CVL Changes sonic-net#2: YValidator infra changes for evaluating xpat…

…h expression (sonic-net#19)

Why I did it
Adding YValidator support so that xpath expression (must/when/leafref) can be evaluated using custom xpath engine. Custom xpath engine will be integrated in subsequent PR.

How I did it
N/A.
Please refer to change log for more details.

How to verify it
No specific test cases to be executed. Run cvl go test cases using - 'make cvl-test'.

Description for the changelog

Modifying cvl.go for adding new data structure to store cache in CVL session cache, add YValidator data type. Adding API to get Redis table name from YANG list.

Modifying cvl_api.go and cvl_cache.go due to change in session cache.

Modifying cvl_syntax.go due to change in API name.

Modifying cvl_semantics.go to add various API which can operate on YValidator nodes.

cvl/cvl.go

@@ -78,6 +78,7 @@ type modelTableInfo struct {
 				//multiple leafref possible for union 
 	mustExp map[string]string
 	tablesForMustExp map[string]CVLOperation
+	dfltLeafVal map[string]string //map of leaf names and default value
 }
 
 
@@ -94,14 +95,21 @@ type CVLErrorInfo struct {
 	ErrAppTag string
 }
 
+// Struct for request data and YANG data
+type requestCacheType struct {
+	reqData CVLEditConfigData
+	yangData *xmlquery.Node
+}
+
 type CVL struct {
 	redisClient *redis.Client
 	yp *yparser.YParser
 	tmpDbCache map[string]interface{} //map of table storing map of key-value pair
-	requestCache map[string]map[string][]CVLEditConfigData //Cache of validated data,
-						//might be used as dependent data in next request
+	requestCache map[string]map[string][]*requestCacheType//Cache of validated data,
+				//per table, per key. Can be used as dependent data in next request
 	batchLeaf string
 	chkLeafRefWithOthCache bool
+	yv *YValidator //Custom YANG validator for validating external dependencies
 }
 
 type modelNamespace struct {
@@ -205,6 +213,11 @@ func Debug(on bool) {
 	yparser.Debug(on)
 }
 
+// isLeafListNode checks if the xml node represents a leaf-list field
+func isLeafListNode(node *xmlquery.Node) bool {
+	return len(node.Attr) != 0 && node.Attr[0].Name.Local == "leaf-list"
+}
+
 //Get attribute value of xml node
 func getXmlNodeAttr(node *xmlquery.Node, attrName string) string {
 	for _, attr := range node.Attr {
@@ -216,6 +229,14 @@ func getXmlNodeAttr(node *xmlquery.Node, attrName string) string {
 	return ""
 }
 
+// getNodeName returns database field name for the xml node.
+func getNodeName(node *xmlquery.Node) string {
+	if isLeafListNode(node) {
+		return node.Data + "@"
+	}
+	return node.Data
+}
+
 //Store useful schema data during initialization
 func storeModelInfo(modelFile string, module *yparser.YParserModule) { //such model info can be maintained in C code and fetched from there 
 	f, err := os.Open(CVL_SCHEMA + modelFile)
@@ -394,6 +415,20 @@ func storeModelInfo(modelFile string, module *yparser.YParserModule) { //such mo
 	}
 }
 
+// Get YANG list to Redis table name
+func getYangListToRedisTbl(yangListName string) string {
+	if (strings.HasSuffix(yangListName, "_LIST")) {
+		yangListName = yangListName[0:len(yangListName) - len("_LIST")]
+	}
+	tInfo, exists := modelInfo.tableInfo[yangListName]
+
+	if exists && (tInfo.redisTableName != "") {
+		return tInfo.redisTableName
+	}
+
+	return yangListName
+}
+
 //Find the tables names in must expression, these tables data need to be fetched 
 //during semantic validation
 func addTableNamesForMustExp() {
@@ -475,24 +510,30 @@ func splitRedisKey(key string) (string, string) {
 	return tblName, key[prefixLen:]
 }
 
-//Get the YANG list name from Redis key
+//Get the YANG list name from Redis key and table name
 //This just returns same YANG list name as Redis table name
 //when 1:1 mapping is there. For one Redis table to 
 //multiple YANG list, it returns appropriate YANG list name
 //INTERFACE:Ethernet12 returns ==> INTERFACE
 //INTERFACE:Ethernet12:1.1.1.0/32 ==> INTERFACE_IPADDR
-func getRedisKeyToYangList(tableName, key string) string {
+func getRedisTblToYangList(tableName, key string) (yangList string) {
+	defer func() {
+		pYangList := &yangList
+		TRACE_LOG(INFO_API, TRACE_SYNTAX, "Got YANG list '%s' " +
+		"from Redis Table '%s', Key '%s'", *pYangList, tableName, key)
+	}()
+
 	mapArr, exists := modelInfo.redisTableToYangList[tableName]
 
-	if exists == false {
+	if !exists || (len(mapArr) == 1) { //no map or only one
 		//1:1 mapping case
 		return tableName
 	}
 
 	//As of now determine the mapping based on number of keys
 	var foundIdx int = -1
 	numOfKeys := 1 //Assume only one key initially
-	for keyDelim, _ := range modelInfo.allKeyDelims {
+	for keyDelim := range modelInfo.allKeyDelims {
 		foundIdx = strings.Index(key, keyDelim)
 		if (foundIdx >= 0) {
 			//Matched with key delim
@@ -505,7 +546,7 @@ func getRedisKeyToYangList(tableName, key string) string {
 	//Check which list has number of keys as 'numOfKeys' 
 	for i := 0; i < len(mapArr); i++ {
 		tblInfo, exists := modelInfo.tableInfo[mapArr[i]]
-		if exists == true {
+		if exists {
 			if (len(tblInfo.keys) == numOfKeys) {
 				//Found the YANG list matching the number of keys
 				return mapArr[i]

cvl/cvl_api.go

@@ -195,7 +195,7 @@ func Finish() {
 func ValidationSessOpen() (*CVL, CVLRetCode) {
 	cvl :=  &CVL{}
 	cvl.tmpDbCache = make(map[string]interface{})
-	cvl.requestCache = make(map[string]map[string][]CVLEditConfigData)
+	cvl.requestCache = make(map[string]map[string][]*requestCacheType)
 	cvl.yp = &yparser.YParser{}
 
 	if (cvl == nil || cvl.yp == nil) {
@@ -324,10 +324,10 @@ func (c *CVL) ValidateEditConfig(cfgData []CVLEditConfigData) (CVLErrorInfo, CVL
 		reqTbl, exists := c.requestCache[tbl]
 		if (exists == false) {
 			//Create new table key data
-			reqTbl = make(map[string][]CVLEditConfigData)
+			reqTbl = make(map[string][]*requestCacheType)
 		}
 		cfgDataItemArr, _ := reqTbl[key]
-		cfgDataItemArr = append(cfgDataItemArr, cfgDataItem)
+		cfgDataItemArr = append(cfgDataItemArr, &requestCacheType{cfgDataItem, nil})
 		reqTbl[key] = cfgDataItemArr
 		c.requestCache[tbl] = reqTbl
 
@@ -431,7 +431,7 @@ func (c *CVL) ValidateEditConfig(cfgData []CVLEditConfigData) (CVLErrorInfo, CVL
 					deletedInSameSession := false
 					if  tbl != ""  && key != "" {
 						for _, cachedCfgData := range c.requestCache[tbl][key] {
-							if cachedCfgData.VOp == OP_DELETE {
+							if cachedCfgData.reqData.VOp == OP_DELETE {
 								deletedInSameSession = true
 								break
 							}

cvl/cvl_cache.go

@@ -46,10 +46,10 @@ func (c *CVL) fetchDataFromRequestCache(tableName string, key string) (d map[str
 	if (cfgDataArr != nil) {
 		for _, cfgReqData := range cfgDataArr {
 			//Delete request doesn't have depedent data
-			if (cfgReqData.VOp == OP_CREATE) {
-				return cfgReqData.Data, false
-			} else	if (cfgReqData.VOp == OP_UPDATE) {
-				return cfgReqData.Data, true
+			if (cfgReqData.reqData.VOp == OP_CREATE) {
+				return cfgReqData.reqData.Data, false
+			} else	if (cfgReqData.reqData.VOp == OP_UPDATE) {
+				return cfgReqData.reqData.Data, true
 			}
 		}
 	}