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implement backtrack

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Signed-off-by: Wangchong Zhou <fffonion@gmail.com>
This commit is contained in:
Wangchong Zhou 2018-09-12 18:18:12 -07:00
parent dad04e9c8b
commit c2742aa299
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GPG key ID: B607274584E8D5E5
2 changed files with 136 additions and 73 deletions
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94
pkg/mapper/mapper.go
View file

@ -48,9 +48,7 @@ type mapperConfigDefaults struct {
}
type mappingState struct {
transitionsMap map[string]*mappingState
transitionsArray []*mappingState
// use to compare length upfront to avoid unnecessary backtrack
transitions map[string]*mappingState
minRemainingLength int
maxRemainingLength int
// result is nil unless there's a metric ends with this state
@ -76,9 +74,13 @@ type templateFormatter struct {
fmtString string
}
type fsmBacktrackRecord struct {
type fsmBacktrackStackCursor struct {
fieldIndex int
captureIdx int
currentCapture string
state *mappingState
prev *fsmBacktrackStackCursor
next *fsmBacktrackStackCursor
}
type matchMetricType string
@ -188,11 +190,11 @@ func (m *MetricMapper) InitFromYAMLString(fileContents string) error {
maxPossibleTransitions := len(n.Mappings)
n.FSM = &mappingState{}
n.FSM.transitionsMap = make(map[string]*mappingState, 3)
n.FSM.transitions = make(map[string]*mappingState, 3)
for _, field := range []MetricType{MetricTypeCounter, MetricTypeTimer, MetricTypeGauge, ""} {
state := &mappingState{}
(*state).transitionsMap = make(map[string]*mappingState, maxPossibleTransitions)
n.FSM.transitionsMap[string(field)] = state
(*state).transitions = make(map[string]*mappingState, maxPossibleTransitions)
n.FSM.transitions[string(field)] = state
}
for i := range n.Mappings {
@ -234,25 +236,25 @@ func (m *MetricMapper) InitFromYAMLString(fileContents string) error {
roots := []*mappingState{}
if currentMapping.MatchMetricType == "" {
for _, metricType := range []MetricType{MetricTypeCounter, MetricTypeTimer, MetricTypeGauge, ""} {
roots = append(roots, n.FSM.transitionsMap[string(metricType)])
roots = append(roots, n.FSM.transitions[string(metricType)])
}
} else {
roots = append(roots, n.FSM.transitionsMap[string(currentMapping.MatchMetricType)])
roots = append(roots, n.FSM.transitions[string(currentMapping.MatchMetricType)])
}
var captureCount int
for _, root := range roots {
captureCount = 0
for i, field := range matchFields {
state, prs := root.transitionsMap[field]
state, prs := root.transitions[field]
if !prs {
state = &mappingState{}
(*state).transitionsMap = make(map[string]*mappingState, maxPossibleTransitions)
(*state).transitions = make(map[string]*mappingState, maxPossibleTransitions)
(*state).maxRemainingLength = len(matchFields) - i - 1
(*state).minRemainingLength = len(matchFields) - i - 1
root.transitionsMap[field] = state
root.transitions[field] = state
// if this is last field, set result to currentMapping instance
if i == len(matchFields)-1 {
root.transitionsMap[field].result = currentMapping
root.transitions[field].result = currentMapping
}
} else {
(*state).maxRemainingLength = max(len(matchFields)-i-1, (*state).maxRemainingLength)
@ -322,7 +324,7 @@ func (m *MetricMapper) InitFromYAMLString(fileContents string) error {
m.Defaults = n.Defaults
m.Mappings = n.Mappings
if len(n.FSM.transitionsMap) > 0 || len(n.FSM.transitionsArray) > 0 {
if len(n.FSM.transitions) > 0 {
m.FSM = n.FSM
m.doRegex = n.doRegex
if m.dumpFSMPath != "" {
@ -335,7 +337,7 @@ func (m *MetricMapper) InitFromYAMLString(fileContents string) error {
backtrackingRules := findBacktrackRules(&n)
if len(backtrackingRules) > 0 {
for _, rule := range backtrackingRules {
log.Infof("backtracking required for match \"%s\", matching performance may be degraded\n", rule)
log.Warnf("backtracking required because of match \"%s\", matching performance may be degraded\n", rule)
}
m.FSMNeedsBacktracking = true
}
@ -366,7 +368,7 @@ func findBacktrackRules(n *MetricMapper) []string {
if mapping.MatchType != MatchTypeGlob {
continue
}
l := len(mapping.Match)
l := len(strings.Split(mapping.Match, "."))
ruleByLength[l] = append(ruleByLength[l], mapping.Match)
metricRe := strings.Replace(mapping.Match, ".", "\\.", -1)
@ -375,6 +377,7 @@ func findBacktrackRules(n *MetricMapper) []string {
if err != nil {
log.Warnf("invalid match %s. cannot compile regex in mapping: %v", mapping.Match, err)
}
// put into array no matter there's error or not, we will skip later if regex is nil
ruleREByLength[l] = append(ruleREByLength[l], regex)
}
@ -393,9 +396,8 @@ func findBacktrackRules(n *MetricMapper) []string {
}
for _, r2 := range rules {
if r2 != r1 && len(re1.FindStringSubmatchIndex(r2)) > 0 {
fmt.Println("subset", r1, "of", r2)
log.Warnf("rule \"%s\" is a super set of rule \"%s\", the later will never be matched\n", r1, r2)
hasSubset = true
break
}
}
if !hasSubset {
@ -419,13 +421,13 @@ func dumpFSM(fileName string, root *mappingState) {
w.WriteString("node [ label=\"\",style=filled,fillcolor=white,shape=circle ]\n") // remove label of node
for idx < len(states) {
for field, transition := range states[idx].transitionsMap {
for field, transition := range states[idx].transitions {
states[len(states)] = transition
w.WriteString(fmt.Sprintf("%d -> %d [label = \"%s\"];\n", idx, len(states)-1, field))
if idx == 0 {
// color for metric types
w.WriteString(fmt.Sprintf("%d [color=\"#D6B656\",fillcolor=\"#FFF2CC\"];\n", len(states)-1))
} else if transition.transitionsMap == nil || len(transition.transitionsMap) == 0 {
} else if transition.transitions == nil || len(transition.transitions) == 0 {
// color for end state
w.WriteString(fmt.Sprintf("%d [color=\"#82B366\",fillcolor=\"#D5E8D4\"];\n", len(states)-1))
}
@ -450,26 +452,48 @@ func (m *MetricMapper) InitFromFile(fileName string) error {
func (m *MetricMapper) GetMapping(statsdMetric string, statsdMetricType MetricType) (*MetricMapping, prometheus.Labels, bool) {
// glob matching
if root := m.FSM; root != nil {
root = root.transitionsMap[string(statsdMetricType)]
root = root.transitions[string(statsdMetricType)]
matchFields := strings.Split(statsdMetric, ".")
captures := make(map[int]string, len(matchFields))
captureIdx := 0
var backtrackCursor *fsmBacktrackStackCursor
backtrackCursor = nil
filedsCount := len(matchFields)
for i, field := range matchFields {
if root.transitionsMap == nil {
i := 0
for {
for i < filedsCount {
if root.transitions == nil {
break
}
state, prs := root.transitionsMap[field]
field := matchFields[i]
state, prs := root.transitions[field]
fieldsLeft := filedsCount - i - 1
// also compare length upfront to avoid unnecessary loop or backtrack
if !prs || fieldsLeft > state.maxRemainingLength || fieldsLeft < state.minRemainingLength {
state, prs = root.transitionsMap["*"]
state, prs = root.transitions["*"]
if !prs || fieldsLeft > state.maxRemainingLength || fieldsLeft < state.minRemainingLength {
break
}
} else {
captures[captureIdx] = field
captureIdx++
}
if state.result != nil && i == filedsCount-1 {
} else if m.FSMNeedsBacktracking {
otherState, prs := root.transitions["*"]
if !prs || fieldsLeft > otherState.maxRemainingLength || fieldsLeft < otherState.minRemainingLength {
} else {
newCursor := fsmBacktrackStackCursor{prev: backtrackCursor, state: otherState,
fieldIndex: i + 1,
captureIdx: captureIdx + 1, currentCapture: field,
}
if backtrackCursor != nil {
backtrackCursor.next = &newCursor
}
backtrackCursor = &newCursor
}
}
// found!
if state != nil && state.result != nil && i == filedsCount-1 {
mapping := *state.result
state.result.Name = formatTemplate(mapping.NameFormatter, captures)
@ -480,11 +504,25 @@ func (m *MetricMapper) GetMapping(statsdMetric string, statsdMetricType MetricTy
return state.result, labels, true
}
root = state
i++
}
// if we are not doing backtracking or all path has been travesaled
if backtrackCursor == nil {
// if there's no regex match type, return immediately
if !m.doRegex {
return nil, nil, false
} else {
break
}
} else {
// pop one from stack
root = backtrackCursor.state
i = backtrackCursor.fieldIndex
captureIdx = backtrackCursor.captureIdx
// put the * capture back
captures[captureIdx-1] = backtrackCursor.currentCapture
backtrackCursor = backtrackCursor.prev
}
}
}

75
pkg/mapper/mapper_test.go
View file

@ -139,6 +139,56 @@ mappings:
},
},
},
//Config with backtracking
{
config: `
mappings:
- match: test.*.bbb
name: "testb"
labels:
label: "${1}_foo"
- match: test.justatest.aaa
name: "testa"
labels:
label: "${1}_foo"
`,
mappings: mappings{
"test.good.bbb": {
name: "testb",
labels: map[string]string{
"label": "good_foo",
},
},
"test.justatest.bbb": {
name: "testb",
labels: map[string]string{
"label": "justatest_foo",
},
},
},
},
//Config with super sets
{
config: `
mappings:
- match: test.*.bbb
name: "testb"
labels:
label: "${1}_foo"
- match: test.*.*
name: "testa"
labels:
label: "${1}_foo"
`,
mappings: mappings{
"test.good.bbb": {
name: "testb",
labels: map[string]string{
"label": "good_foo",
},
},
},
},
// Config with bad regex reference.
{
config: `---
@ -471,31 +521,6 @@ mappings:
},
},
},
//Config with backtracking
{
config: `mappings:
- match: foo.*.ccc
name: "fooc"
labels: {}
- match: foo.bbb.aaa
name: "foob"
labels: {}
`,
mappings: mappings{
"foo.bbb.ccc": {
name: "fooc",
labels: map[string]string{},
},
"foo.ddd.ccc": {
name: "fooc",
labels: map[string]string{},
},
"foo.bbb.aaa": {
name: "foob",
labels: map[string]string{},
},
},
},
}
mapper := MetricMapper{}