// Copyright (C) 2009 The Android Open Source Project
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

package com.google.gerrit.server.config;

import com.google.gerrit.reviewdb.server.ReviewDb;
import com.google.gerrit.server.RequestCleanup;
import com.google.gwtorm.server.OrmException;
import com.google.gwtorm.server.SchemaFactory;
import com.google.inject.Inject;
import com.google.inject.Provider;
import com.google.inject.ProvisionException;
import com.google.inject.servlet.RequestScoped;

/** Provides {@link ReviewDb} database handle live only for this request. */
@RequestScoped
public class RequestScopedReviewDbProvider implements Provider<ReviewDb> {
  private final SchemaFactory<ReviewDb> schema;
  private final Provider<RequestCleanup> cleanup;
  private ReviewDb db;

  @Inject
  public RequestScopedReviewDbProvider(final SchemaFactory<ReviewDb> schema,
      final Provider<RequestCleanup> cleanup) {
    this.schema = schema;
    this.cleanup = cleanup;
  }

  @SuppressWarnings("resource")
  @Override
  public ReviewDb get() {
    if (db == null) {
      final ReviewDb c;
      try {
        c = schema.open();
      } catch (OrmException e) {
        throw new ProvisionException("Cannot open ReviewDb", e);
      }
      try {
        cleanup.get().add(new Runnable() {
          @Override
          public void run() {
            c.close();
            db = null;
          }
        });
      } catch (Throwable e) {
        c.close();
        throw new ProvisionException("Cannot defer cleanup of ReviewDb", e);
      }
      db = c;
    }
    return db;
  }
}