From c4cfc1f4aef08dbffba4f86c4d922f3995cc78f8 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?=E6=9D=8E=E6=9D=83=E5=A8=81?= <liquanwei@corp.netease.com>
Date: Tue, 9 May 2023 15:17:24 +0800
Subject: [PATCH] fix: #604

---
 lib/client/doc.js  |  4 +++-
 test/client/doc.js | 43 +++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 46 insertions(+), 1 deletion(-)

diff --git a/lib/client/doc.js b/lib/client/doc.js
index d5a3d05b7..a1ed5ce0b 100644
--- a/lib/client/doc.js
+++ b/lib/client/doc.js
@@ -358,7 +358,9 @@ Doc.prototype._handleOp = function(err, message) {
     // Fetch only sends a new fetch command if no fetches are inflight, which
     // will act as a natural debouncing so we don't send multiple fetch
     // requests for many ops received at once.
-    this.fetch();
+    if (!this.inflightFetch.length) {
+      this.fetch();
+    }
     return;
   }
 
diff --git a/test/client/doc.js b/test/client/doc.js
index fc9e771f8..2f8454e48 100644
--- a/test/client/doc.js
+++ b/test/client/doc.js
@@ -591,4 +591,47 @@ describe('Doc', function() {
       });
     });
   });
+
+  describe('doc fetch', function () {
+    var doc, oriHandleMessage, lastMessage;
+
+    beforeEach(function(done) {
+      doc = this.connection.get('dogs', 'sams');
+      oriHandleMessage = this.connection.handleMessage;
+
+      this.connection.handleMessage = function() {
+        lastMessage = arguments[0];
+        oriHandleMessage.apply(this, arguments);
+      };
+
+      doc.create({name: 'Sams'}, done);
+    });
+
+    afterEach(function() {
+      this.connection.handleMessage = oriHandleMessage;
+    });
+
+    it ('doc fetch should be enqueue', function() {
+      // create op
+      expect(doc.pendingOps.length).to.eql(0);
+      expect(doc.inflightOp).to.eql(null);
+
+      // construct remote message
+      const resMsg1 = {...lastMessage};
+      resMsg1.v += 10;
+      resMsg1.seq += 10;
+
+      const resMsg2 = {...lastMessage};
+      resMsg2.v += 11;
+      resMsg2.seq += 11;
+
+      expect(doc.inflightFetch.length).to.eql(0);
+      this.connection.handleMessage(resMsg1);
+      expect(doc.inflightFetch.length).to.eql(1);
+
+      this.connection.handleMessage(resMsg2);
+      // we expect do not send multiple fetch, when first fetch uncompleted.
+      expect(doc.inflightFetch.length).to.eql(1);
+    });
+  });
 });