evolution: 5-MOAD scan; evolution-0002 CWE-407 search_hit_cache dedup O(N^2) 433x at N=1000
cal_searching_got_instance_cb() scans entire search_hit_cache GSList with g_slist_find_custom() for each new calendar instance: O(1)+O(2)+...+O(N) = O(N^2). Fix: parallel GHashTable for O(1) membership test. 433x op-count speedup at N=1000. MOADs 0002/0003/0004/0005 CLEAN.
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@ -35,7 +35,7 @@ Rule: clone, scan, delete clone after. Keep disk under 90%.
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- [x] Pidgin/Finch (C, chat client) — pidgin-0001 CWE-407 499.5x, pidgin-0002 CWE-312
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- [x] Pidgin/Finch (C, chat client) — pidgin-0001 CWE-407 499.5x, pidgin-0002 CWE-312
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- [ ] HexChat (C, IRC client)
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- [ ] HexChat (C, IRC client)
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- [ ] Evolution (C, email/calendar)
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- [x] Evolution (C, email/calendar) — evolution-0002 MOAD-0001 CWE-407 search_hit_cache g_slist_find_custom O(N^2) 433x at N=1000; MOADs 0002/0003/0004/0005 CLEAN
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- [x] Thunderbird (C++, email) — see Priority 1 entry above; 8 defects total
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- [x] Thunderbird (C++, email) — see Priority 1 entry above; 8 defects total
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- [x] Calibre (deeper, Python ebook manager) — calibre-0003 MOAD-0001 CWE-407 depth_first flat.index() O(L*F) 38x at F=500; calibre-0004 MOAD-0001 CWE-407 HTMLFile.find_links list dedup O(L^2) 124x at L=1000; MOADs 0002/0003/0004/0005 CLEAN
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- [x] Calibre (deeper, Python ebook manager) — calibre-0003 MOAD-0001 CWE-407 depth_first flat.index() O(L*F) 38x at F=500; calibre-0004 MOAD-0001 CWE-407 HTMLFile.find_links list dedup O(L^2) 124x at L=1000; MOADs 0002/0003/0004/0005 CLEAN
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- [ ] Okular/Evince/Zathura (PDF viewers)
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- [ ] Okular/Evince/Zathura (PDF viewers)
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61
defects/evolution-0002/TICKET.md
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61
defects/evolution-0002/TICKET.md
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# evolution-0002: Calendar Search Hit Cache Dedup O(N^2) in cal_searching_got_instance_cb
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## Target
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GNOME Evolution email/calendar client
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## Severity
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MEDIUM
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## MOAD
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0001 (CWE-407: Inefficient Algorithmic Complexity)
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## Location
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`src/modules/calendar/e-cal-shell-view-private.c` — `cal_searching_got_instance_cb()`
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## Description
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`cal_searching_got_instance_cb()` is the per-instance callback for Evolution's
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calendar "next/previous occurrence" search. It is invoked once per calendar
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event instance as `e_cal_client_generate_instances_for_object()` expands
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recurring events over a search window.
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Inside the callback, each new instance is deduplicated against
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`priv->search_hit_cache` (a GSList of `time_t *`) using `g_slist_find_custom()`.
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As instances accumulate the list grows, so the I-th instance check scans up to
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I-1 entries: O(1) + O(2) + ... + O(N-1) = O(N^2/2) total comparisons.
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A search over multiple subscribed calendars each containing long-running weekly
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recurring events (e.g., a team standup repeated since 2020) easily reaches
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hundreds to thousands of instances per search invocation. Navigation
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("next occurrence") triggers this search repeatedly.
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## Fix
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Add a parallel `GHashTable *search_hit_cache_set` (keyed on `time_t` cast to
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`gpointer`) to `ECalShellViewPrivate`. Membership check in
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`cal_searching_got_instance_cb()` becomes an O(1) `g_hash_table_contains()`.
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Clear and destroy the hash table wherever the GSList is freed.
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## Speedup
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| N instances | Ops defective | Ops fixed | Ratio |
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|-------------|---------------|-----------|-------|
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| 50 | 1225 | 50 | 24.5x |
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| 100 | 4950 | 100 | 49.5x |
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| 200 | 19900 | 200 | 99.5x |
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| 500 | 124750 | 500 | 249.5x |
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| 1000 | 499500 | 1000 | 499.5x |
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## MOAD-0002 (Intertangle)
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See evolution-0001 SCAN-NOTES.md — `mail-send-recv.c` static globals
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(`send_data`, `glob_ongoing_downsyncs`) are shared mutable state with no mutex.
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Architectural finding, not patched here.
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## MOAD-0003
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CLEAN. No ThreadLocal or GPrivate request-scoped identity leakage beyond
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what was identified in evolution-0001 scan.
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## MOAD-0004
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CLEAN. No credential values (passwords, tokens) logged verbatim. Debug
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messages reference password operations by description only.
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## MOAD-0005
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CLEAN. Evolution uses GLib main loop (single UI thread). No concurrent
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cache-get+put race conditions.
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53
defects/evolution-0002/patch/evolution-0002.patch
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53
defects/evolution-0002/patch/evolution-0002.patch
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# UNDF: TBD
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--- a/src/modules/calendar/e-cal-shell-view-private.h
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+++ b/src/modules/calendar/e-cal-shell-view-private.h
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@@ -113,7 +113,8 @@ struct _ECalShellViewPrivate {
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gint search_direction; /* negative value is backward, positive is forward, zero is error; in days */
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GSList *search_hit_cache; /* pointers on time_t for matched events */
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+ GHashTable *search_hit_cache_set; /* time_t values as gpointer keys for O(1) dedup */
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/* Event/Task/Memo transferring */
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gpointer transfer_alert; /* weak pointer to EAlert * */
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--- a/src/modules/calendar/e-cal-shell-view-private.c
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+++ b/src/modules/calendar/e-cal-shell-view-private.c
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@@ -878,10 +878,14 @@ cal_searching_got_instance_cb (ICalComponent *icomp,
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priv = gid->cal_shell_view->priv;
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value = g_new (time_t, 1);
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*value = start;
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- if (!g_slist_find_custom (priv->search_hit_cache, value, cal_time_t_ptr_compare))
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+ if (!priv->search_hit_cache_set)
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+ priv->search_hit_cache_set = g_hash_table_new (g_direct_hash, g_direct_equal);
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+ if (!g_hash_table_contains (priv->search_hit_cache_set, GINT_TO_POINTER ((gint) start))) {
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+ g_hash_table_add (priv->search_hit_cache_set, GINT_TO_POINTER ((gint) start));
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priv->search_hit_cache = g_slist_append (priv->search_hit_cache, value);
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- else
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+ } else {
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g_free (value);
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+ }
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return TRUE;
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}
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@@ -1271,6 +1275,10 @@ e_cal_shell_view_search_start (ECalShellView *cal_shell_view,
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if (priv->search_hit_cache) {
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g_slist_free_full (priv->search_hit_cache, g_free);
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priv->search_hit_cache = NULL;
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}
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+ if (priv->search_hit_cache_set) {
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+ g_hash_table_destroy (priv->search_hit_cache_set);
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+ priv->search_hit_cache_set = NULL;
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+ }
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cal_iterate_searching (cal_shell_view);
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}
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@@ -1300,6 +1308,10 @@ e_cal_shell_view_search_stop (ECalShellView *cal_shell_view)
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if (priv->search_hit_cache) {
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g_slist_free_full (priv->search_hit_cache, g_free);
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priv->search_hit_cache = NULL;
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}
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+ if (priv->search_hit_cache_set) {
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+ g_hash_table_destroy (priv->search_hit_cache_set);
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+ priv->search_hit_cache_set = NULL;
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+ }
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priv->search_direction = 0;
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}
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130
defects/evolution-0002/test/test_evolution_0002.py
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130
defects/evolution-0002/test/test_evolution_0002.py
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"""
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Unit test for evolution-0002: Calendar search_hit_cache dedup O(N^2) fix.
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Simulates cal_searching_got_instance_cb() collecting unique time_t values
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into a dedup'd cache. Measures op-count for defective (GSList linear scan)
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vs fixed (GHashTable O(1)) implementations.
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Asserts speedup > 3x at N=100 and N=1000.
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"""
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import time
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import sys
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PASS = True
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def collect_instances_defective(instances):
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"""
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Defective: linear scan for each new instance.
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Equivalent to g_slist_find_custom on a growing GSList.
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Returns (cache_list, op_count).
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"""
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cache = []
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ops = 0
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for val in instances:
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# Scan entire cache for duplicate — O(k) per insert
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found = False
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for c in cache:
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ops += 1
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if c == val:
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found = True
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break
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if not found:
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cache.append(val)
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return cache, ops
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def collect_instances_fixed(instances):
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"""
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Fixed: O(1) hash set membership check.
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Equivalent to g_hash_table_contains before g_slist_append.
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Returns (cache_list, op_count).
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"""
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cache = []
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cache_set = set()
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ops = 0
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for val in instances:
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ops += 1 # One hash lookup per insert
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if val not in cache_set:
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cache_set.add(val)
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cache.append(val)
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return cache, ops
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def run_test(label, n_instances, expected_speedup):
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global PASS
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# Generate N unique timestamps (weekly recurring event instances)
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# Mix in some duplicates: same event across two calendars = same timestamp
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unique = list(range(n_instances))
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# 20% duplicates simulating overlapping calendar subscriptions
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duplicates = unique[: n_instances // 5]
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instances = unique + duplicates
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# Shuffle deterministically for reproducibility
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# (keep order as-is; order doesn't change big-O result)
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_, ops_defective = collect_instances_defective(instances)
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cache_fixed, ops_fixed = collect_instances_fixed(instances)
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ratio = ops_defective / max(ops_fixed, 1)
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status = "PASS" if ratio >= expected_speedup else "FAIL"
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if status == "FAIL":
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PASS = False
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print(
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f"[{status}] {label}: N={n_instances} | "
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f"defective={ops_defective} ops | fixed={ops_fixed} ops | ratio={ratio:.1f}x "
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f"(expected >= {expected_speedup}x)"
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)
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# Verify correctness: both produce same unique set
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cache_defective, _ = collect_instances_defective(instances)
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if sorted(cache_defective) != sorted(cache_fixed):
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print(f" [FAIL] correctness: cache contents differ!")
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PASS = False
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else:
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print(f" correctness: caches match ({len(cache_fixed)} unique timestamps)")
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def run_wall_time_test(label, n_instances):
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"""Wall-clock speedup check for large N."""
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unique = list(range(n_instances))
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duplicates = unique[: n_instances // 5]
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instances = unique + duplicates
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t0 = time.perf_counter()
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collect_instances_defective(instances)
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t1 = time.perf_counter()
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collect_instances_fixed(instances)
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t2 = time.perf_counter()
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defective_ms = (t1 - t0) * 1000
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fixed_ms = (t2 - t1) * 1000
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ratio = defective_ms / max(fixed_ms, 1e-9)
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print(
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f" wall-clock {label}: defective={defective_ms:.2f}ms fixed={fixed_ms:.2f}ms ratio={ratio:.1f}x"
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)
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if __name__ == "__main__":
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print("evolution-0002: Calendar search_hit_cache dedup O(N^2) fix")
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print("=" * 65)
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run_test("N=50 op-count", 50, 3.0)
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run_test("N=100 op-count", 100, 10.0)
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run_test("N=500 op-count", 500, 50.0)
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run_test("N=1000 op-count", 1000, 100.0)
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print()
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run_wall_time_test("N=1000 wall-clock", 1000)
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run_wall_time_test("N=5000 wall-clock", 5000)
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print()
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if PASS:
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print("ALL TESTS PASSED")
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sys.exit(0)
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else:
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print("SOME TESTS FAILED")
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sys.exit(1)
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