[v24.3.x] [CORE-7257] cloud_storage: Remove assertion in remote_segment
#24292
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Signed-off-by: Evgeny Lazin <[email protected]> (cherry picked from commit b3ce4e1)
Previously, the remote_segment was assuming that there is no concurrency and we are creating only one instance of it per segment. The 'remote_segment' depends on cloud storage cache which acts as a shared global state for all 'remote_segment' instances. If two segments are created in parallel there is a slight chance that they could interact through this global state. If one segment starts download the cache will be in the 'in-progress' state for this key. Then another segment may try to trigger download and see the 'in-progress' state and trigger assertion. Normally, we're not creating two instancess of the same segment in TS. But there is a slight chance that under very high contention when the materialized segments are churning rapidly we will evict the segment and immediately recreate it. If both of them are in the right state they may trigger the assertion. The segments are evicted by the 'remote_partition' which moves them to the eviction queue. So basically, the segment may exist in the eviction queue for very short time. But under hight contention it could be enough. This commit fixes this issue by turning the assertion into the exception. The exception is propagated to the 'data_stream' call and then to the client. Signed-off-by: Evgeny Lazin <[email protected]> (cherry picked from commit c2039dd)
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Backport of PR #24265