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chrbala / lmdb-leveldown

leveldown compatible binding to LMDB

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Iterator does not work correctly when the supplied range is not a key

chrbala opened this issue · comments

commented

The iterator currently starts with a key when getting the initial value to iterate through. This does not work if the range is defined by values that are not keys.

lmdb-leveldown/src/index.js

Lines 144 to 168 in 5d34800

const getInitialCurrentValue = (
{ gt, gte, lt, lte, reverse }: IteratorOptionsType,
cursor: *
) => {
const invalid = (a: string, b: string) =>
`${a} can not be provided with ${b}`;
if (gt) {
if (gte) throw new Error(invalid('gt', 'gte'));
if (reverse) return cursor.goToLast();
cursor.goToKey(gt);
return cursor.goToNext();
} else if (gte) return cursor.goToKey(gte);
else if (lt) {
if (lte) throw new Error(invalid('lt', 'lte'));
if (reverse) {
cursor.goToKey(lt);
return cursor.goToPrev();
}
return cursor.goToFirst();
} else if (lte) return reverse ? cursor.goToKey(lte) : cursor.goToFirst();
return reverse ? cursor.goToLast() : cursor.goToFirst();
};

Example test output:

# test iterator with gte=49.5 (midway)
ok 200 undefined
not ok 201 correct number of entries
  ---
    operator: equal
    expected: 50
    actual:   0
  ...
not ok 202 should be equivalent
  ---
    operator: deepEqual
    expected: |-
      [ { key: '50', value: '0.9926293454942214' }, { key: '51', value: '0.36530754007971344' }, { key: '52', value: '0.07948485238433345' }, { key: '53', value: '0.4460314320292509' }, { key: '54', value: '0.6563670401821771' }, { key: '55', value: '0.7778772324231' }, { key: '56', value: '0.6401857734726797' }, { key: '57', value: '0.8552353376818715' }, { key: '58', value: '0.5319237025637298' }, { key: '59', value: '0.5568737819443985' }, { key: '60', value: '0.9624005486051628' }, { key: '61', value: '0.42510185325347893' }, { key: '62', value: '0.11216823705999612' }, { key: '63', value: '0.12620420026129908' }, { key: '64', value: '0.49373167690324027' }, { key: '65', value: '0.030064742250546006' }, { key: '66', value: '0.9132791307734551' }, { key: '67', value: '0.3480505763258064' }, { key: '68', value: '0.10233997012150153' }, { key: '69', value: '0.5664507517525017' }, { key: '70', value: '0.8025281173721805' }, { key: '71', value: '0.5920517761246549' }, { key: '72', value: '0.7022464461638869' }, { key: '73', value: '0.10957992173264319' }, { key: '74', value: '0.7761877436457496' }, { key: '75', value: '0.5781361569669583' }, { key: '76', value: '0.3111166336007185' }, { key: '77', value: '0.4878780537177789' }, { key: '78', value: '0.12655914496335186' }, { key: '79', value: '0.38618150055929523' }, { key: '80', value: '0.31609012678322257' }, { key: '81', value: '0.6589613745332377' }, { key: '82', value: '0.6048494277682703' }, { key: '83', value: '0.2066701342922257' }, { key: '84', value: '0.0018538658409072983' }, { key: '85', value: '0.8492683128917726' }, { key: '86', value: '0.0848514102379645' }, { key: '87', value: '0.9711296854693521' }, { key: '88', value: '0.49853902528205385' }, { key: '89', value: '0.9740776483919469' }, { key: '90', value: '0.6530275273713964' }, { key: '91', value: '0.25511761710292546' }, { key: '92', value: '0.28199455595791534' }, { key: '93', value: '0.57805842900936' }, { key: '94', value: '0.20249379034314852' }, { key: '95', value: '0.3205214395313847' }, { key: '96', value: '0.15968226699990007' }, { key: '97', value: '0.6626543905212701' }, { key: '98', value: '0.08386572138126924' }, { key: '99', value: '0.8048711309013743' } ]
    actual: |-
      []
    stack: |-
      Error: should be equivalent
          at Test.assert [as _assert] (/Users/chris/lmdb-leveldown/node_modules/tape/lib/test.js:212:54)
          at Test.bound [as _assert] (/Users/chris/lmdb-leveldown/node_modules/tape/lib/test.js:64:32)
          at Test.deepEqual.Test.deepEquals.Test.isEquivalent.Test.same (/Users/chris/lmdb-leveldown/node_modules/tape/lib/test.js:380:10)
          at Test.bound [as same] (/Users/chris/lmdb-leveldown/node_modules/tape/lib/test.js:64:32)
          at /Users/chris/lmdb-leveldown/node_modules/abstract-leveldown/abstract/iterator-range-test.js:29:11
          at /Users/chris/lmdb-leveldown/node_modules/abstract-leveldown/testCommon.js:56:11
          at /Users/chris/lmdb-leveldown/src/index.js:281:48
  ...
commented

Resolved by creating bogus key/value pairs, starting the cursor at the target, then aborting the transaction when done.