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file_index.go
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file_index.go
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package index
import (
"encoding/json"
"reflect"
bosherr "github.com/cloudfoundry/bosh-utils/errors"
boshsys "github.com/cloudfoundry/bosh-utils/system"
)
type FileIndex struct {
path string
fs boshsys.FileSystem
}
type indexEntry struct {
Key map[string]interface{}
Value json.RawMessage
}
func NewFileIndex(path string, fs boshsys.FileSystem) FileIndex {
return FileIndex{path: path, fs: fs}
}
func (ri FileIndex) Find(key interface{}, value interface{}) error {
rawEntries, err := ri.readRawEntries()
if err != nil {
return err
}
rawKey, err := ri.structToMap(key)
if err != nil {
return err
}
for _, rawEntry := range rawEntries {
if reflect.DeepEqual(rawEntry.Key, rawKey) {
err := json.Unmarshal(rawEntry.Value, value)
if err != nil {
return err
}
return nil
}
}
return ErrNotFound
}
func (ri FileIndex) Save(key interface{}, value interface{}) error {
rawEntries, err := ri.readRawEntries()
if err != nil {
return err
}
rawKey, err := ri.structToMap(key)
if err != nil {
return err
}
rawValue, err := json.Marshal(value)
if err != nil {
return err
}
foundI := -1
for i, rawEntry := range rawEntries {
if reflect.DeepEqual(rawEntry.Key, rawKey) {
foundI = i
break
}
}
if foundI >= 0 {
rawEntries[foundI].Value = rawValue
} else {
rawEntries = append(rawEntries, indexEntry{
Key: rawKey,
Value: rawValue,
})
}
err = ri.writeRawEntries(rawEntries)
if err != nil {
return err
}
return nil
}
func (ri FileIndex) readRawEntries() ([]indexEntry, error) {
var entries []indexEntry
if ri.fs.FileExists(ri.path) {
bytes, err := ri.fs.ReadFile(ri.path)
if err != nil {
return entries, bosherr.WrapErrorf(err, "Reading index file %s", ri.path)
}
err = json.Unmarshal(bytes, &entries)
if err != nil {
return entries, bosherr.WrapError(err, "Unmarshalling index entries")
}
}
return entries, nil
}
func (ri FileIndex) writeRawEntries(entries []indexEntry) error {
bytes, err := json.Marshal(entries)
if err != nil {
return bosherr.WrapError(err, "Marshalling index entries")
}
err = ri.fs.WriteFile(ri.path, bytes)
if err != nil {
return bosherr.WrapErrorf(err, "Writing index file %s", ri.path)
}
return nil
}
func (ri FileIndex) structToMap(s interface{}) (map[string]interface{}, error) {
res := map[string]interface{}{}
st := reflect.TypeOf(s)
stv := reflect.ValueOf(s)
if stv.Kind() != reflect.Struct {
return res, bosherr.Errorf(
"Must be reflect.Struct: %#v (%#v)", stv, ri.kindToStr(stv.Kind()))
}
for i := 0; i < st.NumField(); i++ {
res[st.Field(i).Name] = stv.Field(i).Interface()
}
return res, nil
}
func (ri FileIndex) mapToStruct(m map[string]interface{}, t interface{}) (reflect.Value, error) {
return ri.mapToNewStruct(m, reflect.ValueOf(t).Elem().Type())
}
func (ri FileIndex) mapToStructFromSlice(m map[string]interface{}, t interface{}) (reflect.Value, error) {
slice := reflect.ValueOf(t).Elem()
if slice.Kind() != reflect.Slice {
return reflect.Value{}, bosherr.Errorf(
"Must be reflect.Slice: %#v (%#v)",
slice, ri.kindToStr(slice.Kind()),
)
}
return ri.mapToNewStruct(m, slice.Type().Elem())
}
func (ri FileIndex) mapToNewStruct(m map[string]interface{}, t reflect.Type) (reflect.Value, error) {
if t.Kind() != reflect.Struct {
return reflect.Value{}, bosherr.Errorf(
"Must be reflect.Struct: %#v (%#v)",
t, ri.kindToStr(t.Kind()),
)
}
newStruct := reflect.New(t).Elem()
for k, v := range m {
f := newStruct.FieldByName(k)
if f.IsValid() && f.CanSet() {
// todo float64 -> int
// todo pointer values
// todo slices
f.Set(reflect.ValueOf(v))
}
}
return newStruct, nil
}
var kindToStrMap = map[reflect.Kind]string{
reflect.Invalid: "Invalid",
reflect.Bool: "Bool",
reflect.Int: "Int",
reflect.Int8: "Int8",
reflect.Int16: "Int16",
reflect.Int32: "Int32",
reflect.Int64: "Int64",
reflect.Uint: "Uint",
reflect.Uint8: "Uint8",
reflect.Uint16: "Uint16",
reflect.Uint32: "Uint32",
reflect.Uint64: "Uint64",
reflect.Uintptr: "Uintptr",
reflect.Float32: "Float32",
reflect.Float64: "Float64",
reflect.Complex64: "Complex64",
reflect.Complex128: "Complex128",
reflect.Array: "Array",
reflect.Chan: "Chan",
reflect.Func: "Func",
reflect.Interface: "Interface",
reflect.Map: "Map",
reflect.Ptr: "Ptr",
reflect.Slice: "Slice",
reflect.String: "String",
reflect.Struct: "Struct",
reflect.UnsafePointer: "UnsafePointer",
}
func (ri FileIndex) kindToStr(k reflect.Kind) string {
return kindToStrMap[k]
}