270 lines
10 KiB
Python
270 lines
10 KiB
Python
"""Web UI for the Days Without Strife planner (see solve.py).
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A dependency-free (stdlib only) HTTP server that exposes every input the
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solver accepts: turns, starting resources, cities, agents, scoring terms
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(linear or log), resource constraints and the misc Problem knobs.
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For log-scored terms the user supplies a JavaScript expression that evals into
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a single-argument function (e.g. ``(x) => Math.log2(x)``). The browser evals it
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once, then calls it over the amounts it needs (0..max_resource) to build the
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``log_mapping`` lookup table, which is sent to the server as a plain array.
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"""
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from __future__ import annotations
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import json
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import os
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import select
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import socket
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import sqlite3
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import threading
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import time
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from http.server import BaseHTTPRequestHandler, ThreadingHTTPServer
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from pathlib import Path
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from urllib.parse import parse_qs, unquote, urlsplit
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from solve import problem_from_dict, solve, solution_to_dict
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# The UI is a single static page served from index.html next to this module.
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INDEX_HTML = (Path(__file__).resolve().parent / "index.html").read_text(encoding="utf-8")
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# Completed solves are persisted to SQLite so they can be looked up later by
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# their UUID (GET /solve/<uuid>) and shared via /?solve=<uuid> deep links. Point
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# DB_PATH at a mounted volume so history survives container restarts/redeploys.
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# Old rows are evicted so the DB stays bounded (keep the newest MAX_SOLVES).
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DB_PATH = os.environ.get(
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"DB_PATH", str(Path(__file__).resolve().parent / "data" / "solves.db"))
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MAX_SOLVES = int(os.environ.get("MAX_SOLVES", "500"))
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def _db():
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conn = sqlite3.connect(DB_PATH, timeout=5.0)
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# WAL lets the concurrent /solve/<uuid> readers run alongside a writer.
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conn.execute("PRAGMA journal_mode=WAL")
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conn.execute("PRAGMA busy_timeout=5000")
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return conn
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def init_db():
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Path(DB_PATH).parent.mkdir(parents=True, exist_ok=True)
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conn = _db()
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try:
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with conn:
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conn.execute(
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"CREATE TABLE IF NOT EXISTS solves ("
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"token TEXT PRIMARY KEY, ts REAL NOT NULL, status TEXT, "
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"problem TEXT NOT NULL, solution TEXT NOT NULL)")
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conn.execute("CREATE INDEX IF NOT EXISTS idx_solves_ts ON solves(ts)")
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finally:
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conn.close()
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def store_solve(token, problem, solution):
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# token is client-generated; skip blanks. INSERT OR REPLACE means a repeated
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# token overwrites (a client could clobber its own/another's row — acceptable
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# for this app; switch to a server-issued id if that ever matters).
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if not token:
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return
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conn = _db()
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try:
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with conn:
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conn.execute(
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"INSERT OR REPLACE INTO solves (token, ts, status, problem, solution) "
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"VALUES (?, ?, ?, ?, ?)",
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(token, time.time(), solution.get("status"),
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json.dumps(problem), json.dumps(solution)))
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conn.execute(
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"DELETE FROM solves WHERE token NOT IN "
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"(SELECT token FROM solves ORDER BY ts DESC LIMIT ?)",
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(MAX_SOLVES,))
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finally:
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conn.close()
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def fetch_solve(token):
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conn = _db()
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try:
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row = conn.execute(
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"SELECT token, ts, status, problem, solution FROM solves WHERE token = ?",
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(token,)).fetchone()
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finally:
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conn.close()
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if row is None:
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return None
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return {"token": row[0], "ts": row[1], "status": row[2],
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"problem": json.loads(row[3]), "solution": json.loads(row[4])}
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# Only one solve may run at a time across all viewers. While it's held, other
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# clients get an immediate 429 from /solve and disable their button (they learn
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# the busy state by polling /status).
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_solve_lock = threading.Lock()
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# Tracks the in-flight solve so /cancel can stop it. /cancel is hit two ways:
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# the user clicking Cancel (a normal fetch, tab stays open) and a closing tab
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# firing navigator.sendBeacon("/cancel?token=...") — both small requests that
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# pass cleanly through reverse proxies, unlike a dropped upstream socket (which
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# the proxy keeps alive). Guarded by _active_lock; only one solve runs at a
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# time, but the lock keeps the token / solver handoff race-free against a
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# concurrent /cancel.
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_active_lock = threading.Lock()
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_active = {"token": None, "solver": None}
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def _stop_search(solver):
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# StopSearch() exists in OR-Tools 9.x+; degrade gracefully on older builds
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# (the solve then just runs to max_time_seconds).
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stop = getattr(solver, "StopSearch", None)
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if callable(stop):
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stop()
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class Handler(BaseHTTPRequestHandler):
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def _send(self, code, body, content_type="application/json", no_cache=False):
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if isinstance(body, str):
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body = body.encode("utf-8")
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self.send_response(code)
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self.send_header("Content-Type", content_type)
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self.send_header("Content-Length", str(len(body)))
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if no_cache:
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self.send_header("Cache-Control", "no-store")
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self.end_headers()
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self.wfile.write(body)
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def do_GET(self):
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path = urlsplit(self.path).path
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if path in ("/", "/index.html"):
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self._send(200, INDEX_HTML, "text/html; charset=utf-8")
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elif path == "/status":
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self._send(200, json.dumps({"solving": _solve_lock.locked()}), no_cache=True)
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elif path.startswith("/solve/"):
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token = unquote(path[len("/solve/"):])
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rec = fetch_solve(token)
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if rec is None:
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self._send(404, json.dumps({"error": "not found"}), no_cache=True)
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else:
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self._send(200, json.dumps(rec), no_cache=True)
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else:
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self._send(404, json.dumps({"error": "not found"}))
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def _client_gone(self):
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# True once the peer has closed its end. We've already consumed the
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# request body, so any readable data here is EOF (b"") for a closed tab.
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sock = self.connection
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try:
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r, _, _ = select.select([sock], [], [], 0)
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if r:
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return sock.recv(1, socket.MSG_PEEK) == b""
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except OSError:
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return True
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return False
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def do_POST(self):
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path = urlsplit(self.path)
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if path.path == "/cancel":
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self._handle_cancel(parse_qs(path.query))
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return
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if path.path != "/solve":
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self._send(404, json.dumps({"error": "not found"}))
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return
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# Reject immediately if another viewer is already solving.
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if not _solve_lock.acquire(blocking=False):
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self._send(429, json.dumps({"error": "Another solve is already in progress"}))
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return
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released = False
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token = None
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try:
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length = int(self.headers.get("Content-Length", 0))
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payload = json.loads(self.rfile.read(length) or b"{}")
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raw_problem = payload.get("problem", {})
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problem = problem_from_dict(raw_problem)
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max_time = float(payload.get("max_time_seconds", 30.0))
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token = str(payload.get("token") or "")
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# Mark this token as the in-flight solve so a matching /cancel beacon
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# (sent when the requesting tab closes) can stop it.
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with _active_lock:
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_active["token"] = token
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_active["solver"] = None
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# Run the (blocking) solve in a worker thread so this thread is free
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# to watch the socket. solver_sink hands us the CpSolver so both the
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# local disconnect watcher and /cancel can abort the search.
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result = {}
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def register(s):
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with _active_lock:
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if _active["token"] == token:
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_active["solver"] = s
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def run():
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try:
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result["sol"] = solve(
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problem, max_time_seconds=max_time, solver_sink=register,
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)
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except Exception as exc:
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result["err"] = exc
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worker = threading.Thread(target=run, daemon=True)
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worker.start()
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while worker.is_alive():
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worker.join(0.25)
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# Direct connections (no proxy) still get fast release via socket
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# EOF; behind a proxy the /cancel beacon is what stops the solve.
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if worker.is_alive() and self._client_gone():
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with _active_lock:
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if _active["solver"] is not None:
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_stop_search(_active["solver"])
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_solve_lock.release()
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released = True
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return
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if "err" in result:
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raise result["err"]
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sol_dict = solution_to_dict(result["sol"])
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# Persist the completed solve so it can be looked up by its UUID.
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# (Cancelled solves take the early return above and aren't stored.)
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store_solve(token, raw_problem, sol_dict)
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self._send(200, json.dumps(sol_dict))
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except Exception as exc: # surface errors to the browser
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self._send(400, json.dumps({"error": f"{type(exc).__name__}: {exc}"}))
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finally:
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with _active_lock:
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if _active["token"] == token:
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_active["token"] = None
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_active["solver"] = None
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if not released:
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_solve_lock.release()
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def _handle_cancel(self, query):
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# Stop the in-flight solve iff the request's token matches it, so a Cancel
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# click (or closing tab) can't cancel a *different* viewer's solve. The
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# running /solve handler then returns normally — with the best plan found
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# so far — and releases the lock.
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token = (query.get("token") or [""])[0]
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stopped = False
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with _active_lock:
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if token and token == _active["token"] and _active["solver"] is not None:
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_stop_search(_active["solver"])
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stopped = True
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self._send(200, json.dumps({"cancelled": stopped}), no_cache=True)
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def log_message(self, fmt, *args): # quieter console
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pass
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def main():
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init_db()
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host = os.environ.get("HOST", "127.0.0.1")
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port = int(os.environ.get("PORT", "8000"))
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server = ThreadingHTTPServer((host, port), Handler)
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print(f"Days Without Strife planner UI: http://{host}:{port}")
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try:
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server.serve_forever()
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except KeyboardInterrupt:
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print("\nshutting down")
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server.shutdown()
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if __name__ == "__main__":
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main()
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