From 096379e6f9af6929d86781820b1d7d53d730e3a1 Mon Sep 17 00:00:00 2001
From: Richard Hansen <rhansen@rhansen.org>
Date: Fri, 15 Apr 2022 02:57:43 -0400
Subject: [PATCH] Pad: Limit DB concurrency when copying a pad

---
 CHANGELOG.md       | 2 ++
 src/node/db/Pad.js | 5 +++--
 2 files changed, 5 insertions(+), 2 deletions(-)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 0bdd41a50..672d5feb9 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -35,6 +35,8 @@
 * Docker now uses the new `/health` endpoint for health checks, which avoids
   issues when authentication is enabled. It also avoids the unnecessary creation
   of database records for managing browser sessions.
+* When copying a pad, the pad's records are copied in batches to avoid database
+  timeouts with large pads.
 
 #### For plugin authors
 
diff --git a/src/node/db/Pad.js b/src/node/db/Pad.js
index 920d1661f..7cc46cdb8 100644
--- a/src/node/db/Pad.js
+++ b/src/node/db/Pad.js
@@ -383,13 +383,14 @@ class Pad {
       await db.set(`pad:${destinationID}${keySuffix}`, val);
     };
 
-    await Promise.all((function* () {
+    const promises = (function* () {
       yield copyRecord('');
       yield* Stream.range(0, this.head + 1).map((i) => copyRecord(`:revs:${i}`));
       yield* Stream.range(0, this.chatHead + 1).map((i) => copyRecord(`:chat:${i}`));
       yield this.copyAuthorInfoToDestinationPad(destinationID);
       if (destGroupID) yield db.setSub(`group:${destGroupID}`, ['pads', destinationID], 1);
-    }).call(this));
+    }).call(this);
+    for (const p of new Stream(promises).batch(100).buffer(99)) await p;
 
     // Initialize the new pad (will update the listAllPads cache)
     const dstPad = await padManager.getPad(destinationID, null);