| 398 | |
| 399 | template <class Iter> |
| 400 | static void resolveKeySelectorFromCache(KeySelector& key, |
| 401 | Iter& it, |
| 402 | KeyRef const& maxKey, |
| 403 | bool* readToBegin, |
| 404 | bool* readThroughEnd, |
| 405 | int* actualOffset) { |
| 406 | // If the key indicated by `key` can be determined without reading unknown data from the snapshot, then |
| 407 | // it.kv().key is the resolved key. If the indicated key is determined to be "off the beginning or end" of the |
| 408 | // database, it points to the first or last segment in the DB, |
| 409 | // and key is an equivalent key selector relative to the beginning or end of the database. |
| 410 | // Otherwise it points to an unknown segment, and key is an equivalent key selector whose base key is in or |
| 411 | // adjoining the segment. |
| 412 | |
| 413 | key.removeOrEqual(key.arena()); |
| 414 | |
| 415 | bool alreadyExhausted = key.offset == 1; |
| 416 | |
| 417 | it.skip(key.getKey()); // TODO: or precondition? |
| 418 | |
| 419 | if (key.offset <= 0 && it.beginKey() == key.getKey() && key.getKey() != allKeys.begin) |
| 420 | --it; |
| 421 | |
| 422 | ExtStringRef keykey = key.getKey(); |
| 423 | bool keyNeedsCopy = false; |
| 424 | |
| 425 | // Invariant: it.beginKey() <= keykey && keykey <= it.endKey() && (key.isBackward() ? it.beginKey() != keykey : |
| 426 | // it.endKey() != keykey) Maintaining this invariant, we transform the key selector toward firstGreaterOrEqual |
| 427 | // form until we reach an unknown range or the result |
| 428 | while (key.offset > 1 && !it.is_unreadable() && !it.is_unknown_range() && it.endKey() < maxKey) { |
| 429 | if (it.is_kv()) |
| 430 | --key.offset; |
| 431 | ++it; |
| 432 | keykey = it.beginKey(); |
| 433 | keyNeedsCopy = true; |
| 434 | } |
| 435 | while (key.offset < 1 && !it.is_unreadable() && !it.is_unknown_range() && it.beginKey() != allKeys.begin) { |
| 436 | if (it.is_kv()) { |
| 437 | ++key.offset; |
| 438 | if (key.offset == 1) { |
| 439 | keykey = it.beginKey(); |
| 440 | keyNeedsCopy = true; |
| 441 | break; |
| 442 | } |
| 443 | } |
| 444 | --it; |
| 445 | keykey = it.endKey(); |
| 446 | keyNeedsCopy = true; |
| 447 | } |
| 448 | |
| 449 | if (!alreadyExhausted) { |
| 450 | *actualOffset = key.offset; |
| 451 | } |
| 452 | |
| 453 | if (!it.is_unreadable() && !it.is_unknown_range() && key.offset < 1) { |
| 454 | *readToBegin = true; |
| 455 | key.setKey(allKeys.begin); |
| 456 | key.offset = 1; |
| 457 | return; |
no test coverage detected