From b3daba77bd523e9acc1fe5211d9fa3cdd21f4edf Mon Sep 17 00:00:00 2001
From: or-else <or.else@gmail.com>
Date: Mon, 26 Apr 2021 21:36:49 -0700
Subject: [PATCH] cherrypicking support for browsable subscriptions

---
 server/db/mongodb/adapter.go   |  6 +++---
 server/db/mysql/adapter.go     | 11 ++++++-----
 server/db/rethinkdb/adapter.go |  6 +++---
 3 files changed, 12 insertions(+), 11 deletions(-)

diff --git a/server/db/mongodb/adapter.go b/server/db/mongodb/adapter.go
index 0070cdd5d..5f8f37893 100644
--- a/server/db/mongodb/adapter.go
+++ b/server/db/mongodb/adapter.go
@@ -1285,9 +1285,9 @@ func (a *adapter) TopicsForUser(uid t.Uid, keepDeleted bool, opts *t.QueryOpt) (
 	}
 	limit := a.maxResults
 	if opts != nil {
-		// Ignore IfModifiedSince - we must return all entries
-		// Those unmodified will be stripped of Public & Private.
-
+		if opts.IfModifiedSince != nil {
+			filter["updatedat"] = b.M{"$gt": opts.IfModifiedSince}
+		}
 		if opts.Topic != "" {
 			filter["topic"] = opts.Topic
 		}
diff --git a/server/db/mysql/adapter.go b/server/db/mysql/adapter.go
index 7eacf101c..6db68efb7 100644
--- a/server/db/mysql/adapter.go
+++ b/server/db/mysql/adapter.go
@@ -1428,9 +1428,10 @@ func (a *adapter) TopicsForUser(uid t.Uid, keepDeleted bool, opts *t.QueryOpt) (
 
 	limit := a.maxResults
 	if opts != nil {
-		// Ignore IfModifiedSince - we must return all entries
-		// Those unmodified will be stripped of Public & Private.
-
+		if opts.IfModifiedSince != nil {
+			q += " AND updatedat>?"
+			args = append(args, opts.IfModifiedSince)
+		}
 		if opts.Topic != "" {
 			q += " AND topic=?"
 			args = append(args, opts.Topic)
@@ -1597,7 +1598,7 @@ func (a *adapter) TopicsForUser(uid t.Uid, keepDeleted bool, opts *t.QueryOpt) (
 }
 
 // UsersForTopic loads users subscribed to the given topic.
-// The difference between UsersForTopic vs SubsForTopic is that the former loads user.public,
+// The difference between UsersForTopic vs SubsForTopic is that the former loads user.Public,
 // the latter does not.
 func (a *adapter) UsersForTopic(topic string, keepDeleted bool, opts *t.QueryOpt) ([]t.Subscription, error) {
 	tcat := t.GetTopicCat(topic)
@@ -1624,7 +1625,7 @@ func (a *adapter) UsersForTopic(topic string, keepDeleted bool, opts *t.QueryOpt
 	limit := a.maxResults
 	var oneUser t.Uid
 	if opts != nil {
-		// Ignore IfModifiedSince - we must return all entries
+		// Ignore IfModifiedSince: loading all entries because a topic cannot have too many subscribers.
 		// Those unmodified will be stripped of Public & Private.
 
 		if !opts.User.IsZero() {
diff --git a/server/db/rethinkdb/adapter.go b/server/db/rethinkdb/adapter.go
index 779d9b56a..d778e2ddc 100644
--- a/server/db/rethinkdb/adapter.go
+++ b/server/db/rethinkdb/adapter.go
@@ -1091,9 +1091,9 @@ func (a *adapter) TopicsForUser(uid t.Uid, keepDeleted bool, opts *t.QueryOpt) (
 	}
 	limit := a.maxResults
 	if opts != nil {
-		// Ignore IfModifiedSince - we must return all entries
-		// Those unmodified will be stripped of Public & Private.
-
+		if opts.IfModifiedSince != nil {
+			q = q.Filter(rdb.Row.Field("UpdatedAt").Gt(opts.IfModifiedSince))
+		}
 		if opts.Topic != "" {
 			q = q.Filter(rdb.Row.Field("Topic").Eq(opts.Topic))
 		}