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| 1 | +"""Append-only event store with replay capability.""" |
| 2 | +from __future__ import annotations |
| 3 | +import json |
| 4 | +import sqlite3 |
| 5 | +import time |
| 6 | +from dataclasses import dataclass |
| 7 | +from pathlib import Path |
| 8 | +from typing import Any |
| 9 | + |
| 10 | +@dataclass |
| 11 | +class StoredEvent: |
| 12 | + id: int |
| 13 | + stream: str |
| 14 | + event_type: str |
| 15 | + data: dict[str, Any] |
| 16 | + timestamp: float |
| 17 | + version: int |
| 18 | + |
| 19 | +class EventStore: |
| 20 | + def __init__(self, db_path: str = "data/events.db"): |
| 21 | + Path(db_path).parent.mkdir(parents=True, exist_ok=True) |
| 22 | + self.conn = sqlite3.connect(db_path) |
| 23 | + self.conn.executescript(""" |
| 24 | + CREATE TABLE IF NOT EXISTS events ( |
| 25 | + id INTEGER PRIMARY KEY AUTOINCREMENT, |
| 26 | + stream TEXT NOT NULL, |
| 27 | + event_type TEXT NOT NULL, |
| 28 | + data TEXT NOT NULL, |
| 29 | + timestamp REAL NOT NULL, |
| 30 | + version INTEGER NOT NULL DEFAULT 1 |
| 31 | + ); |
| 32 | + CREATE INDEX IF NOT EXISTS idx_stream ON events(stream); |
| 33 | + CREATE INDEX IF NOT EXISTS idx_type ON events(event_type); |
| 34 | + CREATE INDEX IF NOT EXISTS idx_ts ON events(timestamp); |
| 35 | + """) |
| 36 | + |
| 37 | + def append(self, stream: str, event_type: str, data: dict) -> StoredEvent: |
| 38 | + version = self._next_version(stream) |
| 39 | + now = time.time() |
| 40 | + cur = self.conn.execute( |
| 41 | + "INSERT INTO events (stream, event_type, data, timestamp, version) VALUES (?,?,?,?,?)", |
| 42 | + (stream, event_type, json.dumps(data), now, version), |
| 43 | + ) |
| 44 | + self.conn.commit() |
| 45 | + return StoredEvent(cur.lastrowid, stream, event_type, data, now, version) |
| 46 | + |
| 47 | + def _next_version(self, stream: str) -> int: |
| 48 | + row = self.conn.execute("SELECT MAX(version) FROM events WHERE stream = ?", (stream,)).fetchone() |
| 49 | + return (row[0] or 0) + 1 |
| 50 | + |
| 51 | + def replay(self, stream: str, from_version: int = 0) -> list[StoredEvent]: |
| 52 | + rows = self.conn.execute( |
| 53 | + "SELECT id, stream, event_type, data, timestamp, version FROM events WHERE stream = ? AND version > ? ORDER BY version", |
| 54 | + (stream, from_version), |
| 55 | + ).fetchall() |
| 56 | + return [StoredEvent(r[0], r[1], r[2], json.loads(r[3]), r[4], r[5]) for r in rows] |
| 57 | + |
| 58 | + def query(self, event_type: str | None = None, since: float = 0, limit: int = 100) -> list[StoredEvent]: |
| 59 | + if event_type: |
| 60 | + rows = self.conn.execute( |
| 61 | + "SELECT id, stream, event_type, data, timestamp, version FROM events WHERE event_type = ? AND timestamp > ? ORDER BY timestamp DESC LIMIT ?", |
| 62 | + (event_type, since, limit), |
| 63 | + ).fetchall() |
| 64 | + else: |
| 65 | + rows = self.conn.execute( |
| 66 | + "SELECT id, stream, event_type, data, timestamp, version FROM events WHERE timestamp > ? ORDER BY timestamp DESC LIMIT ?", |
| 67 | + (since, limit), |
| 68 | + ).fetchall() |
| 69 | + return [StoredEvent(r[0], r[1], r[2], json.loads(r[3]), r[4], r[5]) for r in rows] |
| 70 | + |
| 71 | + def streams(self) -> list[str]: |
| 72 | + return [r[0] for r in self.conn.execute("SELECT DISTINCT stream FROM events").fetchall()] |
| 73 | + |
| 74 | + def count(self, stream: str | None = None) -> int: |
| 75 | + if stream: |
| 76 | + return self.conn.execute("SELECT COUNT(*) FROM events WHERE stream = ?", (stream,)).fetchone()[0] |
| 77 | + return self.conn.execute("SELECT COUNT(*) FROM events").fetchone()[0] |
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