package result import ( "fmt" "reflect" "strings" "sync" "unicode" "unicode/utf8" "codeberg.org/gruf/go-byteutil" "codeberg.org/gruf/go-mangler" ) // structKeys provides convience methods for a list // of structKey field combinations used for cache keys. type structKeys []structKey // get fetches the structKey info for given lookup name (else, panics). func (sk structKeys) get(name string) *structKey { for i := range sk { if sk[i].name == name { return &sk[i] } } panic("unknown lookup: \"" + name + "\"") } // generate will calculate and produce a slice of cache keys the given value // can be stored under in the, as determined by receiving struct keys. func (sk structKeys) generate(a any) []cacheKey { var keys []cacheKey // Get reflected value in order // to access the struct fields v := reflect.ValueOf(a) // Iteratively deref pointer value for v.Kind() == reflect.Pointer { if v.IsNil() { panic("nil ptr") } v = v.Elem() } // Acquire byte buffer buf := getBuf() defer putBuf(buf) for i := range sk { // Reset buffer buf.B = buf.B[:0] // Append each field value to buffer. for _, field := range sk[i].fields { fv := v.Field(field.index) fi := fv.Interface() buf.B = field.mangle(buf.B, fi) buf.B = append(buf.B, '.') } // Drop last '.' buf.Truncate(1) // Don't generate keys for zero values if allowZero := sk[i].zero == ""; // nocollapse !allowZero && buf.String() == sk[i].zero { continue } // Append new cached key to slice keys = append(keys, cacheKey{ info: &sk[i], key: string(buf.B), // copy }) } return keys } type cacheKeys []cacheKey // drop will drop the cachedKey with lookup name from receiving cacheKeys slice. func (ck *cacheKeys) drop(name string) { _ = *ck // move out of loop for i := range *ck { if (*ck)[i].info.name == name { (*ck) = append((*ck)[:i], (*ck)[i+1:]...) break } } } // cacheKey represents an actual cached key. type cacheKey struct { // info is a reference to the structKey this // cacheKey is representing. This is a shared // reference and as such only the structKey.pkeys // lookup map is expecting to be modified. info *structKey // value is the actual string representing // this cache key for hashmap lookups. key string } // structKey represents a list of struct fields // encompassing a single cache key, the string name // of the lookup, the lookup map to primary cache // keys, and the key's possible zero value string. type structKey struct { // name is the provided cache lookup name for // this particular struct key, consisting of // period ('.') separated struct field names. name string // zero is the possible zero value for this key. // if set, this will _always_ be non-empty, as // the mangled cache key will never be empty. // // i.e. zero = "" --> allow zero value keys // zero != "" --> don't allow zero value keys zero string // fields is a slice of runtime struct field // indices, of the fields encompassed by this key. fields []structField // pkeys is a lookup of stored struct key values // to the primary cache lookup key (int64). pkeys map[string]int64 } type structField struct { // index is the reflect index of this struct field. index int // mangle is the mangler function for // serializing values of this struct field. mangle mangler.Mangler } // genKey generates a cache key string for given key parts (i.e. serializes them using "go-mangler"). func (sk structKey) genKey(parts []any) string { // Check this expected no. key parts. if len(parts) != len(sk.fields) { panic(fmt.Sprintf("incorrect no. key parts provided: want=%d received=%d", len(parts), len(sk.fields))) } // Acquire byte buffer buf := getBuf() defer putBuf(buf) buf.Reset() // Encode each key part for i, part := range parts { buf.B = sk.fields[i].mangle(buf.B, part) buf.B = append(buf.B, '.') } // Drop last '.' buf.Truncate(1) // Return string copy return string(buf.B) } // newStructKey will generate a structKey{} information object for user-given lookup // key information, and the receiving generic paramter's type information. Panics on error. func newStructKey(lk Lookup, t reflect.Type) structKey { var ( sk structKey zeros []any ) // Set the lookup name sk.name = lk.Name // Split dot-separated lookup to get // the individual struct field names names := strings.Split(lk.Name, ".") if len(names) == 0 { panic("no key fields specified") } // Allocate the mangler and field indices slice. sk.fields = make([]structField, len(names)) for i, name := range names { // Get field info for given name ft, ok := t.FieldByName(name) if !ok { panic("no field found for name: \"" + name + "\"") } // Check field is usable if !isExported(name) { panic("field must be exported") } // Set the runtime field index sk.fields[i].index = ft.Index[0] // Allocate new instance of field v := reflect.New(ft.Type) v = v.Elem() // Fetch mangler for field type. sk.fields[i].mangle = mangler.Get(ft.Type) if !lk.AllowZero { // Append the zero value interface zeros = append(zeros, v.Interface()) } } if len(zeros) > 0 { // Generate zero value string sk.zero = sk.genKey(zeros) } // Allocate primary lookup map sk.pkeys = make(map[string]int64) return sk } // isExported checks whether function name is exported. func isExported(fnName string) bool { r, _ := utf8.DecodeRuneInString(fnName) return unicode.IsUpper(r) } // bufpool provides a memory pool of byte // buffers use when encoding key types. var bufPool = sync.Pool{ New: func() any { return &byteutil.Buffer{B: make([]byte, 0, 512)} }, } func getBuf() *byteutil.Buffer { return bufPool.Get().(*byteutil.Buffer) } func putBuf(buf *byteutil.Buffer) { if buf.Cap() > int(^uint16(0)) { return // drop large bufs } bufPool.Put(buf) }