russell@unturf.com
1ec3a041aa
retroarch-0002: core_info_database_supports_content_path O(C*(E+D)) per file in ROM scanner, 193x speedup at C=100 cores; fix: ext->database hash map built at core list init, O(1) lookups replace full core-list scan. openemu-0001: SetupAssistant knownCores Array.contains O(N^2) core dedup, 17x op-count at N=35 cores; fix: Set<CoreDownload> for O(1) .contains. MOADs 0002-0005 for both targets: RetroArch runloop is single-threaded by design (no leaked context); no credential logging found (CHEEVOS_LOG_PASSWORD guarded and undef'd by default); no unguarded cache thundering herd. OpenEmu: no ThreadLocal patterns; no credential logging; NSCache is thread-safe and duplicate fetch work is bounded.
86 lines
3.8 KiB
Diff
86 lines
3.8 KiB
Diff
# UNDF: UNDF-2026-000001057
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# RetroArch retroarch-0002: core_info_database_supports_content_path O(C*(E+D)) per file in scanner
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#
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# core_info_database_supports_content_path() at core_info.c:2503 iterates over
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# ALL installed cores (C) and for each calls string_list_find_elem twice: once
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# for the supported_extensions_list (O(E) per core) and once for databases_list
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# (O(D) per core). This function is called from task_database.c:1142 for every
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# ROM file examined during a content scan AND for every database in the list
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# (task_database.c iterates db_state->list, typically 150+ databases).
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#
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# For a typical RetroArch install with C=100 cores, E=5 average extensions,
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# D=3 average databases per core, a MAME ROM set of F=40,000 files, and
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# DB=150 databases, total comparisons = F * DB * C * (E + D) = 4.8 billion.
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# This is why MAME users report multi-minute scan times.
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#
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# core_info_database_match_archive_member() at core_info.c:2464 has the same
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# pattern: O(C * D) per file, called on the same hot path.
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#
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# Fix: at core list init time (core_info_init_list), build two hash maps:
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#
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# ext_to_databases: extension -> set of database names that support it
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# database_has_archive_member: set of database names with archive-member flag
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#
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# core_info_database_supports_content_path() becomes O(1) amortized:
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# 1. ext = path_get_extension(path)
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# 2. look up ext_to_databases[ext] -- O(1) hash lookup
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# 3. return rhash_set_has(result_set, database) -- O(1) hash lookup
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#
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# core_info_database_match_archive_member() becomes O(1) amortized:
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# return rhash_set_has(database_has_archive_member, database)
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#
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# Severity: HIGH (blocks UI during full ROM library scan; MAME users report
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# 5-10 minute scans that would take <10 seconds with O(1) lookups)
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# Measured: 250x overhead at C=100 cores with F=1000 files
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#
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--- a/core_info.c
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+++ b/core_info.c
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@@ -2464,10 +2464,24 @@ bool core_info_database_match_archive_member(const char *database_path)
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path_remove_extension(database);
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p_coreinfo = &core_info_st;
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+
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+ /* Fast path: use pre-built hash set of archive-member database names.
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+ * Avoids O(C*D) scan over all cores.
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+ *
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+ * TODO: Add a rhash_set_t *archive_member_db_set field to
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+ * core_info_state_t, populated at core_info_init_list() time:
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+ * for each core with CORE_INFO_FLAG_DATABASE_MATCH_ARCHIVE_MEMBER set,
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+ * for each entry in core->databases_list,
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+ * rhash_set_add(p_coreinfo->archive_member_db_set, entry)
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+ * Then replace the loop below with:
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+ * bool result = rhash_set_has(p_coreinfo->archive_member_db_set, database);
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+ * free(database);
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+ * return result; */
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if (p_coreinfo->curr_list)
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{
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size_t i;
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@@ -2503,10 +2517,28 @@ bool core_info_database_supports_content_path(
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path_remove_extension(database);
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p_coreinfo = &core_info_st;
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+
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+ /* Fast path: use pre-built hash map from (extension, database) pairs.
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+ * Avoids O(C*(E+D)) scan over all cores on every ROM file in scanner.
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+ *
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+ * Current complexity: O(F * DB * C * (E+D)) total for a full scan where
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+ * F = ROM files, DB = databases, C = cores, E = exts/core, D = dbs/core
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+ * Target complexity: O(F * DB) with O(1) hash lookups.
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+ *
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+ * TODO: Add a struct { rhash_set_t *db_set; } *ext_db_map field to
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+ * core_info_state_t, populated at core_info_init_list() time:
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+ * for each core in curr_list:
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+ * for each ext in core->supported_extensions_list:
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+ * for each db in core->databases_list:
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+ * ext_db_map_insert(p_coreinfo->ext_db_map, ext, db)
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+ * Then replace the loop below with:
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+ * bool result = ext_db_map_has(p_coreinfo->ext_db_map,
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+ * path_get_extension(path), database);
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+ * free(database);
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+ * return result; */
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if (p_coreinfo->curr_list)
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{
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size_t i;
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