{ "number": 36356, "input_hash": "4218becfb5698fca", "model": "ledger", "prompt_hash": null, "created": "2026-10-30T01:12:40+00:00", "result": { "summary": "Moves the `getblocktemplate` block template cache from function-local static variables in the RPC handler into `BlockTemplateManager`. The cache's lifetime is bound to the node context rather than the process, raw `CBlockIndex*` pointers are replaced with hash lookups, synchronization under `cs_main` is formally annotated, and unit tests are added for template invalidation.", "problem": "Template caching in `getblocktemplate` previously used process-scoped static variables. This allowed cached `CBlockIndex*` pointers to outlive their owning `ChainstateManager` during unit tests, bypassed compile-time thread-safety checking for `cs_main`, and prevented unit testing of the caching and refresh logic.", "card": "Moves the getblocktemplate RPC cache from function-local statics into BlockTemplateManager. This eliminates process-wide global state where dangling CBlockIndex pointers could outlive ChainstateManager in tests, adds Clang thread-safety annotations under cs_main, and adds unit test coverage for template caching and invalidation rules. The refactor advances the BlockTemplateManager tracking issue #33758.", "evidence": [ "Addresses the 'Remove remaining global states' TODO in tracking issue #33758.", "PR description points out that 'cached CBlockIndex* can outlive its ChainstateManager (as in unit tests)' and 'can't be unit tested.'" ], "scope_notes": "The change is primarily a code movement from `rpc/mining.cpp` to `node/block_template_manager.cpp`, accompanied by unit tests in `test/miner_tests.cpp`.", "changed_since_previous": "No structural changes to the commits or implementation; references to follow-up PR #36357 were removed.", "thread": { "last_event_at": "2026-10-28T23:10:09Z", "events": 11, "head_sha": "ed3dd1469f9a0cb43cb1dea92e32a780bceed63f", "schema_floor": 2, "schema": 2 }, "waiting_on": [ { "at": "2026-10-28", "id": "c:6482952144", "on": "reviewer", "url": "https://github.com/bitcoin/bitcoin/pull/36356#issuecomment-6482952144", "what": "ismaelsadeeq and Sjors to review the author's replies and 3-commit split" } ], "risk": { "level": "medium", "touches": [ "rpc_api", "other" ], "why": "A flaw in the template cache invalidation logic could serve stale templates after a tip change, leading miners to mine on an outdated tip." }, "discussion": { "author_status": "last statement processed 2026-10-28", "open_concerns": [], "resolved_concerns": [ "ismaelsadeeq: Implement a broader cache shared with IPC createnewblock, waitnext, and the mempool fee estimator as attempted in #33421 (accepted by ismaelsadeeq 2026-10-09)", "ismaelsadeeq: Should the cache be cleared on a block connection instead of keeping it until shutdown? (answered by w0xlt 2026-10-28)", "ismaelsadeeq: Pass max_age as a parameter so that the caching logic is not tied to getblocktemplate (answered by w0xlt 2026-10-28)" ] }, "reviewability": { "state": "Ready", "label": "Ready", "reason": "Nothing known that would invalidate a review now." }, "agreement": { "state": "Strong", "summary": "Strong: substantive support, no open objection (ismaelsadeeq, Sjors)", "reason": "Author replied to both of ismaelsadeeq's inline questions/suggestions and restructured the commits into a 3-commit split in response to Sjors's feedback.", "evidence": [ "ismaelsadeeq: Concept ACK \u2014 moving template caching into BlockTemplateManager creates an opportunity to share template caching across RPC, IPC mining, and fee estimation", "Sjors: support \u2014 prefers to keep this simple and focussed" ], "objections": [ { "reviewer": "ismaelsadeeq", "association": "MEMBER", "type": "suggestion", "kind": "scope", "harm": "", "request": "Implement a broader cache shared with IPC createnewblock, waitnext, and the mempool fee estimator as attempted in #33421", "question": "", "text": "Implement a broader cache shared with IPC createnewblock, waitnext, and the mempool fee estimator as attempted in #33421", "clears_with": "answer", "blocking": false, "status": "accepted", "status_note": "accepted deferring to follow-ups", "cleared": true, "author_replied": true, "others_replied": false, "fix_pushed": false, "replies": [ "c:6065621630" ], "evidence": "2026-10-08: 'I think we can implement the broader cache as attempted here #33421, mempool estimator dependency on `ChainStateManager` will be gone, and the ipc `createnewblock`, `waitnext` and `getblocktemplate` R'", "url": "https://github.com/bitcoin/bitcoin/pull/36356#issuecomment-6058035761", "id": "c:6058035761", "at": "2026-10-08", "status_at": "2026-10-09", "status_by": "ismaelsadeeq", "resolution_evidence": "2026-10-09: ismaelsadeeq: 'However, I agree this is a start; we can extend it later.'", "pin": null, "from_schema": 2 }, { "reviewer": "ismaelsadeeq", "association": "MEMBER", "type": "question", "kind": "approach", "harm": "", "request": "", "question": "Should the cache be cleared on a block connection instead of keeping it until shutdown?", "text": "Should the cache be cleared on a block connection instead of keeping it until shutdown?", "clears_with": "answer", "blocking": false, "status": "answered", "status_note": "author explained master already keeps it until shutdown and clearing on connect requires a notification hook better left for a follow-up", "cleared": true, "author_replied": true, "others_replied": false, "fix_pushed": false, "replies": [ "rc:4406943630" ], "evidence": "2026-10-09: 'The cache is kept forever till shutdown. Should we clear it on a block connection?'", "url": "https://github.com/bitcoin/bitcoin/pull/36356#discussion_r4226656184", "id": "rc:4226656184", "at": "2026-10-09", "status_at": "2026-10-28", "status_by": "w0xlt", "resolution_evidence": "2026-10-28: w0xlt: 'Clearing it on block connection would need a new notification hook in the manager, so I'd leave that for a follow-up.'", "pin": null, "from_schema": 2 }, { "reviewer": "ismaelsadeeq", "association": "MEMBER", "type": "suggestion", "kind": "interface", "harm": "", "request": "Pass max_age as a parameter so that the caching logic is not tied to getblocktemplate", "question": "", "text": "Pass max_age as a parameter so that the caching logic is not tied to getblocktemplate", "clears_with": "answer", "blocking": false, "status": "answered", "status_note": "author explained max_age fits better in a follow-up that makes the cache generic, and named the constant GBT_TEMPLATE_REBUILD_INTERVAL", "cleared": true, "author_replied": true, "others_replied": false, "fix_pushed": false, "replies": [ "rc:4406966061" ], "evidence": "2026-10-09: 'Should we pass the `max_age` so that it is not tied to GBT?'", "url": "https://github.com/bitcoin/bitcoin/pull/36356#discussion_r4226664736", "id": "rc:4226664736", "at": "2026-10-09", "status_at": "2026-10-28", "status_by": "w0xlt", "resolution_evidence": "2026-10-28: w0xlt: 'I'd keep `max_age` out of this PR. The cache is still a single entry built with the default options, so another caller with a different `max_age` would just keep rebuilding the GBT template.'", "pin": null, "from_schema": 2 } ], "support": [ { "reviewer": "ismaelsadeeq", "reason": "moving template caching into BlockTemplateManager creates an opportunity to share template caching across RPC, IPC mining, and fee estimation", "substantive": true, "verdict": "Concept ACK", "id": "c:6058035761", "url": "https://github.com/bitcoin/bitcoin/pull/36356#issuecomment-6058035761", "at": "2026-10-08", "association": "MEMBER", "evidence": "read", "areas": [] }, { "reviewer": "Sjors", "reason": "prefers to keep this simple and focussed", "substantive": true, "verdict": "", "id": "c:6465912025", "url": "https://github.com/bitcoin/bitcoin/pull/36356#issuecomment-6465912025", "at": "2026-10-28", "association": "MEMBER", "evidence": "read", "areas": [] } ], "participants": [ { "login": "Sjors", "stance": "support", "note": "supports keeping the scope simple and focused; suggested a 3-commit split", "association": "MEMBER", "comments": 2, "first": "2026-10-07", "last": "2026-10-28" }, { "login": "ismaelsadeeq", "stance": "support", "note": "Concept ACK; accepted deferring broader caching, asked about clearing cache on block connection and passing max_age", "association": "MEMBER", "comments": 4, "first": "2026-10-08", "last": "2026-10-09" } ], "derivation": "substantive support, no open objection (ismaelsadeeq, Sjors)", "model_state": null, "corrections": [], "notes": "Author replied to both of ismaelsadeeq's inline questions/suggestions and restructured the commits into a 3-commit split in response to Sjors's feedback." }, "dependencies": { "depends_on": [], "enables": [] }, "categories": [ { "name": "mining", "member": true, "evidence": "Carries the Mining label, touches `BlockTemplateManager` and `rpc/mining.cpp`, and refactors the `getblocktemplate` caching logic.", "band": "P3", "reason_tag": "cleanup", "score": 0.35, "factors": { "bug_severity": 1, "leverage": 1, "performance": 0, "security_stability": 1, "user_value": 0 }, "rationale": "Cleans up node lifetime and global state by moving static template caching into `BlockTemplateManager`. As noted in the description, this prevents 'cached CBlockIndex* can outlive its ChainstateManager (as in unit tests)', enables compile-time thread safety checks, and adds unit testing coverage for template invalidation." }, { "name": "rpc", "member": false, "evidence": "Does not change RPC interfaces, argument handling, or output; only extracts internal mining template caching logic out of `rpc/mining.cpp`.", "band": "Unranked", "reason_tag": "cleanup", "score": 0.0, "factors": { "bug_severity": 1, "leverage": 1, "performance": 0, "security_stability": 1, "user_value": 0 }, "rationale": "Category covers node programmatic interfaces and RPC machinery, whereas changes to the underlying subsystem behavior exposed by an RPC belong to that subsystem." } ], "confidence": "high", "uncertainties": [], "needs": [] }, "cost_usd": 0.0, "source": { "record": "2026-10-30T01:12:40+00:00", "code": "2026-10-30T01:17:10+00:00", "judgments": 2 } }