java-topology/docs/tickets/love2d-0001-getjoystickfromid-linear-scan-per-event.md
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Add 88 new defect entries to HIGH and MEDIUM tables:
  HIGH: mysql-0001/0002, mariadb-0001, redis-0001/0002, valkey-0001/0002, openvpn-0001,
        vlc-0001, prometheus-0001, otel-collector-0001, cockroachdb-0001..0004,
        tidb-0001..0008, kubernetes-0001/0002, go-0001, kotlin-0002, scala-0001,
        allegro5-0001, sdl2-0001, grafana-0001, clickhouse-0001, duckdb-0001,
        mongodb-0001, envoy-0001, istio-0001, cilium-0001, linkerd2-0001,
        linux-0001/0002/0003, tor-0002/0003, curl-0001, julia-0001, lua-0001,
        perl5-0001, nats-0001, spring-0003/0004, tomcat-0001, onos-0002, odl-0002

  MEDIUM: helm-0001, mariadb-0002, openssl-0001/0002, memcached-0001,
          cassandra-0001..0004, flink-0001, storm-0001/0002, zookeeper-0001..0003,
          pip-0001, gradle-0001, nginx-0001, haproxy-0001, caddy-0001, varnish-0001,
          ffmpeg-0001, gstreamer-0001, raylib-0001, love2d-0001, php-0001/0002,
          r-source-0001, cpython-0002, ruby-0001, rabbitmq-0003/0004, activemq-0001,
          ovs-0001, onos-0003, odl-0002, jetty-0001

PDF: 976K
2026-03-27 15:23:43 -04:00

1.7 KiB

love2d-0001 — getJoystickFromID O(n) linear scan per SDL joystick event

Status

PATCHED

Severity

MEDIUM

Target

love2d src/modules/joystick/sdl/JoystickModule.cpp

CWE

CWE-407: Algorithmic Complexity — Insufficient Complexity Reduction Before Algorithmic Intensive Operation

Description

JoystickModule::getJoystickFromID(int instanceid) performs an O(n) linear scan of activeSticks (a std::vector<Joystick*>) to find a joystick by its SDL instance ID. This function is called once per SDL joystick event in the SDL event dispatch loop.

// JoystickModule.cpp:98
love::joystick::Joystick *JoystickModule::getJoystickFromID(int instanceid)
{
    for (auto stick : activeSticks)  // O(n) every event
    {
        if (stick->getInstanceID() == instanceid)
            return stick;
    }
    return nullptr;
}

Call Sites (Event.cpp)

Event.cpp:640  getJoystickFromID(e.jbutton.which)
Event.cpp:652  getJoystickFromID(e.jaxis.which)
Event.cpp:667  getJoystickFromID(e.jhat.which)
Event.cpp:686  getJoystickFromID(b.which)
Event.cpp:703  getJoystickFromID(a.which)
Event.cpp:725  getJoystickFromID(e.jdevice.which)
Event.cpp:737  getJoystickFromID(sens.which)

7 separate event types, each calling O(n) scan. With N connected joysticks and E events per frame, cost is O(N * E) per frame update.

Fix

Replace the std::vector<Joystick*> activeSticks scan with a std::unordered_map<int, Joystick*> sticksById keyed on instance ID. Updated on addJoystick/removeJoystick. Lookup becomes O(1).

Complexity

  • Before: O(n) per event where n = number of active joysticks
  • After: O(1) per event

Files

  • defects/love2d/patch/love2d-0001.patch
  • defects/love2d/unit/Love2dJoystickLookupTest.java