feat(achievement): 添加判定核心、通知模块并接入判题链路

achievement/checker.py

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+"""成就判定核心，被异步任务和管理命令共用。
+
+判定刻意做成"一次查询取全部候选 + 内存比对"，与 problemset 里逐条查询的
+旧写法相反：一次判题只多 3~4 条 SQL。
+"""
+
+import logging
+
+from django.db import transaction
+from django.db.models import F
+
+from achievement.metrics import META_METRICS, METRIC_REGISTRY, build_ctx
+from achievement.models import Achievement, Operator, UserAchievement, UserStat
+
+logger = logging.getLogger(__name__)
+
+
+def get_or_create_stat(user):
+    stat, _ = UserStat.objects.get_or_create(user=user)
+    return stat
+
+
+def evaluate(user, metrics, only_metrics=None):
+    """返回该用户应解锁但尚未解锁的成就列表。"""
+    unlocked_ids = set(UserAchievement.objects.filter(user=user).values_list("achievement_id", flat=True))
+    qs = Achievement.objects.filter(visible=True).exclude(id__in=unlocked_ids)
+    if only_metrics is not None:
+        qs = qs.filter(metric__in=only_metrics)
+
+    hits = []
+    for achievement in qs:
+        value = metrics.get(achievement.metric)
+        # 指标从未产生有效值时 key 不存在，直接跳过：
+        # 否则 min_ac_code_chars 这类极小值指标会对新用户恒成立
+        if value is None:
+            continue
+        if achievement.operator == Operator.GTE and value >= achievement.threshold:
+            hits.append(achievement)
+        elif achievement.operator == Operator.LTE and value <= achievement.threshold:
+            hits.append(achievement)
+    return hits
+
+
+def unlock(user, achievements, backfilled=False, notified=False):
+    """写入解锁记录并累加 unlock_count，返回实际新建的记录。
+
+    刻意逐条 get_or_create 而不是 bulk_create：unique_user_achievement 约束负责
+    并发竞态，was_created 是"这一条确实是我新建的"的唯一可信判据。用
+    bulk_create(ignore_conflicts=True) 则无法区分新建与已存在，并发判题时会把
+    unlock_count 重复累加（获得率永久偏高），并对同一个奖杯重复推送通知。
+
+    循环次数是"本次新解锁的成就数"，常态为 0，因此常态零查询。
+    """
+    created = []
+    for achievement in achievements:
+        record, was_created = UserAchievement.objects.get_or_create(
+            user=user,
+            achievement=achievement,
+            defaults={"backfilled": backfilled, "notified": notified},
+        )
+        if was_created:
+            Achievement.objects.filter(id=achievement.id).update(unlock_count=F("unlock_count") + 1)
+            created.append(record)
+    return created
+
+
+def run_for_submission(user, submission):
+    """判题后的完整流程：更新指标 → 第一轮判定 → 元指标第二轮判定。"""
+    ctx = build_ctx(user.id, submission)
+    if ctx["skip"]:
+        # 比赛提交不计入成就
+        return []
+
+    with transaction.atomic():
+        stat = UserStat.objects.select_for_update().get_or_create(user=user)[0]
+        for key, m in METRIC_REGISTRY.items():
+            if key in META_METRICS:
+                continue
+            m.on_submission(stat.metrics, submission, ctx)
+        stat.save(update_fields=["metrics", "update_time"])
+
+    first = unlock(user, evaluate(user, stat.metrics))
+    if not first:
+        return []
+
+    # 第二轮：只重算元指标、只判定依赖元指标的成就，不再有第三轮
+    for key in META_METRICS:
+        value = METRIC_REGISTRY[key].recompute(user)
+        if value is None:
+            stat.metrics.pop(key, None)
+        else:
+            stat.metrics[key] = value
+    stat.save(update_fields=["metrics", "update_time"])
+    second = unlock(user, evaluate(user, stat.metrics, only_metrics=META_METRICS))
+
+    return first + second