This PR changes the chain view update mechanism of the log filter.
Previously the head updates were all wired through the indexer, even in
unindexed mode. This was both a bit weird and also unsafe as the
indexer's chain view was updates asynchronously with some delay, making
some log related tests flaky. Also, the reorg safety of the indexed
search was integrated with unindexed search in a weird way, relying on
`syncRange.ValidBlocks` in the unindexed case too, with a special
condition added to only consider the head of the valid range but not the
tail in the unindexed case.
In this PR the current chain view is directly accessible through the
filter backend and unindexed search is also chain view based, making it
inherently safe. The matcher sync mechanism is now only used for indexed
search as originally intended, removing a few ugly special conditions.
The PR is currently based on top of
https://github.com/ethereum/go-ethereum/pull/31642
Together they fix https://github.com/ethereum/go-ethereum/issues/31518
and replace https://github.com/ethereum/go-ethereum/pull/31542
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Co-authored-by: Gary Rong <garyrong0905@gmail.com>
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