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CVL Changes sonic-net#8: 'must' and 'when' expression evaluation (son…
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…ic-net#31)

Adding support for evaluating 'must' and 'when' expression based on customized xpath engine.
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dutta-partha authored Oct 23, 2020
1 parent dabf231 commit 3c6cdb3
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Showing 2 changed files with 399 additions and 15 deletions.
48 changes: 33 additions & 15 deletions cvl/cvl.go
Original file line number Diff line number Diff line change
Expand Up @@ -63,13 +63,27 @@ var dbNameToDbNum map[string]uint8
//map of lua script loaded
var luaScripts map[string]*redis.Script

type whenInfo struct {
expr string //when expression
exprTree *xpath.Expr //compiled expression tree
nodeNames []string //list of nodes under when condition
yangListNames []string //all yang list in expression
}

type leafRefInfo struct {
path string //leafref path
exprTree *xpath.Expr //compiled expression tree
yangListNames []string //all yang list in path
targetNodeName string //target node name
}

type mustInfo struct {
expr string //must expression
exprTree *xpath.Expr //compiled expression tree
errCode string //err-app-tag
errStr string //error message
}

//Important schema information to be loaded at bootup time
type modelTableInfo struct {
dbNum uint8
Expand All @@ -82,7 +96,8 @@ type modelTableInfo struct {
mapLeaf []string //for 'mapping list'
leafRef map[string][]*leafRefInfo //for storing all leafrefs for a leaf in a table,
//multiple leafref possible for union
mustExp map[string]string
mustExpr map[string][]*mustInfo
whenExpr map[string][]*whenInfo
tablesForMustExp map[string]CVLOperation
refFromTables []tblFieldPair //list of table or table/field referring to this table
dfltLeafVal map[string]string //map of leaf names and default value
Expand Down Expand Up @@ -370,7 +385,7 @@ func storeModelInfo(modelFile string, module *yparser.YParserModule) { //such mo
fieldCount++
keypattern := []string{tableName}

/* Create the default key pattern of the form Table Name|{key1}|{key2}. */
// Create the default key pattern of the form Table Name|{key1}|{key2}.
for _ , key := range tableInfo.keys {
keypattern = append(keypattern, fmt.Sprintf("{%s}",key))
}
Expand Down Expand Up @@ -420,7 +435,7 @@ func storeModelInfo(modelFile string, module *yparser.YParserModule) { //such mo
continue
}

tableInfo.leafRef = make(map[string][]*leafRefInfo)
tableInfo.leafRef = make(map[string][]*leafRefInfo)

for _, leafRefNode := range leafRefNodes {
if (leafRefNode.Parent == nil || leafRefNode.FirstChild == nil) {
Expand Down Expand Up @@ -452,7 +467,7 @@ func storeModelInfo(modelFile string, module *yparser.YParserModule) { //such mo
continue
}

tableInfo.mustExp = make(map[string]string)
tableInfo.mustExpr = make(map[string][]*mustInfo)
for _, mustExp := range mustExps {
if (mustExp.Parent == nil) {
continue
Expand All @@ -467,7 +482,10 @@ func storeModelInfo(modelFile string, module *yparser.YParserModule) { //such mo
}
}
if (parentName != "") {
tableInfo.mustExp[parentName] = getXmlNodeAttr(mustExp, "condition")
tableInfo.mustExpr[parentName] = append(tableInfo.mustExpr[parentName],
&mustInfo{
expr: getXmlNodeAttr(mustExp, "condition"),
})
}
}

Expand Down Expand Up @@ -559,22 +577,22 @@ func buildRefTableInfo() {
func addTableNamesForMustExp() {

for tblName, tblInfo := range modelInfo.tableInfo {
if (tblInfo.mustExp == nil) {
if (tblInfo.mustExpr == nil) {
continue
}

tblInfo.tablesForMustExp = make(map[string]CVLOperation)

for _, mustExp := range tblInfo.mustExp {
for _, mustExp := range tblInfo.mustExpr {
var op CVLOperation = OP_NONE
//Check if 'must' expression should be executed for a particular operation
if (strings.Contains(mustExp,
if (strings.Contains(mustExp[0].expr,
"/scommon:operation/scommon:operation != CREATE") == true) {
op = op | OP_CREATE
} else if (strings.Contains(mustExp,
} else if (strings.Contains(mustExp[0].expr,
"/scommon:operation/scommon:operation != UPDATE") == true) {
op = op | OP_UPDATE
} else if (strings.Contains(mustExp,
} else if (strings.Contains(mustExp[0].expr,
"/scommon:operation/scommon:operation != DELETE") == true) {
op = op | OP_DELETE
}
Expand All @@ -592,7 +610,7 @@ func addTableNamesForMustExp() {
//Table name should appear like "../VLAN_MEMBER/tagging_mode' or '
// "/prt:PORT/prt:ifname"
re := regexp.MustCompile(fmt.Sprintf(".*[/]([a-zA-Z]*:)?%s[\\[/]", tblNameSrch))
matches := re.FindStringSubmatch(mustExp)
matches := re.FindStringSubmatch(mustExp[0].expr)
if (len(matches) > 0) {
//stores the table name
tblInfo.tablesForMustExp[tblNameSrch] = op
Expand Down Expand Up @@ -881,11 +899,11 @@ func (c *CVL) checkPathForTableEntry(tableName string, currentValue string, cfgD
//Node-set function such count() can be quite expensive and
//should be avoided through this function
func (c *CVL) addTableEntryForMustExp(cfgData *CVLEditConfigData, tableName string) CVLRetCode {
if (modelInfo.tableInfo[tableName].mustExp == nil) {
if (modelInfo.tableInfo[tableName].mustExpr == nil) {
return CVL_SUCCESS
}

for fieldName, mustExp := range modelInfo.tableInfo[tableName].mustExp {
for fieldName, mustExp := range modelInfo.tableInfo[tableName].mustExpr {

currentValue := "" // Current value for current() function

Expand Down Expand Up @@ -927,7 +945,7 @@ func (c *CVL) addTableEntryForMustExp(cfgData *CVLEditConfigData, tableName stri
}

mustExpStk := []string{} //Use the string slice as stack
mustExpStr := "(" + mustExp + ")"
mustExpStr := "(" + mustExp[0].expr + ")"
strLen := len(mustExpStr)
strTmp := ""
//Parse the xpath expression and fetch Redis entry by looking at xpath,
Expand Down Expand Up @@ -1005,7 +1023,7 @@ func (c *CVL) addTableEntryForMustExp(cfgData *CVLEditConfigData, tableName stri

//Add all other table data for validating all 'must' exp for tableName
func (c *CVL) addTableDataForMustExp(op CVLOperation, tableName string) CVLRetCode {
if (modelInfo.tableInfo[tableName].mustExp == nil) {
if (modelInfo.tableInfo[tableName].mustExpr == nil) {
return CVL_SUCCESS
}

Expand Down
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