From a9f8bbbcce197dfb62b4a1ad25930942ab861f6b Mon Sep 17 00:00:00 2001
From: Mononaut <github@monospace.live>
Date: Fri, 16 Jun 2023 19:00:52 -0400
Subject: [PATCH] Add network and schema versioning to redis cache

---
 backend/src/api/redis-cache.ts | 31 ++++++++++++++++++++++++++-----
 1 file changed, 26 insertions(+), 5 deletions(-)

diff --git a/backend/src/api/redis-cache.ts b/backend/src/api/redis-cache.ts
index 4b3c956c0..facbafd34 100644
--- a/backend/src/api/redis-cache.ts
+++ b/backend/src/api/redis-cache.ts
@@ -6,9 +6,18 @@ import config from '../config';
 import { BlockExtended, BlockSummary, MempoolTransactionExtended } from '../mempool.interfaces';
 import rbfCache from './rbf-cache';
 
+enum NetworkDB {
+  mainnet = 0,
+  testnet,
+  signet,
+  liquid,
+  liquidtestnet,
+}
+
 class RedisCache {
   private client;
   private connected = false;
+  private schemaVersion = 1;
 
   private cacheQueue: MempoolTransactionExtended[] = [];
   private txFlushLimit: number = 1000;
@@ -18,7 +27,8 @@ class RedisCache {
       const redisConfig = {
         socket: {
           path: config.REDIS.UNIX_SOCKET_PATH
-        }
+        },
+        database: NetworkDB[config.MEMPOOL.NETWORK],
       };
       this.client = createClient(redisConfig);
       this.client.on('error', (e) => {
@@ -30,9 +40,16 @@ class RedisCache {
 
   private async $ensureConnected(): Promise<void> {
     if (!this.connected && config.REDIS.ENABLED) {
-      return this.client.connect().then(() => {
+      return this.client.connect().then(async () => {
         this.connected = true;
         logger.info(`Redis client connected`);
+        const version = await this.client.get('schema_version');
+        if (version !== this.schemaVersion) {
+          // schema changed
+          // perform migrations or flush DB if necessary
+          logger.info(`Redis schema version changed from ${version} to ${this.schemaVersion}`);
+          await this.client.set('schema_version', this.schemaVersion);
+        }
       });
     }
   }
@@ -63,18 +80,22 @@ class RedisCache {
   }
 
   async $flushTransactions() {
-    await this.$addTransactions(this.cacheQueue);
-    this.cacheQueue = [];
+    const success = await this.$addTransactions(this.cacheQueue);
+    if (success) {
+      this.cacheQueue = [];
+    }
   }
 
-  async $addTransactions(newTransactions: MempoolTransactionExtended[]) {
+  async $addTransactions(newTransactions: MempoolTransactionExtended[]): Promise<boolean> {
     try {
       await this.$ensureConnected();
       await Promise.all(newTransactions.map(tx => {
         return this.client.json.set('tx:' + tx.txid, '$', tx);
       }));
+      return true;
     } catch (e) {
       logger.warn(`Failed to add ${newTransactions.length} transactions to Redis cache: ${e instanceof Error ? e.message : e}`);
+      return false;
     }
   }