fix: don't panic if a bloom counter underflows #3614
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jcnelson
requested review from
kantai,
sergey-shandar,
obycode,
jio-gl and
jferrant
jcnelson
commented
Mar 14, 2023
| @@ -365,15 +365,15 @@ impl<H: BloomHash + Clone + StacksMessageCodec> BloomCounter<H> { | |||
| let sql = format!("CREATE TABLE IF NOT EXISTS {}(counts BLOB NOT NULL, num_bins INTEGER NOT NULL, num_hashes INTEGER NOT NULL, hasher BLOB NOT NULL);", table_name); | |||
| tx.execute(&sql, NO_PARAMS).map_err(db_error::SqliteError)?; | |||
|
|
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| let (num_bits, num_hashes) = bloom_hash_count(error_rate, max_items); | |||
| let counts_vec = vec![0u8; (num_bits * 4) as usize]; | |||
| let (num_bins, num_hashes) = bloom_hash_count(error_rate, max_items); | |||
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Note to the reviewer: this is just fixing a typo.
Codecov Report
@@ Coverage Diff @@
## master #3614 +/- ##
==========================================
- Coverage 30.33% 24.77% -5.57%
==========================================
Files 298 298
Lines 275069 275068 -1
==========================================
- Hits 83435 68136 -15299
- Misses 191634 206932 +15298
... and 126 files with indirect coverage changes 📣 We’re building smart automated test selection to slash your CI/CD build times. Learn more |
kantai
approved these changes
Mar 14, 2023
jio-gl
approved these changes
Mar 14, 2023
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This fixes #3599.
The Stacks node uses a persistent bloom counter to sketch the recent contents of its mempool in a space-efficient way, which it uses to derive a bloom filter in order to query other nodes' mempools for transactions it does not have. The bloom counter's
remove_raw()method had been panicking in #3599 because it seemed that an item was simultaneously reported as present in the bloom counter and then turned out to be absent.While this seems like a logic error (hence the original implementation's
panic!()in this condition), it turns out this can happen naturally because an item can hash to the same bin multiple times. If the bin has value B and the item hashes to the same bin C times, where B < C, then this panic condition arises.The solution is to simply remove the panic.