fix(rdb_load): EnsureRead(min) requesting more bytes than min #2604
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@dranikpg I was wrong, there is no other bug other than the one I fix here (the flake I was looking at was my bug once I was trying to reproduce this one). I rerun the test 800 times without any failures. We should be good. |
dranikpg
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Feb 19, 2024
src/server/rdb_load.cc
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| error_code RdbLoaderBase::EnsureReadInternal(size_t min_sz) { | ||
| DCHECK_LT(mem_buf_->InputLen(), min_sz); | ||
| DCHECK_LT(mem_buf_->InputLen(), min_sz + mem_buf_->InputLen()); |
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this is awalys true for unsigned integers 🙂
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it's just that the meaning of the variable changed now, it's not min_sz (as min required size), but min_to_read (as to minimally should be read), so the fix could have also been applied here
dranikpg
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Feb 19, 2024
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…flydb#2604) * fixes EnsureRead(min) to request exactly min bytes
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This is the bug we saw in a few regression tests (redis replication, rotating master).
The issue is that
EnsureRead(num)did not include the bytes already read in theInputBufferand in some rare cases ended up blocking forever. An example of that is the last 8 empty bytes after aSendFullSyncCut(). Replica node would receiveRDB_OPCODE_FULLSYNC_ENDand theInputBufferwould already contain n out of 8 empty bytes. If let's say n=4,EnsureRead(8)would request 8 bytes when in fact we needed 4 more leading to a deadlock (because full sync would not proceed).