add code comment for connector (#32)

nebula-spark-connector/src/main/scala/com/vesoft/nebula/connector/NebulaConfig.scala

@@ -56,11 +56,17 @@ object NebulaConnectionConfig {
  protected var caSignParam: CASSLSignParams = null
  protected var selfSignParam: SelfSSLSignParams = null
 
+ /**
+ * set nebula meta server address, multi addresses is split by English comma
+ */
  def withMetaAddress(metaAddress: String): ConfigBuilder = {
  this.metaAddress = metaAddress
  this
  }
 
+ /**
+ * set nebula graph server address, multi addresses is split by English comma
+ */
  def withGraphAddress(graphAddress: String): ConfigBuilder = {
  this.graphAddress = graphAddress
  this
@@ -264,16 +270,25 @@ object WriteNebulaVertexConfig {
  /** whether set vid as property */
  var vidAsProp: Boolean = false
 
+ /**
+ * set space name
+ */
  def withSpace(space: String): WriteVertexConfigBuilder = {
  this.space = space
  this
  }
 
+ /**
+ * set tag name
+ */
  def withTag(tagName: String): WriteVertexConfigBuilder = {
  this.tagName = tagName
  this
  }
 
+ /**
+ * set which field in dataframe as nebula tag's id
+ */
  def withVidField(vidField: String): WriteVertexConfigBuilder = {
  this.vidField = vidField
  this
@@ -304,21 +319,33 @@ object WriteNebulaVertexConfig {
  this
  }
 
+ /**
+ * set user name for nebula graph
+ */
  def withUser(user: String): WriteVertexConfigBuilder = {
  this.user = user
  this
  }
 
+ /**
+ * set password for nebula graph's user
+ */
  def withPasswd(passwd: String): WriteVertexConfigBuilder = {
  this.passwd = passwd
  this
  }
 
+ /**
+ * set nebula write mode for nebula tag, INSERT or UPDATE
+ */
  def withWriteMode(writeMode: WriteMode.Value): WriteVertexConfigBuilder = {
  this.writeMode = writeMode.toString
  this
  }
 
+ /**
+ * check and get WriteNebulaVertexConfig
+ */
  def build(): WriteNebulaVertexConfig = {
  check()
  new WriteNebulaVertexConfig(space,
@@ -417,6 +444,9 @@ object WriteNebulaEdgeConfig {
 
  private val LOG: Logger = LoggerFactory.getLogger(WriteNebulaEdgeConfig.getClass)
 
+ /**
+ * a builder to create {@link WriteNebulaEdgeConfig}
+ */
  class WriteEdgeConfigBuilder {
 
  var space: String = _
@@ -440,27 +470,37 @@ object WriteNebulaEdgeConfig {
  /** whether set rank as property */
  var rankAsProp: Boolean = false
 
+ /** write mode for nebula, insert or update */
  var writeMode: String = WriteMode.INSERT.toString
 
+ /**
+ * set space name
+ */
  def withSpace(space: String): WriteEdgeConfigBuilder = {
  this.space = space
  this
  }
 
+ /**
+ * set edge type name
+ */
  def withEdge(edgeName: String): WriteEdgeConfigBuilder = {
  this.edgeName = edgeName
  this
  }
 
  /**
  * set rank field in dataframe
- * it rankField is not set, then edge has no rank value
+ * it rankField is not set, then edge has default 0 rank value
  * */
  def withRankField(rankField: String): WriteEdgeConfigBuilder = {
  this.rankField = rankField
  this
  }
 
+ /**
+ * set which field in dataframe as nebula edge's src id
+ */
  def withSrcIdField(srcIdField: String): WriteEdgeConfigBuilder = {
  this.srcIdField = srcIdField
  this
@@ -474,6 +514,9 @@ object WriteNebulaEdgeConfig {
  this
  }
 
+ /**
+ * set which field in dataframe as nebula edge's dst id
+ */
  def withDstIdField(dstIdField: String): WriteEdgeConfigBuilder = {
  this.dstIdField = dstIdField
  this
@@ -519,21 +562,33 @@ object WriteNebulaEdgeConfig {
  this
  }
 
+ /**
+ * set user name for nebula graph
+ */
  def withUser(user: String): WriteEdgeConfigBuilder = {
  this.user = user
  this
  }
 
+ /**
+ * set password for nebula graph's user
+ */
  def withPasswd(passwd: String): WriteEdgeConfigBuilder = {
  this.passwd = passwd
  this
  }
 
+ /**
+ * set write mode for nebula edge, INSERT or UPDATE
+ */
  def withWriteMode(writeMode: WriteMode.Value): WriteEdgeConfigBuilder = {
  this.writeMode = writeMode.toString
  this
  }
 
+ /**
+ * check configs and get WriteNebulaEdgeConfig
+ */
  def build(): WriteNebulaEdgeConfig = {
  check()
  new WriteNebulaEdgeConfig(space,

nebula-spark-connector/src/main/scala/com/vesoft/nebula/connector/PartitionUtils.scala

@@ -8,6 +8,15 @@ package com.vesoft.nebula.connector
 import scala.collection.mutable.ListBuffer
 
 object PartitionUtils {
+
+ /**
+ * compute each spark partition should assign how many nebula parts
+ *
+ * @param index spark partition index
+ * @param nebulaTotalPart nebula space partition number
+ * @param sparkPartitionNum spark total partition number
+ * @return the list of nebula partitions assign to spark index partition
+ */
  def getScanParts(index: Int, nebulaTotalPart: Int, sparkPartitionNum: Int): List[Integer] = {
  val scanParts = new ListBuffer[Integer]
  var currentPart = index

nebula-spark-connector/src/main/scala/com/vesoft/nebula/connector/nebula/GraphProvider.scala

@@ -64,6 +64,9 @@ class GraphProvider(addresses: List[Address],
 
  var session: Session = null
 
+ /**
+ * release session
+ */
  def releaseGraphClient(session: Session): Unit = {
  session.release()
  }
@@ -72,6 +75,14 @@ class GraphProvider(addresses: List[Address],
  pool.close()
  }
 
+ /**
+ * switch space
+ *
+ * @param user
+ * @param password
+ * @param space
+ * @return if execute succeed
+ */
  def switchSpace(user: String, password: String, space: String): Boolean = {
  if (session == null) {
  session = pool.getSession(user, password, true)
@@ -82,6 +93,12 @@ class GraphProvider(addresses: List[Address],
  result.isSucceeded
  }
 
+ /**
+ * execute the statement
+ *
+ * @param statement insert tag/edge statement
+ * @return execute result
+ */
  def submit(statement: String): ResultSet = {
  if (session == null) {
  LOG.error("graph session is null")

nebula-spark-connector/src/main/scala/com/vesoft/nebula/connector/nebula/MetaProvider.scala

@@ -52,10 +52,16 @@ class MetaProvider(addresses: List[Address],
  }
  client.connect()
 
+ /**
+ * get the partition num of nebula space
+ */
  def getPartitionNumber(space: String): Int = {
  client.getPartsAlloc(space).size()
  }
 
+ /**
+ * get the vid type of nebula space
+ */
  def getVidType(space: String): VidType.Value = {
  val vidType = client.getSpace(space).getProperties.getVid_type.getType
  if (vidType == PropertyType.FIXED_STRING) {
@@ -64,14 +70,35 @@ class MetaProvider(addresses: List[Address],
  VidType.INT
  }
 
+ /**
+ * get {@link Schema} of nebula tag
+ *
+ * @param space
+ * @param tag
+ * @return schema
+ */
  def getTag(space: String, tag: String): Schema = {
  client.getTag(space, tag)
  }
 
+ /**
+ * get {@link Schema} of nebula edge type
+ *
+ * @param space
+ * @param edge
+ * @return schema
+ */
  def getEdge(space: String, edge: String): Schema = {
  client.getEdge(space, edge)
  }
 
+ /**
+ * get tag's schema info
+ *
+ * @param space
+ * @param tag
+ * @return Map, property name -> data type {@link PropertyType}
+ */
  def getTagSchema(space: String, tag: String): Map[String, Integer] = {
  val tagSchema = client.getTag(space, tag)
  val schema = new mutable.HashMap[String, Integer]
@@ -83,6 +110,13 @@ class MetaProvider(addresses: List[Address],
  schema.toMap
  }
 
+ /**
+ * get edge's schema info
+ *
+ * @param space
+ * @param edge
+ * @return Map, property name -> data type {@link PropertyType}
+ */
  def getEdgeSchema(space: String, edge: String): Map[String, Integer] = {
  val edgeSchema = client.getEdge(space, edge)
  val schema = new mutable.HashMap[String, Integer]
@@ -94,6 +128,9 @@ class MetaProvider(addresses: List[Address],
  schema.toMap
  }
 
+ /**
+ * check if a label is Tag or Edge
+ */
  def getLabelType(space: String, label: String): DataTypeEnum.Value = {
  val tags = client.getTags(space)
  for (tag <- tags.asScala) {

nebula-spark-connector/src/main/scala/com/vesoft/nebula/connector/writer/NebulaEdgeWriter.scala

@@ -77,6 +77,9 @@ class NebulaEdgeWriter(nebulaOptions: NebulaOptions,
  }
  }
 
+ /**
+ * submit buffer edges to nebula
+ */
  def execute(): Unit = {
  val nebulaEdges = NebulaEdges(propNames, edges.toList, srcPolicy, dstPolicy)
  val exec = nebulaOptions.writeMode match {

nebula-spark-connector/src/main/scala/com/vesoft/nebula/connector/writer/NebulaVertexWriter.scala

@@ -56,6 +56,9 @@ class NebulaVertexWriter(nebulaOptions: NebulaOptions, vertexIndex: Int, schema:
  }
  }
 
+ /**
+ * submit buffer vertices to nebula
+ */
  def execute(): Unit = {
  val nebulaVertices = NebulaVertices(propNames, vertices.toList, policy)
  val exec = nebulaOptions.writeMode match {