[addon] adaptive availability cache ttl

addon/lib/cache.js

@@ -8,6 +8,8 @@ const RESOLVED_URL_KEY_PREFIX = `${GLOBAL_KEY_PREFIX}|resolved`;
 
 const STREAM_TTL = process.env.STREAM_TTL || 4 * 60 * 60; // 4 hours
 const STREAM_EMPTY_TTL = process.env.STREAM_EMPTY_TTL || 30 * 60; // 30 minutes
+const AVAILABILITY_TTL = 8 * 60 * 60; // 8 hours
+const AVAILABILITY_EMPTY_TTL = 60 * 60; // 1 hours
 const RESOLVED_URL_TTL = 60; // 1 minutes
 // When the streams are empty we want to cache it for less time in case of timeouts or failures
 
@@ -67,14 +69,13 @@ function cacheWrapResolvedUrl(id, method) {
 }
 
 function cacheAvailabilityResults(results) {
-  const flatResults = Object.keys(results)
-      .map(infoHash => [`${AVAILABILITY_KEY_PREFIX}:${infoHash}`, results[infoHash]])
-      .reduce((a, b) => a.concat(b), []);
-  memoryCache.mset(...flatResults, { ttl: STREAM_TTL }, (error) => {
-    if (error) {
-      console.log('Failed storing availability cache', error);
-    }
-  });
+  Object.keys(results)
+      .forEach(infoHash => {
+        const key = `${AVAILABILITY_KEY_PREFIX}:${infoHash}`;
+        const value = results[infoHash];
+        const ttl = value && value.length ? AVAILABILITY_TTL : AVAILABILITY_EMPTY_TTL;
+        memoryCache.set(key, value, ttl)
+      });
   return results;
 }