// MatchByPrefix returns the longest matching PrefixConfig. If the key
// specified does not match an existing prefix, a panic will
// result. Based on the comments in NewPrefixConfigMap, that example
// will have a final list of PrefixConfig entries which look like:
//
// "/": config1
// "/db1": config2
// "/db1/table": config3
// "/db1/tablf": config2
// "/db2": config1
// "/db3": config4
// "/db4": config1
//
// To find the longest matching prefix, we take the lower bound of the
// specified key.
func (p PrefixConfigMap) MatchByPrefix(key proto.Key) *PrefixConfig {
n := sort.Search(len(p), func(i int) bool {
return key.Compare(p[i].Prefix) < 0
})
if n == 0 || n > len(p) {
panic("should never match a key outside of default range")
}
// If the matched prefix config is already canonical, return it immediately.
pc := p[n-1]
if pc.Canonical == nil {
return pc
}
// Otherwise, search for the canonical prefix config.
n = sort.Search(len(p), func(i int) bool {
return pc.Canonical.Compare(p[i].Prefix) <= 0
})
// Should find an exact match every time.
if n >= len(p) || !pc.Canonical.Equal(p[n].Prefix) {
panic(fmt.Sprintf("canonical lookup for key %q failed", string(pc.Canonical)))
}
return p[n]
}
// VisitPrefixes invokes the visitor function for each prefix overlapped
// by the specified key range [start, end). If visitor returns done=true
// or an error, the visitation is halted.
func (p PrefixConfigMap) VisitPrefixes(start, end proto.Key,
visitor func(start, end proto.Key, config gogoproto.Message) (bool, error)) error {
comp := start.Compare(end)
if comp > 0 {
return util.Errorf("start key %q not less than or equal to end key %q", start, end)
}
startIdx := sort.Search(len(p), func(i int) bool {
return start.Compare(p[i].Prefix) < 0
})
// Common case of start == end.
endIdx := startIdx
if comp != 0 {
endIdx = sort.Search(len(p), func(i int) bool {
return end.Compare(p[i].Prefix) < 0
})
}
if startIdx > len(p) || endIdx > len(p) {
return util.Errorf("start and/or end keys (%q, %q) fall outside prefix range; "+
"startIdx: %d, endIdx: %d, len(p): %d", start, end, startIdx, endIdx, len(p))
}
if startIdx == endIdx {
_, err := visitor(start, end, p[startIdx-1].Config)
return err
}
for i := startIdx; i < endIdx; i++ {
done, err := visitor(start, p[i].Prefix, p[i-1].Config)
if done || err != nil {
return err
}
if p[i].Prefix.Equal(end) {
return nil
}
start = p[i].Prefix
}
done, err := visitor(start, end, p[endIdx-1].Config)
if done || err != nil {
return err
}
return nil
}