Configuration System Initialization Process

When open a graph, we need to pass a configuration file.

    public static HugeGraph open(String shortcutOrFile) {        return open(getLocalConfiguration(shortcutOrFile));    }

private static ReadConfiguration getLocalConfiguration(String shortcutOrFile) {        File file = new File(shortcutOrFile);        if (file.exists()) return getLocalConfiguration(file);        else {          // ...        }    }

private static ReadConfiguration getLocalConfiguration(File file) {            PropertiesConfiguration configuration = new PropertiesConfiguration(file);           // ...             return new CommonsConfiguration(configuration);    }

PropertiesConfiguration is a class in apache common jar, we do not delve into it in order to reduce complexity.

Then pass the PropertiesConfiguration object to GraphDatabaseConfiguration.

  public static HugeGraph open(ReadConfiguration configuration) {        return new StandardHugeGraph(new GraphDatabaseConfiguration(configuration));    }

The constructor mehtod of GraphDatabaseConfiguration.

public GraphDatabaseConfiguration(ReadConfiguration localConfig) {         this.configurationAtOpen = localConfig;         BasicConfiguration localbc = new BasicConfiguration(ROOT_NS,localConfig, BasicConfiguration.Restriction.NONE);        ModifiableConfiguration overwrite = new ModifiableConfiguration(ROOT_NS,new CommonsConfiguration(), BasicConfiguration.Restriction.NONE);//...    }

• BasicConfiguration localbc = new BasicConfiguration(ROOT_NS,localConfig, BasicConfiguration.Restriction.NONE);
  The definition of BasicConfiguration.Restriction.

  public enum Restriction { LOCAL, GLOBAL, NONE }

public BasicConfiguration(ConfigNamespace root, ReadConfiguration config, Restriction restriction) {        super(root);        Preconditions.checkNotNull(config);        Preconditions.checkNotNull(restriction);        this.config = config;        this.restriction = restriction;    }

super(root) call the constructor method of AbstractConfiguration.

 protected AbstractConfiguration(ConfigNamespace root) {        Preconditions.checkNotNull(root);        Preconditions.checkArgument(!root.isUmbrella(),"Root cannot be an umbrella namespace");        this.root = root;    }

KCVSConfiguration

KCVSConfiguration kcvsConfig=Backend.getStandaloneGlobalConfiguration(storeManager,localbc);...globalConfig = kcvsConfig.asReadConfiguration();

ModifiableConfiguration overwrite Introduction

 Configuration combinedConfig = new MixedConfiguration(ROOT_NS,globalConfig,localConfig); ... this.configuration = new MergedConfiguration(overwrite,combinedConfig);  preLoadConfiguration();

MixedConfiguration Introduction
MergedConfiguration
preLoadConfiguration()
The configuration initialize is over.

The architecture of config
MergedConfiguration

1. overwrite: dynamic generated runtime information like graph uuid
2. combinedConfig


1. globalConfig
2. localConfig