tdlight-java-natives/src/main/jni-java-src/it/tdlight/tdnative/NativeLog.java

package it.tdlight.tdnative;

import it.tdlight.jni.TdApi;
import java.util.function.Consumer;
import java.util.concurrent.atomic.AtomicReference;

/**
 * Class used for managing internal TDLib logging.
 */
public class NativeLog {

    private static final Consumer<String> defaultFatalErrorCallback = NativeLog::printFatalError;
    private static final AtomicReference<Consumer<String>> fatalErrorCallback
				= new AtomicReference<>(defaultFatalErrorCallback);

    /**
     * This function is called from the JNI when a fatal error happens to provide a better error message.
     * The function does not return.
     *
     * @param errorMessage Error message.
     */
    private static void onFatalError(String errorMessage) {
        new Thread(() -> NativeLog.fatalErrorCallback.get().accept(errorMessage)).start();
    }

    /**
     * Sets the callback that will be called when a fatal error happens.
		 * None of the TDLib methods can be called from the callback.
		 * TDLib will crash as soon as the callback returns.
		 * By default the callback set to print in stderr.
     * @param fatalErrorCallback Callback that will be called when a fatal error happens.
		 *                           Pass null to restore default callback.
     */
    public static void setFatalErrorCallback(Consumer<String> fatalErrorCallback) {
			if (fatalErrorCallback == null) {
				fatalErrorCallback = defaultFatalErrorCallback;
			}
			NativeLog.fatalErrorCallback.set(fatalErrorCallback);
    }

		private static void printFatalError(String errorMessage) {
			System.err.println("TDLib fatal error: " + errorMessage);
		}
}