SDiff returns the members of the set resulting from the difference between the first set and all the successive sets.
(ctx *Context, txn *db.Transaction)
| 276 | |
| 277 | // SDiff returns the members of the set resulting from the difference between the first set and all the successive sets. |
| 278 | func SDiff(ctx *Context, txn *db.Transaction) (OnCommit, error) { |
| 279 | var members [][]byte |
| 280 | var setsIter []*db.SetIter |
| 281 | for i, key := range ctx.Args { |
| 282 | set, err := txn.Set([]byte(key)) |
| 283 | if err != nil { |
| 284 | if err == db.ErrTypeMismatch { |
| 285 | return nil, ErrTypeMismatch |
| 286 | } |
| 287 | return nil, errors.New("ERR " + err.Error()) |
| 288 | } |
| 289 | if !set.Exists() && i != 0 { |
| 290 | continue |
| 291 | } |
| 292 | siter, err := set.Iter() |
| 293 | if err != nil { |
| 294 | return nil, errors.New("ERR " + err.Error()) |
| 295 | } |
| 296 | defer siter.Iter.Close() |
| 297 | setsIter = append(setsIter, siter) |
| 298 | } |
| 299 | iter := setsIter[0] |
| 300 | h := MinHeap(setsIter[1:]) |
| 301 | heap.Init(&h) |
| 302 | for iter.Valid() { |
| 303 | member := iter.Value() |
| 304 | if len(h) == 0 { |
| 305 | members = append(members, member) |
| 306 | if err := iter.Iter.Next(); err != nil { |
| 307 | return nil, errors.New("ERR " + err.Error()) |
| 308 | } |
| 309 | continue |
| 310 | } |
| 311 | |
| 312 | min := h[0].Value() |
| 313 | switch bytes.Compare(member, min) { |
| 314 | case -1: |
| 315 | members = append(members, member) |
| 316 | if err := iter.Iter.Next(); err != nil { |
| 317 | return nil, errors.New("ERR " + err.Error()) |
| 318 | } |
| 319 | case 0: |
| 320 | if err := iter.Iter.Next(); err != nil { |
| 321 | return nil, errors.New("ERR " + err.Error()) |
| 322 | } |
| 323 | fallthrough |
| 324 | case 1: |
| 325 | if err := h[0].Iter.Next(); err != nil { |
| 326 | return nil, errors.New("ERR " + err.Error()) |
| 327 | } |
| 328 | if h[0].Valid() { |
| 329 | heap.Fix(&h, 0) |
| 330 | } else { |
| 331 | heap.Remove(&h, 0) |
| 332 | } |
| 333 | } |
| 334 | } |
| 335 | return BytesArray(ctx.Out, members), nil |