Fix rehashingStarted miscalculating bucket_count in dict initialization#12846
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oranagra merged 9 commits intoredis:unstablefrom Dec 10, 2023
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Fix rehashingStarted miscalculating bucket_count in dict initialization#12846oranagra merged 9 commits intoredis:unstablefrom
oranagra merged 9 commits intoredis:unstablefrom
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…tion In the old dictRehashingInfo implementation, for the initialization scenario, it mistakenly directly set to_size to DICTHT_SIZE(DICT_HT_INITIAL_EXP), which is 4 in our code by default. In scenarios where dictExpand directly passes the target size as initialization, the code will calculate bucket_count incorrectly. For example, in DEBUG POPULATE or RDB load scenarios, it will cause the final bucket_count to be initialized to 65536 (16384 * 4), see: ``` before: DB 0: 10000000 keys (0 volatile) in 65536 slots HT. it should be: DB 0: 10000000 keys (0 volatile) in 16777216 slots HT. ``` In PR, new ht will also be initialized before calling rehashingStarted in _dictExpand, so that the calls in dictRehashingInfo can be unified. This PR also cleans up dictRehashingStarted* and dictRehashingCompleted*, eliminating some duplicate code. Bug was introduced in redis#12697.
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Dec 8, 2023
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The last two commits dropped these two parts: This PR also cleans up dictRehashingStarted* and dictRehashingCompleted*, This PR also optimizes the situation in _dictExpand when old ht is empty. |
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LGTM.
please remove the obsolete parts from the top comment.
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In the old dictRehashingInfo implementation, for the initialization scenario,
it mistakenly directly set to_size to DICTHT_SIZE(DICT_HT_INITIAL_EXP), which
is 4 in our code by default.
In scenarios where dictExpand directly passes the target size as initialization,
the code will calculate bucket_count incorrectly. For example, in DEBUG POPULATE
or RDB load scenarios, it will cause the final bucket_count to be initialized to
65536 (16384 * 4), see:
In PR, new ht will also be initialized before calling rehashingStarted in
_dictExpand, so that the calls in dictRehashingInfo can be unified.
Bug was introduced in #12697.