ThordekkCore/DEADLOCK_FIX_PHASE2_PATTERN.md

DEADLOCK FIX PHASE 2 - ClassAI UpdateRotation Pattern

ROOT CAUSE ANALYSIS

Problem: 86 files in src/modules/Playerbot call ObjectAccessor::GetUnit(), ObjectAccessor::GetCreature(), or ObjectAccessor::GetPlayer() from WORKER THREADS during UpdateRotation() execution.

Why This Causes Deadlock:

• UpdateRotation() is called from worker thread pool by BotAI
• ObjectAccessor::GetUnit(*bot, guid) calls Map::GetCreature(guid)
• Map::_objectsStore has NO MUTEX (single-threaded by design)
• Multiple worker threads accessing Map::_objectsStore simultaneously → DEADLOCK
• Futures 3-14 never complete with 5000+ bots

INCORRECT PATTERN (DEADLOCK)

void UnholySpecialization::UpdateRotation(Unit* target)
{
    Player* bot = GetBot();

    // ❌ DEADLOCK: Calling ObjectAccessor from worker thread!
    ::Unit* target = ObjectAccessor::GetUnit(*bot, bot->GetTarget());

    if (!target)
        return;

    // Use target...
    float targetHealthPct = target->GetHealthPct();

    // Cast spells using ObjectAccessor calls...
}

Why This is Wrong:

1. UpdateRotation() is called from worker thread
2. ObjectAccessor::GetUnit() accesses Map::_objectsStore (NOT thread-safe)
3. Multiple bots doing this simultaneously → deadlock

CORRECT PATTERN (THREAD-SAFE)

void UnholySpecialization::UpdateRotation(Unit* target)
{
    Player* bot = GetBot();

    // ✅ CORRECT: Use the target parameter passed from main thread!
    if (!target || !target->IsInWorld())
        return;

    // Use target directly - NO ObjectAccessor calls!
    float targetHealthPct = target->GetHealthPct();

    // Queue actions using BotActionManager (thread-safe)
    sBotActionMgr->QueueAction(BotAction::CastSpell(
        bot->GetGUID(),
        DEATH_STRIKE,
        target->GetGUID(),
        getMSTime()
    ));
}

Why This is Correct:

1. Use target parameter (already resolved on main thread)
2. NO ObjectAccessor calls from worker thread
3. Queue actions using sBotActionMgr (thread-safe queue)
4. Main thread executes actions with Map access

FILES REQUIRING FIX (86 total)

High Priority (Class AI Specializations - Run on Worker Threads)

1. src/modules/Playerbot/AI/ClassAI/DeathKnights/UnholySpecialization.cpp (4 locations)
2. src/modules/Playerbot/AI/ClassAI/DeathKnights/FrostSpecialization.cpp (1 location)
3. src/modules/Playerbot/AI/ClassAI/DeathKnights/DeathKnightAI.cpp (1 location)
4. src/modules/Playerbot/AI/ClassAI/Warriors/*.cpp
5. src/modules/Playerbot/AI/ClassAI/Hunters/*.cpp
6. src/modules/Playerbot/AI/ClassAI/Rogues/*.cpp
7. src/modules/Playerbot/AI/ClassAI/Mages/*.cpp
8. src/modules/Playerbot/AI/ClassAI/Warlocks/*.cpp
9. src/modules/Playerbot/AI/ClassAI/Shamans/*.cpp
10. src/modules/Playerbot/AI/ClassAI/Paladins/*.cpp
11. src/modules/Playerbot/AI/ClassAI/Priests/*.cpp
12. src/modules/Playerbot/AI/ClassAI/Druids/*.cpp
13. src/modules/Playerbot/AI/ClassAI/Monks/*.cpp
14. src/modules/Playerbot/AI/ClassAI/DemonHunters/*.cpp
15. src/modules/Playerbot/AI/ClassAI/Evokers/*.cpp

Medium Priority (Combat Managers - May Run on Worker Threads)

16. src/modules/Playerbot/AI/Combat/CombatStateAnalyzer.cpp
17. src/modules/Playerbot/AI/Combat/TargetSelector.cpp
18. src/modules/Playerbot/AI/Combat/PositionManager.cpp
19. src/modules/Playerbot/AI/Combat/InterruptManager.cpp
20. src/modules/Playerbot/AI/Strategy/CombatMovementStrategy.cpp

Low Priority (Main Thread Only - Safe but Should Still Use Actions)

21. src/modules/Playerbot/Threading/BotActionProcessor.cpp (✅ Already uses actions)
22. src/modules/Playerbot/AI/BotAI.cpp (✅ Main thread, but good to use actions)
23. Quest/Interaction managers (main thread operations)

IMPLEMENTATION STRATEGY

Phase 2A: Remove ObjectAccessor from UpdateRotation

For each ClassAI file:

1. Find all ObjectAccessor::GetUnit(*bot, bot->GetTarget()) calls
2. Replace with use of target parameter
3. Add validation: if (!target || !target->IsInWorld()) return;

Phase 2B: Convert Direct Spell Casts to Action Queue

For each spell cast:

// ❌ BEFORE (Direct cast from worker thread - unsafe with future changes):
bot->CastSpell(target, DEATH_STRIKE, false);

// ✅ AFTER (Queue action for main thread execution):
sBotActionMgr->QueueAction(BotAction::CastSpell(
    bot->GetGUID(),
    DEATH_STRIKE,
    target->GetGUID(),
    getMSTime()
));

Phase 2C: Convert Direct Attacks to Action Queue

// ❌ BEFORE:
bot->Attack(target, true);

// ✅ AFTER:
sBotActionMgr->QueueAction(BotAction::AttackTarget(
    bot->GetGUID(),
    target->GetGUID(),
    getMSTime()
));

AUTOMATION SCRIPT

Create Python script to automate the fix across all 86 files:

import re
import os

def fix_update_rotation_file(filepath):
    with open(filepath, 'r', encoding='utf-8') as f:
        content = f.read()

    # Pattern 1: Remove ObjectAccessor::GetUnit(*bot, bot->GetTarget())
    pattern1 = r'::Unit\*\s+target\s*=\s*ObjectAccessor::GetUnit\(\*bot,\s*bot->GetTarget\(\)\);'
    replacement1 = '// DEADLOCK FIX: Use target parameter instead of ObjectAccessor'

    content = re.sub(pattern1, replacement1, content)

    # Pattern 2: Add target validation if missing
    if 'if (!target' not in content:
        # Add after function start
        pass

    with open(filepath, 'w', encoding='utf-8') as f:
        f.write(content)

# Run on all ClassAI files
base_dir = 'src/modules/Playerbot/AI/ClassAI'
for root, dirs, files in os.walk(base_dir):
    for file in files:
        if file.endswith('.cpp'):
            filepath = os.path.join(root, file)
            fix_update_rotation_file(filepath)

EXPECTED RESULTS AFTER FIX

✅ All ObjectAccessor calls removed from worker threads ✅ UpdateRotation methods use passed target parameter ✅ All spell casts queued via BotActionManager ✅ Main thread processes queued actions with safe Map access ✅ Futures 3-14 complete with 5000+ bots ✅ No more 60-second hangs or deadlocks

TESTING CHECKLIST

• Build succeeds with zero errors
• Spawn 100 bots - all futures complete
• Spawn 1000 bots - all futures complete
• Spawn 5000 bots - futures 3-14 complete (THIS IS THE KEY TEST)
• No server hangs or 60-second pauses
• Bots execute rotations correctly
• Combat system works normally

REFERENCES

• Action Queue Implementation: src/modules/Playerbot/Threading/BotActionManager.h
• Action Definitions: src/modules/Playerbot/Threading/BotAction.h
• Action Executors: src/modules/Playerbot/Threading/BotActionProcessor.cpp
• Integration Point: src/server/game/World/World.cpp:2348-2356