mutex on txinfo to enforce cache hits

package.json

@@ -14,6 +14,7 @@
   "dependencies": {
     "@types/bs58": "^4.0.1",
     "apex-logs-winston": "^1.1.0",
+    "async-mutex": "^0.2.4",
     "axios": "^0.20.0",
     "bitcoinjs-lib": "^5.1.10",
     "bitcoinjs-message": "^2.1.3",

src/index.ts

@@ -3,6 +3,7 @@ import { FullServiceHandlers, AssetTransactionData, TransactionInformation } fro
 import { BcoinHandlers, BlockcyperHandlers } from './implementations';
 import { configureLogger, logger } from './log';
 import NodeCache from 'node-cache';
+import { Mutex } from 'async-mutex';
 require('dotenv').config();
 
 if (process.env.NODE_ENV === 'production' || process.env.NODE_ENV === 'local_with_logger') {
@@ -40,23 +41,40 @@ switch (process.env.SOURCE) {
     logger.info('USING BCOIN');
     handlers = BcoinHandlers;
 }
-
+const mx = new Mutex();
 const txInfoCache = new NodeCache({ stdTTL: 10, checkperiod: 1 });
+
+async function getTransactionInfoResult(reference: string, poolAddress: string) {
+  const release = await mx.acquire();
+  try {
+    const key = `${reference}-${poolAddress}`;
+    const fromCache: TransactionInformation | undefined = txInfoCache.get(key);
+    if (fromCache) {
+      logger.info('delivering from cache', { key });
+      return fromCache;
+    } else {
+      logger.info('no cache hit', { key });
+      const result = await handlers.oracle.getTransactionInformation(reference as string, poolAddress as string);
+      txInfoCache.set(key, result);
+      return result;
+    }
+  } catch (error) {
+    logger.error('Error getTransactionInfoResult', { error });
+    return null;
+  } finally {
+    release();
+  }
+}
+
 app.get('/oracle/transactionInfo', async (req, res) => {
   const { reference, poolAddress } = req.query;
   logger.info('Called /oracle/transactionInfo', { reference, poolAddress });
   if (!reference || !poolAddress) return res.status(400).json({ status: 'MISSING_PARAMS' });
-  const key = `${reference}-${poolAddress}`;
-  const fromCache: TransactionInformation | undefined = txInfoCache.get(key);
-  if (fromCache) {
-    logger.info('delivering from cache', { key });
-    return res.json(fromCache);
-  } else {
-    logger.info('no cache hit', { key });
-    const result = await handlers.oracle.getTransactionInformation(reference as string, poolAddress as string);
-    txInfoCache.set(key, result);
-    return res.json(result);
+  const result = await getTransactionInfoResult(reference as string, poolAddress as string);
+  if (result === null) {
+    res.status(500);
   }
+  return res.json(result);
 });
 
 app.post('/oracle/validateSignature', async (req, res) => {

yarn.lock

@@ -372,6 +372,13 @@ async-each@^1.0.1:
   resolved "https://registry.yarnpkg.com/async-each/-/async-each-1.0.3.tgz#b727dbf87d7651602f06f4d4ac387f47d91b0cbf"
   integrity sha512-z/WhQ5FPySLdvREByI2vZiTWwCnF0moMJ1hK9YQwDTHKh6I7/uSckMetoRGb5UBZPC1z0jlw+n/XCgjeH7y1AQ==
 
+async-mutex@^0.2.4:
+  version "0.2.4"
+  resolved "https://registry.yarnpkg.com/async-mutex/-/async-mutex-0.2.4.tgz#f6ea5f9cc73147f395f86fa573a2af039fe63082"
+  integrity sha512-fcQKOXUKMQc57JlmjBCHtkKNrfGpHyR7vu18RfuLfeTAf4hK9PgOadPR5cDrBQ682zasrLUhJFe7EKAHJOduDg==
+  dependencies:
+    tslib "^2.0.0"
+
 [email protected]:
   version "0.2.9"
   resolved "https://registry.yarnpkg.com/async/-/async-0.2.9.tgz#df63060fbf3d33286a76aaf6d55a2986d9ff8619"
@@ -3938,6 +3945,11 @@ tsconfig-paths@^3.9.0:
     minimist "^1.2.0"
     strip-bom "^3.0.0"
 
+tslib@^2.0.0:
+  version "2.0.3"
+  resolved "https://registry.yarnpkg.com/tslib/-/tslib-2.0.3.tgz#8e0741ac45fc0c226e58a17bfc3e64b9bc6ca61c"
+  integrity sha512-uZtkfKblCEQtZKBF6EBXVZeQNl82yqtDQdv+eck8u7tdPxjLu2/lp5/uPW+um2tpuxINHWy3GhiccY7QgEaVHQ==
+
 type-check@^0.4.0, type-check@~0.4.0:
   version "0.4.0"
   resolved "https://registry.yarnpkg.com/type-check/-/type-check-0.4.0.tgz#07b8203bfa7056c0657050e3ccd2c37730bab8f1"