[v23.3.x] Fix/inconsistent flushed offset #16501
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add extra logging to flush and truncate methods (cherry picked from commit 1aef8ff)
Method returns the counter which is guaranteed to be incremented after suffix truncation. It's not guaranteed to be incremented exactly once per logical truncation. It can only be used to detect that truncation actually happened. (cherry picked from commit 8d781ab)
Use get_log_truncation_counter method in read_write_truncate test. (cherry picked from commit 6a86a83)
Use get_truncation_counter method in write_truncate_compact method. (cherry picked from commit af0e2c2)
The 'flush_log' method checks the dirty offset before and after flush. If the truncation happened concurrently it detects this by comparing offsets (the offset after flush is smaller than the offset before the flush in this case). Then it uses assertion to check if the flushed offset is not smaller than the committed offset. This may not work as expected in case if there is a concurrent truncation and append. For instance, before the truncation the dirty offset is 32. The 'flush_log' method records flushed offset 32 and calls log->flush. Before 'flush_log' is resumed the log gets truncated and then new value gets added. So the committed offset of the log is now 31 but dirty offset is 32. Because of that the method won't be able to detect the concurrent flush operation will trigger an assertion. This commit fixes this problem by checking not only dirty offset but also a truncation counter. If the counter was incremented then the log was truncated and new data was added to the end of the log. (cherry picked from commit 8a4b612)
Lazin
approved these changes
Feb 6, 2024
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Backport of PR #16105
Fixes: #16500,