From 589912b4202a477becf07ba6b5ba496669f94b75 Mon Sep 17 00:00:00 2001
From: Andrei Mihu <andrei@heroiclabs.com>
Date: Thu, 29 Dec 2022 13:39:22 +0000
Subject: [PATCH] Fix exact enforcement of maximum party size.

---
 CHANGELOG.md            |  3 ++-
 server/party_handler.go | 31 +++++++++++++++++++++++--------
 2 files changed, 25 insertions(+), 9 deletions(-)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 9732282fe..8dfe8e43e 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -40,8 +40,9 @@ The format is based on [keep a changelog](http://keepachangelog.com) and this pr
 - Ensure rank cache is correctly updated when joining tournaments.
 - Ensure default parameters for tournament listings are consistent between API and runtimes.
 - Fix devconsole groups view incorrect visual removal of last group member.
-- Fix iap subscription notification handling.
+- Fix In-App Purchase subscription notification handling.
 - Fix handling of party leader transition if previous leader and other members leave concurrently.
+- Fix exact enforcement of maximum party size.
 
 ## [3.14.0] - 2022-10-14
 ### Added
diff --git a/server/party_handler.go b/server/party_handler.go
index 6d5d9023e..1cd20346b 100644
--- a/server/party_handler.go
+++ b/server/party_handler.go
@@ -49,7 +49,7 @@ type PartyHandler struct {
 	leaderUserPresence       *rtapi.UserPresence
 	members                  []*PresenceID
 	memberUserPresences      []*rtapi.UserPresence
-	joinsInProgress          int
+	joinsInProgress          []*PresenceID
 	joinRequests             []*Presence
 	joinRequestUserPresences []*rtapi.UserPresence
 }
@@ -80,7 +80,7 @@ func NewPartyHandler(logger *zap.Logger, partyRegistry PartyRegistry, matchmaker
 		leaderUserPresence:       nil,
 		members:                  make([]*PresenceID, 0, maxSize),
 		memberUserPresences:      make([]*rtapi.UserPresence, 0, maxSize),
-		joinsInProgress:          0,
+		joinsInProgress:          make([]*PresenceID, 0, maxSize),
 		joinRequests:             make([]*Presence, 0, maxSize),
 		joinRequestUserPresences: make([]*rtapi.UserPresence, 0, maxSize),
 	}
@@ -101,13 +101,13 @@ func (p *PartyHandler) JoinRequest(presence *Presence) (bool, error) {
 	}
 
 	// Check if party is full.
-	if len(p.members)+p.joinsInProgress >= p.MaxSize {
+	if len(p.members)+len(p.joinsInProgress) >= p.MaxSize {
 		p.Unlock()
 		return false, runtime.ErrPartyFull
 	}
 	// Check if party is open, and therefore automatically accepts join requests.
 	if p.Open {
-		p.joinsInProgress++
+		p.joinsInProgress = append(p.joinsInProgress, &presence.ID)
 		p.Unlock()
 		return true, nil
 	}
@@ -200,7 +200,15 @@ func (p *PartyHandler) Join(presences []*Presence) {
 		p.members = append(p.members, &currentPresence.ID)
 		p.memberUserPresences = append(p.memberUserPresences, memberUserPresence)
 		memberUserPresences = append(memberUserPresences, memberUserPresence)
-		p.joinsInProgress--
+
+		for i := 0; i < len(p.joinsInProgress); i++ {
+			if p.joinsInProgress[i].SessionID == presence.ID.SessionID && p.joinsInProgress[i].Node == presence.ID.Node {
+				copy(p.joinsInProgress[i:], p.joinsInProgress[i+1:])
+				p.joinsInProgress[len(p.joinsInProgress)-1] = nil
+				p.joinsInProgress = p.joinsInProgress[:len(p.joinsInProgress)-1]
+				break
+			}
+		}
 
 		// Prepare message to be sent to the new presences.
 		if initialLeader != nil && presence == initialLeader {
@@ -359,7 +367,7 @@ func (p *PartyHandler) Accept(sessionID, node string, presence *rtapi.UserPresen
 	}
 
 	// Check if there's room to accept the new party member.
-	if len(p.members)+p.joinsInProgress >= p.MaxSize {
+	if len(p.members)+len(p.joinsInProgress) >= p.MaxSize {
 		p.Unlock()
 		return runtime.ErrPartyFull
 	}
@@ -386,14 +394,21 @@ func (p *PartyHandler) Accept(sessionID, node string, presence *rtapi.UserPresen
 		return runtime.ErrPartyNotRequest
 	}
 
-	p.joinsInProgress++
+	p.joinsInProgress = append(p.joinsInProgress, &joinRequestPresence.ID)
 	p.Unlock()
 
 	// Add the presence to the party stream, which will trigger the Join() hook above.
 	success, _, err := p.streamManager.UserJoin(p.Stream, joinRequestPresence.UserID, joinRequestPresence.ID.SessionID, false, false, "")
 	if err != nil || !success {
 		p.Lock()
-		p.joinsInProgress--
+		for i := 0; i < len(p.joinsInProgress); i++ {
+			if p.joinsInProgress[i].SessionID == joinRequestPresence.ID.SessionID && p.joinsInProgress[i].Node == joinRequestPresence.ID.Node {
+				copy(p.joinsInProgress[i:], p.joinsInProgress[i+1:])
+				p.joinsInProgress[len(p.joinsInProgress)-1] = nil
+				p.joinsInProgress = p.joinsInProgress[:len(p.joinsInProgress)-1]
+				break
+			}
+		}
 		p.Unlock()
 		return runtime.ErrPartyAcceptRequest
 	}
-- 
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