|
| 1 | +""" |
| 2 | +Test concurrent stroke submissions to verify atomic counter prevents race conditions. |
| 3 | +
|
| 4 | +This test simulates multiple users submitting strokes simultaneously to ensure: |
| 5 | +1. No duplicate stroke IDs are generated |
| 6 | +2. Counter increments correctly under concurrent load |
| 7 | +3. Race conditions are eliminated by atomic redis.incr() |
| 8 | +4. System can handle 10+ concurrent users (vs 2-3 before optimization) |
| 9 | +""" |
| 10 | + |
| 11 | +import pytest |
| 12 | +import sys |
| 13 | +import os |
| 14 | +import threading |
| 15 | +import time |
| 16 | +from concurrent.futures import ThreadPoolExecutor, as_completed |
| 17 | + |
| 18 | +# Add backend to path |
| 19 | +sys.path.insert(0, os.path.abspath(os.path.join(os.path.dirname(__file__), '..'))) |
| 20 | + |
| 21 | +from services.canvas_counter import increment_canvas_draw_count, get_canvas_draw_count |
| 22 | +from services.db import redis_client |
| 23 | + |
| 24 | + |
| 25 | +@pytest.fixture(autouse=True) |
| 26 | +def reset_counter(): |
| 27 | + """Reset counter before each test.""" |
| 28 | + redis_client.set('res-canvas-draw-count', 0) |
| 29 | + yield |
| 30 | + # Cleanup after test |
| 31 | + redis_client.delete('res-canvas-draw-count') |
| 32 | + |
| 33 | + |
| 34 | +def submit_stroke_simulation(user_id, delay=0): |
| 35 | + """ |
| 36 | + Simulate a single user submitting a stroke. |
| 37 | + |
| 38 | + Args: |
| 39 | + user_id: Identifier for the simulated user |
| 40 | + delay: Optional delay before submission (simulates network latency) |
| 41 | + |
| 42 | + Returns: |
| 43 | + tuple: (user_id, stroke_id, draw_count) |
| 44 | + """ |
| 45 | + if delay > 0: |
| 46 | + time.sleep(delay) |
| 47 | + |
| 48 | + # This is the critical path - increment counter and get stroke ID |
| 49 | + draw_count = increment_canvas_draw_count() |
| 50 | + stroke_id = f"res-canvas-draw-{draw_count}" |
| 51 | + |
| 52 | + return (user_id, stroke_id, draw_count) |
| 53 | + |
| 54 | + |
| 55 | +def test_sequential_counter_increments(): |
| 56 | + """Test that sequential submissions work correctly (baseline).""" |
| 57 | + results = [] |
| 58 | + for i in range(10): |
| 59 | + _, stroke_id, count = submit_stroke_simulation(f"user_{i}") |
| 60 | + results.append((stroke_id, count)) |
| 61 | + |
| 62 | + # Verify all IDs are unique and sequential |
| 63 | + stroke_ids = [r[0] for r in results] |
| 64 | + counts = [r[1] for r in results] |
| 65 | + |
| 66 | + assert len(stroke_ids) == len(set(stroke_ids)), "Duplicate stroke IDs in sequential test" |
| 67 | + assert counts == list(range(1, 11)), f"Counts not sequential: {counts}" |
| 68 | + |
| 69 | + # Verify final counter value |
| 70 | + final_count = get_canvas_draw_count() |
| 71 | + assert final_count == 10, f"Final count should be 10, got {final_count}" |
| 72 | + |
| 73 | + |
| 74 | +def test_concurrent_10_users(): |
| 75 | + """Test 10 users submitting strokes simultaneously.""" |
| 76 | + num_users = 10 |
| 77 | + results = [] |
| 78 | + |
| 79 | + with ThreadPoolExecutor(max_workers=num_users) as executor: |
| 80 | + futures = [ |
| 81 | + executor.submit(submit_stroke_simulation, f"user_{i}") |
| 82 | + for i in range(num_users) |
| 83 | + ] |
| 84 | + |
| 85 | + for future in as_completed(futures): |
| 86 | + results.append(future.result()) |
| 87 | + |
| 88 | + # Extract stroke IDs and counts |
| 89 | + stroke_ids = [r[1] for r in results] |
| 90 | + counts = [r[2] for r in results] |
| 91 | + |
| 92 | + # Critical assertions |
| 93 | + assert len(stroke_ids) == num_users, f"Expected {num_users} strokes, got {len(stroke_ids)}" |
| 94 | + assert len(set(stroke_ids)) == num_users, f"RACE CONDITION: Duplicate stroke IDs found! {stroke_ids}" |
| 95 | + assert len(set(counts)) == num_users, f"RACE CONDITION: Duplicate counts found! {counts}" |
| 96 | + assert set(counts) == set(range(1, num_users + 1)), f"Counts not in expected range: {counts}" |
| 97 | + |
| 98 | + # Verify final counter |
| 99 | + final_count = get_canvas_draw_count() |
| 100 | + assert final_count == num_users, f"Final count should be {num_users}, got {final_count}" |
| 101 | + |
| 102 | + |
| 103 | +def test_concurrent_50_users(): |
| 104 | + """Test 50 users submitting strokes simultaneously (target capacity).""" |
| 105 | + num_users = 50 |
| 106 | + results = [] |
| 107 | + |
| 108 | + with ThreadPoolExecutor(max_workers=num_users) as executor: |
| 109 | + futures = [ |
| 110 | + executor.submit(submit_stroke_simulation, f"user_{i}") |
| 111 | + for i in range(num_users) |
| 112 | + ] |
| 113 | + |
| 114 | + for future in as_completed(futures): |
| 115 | + results.append(future.result()) |
| 116 | + |
| 117 | + # Extract stroke IDs and counts |
| 118 | + stroke_ids = [r[1] for r in results] |
| 119 | + counts = [r[2] for r in results] |
| 120 | + |
| 121 | + # Critical assertions |
| 122 | + assert len(stroke_ids) == num_users, f"Expected {num_users} strokes, got {len(stroke_ids)}" |
| 123 | + assert len(set(stroke_ids)) == num_users, f"RACE CONDITION: Duplicate stroke IDs at scale! {len(stroke_ids) - len(set(stroke_ids))} duplicates" |
| 124 | + assert len(set(counts)) == num_users, f"RACE CONDITION: Duplicate counts at scale! {len(counts) - len(set(counts))} duplicates" |
| 125 | + assert set(counts) == set(range(1, num_users + 1)), f"Counts not in expected range 1-{num_users}" |
| 126 | + |
| 127 | + # Verify final counter |
| 128 | + final_count = get_canvas_draw_count() |
| 129 | + assert final_count == num_users, f"Final count should be {num_users}, got {final_count}" |
| 130 | + |
| 131 | + |
| 132 | +def test_concurrent_100_users(): |
| 133 | + """Test 100 users submitting strokes simultaneously (stretch goal).""" |
| 134 | + num_users = 100 |
| 135 | + results = [] |
| 136 | + |
| 137 | + start_time = time.time() |
| 138 | + |
| 139 | + with ThreadPoolExecutor(max_workers=num_users) as executor: |
| 140 | + futures = [ |
| 141 | + executor.submit(submit_stroke_simulation, f"user_{i}") |
| 142 | + for i in range(num_users) |
| 143 | + ] |
| 144 | + |
| 145 | + for future in as_completed(futures): |
| 146 | + results.append(future.result()) |
| 147 | + |
| 148 | + end_time = time.time() |
| 149 | + elapsed = end_time - start_time |
| 150 | + |
| 151 | + # Extract stroke IDs and counts |
| 152 | + stroke_ids = [r[1] for r in results] |
| 153 | + counts = [r[2] for r in results] |
| 154 | + |
| 155 | + # Critical assertions |
| 156 | + assert len(stroke_ids) == num_users, f"Expected {num_users} strokes, got {len(stroke_ids)}" |
| 157 | + assert len(set(stroke_ids)) == num_users, f"RACE CONDITION: Duplicate stroke IDs at 100 users! {len(stroke_ids) - len(set(stroke_ids))} duplicates" |
| 158 | + assert len(set(counts)) == num_users, f"RACE CONDITION: Duplicate counts at 100 users!" |
| 159 | + |
| 160 | + # Performance assertion: should complete in reasonable time with atomic operations |
| 161 | + # With old lock: ~8 seconds (80ms * 100), with atomic: < 1 second |
| 162 | + print(f"\n100 concurrent users completed in {elapsed:.2f} seconds") |
| 163 | + assert elapsed < 5.0, f"Too slow: {elapsed:.2f}s (atomic operations should be fast)" |
| 164 | + |
| 165 | + # Verify final counter |
| 166 | + final_count = get_canvas_draw_count() |
| 167 | + assert final_count == num_users, f"Final count should be {num_users}, got {final_count}" |
| 168 | + |
| 169 | + |
| 170 | +def test_concurrent_with_network_latency(): |
| 171 | + """Test concurrent submissions with simulated network latency.""" |
| 172 | + num_users = 20 |
| 173 | + results = [] |
| 174 | + |
| 175 | + with ThreadPoolExecutor(max_workers=num_users) as executor: |
| 176 | + futures = [ |
| 177 | + executor.submit(submit_stroke_simulation, f"user_{i}", delay=0.01 * (i % 5)) |
| 178 | + for i in range(num_users) |
| 179 | + ] |
| 180 | + |
| 181 | + for future in as_completed(futures): |
| 182 | + results.append(future.result()) |
| 183 | + |
| 184 | + # Extract stroke IDs and counts |
| 185 | + stroke_ids = [r[1] for r in results] |
| 186 | + counts = [r[2] for r in results] |
| 187 | + |
| 188 | + # Critical assertions |
| 189 | + assert len(set(stroke_ids)) == num_users, f"RACE CONDITION: Duplicate stroke IDs with latency!" |
| 190 | + assert len(set(counts)) == num_users, f"RACE CONDITION: Duplicate counts with latency!" |
| 191 | + assert set(counts) == set(range(1, num_users + 1)), "Counts not in expected range" |
| 192 | + |
| 193 | + |
| 194 | +def test_counter_atomicity_stress(): |
| 195 | + """ |
| 196 | + Stress test: Verify atomicity under extreme concurrent load. |
| 197 | + |
| 198 | + This test hammers the counter with many rapid increments from multiple threads |
| 199 | + to detect any race conditions in the atomic redis.incr() implementation. |
| 200 | + """ |
| 201 | + num_increments = 1000 |
| 202 | + num_threads = 10 |
| 203 | + results = [] |
| 204 | + |
| 205 | + def rapid_fire_increments(thread_id, count): |
| 206 | + """Perform multiple rapid increments from a single thread.""" |
| 207 | + thread_results = [] |
| 208 | + for i in range(count): |
| 209 | + draw_count = increment_canvas_draw_count() |
| 210 | + thread_results.append(draw_count) |
| 211 | + return thread_results |
| 212 | + |
| 213 | + increments_per_thread = num_increments // num_threads |
| 214 | + |
| 215 | + with ThreadPoolExecutor(max_workers=num_threads) as executor: |
| 216 | + futures = [ |
| 217 | + executor.submit(rapid_fire_increments, tid, increments_per_thread) |
| 218 | + for tid in range(num_threads) |
| 219 | + ] |
| 220 | + |
| 221 | + for future in as_completed(futures): |
| 222 | + results.extend(future.result()) |
| 223 | + |
| 224 | + # Critical assertions |
| 225 | + assert len(results) == num_increments, f"Expected {num_increments} increments, got {len(results)}" |
| 226 | + assert len(set(results)) == num_increments, f"RACE CONDITION: {len(results) - len(set(results))} duplicate counts!" |
| 227 | + assert set(results) == set(range(1, num_increments + 1)), "Some counts missing or duplicated" |
| 228 | + |
| 229 | + # Verify final counter |
| 230 | + final_count = get_canvas_draw_count() |
| 231 | + assert final_count == num_increments, f"Final count should be {num_increments}, got {final_count}" |
| 232 | + |
| 233 | + |
| 234 | +if __name__ == "__main__": |
| 235 | + # Run tests with verbose output |
| 236 | + pytest.main([__file__, "-v", "-s"]) |
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