Win32 multithreading: SafeQueue and a 4-thread arena

A week of C++ multithreading with the Win32 API at GTech 3: daily exercises, then an arena where four threads split the map.

Context

Week of November 17 to 24, 2025. The course notes (theory, Win32 threads, thread safety) sit in Semaine Exo/Doc/. Individual work.

What I did

The four exercises of the week, then two versions of the SFML arena: TestMessage (balls that change thread when they change zone) and TestComplet (players, bonuses, fights and game over). Remote collision damage, zone transitions and rewards are sent as messages to the SafeQueue of the thread that owns the target entity.

Links

• 5---Multithreading (code on the Kiki branch)

Weekly exercises (Semaine Exo/)

Day	Exercise	Content
D1	WhackAThread	Console whack-a-mole: each mole is a thread (CreateThread), one thread spawns the moles, events go through a message queue
D2-3	SafeQueue	Bounded ring-buffer queue: CRITICAL_SECTION and two CONDITION_VARIABLEs (not full, not empty), blocking push, tryPush / tryPop, producer-consumer test
D3	CollisionDetector	Collisions between 50,000 spheres: single-threaded, then 2 and 4 threads, a progress monitor thread (Interlocked*)
D3-4	SafeCollision	Same detection as producers and consumers through the SafeQueue, five configurations compared, one with local accumulation of results

Final arena (Final/TestComplet)

Main thread: SFML rendering (800 x 600), game over, stats
ThreadManager
  └── 4 WorkerThreads, each with its entities and a SafeQueue<Message*>
        16 ms loop: messages -> update -> collisions -> transitions
Map: 4 x 3 grid of 200 px cells, cell -> thread (index modulo 4)

• 12 players, 8 bonuses (HP, speed, shield, damage). The last player alive wins.
• Local collision (two players on the same thread): damage and bounce computed in place.
• Remote collision: the lower-index thread applies it to its player and sends a CollisionMessage to the other thread, plus a KillRewardMessage if its player dies.
• Transition: a player that changes cell is serialized into a TransitionMessage, removed from its thread and rebuilt in the target thread. A player's color shows its thread.

Stack

Tech	Role
C++	Language
Win32 API	CreateThread, CRITICAL_SECTION, CONDITION_VARIABLE, Interlocked*
SFML 2.6.1	Arena rendering
Visual Studio	Build