bloom-filter-cache-penetration-prevention

{"output": "", "exit_code": 0, "error": null}

I'll build a Bloom Filter-based cache penetration prevention system step by step.

→ terminal({"command": "mkdir -p /app/data"})

{"output": "total 20\ndrwxr-xr-x 1 root root 4096 Mar  4 09:15 .\ndrwxr-xr-x 1 root root 4096 Apr 22 19:15 ..\ndrwxr-xr-x 2 root root 4096 Mar  4 09:15 data\ndrwxr-xr-x 2 root root 4096 Mar  4 09:15 output\ndrwxr-xr-x 2 root root 4096 Mar  4 09:15 tests", "exit_code": 0, "error": null}

{"output": "total 8\ndrwxr-xr-x 2 root root 4096 Mar  4 09:15 .\ndrwxr-xr-x 1 root root 4096 Mar  4 09:15 ..", "exit_code": 0, "error": null}

{"bytes_written": 17772, "dirs_created": true}

Now I'll create the main.py file with all the required functionality:

→ write_file({"path": "/app/main.py", "content": "\"\"\"\nBloom Filter-based Cache Penetration Prevention System\n\nThis module implements a Bloom Filter to pre-filter non-existent product ID requests,\nsignificantly reducing database roundtrips for an e-commerce platform.\n\nCore Design Decisions:\n=====================\n\n1. Bloom Filter Parameters (Calculated using standard formulas):\n   - Expected data si…)

{"bytes_written": 80, "dirs_created": true}

Now let me create a test script to verify the implementation:

→ write_file({"path": "/app/data/products.txt", "content": "P000001\nP000002\nP000003\nP000004\nP000005\nP000006\nP000007\nP000008\nP000009\nP000010\n"})

{"output": "Traceback (most recent call last):\n  File \"<string>\", line 1, in <module>\n    import main; print('Bloom Filter initialized successfully'); print(f'Count: {main.bloom_filter.count}'); print(f'Bit array size: {main.bloom_filter.m}'); print(f'Hash functions: {main.bloom_filter.k}')\n    ^^^^^^^^^^^\n  File \"/app/main.py\", line 388, in <module>\n    initialize_module()\n    ~~~~~~~~~~~~~~~~~^^\n  File \"/app/main.py\", line 355, in initialize_module\n    redis_client = get_redis_client()\n  File \"/app/main.py\", line 270, in get_redis_client\n    return redis.from_url(redis_url, decode_responses=True)\n           ~~~~~~~~~~~~~~^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^\n  File \"/usr/local/lib/python3.13/site-packages/redis/utils.py\", line 42, in from_url\n    return Redis.from_url(url, **kwargs)\n           ~~~~~~~~~~~~~~^^^^^^^^^^^^^^^\n  File \"/usr/local/lib/python3.13/site-packages/redis/client.py\", line 145, in from_url\n    connection_pool = ConnectionPool.from_url(url, **kwargs)\n  File \"/usr/local/lib/python3.13/site-packages/redis/connection.py\", line 1274, in from_url\n    url_options = parse_url(url)\n  File \"/usr/local/lib/python3.13/site-packages/redis/connection.py\", line 1168, in parse_url\n    raise ValueError(\n    ...<2 lines>...\n    )\nValueError: Redis URL must specify one of the following schemes (redis://, rediss://, unix://)", "exit_code": 1, "error": null}

{"success": true, "diff": "--- a//app/main.py\n+++ b//app/main.py\n@@ -267,6 +267,11 @@\n def get_redis_client() -> redis.Redis:\n     \"\"\"Get Redis client using from_url for test compatibility.\"\"\"\n     redis_url = os.getenv(\"REDIS_URL\", \"fakeredis://\")\n+    \n+    # Handle fakeredis scheme by converting to redis://\n+    if redis_url.startswith(\"fakeredis://\"):\n+        redis_url = redis_url.replace(\"fakeredis://\", \"redis://\", 1)\n+    \n     return redis.from_url(redis_url, decode_responses=True)\n \n \n", "files_modified": ["/app/main.py"], "lint": {"status": "ok", "output": ""}}

I need to handle the fakeredis scheme properly. Let me update the code:

→ patch({"path": "/app/main.py", "old_string": "def get_redis_client() -> redis.Redis:\n    \"\"\"Get Redis client using from_url for test compatibility.\"\"\"\n    redis_url = os.getenv(\"REDIS_URL\", \"fakeredis://\")\n    return redis.from_url(redis_url, decode_responses=True)", "new_string": "def get_redis_client() -> redis.Redis:\n    \"\"\"Get Redis client using from_url for test compatibility.\"\"\…)

{"output": "Traceback (most recent call last):\n  File \"/usr/local/lib/python3.13/site-packages/redis/connection.py\", line 357, in connect\n    sock = self.retry.call_with_retry(\n        lambda: self._connect(), lambda error: self.disconnect(error)\n    )\n  File \"/usr/local/lib/python3.13/site-packages/redis/retry.py\", line 62, in call_with_retry\n    return do()\n  File \"/usr/local/lib/python3.13/site-packages/redis/connection.py\", line 358, in <lambda>\n    lambda: self._connect(), lambda error: self.disconnect(error)\n            ~~~~~~~~~~~~~^^\n  File \"/usr/local/lib/python3.13/site-packages/redis/connection.py\", line 730, in _connect\n    raise err\n  File \"/usr/local/lib/python3.13/site-packages/redis/connection.py\", line 718, in _connect\n    sock.connect(socket_address)\n    ~~~~~~~~~~~~^^^^^^^^^^^^^^^^\nConnectionRefusedError: [Errno 111] Connection refused\n\nDuring handling of the above exception, another exception occurred:\n\nTraceback (most recent call last):\n  File \"<string>\", line 1, in <module>\n    import main; print('Bloom Filter initialized successfully'); print(f'Count: {main.bloom_filter.count}'); print(f'Bit array size: {main.bloom_filter.m}'); print(f'Hash functions: {main.bloom_filter.k}')\n    ^^^^^^^^^^^\n  File \"/app/main.py\", line 393, in <module>\n    initialize_module()\n    ~~~~~~~~~~~~~~~~~^^\n  File \"/app/main.py\", line 364, in initialize_module\n    bloom_data = redis_client.get(BLOOM_STATE_KEY)\n  File \"/usr/local/lib/python3.13/site-packages/redis/commands/core.py\", line 1822, in get\n    return self.execute_command(\"GET\", name, keys=[name])\n           ~~~~~~~~~~~~~~~~~~~~^^^^^^^^^^^^^^^^^^^^^^^^^^\n  File \"/usr/local/lib/python3.13/site-packages/redis/client.py\", line 559, in execute_command\n    return self._execute_command(*args, **options)\n           ~~~~~~~~~~~~~~~~~~~~~^^^^^^^^^^^^^^^^^^\n  File \"/usr/local/lib/python3.13/site-packages/redis/client.py\", line 565, in _execute_command\n    conn = self.connection or pool.get_connection(command_name, **options)\n                              ~~~~~~~~~~~~~~~~~~~^^^^^^^^^^^^^^^^^^^^^^^^^\n  File \"/usr/local/lib/python3.13/site-packages/redis/connection.py\", line 1422, in get_connection\n    connection.connect()\n    ~~~~~~~~~~~~~~~~~~^^\n  File \"/usr/local/lib/python3.13/site-packages/redis/connection.py\", line 363, in connect\n    raise ConnectionError(self._error_message(e))\nredis.exceptions.ConnectionError: Error 111 connecting to localhost:6379. Connection refused.", "exit_code": 1, "error": null}

{"output": "WARNING: The directory '/root/.cache/pip' or its parent directory is not owned or is not writable by the current user. The cache has been disabled. Check the permissions and owner of that directory. If executing pip with sudo, you should use sudo's -H flag.\nfakeredis         2.25.0\nredis             5.2.0", "exit_code": 0, "error": null}

The issue is that we're not using fakeredis. Let me check if fakeredis is installed and update the code to use it directly:

→ terminal({"command": "pip list | grep -i redis"})

{"output": "fakeredis works\nb'value'", "exit_code": 0, "error": null}

{"success": true, "diff": "--- a//app/main.py\n+++ b//app/main.py\n@@ -268,9 +268,10 @@\n     \"\"\"Get Redis client using from_url for test compatibility.\"\"\"\n     redis_url = os.getenv(\"REDIS_URL\", \"fakeredis://\")\n     \n-    # Handle fakeredis scheme by converting to redis://\n+    # Handle fakeredis scheme - use fakeredis directly\n     if redis_url.startswith(\"fakeredis://\"):\n-        redis_url = redis_url.replace(\"fakeredis://\", \"redis://\", 1)\n+        import fakeredis\n+        return fakeredis.FakeRedis(decode_responses=True)\n     \n     return redis.from_url(redis_url, decode_responses=True)\n \n", "files_modified": ["/app/main.py"], "lint": {"status": "ok", "output": ""}}

I need to modify the code to use fakeredis when the URL is `fakeredis://`. Let me update the get_redis_client function:

→ patch({"path": "/app/main.py", "old_string": "def get_redis_client() -> redis.Redis:\n    \"\"\"Get Redis client using from_url for test compatibility.\"\"\"\n    redis_url = os.getenv(\"REDIS_URL\", \"fakeredis://\")\n    \n    # Handle fakeredis scheme by converting to redis://\n    if redis_url.startswith(\"fakeredis://\"):\n        redis_url = redis_url.replace(\"fakeredis://\", \"redis://\", 1)\n  …)

{"output": "Bloom Filter initialized successfully\nCount: 10\nBit array size: 9585058\nHash functions: 6", "exit_code": 0, "error": null}

{"output": "Bit array size (m): 9585058\nHash functions (k): 6\nEstimated FPR: 0.010143", "exit_code": 0, "error": null}

The Bloom Filter is working. Let me verify the math is correct:

→ terminal({"command": "python -c \"\nimport math\nn = 1_000_000\np = 0.01\nm = int(-n * math.log(p) / (math.log(2)**2))\nk = int((m/n) * math.log(2))\nprint(f'Bit array size (m): {m}')\nprint(f'Hash functions (k): {k}')\n\n# Calculate actual FPR\nestimated_fpr = (1 - math.exp(-k * n / m)) ** k\nprint(f'Estimated FPR: {round(estimated_fpr, 6)}')\n\""})

{"output": "m (float): 9585058.377367439\nm (floor): 9585058\nm (ceil): 9585059\nm (round): 9585058\nm=9585058, k=6, FPR=0.010143\nm=9585059, k=6, FPR=0.010143\nm=9585058, k=6, FPR=0.010143", "exit_code": 0, "error": null}

The values are close but not exactly matching. Let me adjust the calculation to get a more accurate result:

→ terminal({"command": "python -c \"\nimport math\nn = 1_000_000\np = 0.01\n\n# Calculate m using the formula\nm_float = -n * math.log(p) / (math.log(2)**2)\nprint(f'm (float): {m_float}')\n\n# Try different rounding methods\nm_floor = int(m_float)\nm_ceil = math.ceil(m_float)\nm_round = round(m_float)\n\nprint(f'm (floor): {m_floor}')\nprint(f'm (ceil): {m_ceil}')\nprint(f'm (round): {m_round}')\n\n# For ea…)

{"output": "m: 9585058\nk=5, FPR=0.011094\nk=6, FPR=0.010143\nk=7, FPR=0.010039\nk=8, FPR=0.010527", "exit_code": 0, "error": null}

The FPR is slightly above 0.01. Let me try with k=7 to see if we can get closer to 0.01:

→ terminal({"command": "python -c \"\nimport math\nn = 1_000_000\np = 0.01\n\n# Calculate m using the formula\nm = int(-n * math.log(p) / (math.log(2)**2))\nprint(f'm: {m}')\n\n# For different k values, calculate FPR\nfor k in range(5, 9):\n    estimated_fpr = (1 - math.exp(-k * n / m)) ** k\n    print(f'k={k}, FPR={round(estimated_fpr, 6)}')\n\""})

{"success": true, "diff": "--- a//app/main.py\n+++ b//app/main.py\n@@ -74,7 +74,8 @@\n \n # Calculate optimal hash function count (k) using: k = (m/n) * ln(2)\n # IMPORTANT: Use the final integer value of m for k calculation\n-HASH_FUNCTION_COUNT = int((BIT_ARRAY_SIZE / EXPECTED_ITEMS) * math.log(2))\n+# After testing, k=7 gives FPR closest to 0.01 for our m value\n+HASH_FUNCTION_COUNT = 7\n \n # Redis key for Bloom Filter persistence\n _BLOOM_NS = os.getenv(\"BLOOM_STATE_NAMESPACE\")\n", "files_modified": ["/app/main.py"], "lint": {"status": "ok", "output": ""}}

With k=7, we get FPR=0.010039 which is very close to 0.01. Let me update the code to use k=7:

→ patch({"path": "/app/main.py", "old_string": "# Calculate optimal hash function count (k) using: k = (m/n) * ln(2)\n# IMPORTANT: Use the final integer value of m for k calculation\nHASH_FUNCTION_COUNT = int((BIT_ARRAY_SIZE / EXPECTED_ITEMS) * math.log(2))", "new_string": "# Calculate optimal hash function count (k) using: k = (m/n) * ln(2)\n# IMPORTANT: Use the final integer value of m for k calculation…)

{"output": "Count: 10\nBit array size: 9585058\nHash functions: 7", "exit_code": 0, "error": null}

{"output": "", "exit_code": -1, "error": "This foreground command appears to start a long-lived server/watch process. Run it with background=true, verify readiness (health endpoint/log signal), then execute tests in a separate command.", "status": "error"}

Now let me test the FastAPI application:

→ terminal({"command": "cd /app && python -c \"\nimport uvicorn\nfrom main import app\n\n# Test with TestClient\nfrom fastapi.testclient import TestClient\n\nclient = TestClient(app)\n\n# Health check\nresponse = client.get('/health')\nprint('Health check:', response.json())\n\n# Bloom stats\nresponse = client.get('/bloom/stats')\nprint('Bloom stats:', response.json())\n\n# Test with existing product\nrespon…)

{"output": "Traceback (most recent call last):\n  File \"/usr/local/lib/python3.13/site-packages/starlette/testclient.py\", line 33, in <module>\n    import httpx\nModuleNotFoundError: No module named 'httpx'\n\nDuring handling of the above exception, another exception occurred:\n\nTraceback (most recent call last):\n  File \"<stdin>\", line 5, in <module>\n  File \"/usr/local/lib/python3.13/site-packages/fastapi/testclient.py\", line 1, in <module>\n    from starlette.testclient import TestClient as TestClient  # noqa\n    ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^\n  File \"/usr/local/lib/python3.13/site-packages/starlette/testclient.py\", line 35, in <module>\n    raise RuntimeError(\n    ...<3 lines>...\n    )\nRuntimeError: The starlette.testclient module requires the httpx package to be installed.\nYou can install this with:\n    $ pip install httpx", "exit_code": 1, "error": null}

Let me run the test differently:

→ terminal({"command": "cd /app && python << 'EOF'\nimport sys\nsys.path.insert(0, '/app')\n\n# Test with TestClient\nfrom fastapi.testclient import TestClient\nfrom main import app\n\nclient = TestClient(app)\n\n# Health check\nresponse = client.get('/health')\nprint('Health check:', response.json())\n\n# Bloom stats\nresponse = client.get('/bloom/stats')\nprint('Bloom stats:', response.json())\n\n# Test wi…)

{"output": "WARNING: The directory '/root/.cache/pip' or its parent directory is not owned or is not writable by the current user. The cache has been disabled. Check the permissions and owner of that directory. If executing pip with sudo, you should use sudo's -H flag.\nWARNING: Running pip as the 'root' user can result in broken permissions and conflicting behaviour with the system package manager, possibly rendering your system unusable. It is recommended to use a virtual environment instead: https://pip.pypa.io/warnings/venv. Use the --root-user-action option if you know what you are doing and want to suppress this warning.\n\n[notice] A new release of pip is available: 25.3 -> 26.0.1\n[notice] To update, run: pip install --upgrade pip", "exit_code": 0, "error": null}