StrikeSync

Asynchronous, latency-compensated hit-registration and knockback for modern Minecraft.

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About

StrikeSync intercepts attack packets on PacketEvents' netty event loop and ships the velocity + hurt-animation packets directly from there to the relevant clients — skipping the 25–100 ms vanilla normally spends queueing the hit through the main thread and waiting for the next entity-tracker pulse.

Damage itself still flows through Bukkit's normal event chain so existing plugins keep working.

Also includes a ported version of 1.8-style knockback calculations and per-player ping-aware vertical-knockback compensation.

For the byte-level pipeline analysis, see FAST_PATH.md.

Requirements

Component	Version
Paper	1.21.x matching api-version: 26.1.2
Java	25+
PacketEvents	2.12.1 (installed as its own plugin)

Install

1. Install PacketEvents.
2. Drop the StrikeSync jar into plugins/.
3. Start the server. Default config at plugins/StrikeSync/config.yml.

Build from source

git clone https://github.com/owengregson/StrikeSync.git
cd StrikeSync
mvn clean package    # → target/StrikeSync-4.0.0.jar

Commands

Command	Permission	Description
/ss help	strikesync.command.use	Show command list
/ss authors	strikesync.command.use	Plugin authors
/ss reload	strikesync.command.reload	Reload config & bounce modules
/ss toggle	strikesync.command.toggle	Toggle async hit registration
/ss knockback <enable|disable|status>	strikesync.command.knockback	Manage 1.8-style knockback module
/ss compensation <enable|disable|status>	strikesync.command.compensation	Manage latency compensation
/ss ping [player]	strikesync.command.ping	RTT, jitter, spike state

Alias: /strikesync ↔ /ss. Tab completion is permission-filtered.

Config

Defaults reproduce 1.8 PvP feel with the latency-saving pre-send on. See config.yml for inline documentation of every key.

async-hitreg:
    enabled: true
    max-cps: 20
    fast-path:
        enabled: true # cancel vanilla packet, run plugin pipeline
        pre-send-feedback: true # ship velocity + hurt animation from netty
        simulate-crits: true # 1.8-style crit multiplier
        reset-attack-cooldown: true

knockback:
    enabled: true
    base: { horizontal: 0.4, vertical: 0.4 }
    extra: { horizontal: 0.5, vertical: 0.1 }
    limits: { vertical: 0.4, horizontal: -1 }
    friction: { x: 0.5, y: 0.5, z: 0.5 }
    modifiers: { sprint: 1.0, armor-resistance: false }

compensation:
    enabled: true
    ping-offset-ms: 25
    spike-threshold-ms: 20
    probe-interval-ticks: 5
    combat-timeout-ticks: 30
    off-ground-sync: true

debug:
    enabled: false

/ss reload swaps the config snapshot atomically — no hit ever sees a torn configuration.

If a downstream plugin is incompatible with the fast path (heavy region/safezone systems that cancel EntityDamageByEntityEvent), set async-hitreg.fast-path.enabled: false to fall back to the passive listener.

API

Hook the cancellable async event to veto hits before vanilla applies them:

@EventHandler
public void onHit(AsyncHitRegisterEvent event) {
    if (!myRegionAllowsPvp(event.getAttacker(), event.getTarget())) {
        event.setCancelled(true);
    }
}

Listeners run on a packet worker thread — do not mutate Bukkit state directly. Schedule back to the main / region thread if needed.

Acknowledgements

Latency-compensation algorithm adapted from caseload/knockbacksync (GPL-3.0). Async-hit-registration concept inspired by frash23/SmashHit.

License

MIT. See LICENSE.