small test
This commit is contained in:
@@ -1,6 +1,209 @@
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def main():
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print("Hello from police-data!")
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import requests
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import time
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import sqlite3
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import threading
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import queue
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from collections import deque
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from typing import List
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# --------------------------------
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# Thread-Safe Leaky Bucket Rate Limiter
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# --------------------------------
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class LeakyBucketRateLimiter:
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def __init__(self, max_rate: float = 15.0):
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self.max_rate = max_rate
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self.timestamps: deque = deque()
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self.lock = threading.Lock()
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self.window: float = 1.0 # Sliding window size in seconds
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def acquire(self) -> None:
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with self.lock:
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now = time.monotonic()
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# Remove timestamps outside the current window
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while self.timestamps and self.timestamps[0] <= now - self.window:
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self.timestamps.popleft()
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# If limit reached, sleep until the oldest request exits the window
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if len(self.timestamps) >= self.max_rate:
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sleep_time = 1.0 - (now - self.timestamps[0])
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if sleep_time > 0:
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time.sleep(sleep_time)
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now = time.monotonic()
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while self.timestamps and self.timestamps[0] <= now - self.window:
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self.timestamps.popleft()
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self.timestamps.append(time.monotonic())
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# --------------------------------
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# Database Initialization
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# --------------------------------
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def init_db(db_path: str = "uk_crimes.db") -> sqlite3.Connection:
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conn = sqlite3.connect(db_path)
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conn.execute("""
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CREATE TABLE IF NOT EXISTS crimes (
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id INTEGER PRIMARY KEY,
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category TEXT,
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month TEXT,
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latitude REAL,
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longitude REAL,
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street_name TEXT,
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outcome_category TEXT
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)
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""")
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conn.commit()
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return conn
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# --------------------------------
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# UK Grid Polygon Generator
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# --------------------------------
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def generate_uk_polygons(lat_min: float = 49.5, lat_max: float = 61.0,
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lng_min: float = -13.0, lng_max: float = 5.0,
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step: float = 0.5) -> List[str]:
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polygons = []
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lats = [l / 10.0 for l in range(int(lat_min * 10), int(lat_max * 10), int(step * 10))]
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lns = [ln / 10.0 for ln in range(int(lng_min * 10), int(lng_max * 10), int(step * 10))]
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for i in range(len(lats) - 1):
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for j in range(len(lns) - 1):
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poly = f"{lats[i]},{lns[j]}:{lats[i]},{lns[j+1]}:{lats[i+1]},{lns[j+1]}:{lats[i+1]},{lns[j]}"
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polygons.append(poly)
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return polygons
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# --------------------------------
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# Producer Thread: Fetch & Queue
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# --------------------------------
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def producer_worker(polygons: List[str], date: str, limiter: LeakyBucketRateLimiter, data_queue: queue.Queue):
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total = len(polygons)
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for i, poly in enumerate(polygons):
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# Skip polygons exceeding the 4094 character limit [1]
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if len(poly) > 4090:
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continue
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# Enforce strict 15 requests/second limit [1]
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limiter.acquire()
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try:
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response = requests.get(
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"https://data.police.uk/api/crimes-street/all-crime",
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params={"date": date, "poly": poly},
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timeout=30
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)
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response.raise_for_status()
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data = response.json()
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# API returns 503 if a custom area contains >10,000 crimes [1]
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if not isinstance(data, list):
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print(f"[PRODUCER] Warning: Received non-list response for poly {poly[:30]}...")
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continue
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if not data:
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continue
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rows = []
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for crime in data:
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loc = crime.get("location", {})
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outcome = crime.get("outcome_status") or {}
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rows.append((
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crime.get("id"),
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crime.get("category"),
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crime.get("month"),
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float(loc.get("latitude", 0)),
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float(loc.get("longitude", 0)),
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loc.get("street", {}).get("name"),
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outcome.get("category")
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))
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# Push batch to memory queue (non-blocking if size allows)
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data_queue.put(rows)
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except requests.exceptions.RequestException as e:
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print(f"[PRODUCER] Network error for poly {poly[:30]}... | {e}")
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except Exception as e:
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print(f"[PRODUCER] Unexpected error: {e}")
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if (i + 1) % 100 == 0 or i == total - 1:
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print(f"[PRODUCER] Progress: {i+1}/{total} fetched | Queue size: {data_queue.qsize()}")
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# Signal completion to consumer
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data_queue.put(None)
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# --------------------------------
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# Consumer Thread: Queue to DB
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# --------------------------------
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def consumer_worker(data_queue: queue.Queue, conn: sqlite3.Connection):
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batch_size = 500
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batch = []
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while True:
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try:
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item = data_queue.get(timeout=5.0)
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except queue.Empty:
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# If queue is empty for 5s, assume production is done
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if not batch:
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break
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else:
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# Flush remaining batch
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conn.executemany(
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"INSERT OR IGNORE INTO crimes (id, category, month, latitude, longitude, street_name, outcome_category) VALUES (?, ?, ?, ?, ?, ?, ?)",
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batch
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)
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conn.commit()
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batch = []
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continue
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if item is None:
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# Flush last batch before exiting
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if batch:
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conn.executemany(
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"INSERT OR IGNORE INTO crimes (id, category, month, latitude, longitude, street_name, outcome_category) VALUES (?, ?, ?, ?, ?, ?, ?)",
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batch
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)
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conn.commit()
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data_queue.task_done()
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break
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batch.extend(item)
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if len(batch) >= batch_size:
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conn.executemany(
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"INSERT OR IGNORE INTO crimes (id, category, month, latitude, longitude, street_name, outcome_category) VALUES (?, ?, ?, ?, ?, ?, ?)",
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batch
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)
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conn.commit()
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batch = []
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data_queue.task_done()
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# --------------------------------
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# Main Orchestrator
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# --------------------------------
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def main():
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limiter = LeakyBucketRateLimiter(max_rate=15.0)
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conn = init_db("uk_crimes.db")
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data_queue = queue.Queue(maxsize=2000) # Backpressure to prevent memory overflow
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date = "2024-01"
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print("Generating UK coverage polygons...")
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polygons = generate_uk_polygons()
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print(f"Total regions to process: {len(polygons)}\n")
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# Start threads
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prod_thread = threading.Thread(target=producer_worker, args=(polygons, date, limiter, data_queue), daemon=True)
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cons_thread = threading.Thread(target=consumer_worker, args=(data_queue, conn), daemon=True)
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cons_thread.start()
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prod_thread.start()
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# Wait for producer to finish
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prod_thread.join()
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print("\n[MAIN] Producer finished. Waiting for consumer to drain queue...")
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# Wait for consumer to finish
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cons_thread.join()
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total = conn.execute('SELECT COUNT(*) FROM crimes').fetchone()[0]
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print(f"[MAIN] Completed. Total unique records stored in uk_crimes.db: {total}")
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conn.close()
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if __name__ == "__main__":
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main()
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