137 lines
5.1 KiB
Python
137 lines
5.1 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 threading
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from http.server import BaseHTTPRequestHandler, ThreadingHTTPServer
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from pathlib import Path
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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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# 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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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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if self.path in ("/", "/index.html"):
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self._send(200, INDEX_HTML, "text/html; charset=utf-8")
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elif self.path == "/status":
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self._send(200, json.dumps({"solving": _solve_lock.locked()}), 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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if self.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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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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problem = problem_from_dict(payload.get("problem", {}))
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max_time = float(payload.get("max_time_seconds", 30.0))
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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 we can
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# abort the search if the client disconnects.
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result = {}
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solver_box = {}
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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,
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solver_sink=lambda s: solver_box.setdefault("s", s),
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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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if worker.is_alive() and self._client_gone():
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# Tab closed: stop the search and free the lock immediately
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# so the next viewer can start. The worker unwinds on its own.
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s = solver_box.get("s")
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if s is not None:
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s.StopSearch()
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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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self._send(200, json.dumps(solution_to_dict(result["sol"])))
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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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if not released:
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_solve_lock.release()
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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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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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