-common/137fb72499a2ee6a98791ffea3961d0c69bf24b7
+  tachi-common: github.com/zkldi/tachi-common/fff6217ee6c483f773fed97848802a774e8c5b70
   typescript: 4.3.2
   winston: 3.3.3
 
@@ -4445,8 +4445,8 @@ packages:
     engines: {node: '>=6'}
     dev: true
 
-  github.com/zkldi/tachi-common/137fb72499a2ee6a98791ffea3961d0c69bf24b7:
-    resolution: {tarball: https://codeload.github.com/zkldi/tachi-common/tar.gz/137fb72499a2ee6a98791ffea3961d0c69bf24b7}
+  github.com/zkldi/tachi-common/fff6217ee6c483f773fed97848802a774e8c5b70:
+    resolution: {tarball: https://codeload.github.com/zkldi/tachi-common/tar.gz/fff6217ee6c483f773fed97848802a774e8c5b70}
     name: kamaitachi-common
     version: 0.1.0
     dependencies:
diff --git a/server/src/external/mongo/db.ts b/server/src/external/mongo/db.ts
index 8abc32358..35139c420 100644
--- a/server/src/external/mongo/db.ts
+++ b/server/src/external/mongo/db.ts
@@ -24,6 +24,7 @@ import {
     PBScoreDocument,
     UserMilestoneDocument,
     BMSCourseDocument,
+    ImportLockDocument,
 } from "tachi-common";
 import monk from "monk";
 import { MONGO_BASE_URL } from "../../lib/setup/config";
@@ -132,6 +133,7 @@ const db = {
     "bms-course-lookup": monkDB.get<BMSCourseDocument>("bms-course-lookup"),
     "api-tokens": monkDB.get<APITokenDocument>("api-tokens"),
     "orphan-scores": monkDB.get<OrphanScoreDocument>("orphan-scores"),
+    "import-locks": monkDB.get<ImportLockDocument>("import-locks"),
 };
 
 export default db;
diff --git a/server/src/lib/score-import/framework/import-locks/lock.ts b/server/src/lib/score-import/framework/import-locks/lock.ts
new file mode 100644
index 000000000..06e53a065
--- /dev/null
+++ b/server/src/lib/score-import/framework/import-locks/lock.ts
@@ -0,0 +1,32 @@
+import db from "../../../../external/mongo/db";
+import { integer } from "tachi-common";
+
+/**
+ * Gets a users "import lock" if one exists. If one does not exist, it is set.
+ * @param userID - The user this import lock is for.
+ * @returns If no lock exists for this user (and one was created), undefined is returned
+ * If a lock exists for the user, the lock is returned.
+ */
+export function GetOrSetUserLock(userID: integer) {
+    return db["import-locks"].findOneAndUpdate(
+        {
+            userID,
+        },
+        {
+            userID,
+        },
+        {
+            upsert: true,
+            returnDocument: "before",
+        }
+    );
+}
+
+/**
+ * Removes a users import lock.
+ */
+export function RemoveUserLock(userID: integer) {
+    return db["import-locks"].remove({
+        userID,
+    });
+}
diff --git a/server/src/lib/score-import/framework/score-import-main.ts b/server/src/lib/score-import/framework/score-import-main.ts
index 9281e6dd1..378c1df9e 100644
--- a/server/src/lib/score-import/framework/score-import-main.ts
+++ b/server/src/lib/score-import/framework/score-import-main.ts
@@ -22,6 +22,8 @@ import { ConverterFunction, ImportInputParser } from "../import-types/common/typ
 import { ScorePlaytypeMap } from "./common/types";
 import { Converters } from "../import-types/converters";
 import { ClassHandler } from "./user-game-stats/types";
+import { GetOrSetUserLock, RemoveUserLock } from "./import-locks/lock";
+import ScoreImportFatalError from "./score-importing/score-import-error";
 
 /**
  * Performs a Score Import.
@@ -33,6 +35,21 @@ export default async function ScoreImportMain<D, C>(
     InputParser: ImportInputParser<D, C>,
     providedImportObjects?: { logger: KtLogger; importID: string }
 ) {
+    const lock = await GetOrSetUserLock(user.id);
+
+    if (lock) {
+        // @danger
+        // Throwing away an import if the user already has one outgoing is *bad*, as in the case
+        // of degraded performance we might just start throwing scores away. This is obviously
+        // not great, but any other solution involves making a queue, which can't be done because
+        // InputParser is a very dynamic function that cannot be stored in redis or something.
+        //
+        // Under normal circumstances, there is no scenario where a user would have two ongoing
+        // imports at the same time - even if they were using single-score imports on a 5 second
+        // chart, as each score import takes only around ~10-15miliseconds.
+        throw new ScoreImportFatalError(409, "This user already has an ongoing import.");
+    }
+
     const timeStarted = Date.now();
     let importID;
     let logger;
@@ -202,6 +219,8 @@ export default async function ScoreImportMain<D, C>(
         },
     });
 
+    await RemoveUserLock(user.id);
+
     return ImportDocument;
 }
 
diff --git a/server/src/test-utils/mock-db/import-locks.json b/server/src/test-utils/mock-db/import-locks.json
new file mode 100644
index 000000000..0637a088a
--- /dev/null
+++ b/server/src/test-utils/mock-db/import-locks.json
@@ -0,0 +1 @@
+[]
\ No newline at end of file