Add Save Events to Server Lifecycle Events (FabricMC#3533)

* Add Server Begin Save and Server End Save event

* rename events

* add tests

* pass more params through

fabric-lifecycle-events-v1/src/main/java/net/fabricmc/fabric/api/event/lifecycle/v1/ServerLifecycleEvents.java

@@ -107,6 +107,24 @@ private ServerLifecycleEvents() {
 		}
 	});
 
+	/**
+	 * Called before a Minecraft server begins saving data.
+	 */
+	public static final Event<BeforeSave> BEFORE_SAVE = EventFactory.createArrayBacked(BeforeSave.class, callbacks -> (server, flush, force) -> {
+		for (BeforeSave callback : callbacks) {
+			callback.onBeforeSave(server, flush, force);
+		}
+	});
+
+	/**
+	 * Called after a Minecraft server finishes saving data.
+	 */
+	public static final Event<AfterSave> AFTER_SAVE = EventFactory.createArrayBacked(AfterSave.class, callbacks -> (server, flush, force) -> {
+		for (AfterSave callback : callbacks) {
+			callback.onAfterSave(server, flush, force);
+		}
+	});
+
 	@FunctionalInterface
 	public interface ServerStarting {
 		void onServerStarting(MinecraftServer server);
@@ -160,4 +178,28 @@ public interface EndDataPackReload {
 		 */
 		void endDataPackReload(MinecraftServer server, LifecycledResourceManager resourceManager, boolean success);
 	}
+
+	@FunctionalInterface
+	public interface BeforeSave {
+		/**
+		 * Called before a Minecraft server begins saving data.
+		 *
+		 * @param server the server
+		 * @param flush is true when all chunks are being written to disk, server will likely freeze during this time
+		 * @param force whether servers that have save-off set should save
+		 */
+		void onBeforeSave(MinecraftServer server, boolean flush, boolean force);
+	}
+
+	@FunctionalInterface
+	public interface AfterSave {
+		/**
+		 * Called before a Minecraft server begins saving data.
+		 *
+		 * @param server the server
+		 * @param flush is true when all chunks are being written to disk, server will likely freeze during this time
+		 * @param force whether servers that have save-off set should save
+		 */
+		void onAfterSave(MinecraftServer server, boolean flush, boolean force);
+	}
 }

fabric-lifecycle-events-v1/src/main/java/net/fabricmc/fabric/mixin/event/lifecycle/MinecraftServerMixin.java

@@ -101,4 +101,14 @@ private void endResourceReload(Collection<String> collection, CallbackInfoReturn
 			return value;
 		}, (MinecraftServer) (Object) this);
 	}
+
+	@Inject(method = "save", at = @At("HEAD"))
+	private void startSave(boolean suppressLogs, boolean flush, boolean force, CallbackInfoReturnable<Boolean> cir) {
+		ServerLifecycleEvents.BEFORE_SAVE.invoker().onBeforeSave((MinecraftServer) (Object) this, flush, force);
+	}
+
+	@Inject(method = "save", at = @At("TAIL"))
+	private void endSave(boolean suppressLogs, boolean flush, boolean force, CallbackInfoReturnable<Boolean> cir) {
+		ServerLifecycleEvents.AFTER_SAVE.invoker().onAfterSave((MinecraftServer) (Object) this, flush, force);
+	}
 }

fabric-lifecycle-events-v1/src/testmod/java/net/fabricmc/fabric/test/event/lifecycle/ServerLifecycleTests.java

@@ -54,5 +54,13 @@ public void onInitialize() {
 		ServerLifecycleEvents.SYNC_DATA_PACK_CONTENTS.register((player, joined) -> {
 			LOGGER.info("SyncDataPackContents received for {}", joined ? "join" : "reload");
 		});
+
+		ServerLifecycleEvents.BEFORE_SAVE.register((server, flush, force) -> {
+			LOGGER.info("Starting Save with settings: Flush:{} Force:{}", flush, force);
+		});
+
+		ServerLifecycleEvents.AFTER_SAVE.register((server, flush, force) -> {
+			LOGGER.info("Save Finished with settings: Flush:{} Force:{}", flush, force);
+		});
 	}
 }