def _load_reaction_data():
    global Hfg_sources, Hfl_sources, Hfs_sources
    global S0g_sources, S0l_sources, S0s_sources
    global _reaction_data_loaded

    # Phase 1: load TSV data (slow, file I/O)
    Hfg_API_TDB_data = data_source('API TDB Albahri Hf (g).tsv')
    Hfg_ATcT_data = data_source('ATcT 1.112 (g).tsv')
    Hfl_ATcT_data = data_source('ATcT 1.112 (l).tsv')
    Hfg_S0g_YAWS_data = data_source('Yaws Hf S0 (g).tsv')
    JANAF_1998_data = data_source('JANAF_1998.tsv')

    _reaction_data_loaded = True        # <-- LINE 134: flag set TOO EARLY

    # Phase 2: assign dicts (executed AFTER flag is already True)
    S0g_sources = {...}
    S0l_sources = {...}
    S0s_sources = {...}
    Hfg_sources = {...}                 # <-- LINE 150: actual data not yet available
    Hfl_sources = {...}
    Hfs_sources = {...}

import chemicals.reaction as reaction
reaction._reaction_data_loaded = True
from chemicals.reaction import Hfg_methods
try:
    Hfg_methods('7664-41-7')
    print('FAIL: no error')
except NameError as e:
    print(f'PASS: NameError: {e}')

#!/usr/bin/env python3
"""repro_thermo_race_en.py — Reproduce race condition in chemicals.reaction lazy init

Usage:
    python3 repro_thermo_race_en.py           # all tests
    python3 repro_thermo_race_en.py --direct  # direct demo only
"""

import sys


def test_direct():
    """Set _reaction_data_loaded=True, no data load → Hfg_methods should NameError"""
    import chemicals.reaction as reaction
    reaction._reaction_data_loaded = True
    from chemicals.reaction import Hfg_methods
    try:
        Hfg_methods('7664-41-7')
        print('[FAIL] No NameError')
        return False
    except NameError:
        print('[PASS] NameError triggered (expected)')
        return True


def test_multithread():
    """Multi-threaded: reset flag while hammering Hfg_methods"""
    import threading
    from chemicals.reaction import Hfg_methods
    import chemicals.reaction as reaction
    errors, lock, stop = [], threading.Lock(), threading.Event()
    cases = ['7664-41-7', '7732-18-5', '1333-74-0', '630-08-0', '124-38-9']

    def worker():
        while not stop.is_set():
            for cas in cases:
                try:
                    Hfg_methods(cas)
                except NameError:
                    with lock: errors.append(cas)
                    stop.set(); return
                except Exception:
                    pass

    def reseter():
        while not stop.is_set():
            reaction._reaction_data_loaded = False

    ts = [threading.Thread(target=worker, daemon=True) for _ in range(8)]
    for t in ts: t.start()
    threading.Thread(target=reseter, daemon=True).start()

    import time; time.sleep(5); stop.set()
    for t in ts: t.join(1)

    if errors:
        print(f'[PASS] Multi-threaded NameError: {len(errors)} hit(s)')
        return True
    else:
        print('[INFO] Not hit in 5s (narrow window, cloud env easier)')
        return False


if __name__ == '__main__':
    if '--direct' in sys.argv:
        ok = test_direct()
    else:
        print('=== Direct root cause (should NameError) ===')
        ok = test_direct()
        print()
        print('=== Multi-threaded ===')
        ok2 = test_multithread()
        ok = ok or ok2
    print('\n[DONE] Bug confirmed.' if ok else '\n[INFO] Not triggered.')
    sys.exit(0 if ok else 1)

def _load_reaction_data():
    global ...
    # ... load TSV data ...
    S0g_sources = {...}
    S0l_sources = {...}
    S0s_sources = {...}
    Hfg_sources = {...}
    Hfl_sources = {...}
    Hfs_sources = {...}
    _reaction_data_loaded = True        # <-- moved here

import threading
_reaction_lock = threading.Lock()

def _load_reaction_data():
    global _reaction_data_loaded
    if _reaction_data_loaded:
        return
    with _reaction_lock:
        if _reaction_data_loaded:
            return
        # ... original loading ...
        _reaction_data_loaded = True    # last line, inside lock