From c931d90f34fd8e1a91fb8dcb76dcc2ac5a41555a Mon Sep 17 00:00:00 2001
From: Domagoj Kriskovic <dom.kriskovic@overleaf.com>
Date: Mon, 15 Jan 2024 10:02:53 +0100
Subject: [PATCH] Wait for "doc:saved" event before compiling (#16153)

* wait doc:saved before compiling

* Refactor DocumentCompiler class to handle pending operations before compilation

* add timeout for pending op

* Increase PENDING_OP_MAX_WAIT to 10000 milliseconds

* check if currentDoc exists

* check doc id on doc:saved

* Fix conditional statement

* Refactor to add and remove event listeners for doc:saved event

* check if getPendingOp exists

* typeof getPendingOp

* forgot to push updates

* add flush-changes event

* use promise for handling pending operations

* Remove console.logs

* add isAwaitingBufferedOps

* Revert "add isAwaitingBufferedOps"

This reverts commit 56b0bbc13caf6375d1cf50e8f65f599e7263c404.

* move _awaitBufferedOps in try block

* dont check for matching doc id

* add a todo comment

GitOrigin-RevId: 9225e7d1a7a69385dc1a26bf7663f89f59db6a8a
---
 .../js/features/pdf-preview/util/compiler.js  | 41 ++++++++++++++++++-
 1 file changed, 39 insertions(+), 2 deletions(-)

diff --git a/services/web/frontend/js/features/pdf-preview/util/compiler.js b/services/web/frontend/js/features/pdf-preview/util/compiler.js
index 2887b9234b..75b3f5a26b 100644
--- a/services/web/frontend/js/features/pdf-preview/util/compiler.js
+++ b/services/web/frontend/js/features/pdf-preview/util/compiler.js
@@ -13,6 +13,9 @@ const AUTO_COMPILE_MAX_WAIT = 5000
 // and then again on ack.
 const AUTO_COMPILE_DEBOUNCE = 2500
 
+// If there is a pending op, wait for it to be saved before compiling
+const PENDING_OP_MAX_WAIT = 10000
+
 const searchParams = new URLSearchParams(window.location.search)
 
 export default class DocumentCompiler {
@@ -60,6 +63,40 @@ export default class DocumentCompiler {
         maxWait: AUTO_COMPILE_MAX_WAIT,
       }
     )
+
+    this._onDocSavedCallback = null
+  }
+
+  async _awaitBufferedOps() {
+    const removeEventListener = () => {
+      clearTimeout(this.pendingOpTimeout)
+      if (this._onDocSavedCallback) {
+        window.removeEventListener('doc:saved', this._onDocSavedCallback)
+        this._onDocSavedCallback = null
+      }
+    }
+
+    removeEventListener()
+    return new Promise(resolve => {
+      if (!this.currentDoc?.hasBufferedOps?.()) {
+        return resolve()
+      }
+
+      this._onDocSavedCallback = docSavedParams => {
+        // TODO: it's possible that there's more than one doc open with buffered ops, and ideally we'd wait for all docs to be flushed
+        removeEventListener()
+        resolve()
+      }
+
+      clearTimeout(this.pendingOpTimeout)
+      this.pendingOpTimeout = setTimeout(() => {
+        removeEventListener()
+        resolve()
+      }, PENDING_OP_MAX_WAIT)
+
+      window.addEventListener('doc:saved', this._onDocSavedCallback)
+      window.dispatchEvent(new CustomEvent('flush-changes'))
+    })
   }
 
   // The main "compile" function.
@@ -83,13 +120,13 @@ export default class DocumentCompiler {
     }
 
     try {
+      await this._awaitBufferedOps()
+
       // reset values
       this.setChangedAt(0) // TODO: wait for doc:saved?
       this.setSavedAt(0)
       this.validationIssues = undefined
 
-      window.dispatchEvent(new CustomEvent('flush-changes')) // TODO: wait for this?
-
       const params = this.buildCompileParams(options)
 
       const t0 = performance.now()