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label_extensions.go
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label_extensions.go
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package protocol
import (
"bytes"
"regexp"
"sort"
"go.gazette.dev/core/labels"
)
// Validate returns an error if the Label is not well-formed.
func (m Label) Validate() error {
if err := ValidateToken(m.Name, TokenSymbols, minLabelLen, maxLabelLen); err != nil {
return ExtendContext(err, "Name")
} else if err = ValidateToken(m.Value, pathSymbols, 0, maxLabelValueLen); err != nil {
return ExtendContext(err, "Value")
}
return nil
}
// MustLabelSet is a convenience for constructing LabelSets from a sequence of
// Name, Value arguments. The result LabelSet must Validate or MustLabelSet panics.
func MustLabelSet(nv ...string) (set LabelSet) {
if len(nv)%2 != 0 {
panic("expected an even number of Name/Value arguments")
}
for i := 0; i != len(nv); i += 2 {
set.AddValue(nv[i], nv[i+1])
}
if err := set.Validate(); err != nil {
panic(err.Error())
}
return
}
// Validate returns an error if the LabelSet is not well-formed.
func (m LabelSet) Validate() error {
for i := range m.Labels {
if err := m.Labels[i].Validate(); err != nil {
return ExtendContext(err, "Labels[%d]", i)
} else if i == 0 {
continue
}
if m.Labels[i-1].Name < m.Labels[i].Name {
// Pass.
} else if m.Labels[i-1].Name == m.Labels[i].Name {
if m.Labels[i-1].Value >= m.Labels[i].Value {
return NewValidationError("Labels not in unique, sorted order (index %d; label %s value %s <= %s)",
i, m.Labels[i].Name, m.Labels[i].Value, m.Labels[i-1].Value)
} else if m.Labels[i-1].Value == "" {
return NewValidationError("Label has empty & non-empty values (index %d; label %s value %s)",
i, m.Labels[i].Name, m.Labels[i].Value)
}
} else {
return NewValidationError("Labels not in unique, sorted order (index %d; label name %s <= %s)",
i, m.Labels[i].Name, m.Labels[i-1].Name)
}
}
return nil
}
// Assign the labels of the |other| set to this LabelSet. If |other| is nil,
// this LabelSet is emptied.
func (m *LabelSet) Assign(other *LabelSet) {
if m.Labels = m.Labels[:0]; other != nil {
m.Labels = append(m.Labels, other.Labels...)
}
}
// ValuesOf returns the values of Label |name|, or nil if it doesn't exist in the LabelSet.
func (m LabelSet) ValuesOf(name string) (values []string) {
var ind = sort.Search(len(m.Labels), func(i int) bool { return m.Labels[i].Name >= name })
for ind != len(m.Labels) && m.Labels[ind].Name == name {
values = append(values, m.Labels[ind].Value)
ind++
}
return
}
// ValueOf returns the first value of Label |name|, or "" if it doesn't exist in the LabelSet.
func (m LabelSet) ValueOf(name string) string {
var ind = sort.Search(len(m.Labels), func(i int) bool { return m.Labels[i].Name >= name })
if ind != len(m.Labels) && m.Labels[ind].Name == name {
return m.Labels[ind].Value
}
return ""
}
// SetValue adds Label |name| with |value|, replacing any existing Labels |name|.
func (m *LabelSet) SetValue(name, value string) {
var begin = sort.Search(len(m.Labels), func(i int) bool { return m.Labels[i].Name >= name })
var end = begin
for end != len(m.Labels) && m.Labels[end].Name == name {
end++
}
if begin == end {
m.Labels = append(m.Labels, Label{})
copy(m.Labels[begin+1:], m.Labels[begin:]) // Insert at |begin|.
end = begin + 1
}
m.Labels[begin] = Label{Name: name, Value: value}
m.Labels = append(m.Labels[:begin+1], m.Labels[end:]...) // Cut |begin+1, end).
}
// AddValue adds Label |name| with |value|, retaining any existing Labels |name|.
func (m *LabelSet) AddValue(name, value string) {
var ind = sort.Search(len(m.Labels), func(i int) bool {
if m.Labels[i].Name != name {
return m.Labels[i].Name > name
} else {
return m.Labels[i].Value >= value
}
})
var label = Label{Name: name, Value: value}
if ind != len(m.Labels) && m.Labels[ind] == label {
// No-op.
} else {
m.Labels = append(m.Labels, Label{})
copy(m.Labels[ind+1:], m.Labels[ind:])
m.Labels[ind] = label
}
}
// Remove all instances of Labels |name|.
func (m *LabelSet) Remove(name string) {
var begin = sort.Search(len(m.Labels), func(i int) bool { return m.Labels[i].Name >= name })
var end = begin
for end != len(m.Labels) && m.Labels[end].Name == name {
end++
}
m.Labels = append(m.Labels[:begin], m.Labels[end:]...) // Cut |begin, end).
}
// ValidateSingleValueLabels compares the LabelSet to labels.SingleValueLabels,
// and returns an error if any labels have multiple values.
func ValidateSingleValueLabels(m LabelSet) error {
for i := range m.Labels {
if i == 0 || m.Labels[i-1].Name != m.Labels[i].Name {
continue
}
if _, ok := labels.SingleValueLabels[m.Labels[i].Name]; ok {
return NewValidationError("expected single-value Label has multiple values (index %d; label %s value %s)",
i, m.Labels[i].Name, m.Labels[i].Value)
}
}
return nil
}
// UnionLabelSets returns the LabelSet having all labels present in either |lhs|
// or |rhs|. Where both |lhs| and |rhs| have values for a label, those of |lhs|
// are preferred.
func UnionLabelSets(lhs, rhs, out LabelSet) LabelSet {
out.Labels = out.Labels[:0]
var it = labelJoin{
setL: lhs.Labels,
setR: rhs.Labels,
lenL: len(lhs.Labels),
lenR: len(rhs.Labels),
}
for cur, ok := it.next(); ok; cur, ok = it.next() {
if cur.lBeg != cur.lEnd { // Prefer |lhs| label values.
out.Labels = append(out.Labels, lhs.Labels[cur.lBeg:cur.lEnd]...)
} else {
out.Labels = append(out.Labels, rhs.Labels[cur.rBeg:cur.rEnd]...)
}
}
return out
}
// IntersectLabelSets returns the LabelSet having all labels present in both
// |lhs| and |rhs| with matched values.
func IntersectLabelSets(lhs, rhs, out LabelSet) LabelSet {
out.Labels = out.Labels[:0]
var it = labelJoin{
setL: lhs.Labels,
setR: rhs.Labels,
lenL: len(lhs.Labels),
lenR: len(rhs.Labels),
}
for cur, ok := it.next(); ok; cur, ok = it.next() {
if labelValuesEqual(it, cur) {
out.Labels = append(out.Labels, lhs.Labels[cur.lBeg:cur.lEnd]...)
}
}
return out
}
// SubtractLabelSets returns the LabelSet having labels in |lhs| which are not
// present in |rhs| with matched values.
func SubtractLabelSet(lhs, rhs, out LabelSet) LabelSet {
out.Labels = out.Labels[:0]
var it = labelJoin{
setL: lhs.Labels,
setR: rhs.Labels,
lenL: len(lhs.Labels),
lenR: len(rhs.Labels),
}
for cur, ok := it.next(); ok; cur, ok = it.next() {
if !labelValuesEqual(it, cur) {
out.Labels = append(out.Labels, lhs.Labels[cur.lBeg:cur.lEnd]...)
}
}
return out
}
// Validate returns an error if the LabelSelector is not well-formed.
func (m LabelSelector) Validate() error {
if err := m.Include.Validate(); err != nil {
return ExtendContext(err, "Include")
} else if err := m.Exclude.Validate(); err != nil {
return ExtendContext(err, "Exclude")
}
return nil
}
// Matches returns whether the LabelSet is matched by the LabelSelector.
func (m LabelSelector) Matches(s LabelSet) bool {
if matchSelector(m.Exclude.Labels, s.Labels, false) {
return false // At least one excluded label is matched.
} else if !matchSelector(m.Include.Labels, s.Labels, true) {
return false // Not every included label is matched.
}
return true
}
// String returns a canonical string representation of the LabelSelector.
func (s LabelSelector) String() string {
var w = bytes.NewBuffer(nil)
var f = func(l []Label, exc bool) {
var it = labelJoin{setL: l, setR: l, lenL: len(l), lenR: len(l)}
for cur, ok := it.next(); ok; cur, ok = it.next() {
if cur.lBeg+1 == cur.lEnd && l[cur.lBeg].Value == "" {
if exc {
w.WriteByte('!')
}
w.WriteString(l[cur.lBeg].Name)
} else if cur.lBeg+1 == cur.lEnd {
w.WriteString(l[cur.lBeg].Name)
if exc {
w.WriteByte('!')
}
w.WriteByte('=')
w.WriteString(l[cur.lBeg].Value)
} else {
w.WriteString(l[cur.lBeg].Name)
if exc {
w.WriteString(" notin (")
} else {
w.WriteString(" in (")
}
w.WriteString(l[cur.lBeg].Value)
for ; cur.lBeg+1 != cur.lEnd; cur.lBeg++ {
w.WriteByte(',')
w.WriteString(l[cur.lBeg+1].Value)
}
w.WriteByte(')')
}
if cur.lEnd != len(l) {
w.WriteByte(',')
}
}
}
f(s.Include.Labels, false)
if w.Len() != 0 && len(s.Exclude.Labels) != 0 {
w.WriteByte(',')
}
f(s.Exclude.Labels, true)
return w.String()
}
func matchSelector(sel, set []Label, reqAll bool) bool {
var it = labelJoin{
setL: sel,
setR: set,
lenL: len(sel),
lenR: len(set),
}
for cur, ok := it.next(); ok; cur, ok = it.next() {
if cur.lBeg == cur.lEnd {
continue // This is a |set| label which is not in |sel|.
}
// Determine if at least one label value of |sel| is present in |set|.
var matched bool
for a, b := sel[cur.lBeg:cur.lEnd], set[cur.rBeg:cur.rEnd]; !matched && len(a) != 0 && len(b) != 0; {
if a[0].Value == "" || a[0].Value == b[0].Value {
matched = true // Selector value "" implicitly matches any value of the label.
} else if a[0].Value < b[0].Value {
a = a[1:]
} else {
b = b[1:]
}
}
if !reqAll && matched {
return true
} else if reqAll && !matched {
return false
}
}
return reqAll
}
// labelJoin performs a full outer join of two sorted []Label sets.
type labelJoin struct {
setL, setR []Label
lenL, lenR int
labelJoinCursor
}
type labelJoinCursor struct {
lBeg, lEnd, rBeg, rEnd int
}
func (j *labelJoin) next() (cur labelJoinCursor, ok bool) {
var c int
if j.lBeg == j.lenL && j.rBeg == j.lenR {
cur = j.labelJoinCursor
return // Both sequences complete.
} else if j.lBeg == j.lenL {
c = +1 // LHS sequence complete. Step RHS.
} else if j.rBeg == j.lenR {
c = -1 // RHS sequence complete. Step LHS.
} else if j.setL[j.lBeg].Name == j.setR[j.rBeg].Name {
c = 0 // Step both.
} else if j.setL[j.lBeg].Name < j.setR[j.rBeg].Name {
c = -1 // Step LHS.
} else {
c = +1 // Step RHS.
}
for j.lEnd != j.lenL && c <= 0 && j.setL[j.lEnd].Name == j.setL[j.lBeg].Name {
j.lEnd++
}
for j.rEnd != j.lenR && c >= 0 && j.setR[j.rEnd].Name == j.setR[j.rBeg].Name {
j.rEnd++
}
cur, ok = j.labelJoinCursor, true
j.lBeg, j.rBeg = j.lEnd, j.rEnd
return
}
// labelValuesEqual returns true if the values of the labels indicated by the
// labelJoinCursor of the labelJoin are exactly matched.
func labelValuesEqual(it labelJoin, cur labelJoinCursor) bool {
if n := cur.lEnd - cur.lBeg; n != (cur.rEnd - cur.rBeg) {
return false
} else {
for i := 0; i != n; i++ {
if it.setL[cur.lBeg+i].Value != it.setR[cur.rBeg+i].Value {
return false
}
}
}
return true
}
// ParseLabelSelector parses a LabelSelector string. Selector strings are
// composed of a comma-separate list of selector expressions. Allowed
// expression types are equality, in-equality, set membership, set exclusion,
// existence, and non-existence. Eg:
//
// * "foo = bar" requires that label "foo" be present with value "bar"
// * "foo != bar" requires that label "foo" not be present with value "bar"
// * "foo" requires that label "foo" be present (with any value).
// * "!foo" requires that label "foo" not be present.
// * "foo in (bar,baz)" requires that "foo" be present with either "bar" or "baz".
// * "foo notin (bar,baz)" requires that "foo", if present, not have value "bar" or "baz".
//
// Additional examples of composite expressions:
// * "topic in (topic/one, topic/two), prefix=/my/journal/prefix"
// * "env in (production, qa), tier not in (frontend,backend), partition"
//
// ParseLabelSelector is invariant to _reasonable_ spacing: eg, "not in" and
// "notin" may be used interchangeably, as may "==" and "=", with or without
// single spacing on either side.
func ParseLabelSelector(s string) (LabelSelector, error) {
var out LabelSelector
for len(s) != 0 {
var m []string
if m = reSelectorEqual.FindStringSubmatch(s); m != nil {
out.Include.Labels = append(out.Include.Labels, Label{Name: m[1], Value: m[2]})
} else if m = reSelectorNotEqual.FindStringSubmatch(s); m != nil {
out.Exclude.Labels = append(out.Exclude.Labels, Label{Name: m[1], Value: m[2]})
} else if m = reSelectorSetIn.FindStringSubmatch(s); m != nil {
if parts, err := parseSetParts(m[1], m[2]); err != nil {
return LabelSelector{}, ExtendContext(err, "parsing %q", s)
} else {
out.Include.Labels = append(out.Include.Labels, parts...)
}
} else if m = reSelectorSetNotIn.FindStringSubmatch(s); m != nil {
if parts, err := parseSetParts(m[1], m[2]); err != nil {
return LabelSelector{}, ExtendContext(err, "parsing %q", s)
} else {
out.Exclude.Labels = append(out.Exclude.Labels, parts...)
}
} else if m = reSelectorSetExists.FindStringSubmatch(s); m != nil {
out.Include.Labels = append(out.Include.Labels, Label{Name: m[1]})
} else if m = reSelectorSetNotExists.FindStringSubmatch(s); m != nil {
out.Exclude.Labels = append(out.Exclude.Labels, Label{Name: m[1]})
} else {
return LabelSelector{}, NewValidationError("could not match %q to a label selector expression", s)
}
s = s[len(m[0]):]
}
for _, l := range [][]Label{out.Include.Labels, out.Exclude.Labels} {
sort.Slice(l, func(i, j int) bool {
if l[i].Name != l[j].Name {
return l[i].Name < l[j].Name
}
return l[i].Value < l[j].Value
})
}
return out, out.Validate()
}
func parseSetParts(name, s string) ([]Label, error) {
var out []Label
for len(s) != 0 {
var m []string
if m = reSelectorSetValue.FindStringSubmatch(s); m != nil {
out = append(out, Label{Name: name, Value: m[1]})
} else {
return nil, NewValidationError("could not match %q to a label selector set expression", s)
}
s = s[len(m[0]):]
}
return out, nil
}
var (
reToken = ` ?([\pL\pN\` + regexp.QuoteMeta(TokenSymbols) + `]{2,})`
rePath = ` ?([\pL\pN\` + regexp.QuoteMeta(pathSymbols) + `]{0,})`
reCommaOrEnd = ` ?(?:,|$)`
reParenthetical = ` ?\(([^)]+)\)`
reSelectorEqual = regexp.MustCompile(`^` + reToken + ` ?=?=` + rePath + reCommaOrEnd)
reSelectorNotEqual = regexp.MustCompile(`^` + reToken + ` ?!=` + rePath + reCommaOrEnd)
reSelectorSetIn = regexp.MustCompile(`^` + reToken + ` in` + reParenthetical + reCommaOrEnd)
reSelectorSetNotIn = regexp.MustCompile(`^` + reToken + ` not ?in` + reParenthetical + reCommaOrEnd)
reSelectorSetExists = regexp.MustCompile(`^` + reToken + reCommaOrEnd)
reSelectorSetNotExists = regexp.MustCompile(`^ ?!` + reToken + reCommaOrEnd)
reSelectorSetValue = regexp.MustCompile(`^` + rePath + reCommaOrEnd)
)
const (
minLabelLen, maxLabelLen = 2, 64
maxLabelValueLen = 1024
)