From 860aff495858ac154ff4082290831beb741ef6f7 Mon Sep 17 00:00:00 2001
From: David Baker <dave@matrix.org>
Date: Mon, 16 Jan 2023 17:27:49 +0000
Subject: [PATCH] Change rageshake persistence to throttled flushing

Rather than every 30 seconds. This way we'll save logs for sessions
lasting less than 30 seconds which we previously didn't. Also save
on window unload just in case that doesn't catch everything.

Plus remove some more unused params.
---
 package.json              |  1 +
 src/settings/rageshake.ts | 65 ++++++++++++++++++++++++++++++---------
 2 files changed, 51 insertions(+), 15 deletions(-)

diff --git a/package.json b/package.json
index f7bbbb0..58001db 100644
--- a/package.json
+++ b/package.json
@@ -45,6 +45,7 @@
     "i18next": "^21.10.0",
     "i18next-browser-languagedetector": "^6.1.8",
     "i18next-http-backend": "^1.4.4",
+    "lodash": "^4.17.21",
     "matrix-js-sdk": "github:matrix-org/matrix-js-sdk#7b10fa367df357b51c2e78e220d39e5e7967f9e3",
     "matrix-widget-api": "^1.0.0",
     "mermaid": "^8.13.8",
diff --git a/src/settings/rageshake.ts b/src/settings/rageshake.ts
index f83a205..268f2ac 100644
--- a/src/settings/rageshake.ts
+++ b/src/settings/rageshake.ts
@@ -37,15 +37,23 @@ limitations under the License.
 //    actually timestamps. We then purge the remaining logs. We also do this
 //    purge on startup to prevent logs from accumulating.
 
+import EventEmitter from "events";
+import { throttle } from "lodash";
 import { logger } from "matrix-js-sdk/src/logger";
 import { randomString } from "matrix-js-sdk/src/randomstring";
 
-// the frequency with which we flush to indexeddb
-const FLUSH_RATE_MS = 30 * 1000;
-
 // the length of log data we keep in indexeddb (and include in the reports)
 const MAX_LOG_SIZE = 1024 * 1024 * 5; // 5 MB
 
+// Shortest amount of time between flushes. We are just appending to an
+// IndexedDB table so we don't expect flushing to be that expensive, but
+// we can batch the writes a little.
+const MAX_FLUSH_INTERVAL = 2 * 1000;
+
+enum ConsoleLoggerEvent {
+  Log = "log",
+}
+
 type LogFunction = (
   ...args: (Error | DOMException | object | string)[]
 ) => void;
@@ -59,7 +67,7 @@ interface LogEntry {
   index?: number;
 }
 
-export class ConsoleLogger {
+export class ConsoleLogger extends EventEmitter {
   private logs = "";
   private originalFunctions: { [key in LogFunctionName]?: LogFunction } = {};
 
@@ -113,6 +121,8 @@ export class ConsoleLogger {
     // Using + really is the quickest way in JS
     // http://jsperf.com/concat-vs-plus-vs-join
     this.logs += line;
+
+    this.emit(ConsoleLoggerEvent.Log);
   }
 
   /**
@@ -142,8 +152,14 @@ export class IndexedDBLogStore {
   private flushAgainPromise: Promise<void> = null;
   private id: string;
 
-  constructor(private indexedDB: IDBFactory, private logger: ConsoleLogger) {
+  constructor(
+    private indexedDB: IDBFactory,
+    private loggerInstance: ConsoleLogger
+  ) {
     this.id = "instance-" + randomString(16);
+
+    loggerInstance.on(ConsoleLoggerEvent.Log, this.onLoggerLog);
+    window.addEventListener("beforeunload", this.flush);
   }
 
   /**
@@ -154,19 +170,18 @@ export class IndexedDBLogStore {
     return new Promise((resolve, reject) => {
       req.onsuccess = () => {
         this.db = req.result;
-        // Periodically flush logs to local storage / indexeddb
-        setInterval(this.flush.bind(this), FLUSH_RATE_MS);
+
         resolve();
       };
 
-      req.onerror = (event) => {
+      req.onerror = () => {
         const err = "Failed to open log database: " + req.error.name;
         logger.error(err);
         reject(new Error(err));
       };
 
       // First time: Setup the object store
-      req.onupgradeneeded = (event) => {
+      req.onupgradeneeded = () => {
         const db = req.result;
         // This is the log entries themselves. Each entry is a chunk of
         // logs (ie multiple lines). 'id' is the instance ID (so logs with
@@ -197,6 +212,26 @@ export class IndexedDBLogStore {
     });
   }
 
+  private onLoggerLog = () => {
+    if (!this.db) return;
+
+    this.throttledFlush();
+  };
+
+  // Throttled function to flush logs. We use throttle rather
+  // than debounce as we want logs to be written regularly, otherwise
+  // if there's a constant stream of logging, we'd never write anything.
+  private throttledFlush = throttle(
+    () => {
+      this.flush();
+    },
+    MAX_FLUSH_INTERVAL,
+    {
+      leading: false,
+      trailing: true,
+    }
+  );
+
   /**
    * Flush logs to disk.
    *
@@ -216,7 +251,7 @@ export class IndexedDBLogStore {
    *
    * @return {Promise} Resolved when the logs have been flushed.
    */
-  public flush(): Promise<void> {
+  public flush = (): Promise<void> => {
     // check if a flush() operation is ongoing
     if (this.flushPromise) {
       if (this.flushAgainPromise) {
@@ -241,14 +276,14 @@ export class IndexedDBLogStore {
         reject(new Error("No connected database"));
         return;
       }
-      const lines = this.logger.popLogs();
+      const lines = this.loggerInstance.popLogs();
       if (lines.length === 0) {
         resolve();
         return;
       }
       const txn = this.db.transaction(["logs", "logslastmod"], "readwrite");
       const objStore = txn.objectStore("logs");
-      txn.oncomplete = (event) => {
+      txn.oncomplete = () => {
         resolve();
       };
       txn.onerror = (event) => {
@@ -262,7 +297,7 @@ export class IndexedDBLogStore {
       this.flushPromise = null;
     });
     return this.flushPromise;
-  }
+  };
 
   /**
    * Consume the most recent logs and return them. Older logs which are not
@@ -433,11 +468,11 @@ function selectQuery<T>(
   const query = store.openCursor(keyRange);
   return new Promise((resolve, reject) => {
     const results = [];
-    query.onerror = (event) => {
+    query.onerror = () => {
       reject(new Error("Query failed: " + query.error.message));
     };
     // collect results
-    query.onsuccess = (event) => {
+    query.onsuccess = () => {
       const cursor = query.result;
       if (!cursor) {
         resolve(results);