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5a2e359213clarify blockfilterindex cache allocation rationale (Sebastian van Staa)d06dabf26bnode: allocate index caches proportional to usage patterns (Sebastian van Staa) Pull request description: The current cache allocation for optional indexes (txindex, txospenderindex, blockfilterindex) uses a sequential total_cache / 8 approach where each index gets 1/8 of the remaining budget after the previous index has been allocated. This means the order in which indexes appear in the code silently determines how much cache each one gets. |Index|Current share of total| |---|---| |txindex|~12%| |txospenderindex|~11%| |blockfilterindex|~10%| This is unintuitive, undocumented, and probably doesn't reflect actual usage patterns. This PR replaces the sequential 1/8 allocation with explicit percentages based on how the indexes are typically used. The current values are an educated guess, and subject to further benchmark and research of typical client usage patterns. |Index|Allocation|Rationale| |---|---|---| |txindex |10% |Serves getrawtransaction RPCs with mostly unique lookups across the entire blockchain: low cache reuse| |txospenderindex|5%|Serves gettxspendingprevout RPCs with very specific outpoint queries: likely the least repetitive access pattern| |blockfilterindex|5%|Serves BIP 157 light clients that repeatedly query the same recent blocks: highest cache benefit| UPDATE: blockfilterindex allocation changed from 15% to 5% in the course of the discussion This is a continuation of the related discussion: https://github.com/bitcoin/bitcoin/pull/24539#discussion_r2809088034 and https://github.com/bitcoin/bitcoin/pull/31483. Further feedback and input is very much appreciated. ACKs for top commit: fjahr: ACK5a2e359213rustaceanrob: ACK5a2e359213achow101: ACK5a2e359213sedited: ACK5a2e359213Tree-SHA512: 69be2b0c274b975da58aef2513c3042be8a4c8acf0a86af86b962d4ebfd8cf90bcb1d9251d53995652b4825d0d1da24aabe92cdada9148c627690f8ad2ad8a29
src/node/
The src/node/ directory contains code that needs to access node state
(state in CChain, CBlockIndex, CCoinsView, CTxMemPool, and similar
classes).
Code in src/node/ is meant to be segregated from code in
src/wallet/ and src/qt/, to ensure wallet and GUI
code changes don't interfere with node operation, to allow wallet and GUI code
to run in separate processes, and to perhaps eventually allow wallet and GUI
code to be maintained in separate source repositories.
As a rule of thumb, code in one of the src/node/,
src/wallet/, or src/qt/ directories should avoid
calling code in the other directories directly, and only invoke it indirectly
through the more limited src/interfaces/ classes.
This directory is at the moment
sparsely populated. Eventually more substantial files like
src/validation.cpp and
src/txmempool.cpp might be moved there.