com.shigengyu.hyperion.cache.WorkflowStateCache.java Source code

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/*******************************************************************************
 * Copyright 2013-2014 Gengyu Shi
 *
 * 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.shigengyu.hyperion.cache;

import java.util.Map;
import java.util.Set;
import java.util.concurrent.ExecutionException;

import javax.annotation.PostConstruct;
import javax.annotation.Resource;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.context.annotation.Lazy;
import org.springframework.stereotype.Service;

import com.google.common.cache.CacheBuilder;
import com.google.common.cache.LoadingCache;
import com.google.common.collect.ImmutableSet;
import com.google.common.collect.Maps;
import com.shigengyu.hyperion.core.State;
import com.shigengyu.hyperion.core.StateDefinitionException;
import com.shigengyu.hyperion.core.WorkflowState;
import com.shigengyu.hyperion.core.WorkflowStateException;
import com.shigengyu.hyperion.dao.WorkflowStateDao;
import com.shigengyu.hyperion.utils.ReflectionsHelper;

@Service
@Lazy(false)
public class WorkflowStateCache {

    private static Logger LOGGER = LoggerFactory.getLogger(WorkflowStateCache.class);

    private LoadingCache<Class<? extends WorkflowState>, WorkflowState> cache;

    private final Map<String, WorkflowState> statesById = Maps.newHashMap();

    @Resource
    private WorkflowStateCacheLoader workflowStateCacheLoader;

    @Resource
    private WorkflowStateDao workflowStateDao;

    private WorkflowStateCache() {
    }

    public final WorkflowState byId(final String workflowStateId) {
        return WorkflowState.class.cast(statesById.get(workflowStateId));
    }

    public <T extends WorkflowState> T get(final Class<T> workflowStateClass) {
        try {
            return workflowStateClass.cast(cache.get(workflowStateClass));
        } catch (final ExecutionException e) {
            throw new WorkflowStateException("Failed to get workflow state by type [{}]", workflowStateClass, e);
        }
    }

    public ImmutableSet<WorkflowState> getAll() {
        return ImmutableSet.copyOf(cache.asMap().values());
    }

    @PostConstruct
    private void initialize() {
        cache = CacheBuilder.newBuilder().build(workflowStateCacheLoader);
    }

    public void scanPackages(final String... packageNames) {
        Set<Class<?>> stateTypes = ReflectionsHelper.createReflections(packageNames)
                .getTypesAnnotatedWith(State.class);
        for (Class<?> clazz : stateTypes) {
            if (WorkflowState.class.isAssignableFrom(clazz)) {
                @SuppressWarnings("unchecked")
                Class<? extends WorkflowState> workflowStateClass = (Class<? extends WorkflowState>) clazz;

                // Get the workflow state to allow it to be cached
                WorkflowState state = get(workflowStateClass);

                statesById.put(state.getWorkflowStateId(), state);

                // Save or update the workflow state in database
                workflowStateDao.saveOrUpdate(state.toEntity());

                LOGGER.info("Workflow state [{}] loaded into cache", state);
            } else {
                throw new StateDefinitionException("Workflow state [{}] does not inherit [{}]", clazz.getName(),
                        WorkflowState.class.getName());
            }
        }
    }
}