Slim3 GlobalTransaction Memo

DataHandler.java

package jp.rh7.utils;

public interface DataHandler {
    // Transactionで実行する処理をここに書く
    public abstract void execute();

    // モデルを取り出す
    public abstract Object[] getModels();
}

PersistWithTx.java

package jp.rh7.dao;

import org.slim3.datastore.Datastore;
import org.slim3.datastore.GlobalTransaction;

import jp.rh7.utils.DataHandler;

public class PersistWithTx {
    private static final int RETRIES = 5;
    private static final int MSLEEP = 500;

    /**
     * Static Class (DO NOT Instantiate!!)
     */
    private PersistWithTx() {
        throw new AssertionError();
    }

    public static void save(DataHandler handler) {
        RuntimeException error = null;
        // 成功するまで繰り返す
        for (int i = 0; i < RETRIES; i++) {
            GlobalTransaction gtx = Datastore.beginGlobalTransaction();
            try {
                handler.execute();
                gtx.put(handler.getModels());
                gtx.commit();
                error = null;
            } catch (Exception e) {
                e.printStackTrace();
                try {
                    // 失敗した場合はしばらく待つ
                    Thread.sleep(MSLEEP);
                } catch (InterruptedException e1) {
                    e1.printStackTrace();
                }
                error = new RuntimeException(e);
                continue;   // リトライ
            } finally {
                if (gtx.isActive()) {
                    gtx.rollback();
                }
            }
            if (error == null) return;
        }
        throw error;
    }
}