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cleanup and add comments

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Signed-off-by: Wangchong Zhou <fffonion@gmail.com>
This commit is contained in:
Wangchong Zhou 2018-09-24 13:36:01 -07:00
parent 668e31e5f1
commit f387766cc2
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GPG key ID: B607274584E8D5E5
1 changed files with 17 additions and 5 deletions
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22
pkg/mapper/fsm/fsm.go
View file

@ -55,6 +55,7 @@ type FSM struct {
statesCount int
}
// NewFSM creates a new FSM instance
func NewFSM(metricTypes []string, maxPossibleTransitions int, disableOrdering bool) *FSM {
fsm := FSM{}
root := &mappingState{}
@ -73,6 +74,7 @@ func NewFSM(metricTypes []string, maxPossibleTransitions int, disableOrdering bo
return &fsm
}
// AddState adds a state into the existing FSM
func (f *FSM) AddState(match string, name string, labels prometheus.Labels, matchMetricType string,
maxPossibleTransitions int, result interface{}) {
// first split by "."
@ -134,6 +136,7 @@ func (f *FSM) AddState(match string, name string, labels prometheus.Labels, matc
}
// DumpFSM accepts a io.writer and write the current FSM into dot file format
func (f *FSM) DumpFSM(w io.Writer) {
idx := 0
states := make(map[int]*mappingState)
@ -162,6 +165,7 @@ func (f *FSM) DumpFSM(w io.Writer) {
w.Write([]byte("}"))
}
// TestIfNeedBacktracking test if backtrack is needed for current FSM
func (f *FSM) TestIfNeedBacktracking(mappings []string) bool {
needBacktrack := false
// rule A and B that has same length and
@ -232,17 +236,20 @@ func (f *FSM) TestIfNeedBacktracking(mappings []string) bool {
return f.needsBacktracking
}
// GetMapping implements a mapping algorithm for Glob pattern
func (f *FSM) GetMapping(statsdMetric string, statsdMetricType string) (interface{}, string, prometheus.Labels, bool) {
matchFields := strings.Split(statsdMetric, ".")
currentState := f.root.transitions[statsdMetricType]
// the cursor/pointer in the backtrack stack
// the cursor/pointer in the backtrack stack implemented as a double-linked list
var backtrackCursor *fsmBacktrackStackCursor
resumeFromBacktrack := false
// the return variable
var finalState *mappingState
captures := make(map[int]string, len(matchFields))
// keep track of captured group so we don't need to do append() on captures
captureIdx := 0
filedsCount := len(matchFields)
i := 0
@ -267,6 +274,7 @@ func (f *FSM) GetMapping(statsdMetric string, statsdMetricType string) (interfac
captureIdx++
}
} else if f.needsBacktracking {
// if backtracking is needed, also check for alternative transition
altState, present := currentState.transitions["*"]
if !present || fieldsLeft > altState.maxRemainingLength || fieldsLeft < altState.minRemainingLength {
} else {
@ -275,13 +283,15 @@ func (f *FSM) GetMapping(statsdMetric string, statsdMetricType string) (interfac
fieldIndex: i,
captureIndex: captureIdx, currentCapture: field,
}
// if this is not the first time, connect to the previous cursor
if backtrackCursor != nil {
backtrackCursor.next = &newCursor
}
backtrackCursor = &newCursor
}
}
} else { // no more transitions for this state
} else {
// no more transitions for this state
break
}
} // backtrack will resume from here
@ -290,8 +300,7 @@ func (f *FSM) GetMapping(statsdMetric string, statsdMetricType string) (interfac
if state.result != nil && i == filedsCount-1 {
if f.disableOrdering {
finalState = state
// do a double break
goto formatLabels
return formatLabels(finalState, captures)
} else if finalState == nil || finalState.resultPriority > state.resultPriority {
// if we care about ordering, try to find a result with highest prioity
finalState = state
@ -327,7 +336,10 @@ func (f *FSM) GetMapping(statsdMetric string, statsdMetricType string) (interfac
}
}
formatLabels:
return formatLabels(finalState, captures)
}
func formatLabels(finalState *mappingState, captures map[int]string) (interface{}, string, prometheus.Labels, bool) {
// format name and labels
if finalState != nil {
name := finalState.resultNameFormatter.format(captures)