janusgraph源码分析2-实例debug

http://www.k6k4.com/blog/show/aaapamn4v1547604938237

一、第一遍调试

还是上次的例子 FirstTest：

public class FirstTest {

    public static void main(String[] args) {

        /*
         * The example below will open a JanusGraph graph instance and load The Graph of the Gods dataset diagrammed above.
         * JanusGraphFactory provides a set of static open methods,
         * each of which takes a configuration as its argument and returns a graph instance.
         * This tutorial calls one of these open methods on a configuration
         * that uses the BerkeleyDB storage backend and the Elasticsearch index backend,
         * then loads The Graph of the Gods using the helper class GraphOfTheGodsFactory.
         * This section skips over the configuration details, but additional information about storage backends,
         * index backends, and their configuration are available in
         * Part III, “Storage Backends”, Part IV, “Index Backends”, and Chapter 13, Configuration Reference.
         */

        // Loading the Graph of the Gods Into JanusGraph
        JanusGraph graph = JanusGraphFactory
                .open("janusgraph-dist/src/assembly/cfilter/conf/janusgraph-berkeleyje-es.properties");

        GraphOfTheGodsFactory.load(graph);
        GraphTraversalSource g = graph.traversal();

        /*
         * The typical pattern for accessing data in a graph database is to first locate the entry point into the graph
         * using a graph index. That entry point is an element (or set of elements) 
         * — i.e. a vertex or edge. From the entry elements,
         * a Gremlin path description describes how to traverse to other elements in the graph via the explicit graph structure.
         * Given that there is a unique index on name property, the Saturn vertex can be retrieved.
         * The property map (i.e. the key/value pairs of Saturn) can then be examined.
         * As demonstrated, the Saturn vertex has a name of "saturn, " an age of 10000, and a type of "titan."
         * The grandchild of Saturn can be retrieved with a traversal that expresses:
         * "Who is Saturn’s grandchild?" (the inverse of "father" is "child"). The result is Hercules.
         */
        // Global Graph Indices
        Vertex saturn = g.V().has("name", "saturn").next();
        GraphTraversal<Vertex, Map<String, Object>> vertexMapGraphTraversal = g.V(saturn).valueMap();

        GraphTraversal<Vertex, Object> values = g.V(saturn).in("father").in("father").values("name");

        /*
         * The property place is also in a graph index. The property place is an edge property.
         * Therefore, JanusGraph can index edges in a graph index.
         * It is possible to query The Graph of the Gods for all events that have happened within 50 kilometers of Athens
          * (latitude:37.97 and long:23.72).
          * Then, given that information, which vertices were involved in those events.
         */
		System.out.println(g.E().has("place", geoWithin(Geoshape.circle(37.97, 23.72, 50))));
        System.out.println(g.E().has("place", geoWithin(Geoshape.circle(37.97, 23.72, 50)))
                .as("source").inV()
                .as("god2")
                .select("source").outV()
                .as("god1").select("god1", "god2")
                .by("name"));
    }

}

删除 db 文件夹，打上断点，开始debug，首先进入：JanusGraphFactory.open

JanusGraphFactory is used to open or instantiate a JanusGraph graph database.
Opens a {@link JanusGraph} database configured according to the provided configuration.

public static JanusGraph open(ReadConfiguration configuration, String backupName) {
    final ModifiableConfiguration config = new ModifiableConfiguration(ROOT_NS, (WriteConfiguration) configuration, BasicConfiguration.Restriction.NONE);
    final String graphName = config.has(GRAPH_NAME) ? config.get(GRAPH_NAME) : backupName;
    final JanusGraphManager jgm = JanusGraphManagerUtility.getInstance();
    if (null != graphName) {
        Preconditions.checkState(jgm != null, JANUS_GRAPH_MANAGER_EXPECTED_STATE_MSG);
        return (JanusGraph) jgm.openGraph(graphName, gName -> new StandardJanusGraph(new GraphDatabaseConfiguration(configuration)));
    } else {
        if (jgm != null) {
            log.warn("...");
        }
        return new StandardJanusGraph(new GraphDatabaseConfiguration(configuration));
    }
}

前面的部分先跳过，然后进入：

1. return new StandardJanusGraph(new GraphDatabaseConfiguration(configuration));
    // 构造方法，分为静态代码和构造方法，这部分目前是跳过，但是后续是重点和核心。
    1. 父类：JanusGraphBlueprintsGraph
        static {
        TraversalStrategies graphStrategies = TraversalStrategies.GlobalCache.getStrategies(Graph.class).clone()
                .addStrategies(AdjacentVertexFilterOptimizerStrategy.instance(), JanusGraphLocalQueryOptimizerStrategy.instance(), JanusGraphStepStrategy.instance());

        //Register with cache
        TraversalStrategies.GlobalCache.registerStrategies(StandardJanusGraph.class, graphStrategies);
        TraversalStrategies.GlobalCache.registerStrategies(StandardJanusGraphTx.class, graphStrategies);
        }
    2. 新建配置，A graph database configuration is uniquely associated with a graph database and must not be used for multiple databases
    
    new GraphDatabaseConfiguration(configuration)
        1. storeManager 
        final KeyColumnValueStoreManager storeManager = Backend.getStorageManager(localBasicConfiguration);
        final StoreFeatures storeFeatures = storeManager.getFeatures();
        2. 检查参数，配置等
    
    3. 然后是构造方法
        1. 成员变量
        private final SchemaCache.StoreRetrieval typeCacheRetrieval = new SchemaCache.StoreRetrieval() {}
        2. backend
        this.backend = configuration.getBackend();
            1. Backend backend = new Backend(configuration);
                1. KeyColumnValueStoreManager manager = getStorageManager(configuration);
                2. indexes = getIndexes(configuration);
                
                3. //这里的 KCVS 是 keycolumnvaluestorageManager
                managementLogManager = getKCVSLogManager(MANAGEMENT_LOG);
        		txLogManager = getKCVSLogManager(TRANSACTION_LOG);
        		userLogManager = getLogManager(USER_LOG);
        		
        		4. scanner = new StandardScanner(storeManager);
                
            2. backend.initialize(configuration);
                1. store 新建
                KeyColumnValueStore idStore = storeManager.openDatabase(config.get(IDS_STORE_NAME));
                KeyColumnValueStore edgeStoreRaw = storeManagerLocking.openDatabase(EDGESTORE_NAME);
            	KeyColumnValueStore indexStoreRaw = storeManagerLocking.openDatabase(INDEXSTORE_NAME);
                
                2. cacheEnabled
                edgeStore = new NoKCVSCache(edgeStoreRaw);
                indexStore = new NoKCVSCache(indexStoreRaw);
            3. storeFeatures = backend.getStoreFeatures();
        3. 初始化
        this.idAssigner = config.getIDAssigner(backend);
        this.idManager = idAssigner.getIDManager();
        this.serializer = config.getSerializer();
        StoreFeatures storeFeatures = backend.getStoreFeatures();
        this.indexSerializer = new IndexSerializer(configuration.getConfiguration(), this.serializer,
        this.backend.getIndexInformation(), storeFeatures.isDistributed() && storeFeatures.isKeyOrdered());
        this.edgeSerializer = new EdgeSerializer(this.serializer);
        this.vertexExistenceQuery = edgeSerializer.getQuery(BaseKey.VertexExists, Direction.OUT, new EdgeSerializer.TypedInterval[0]).setLimit(1);
        this.queryCache = new RelationQueryCache(this.edgeSerializer);
        this.schemaCache = configuration.getTypeCache(typeCacheRetrieval);
        this.times = configuration.getTimestampProvider();
        

然后是open完成后：GraphOfTheGodsFactory.load(graph);
http://www.k6k4.com/blog/show/aaapamn4v1547604938237