feat: 采用fetch_status记录下载状态

apps/resm/models.py

@@ -29,7 +29,7 @@ class Paper(BaseModel):
     has_fulltext_pdf = models.BooleanField(default=False, db_index=True)
     fetch_status = models.CharField(
         max_length=20,
-        default="meta_only",  # meta_only / abstract_ready / fulltext_ready / parsed / failed
+        default="meta_only",  # meta_only / downloading / abstract_ready / fulltext_ready / parsed / failed
         db_index=True
     )
     fail_reason = models.TextField(null=True, blank=True)

apps/resm/tasks.py

@@ -117,16 +117,15 @@ def show_task_run(def_name: str):
     return cache.get(def_name, True)
 
 @shared_task(base=CustomTask)
-def get_abstract_from_elsevier(publication_year: int = None, number_of_task:int = 20):
+def get_abstract_from_elsevier(number_of_task:int = 20):
     def_name = get_abstract_from_elsevier.name
     if not show_task_run(def_name):
         return "stoped"
     qs = Paper.objects.filter(has_abstract=False)
-    if publication_year is not None:
-        qs = qs.filter(publication_year=publication_year)
     qs = qs.exclude(
         fail_reason__contains="elsevier_doi_not_found"
-    ).exclude(fail_reason__contains="elsevier_abstract_not_found").order_by("publication_date")
+    ).exclude(fail_reason__contains="elsevier_abstract_not_found"
+    ).exclude(fetch_status="downloading").order_by("publication_date")
 
     if not qs.exists():
         return "done"
@@ -256,19 +255,18 @@ def get_pdf_from_elsevier(number_of_task=100):
         )
     return f'{def_name}, {err_msg}, remaining {qs_count} papers'
 
-RUNNING_KEY = "download_pdf:running"
+def get_actual_running_count():
+    """获取实际在下载的任务数"""
+    return Paper.objects.filter(fetch_status='downloading').count()
 
-def get_max_running():
-    return cache.get("download_pdf:max_running", 100)
-
-def can_send_more():
-    return cache.get(RUNNING_KEY, 0) < get_max_running()
+def can_send_more(max_running):
+    return get_actual_running_count() < max_running
 
 @shared_task(base=CustomTask)
 def send_download_fulltext_task(number_of_task=100):
-    if number_of_task != get_max_running():
-        cache.set("download_pdf:max_running", number_of_task)
-    qs = Paper.objects.filter(is_oa=True, has_fulltext=False, fail_reason=None)
+    qs = Paper.objects.filter(is_oa=True, has_fulltext=False, fail_reason=None).exclude(
+        fetch_status='downloading'
+    )
     if not qs.exists():
         return "done"
     qs0 = qs.order_by("?")
@@ -276,16 +274,9 @@ def send_download_fulltext_task(number_of_task=100):
     # 分批发送任务，控制并发数量，避免过多请求
     task_count = 0
     for paper in qs0[:number_of_task]:
-        if not can_send_more():
+        if not can_send_more(number_of_task):
             break
         if paper.oa_url:
-            # 发送任务前先增加计数，确保计数准确
-            current_count = incr_running()
-            if current_count > number_of_task:
-                # 超过限制，回滚计数并停止
-                decr_running()
-                break
-            
             # 使用 countdown 错开请求时间，避免过多并发
             countdown = task_count * 1  # 每个任务间隔1秒
             current_app.send_task(
@@ -296,27 +287,8 @@ def send_download_fulltext_task(number_of_task=100):
                 countdown=countdown,
             )
             task_count += 1
-    return f"sent {task_count} download_pdf tasks, running {cache.get(RUNNING_KEY, 0)}/{number_of_task}"
     
-
-def incr_running():
-    try:
-        return cache.incr(RUNNING_KEY)
-    except ValueError:
-        cache.set(RUNNING_KEY, 1)
-        return 1
-
-
-def decr_running():
-    try:
-        current = cache.get(RUNNING_KEY, 0)
-        if current <= 0:
-            cache.set(RUNNING_KEY, 0)
-            return 0
-        return cache.decr(RUNNING_KEY)
-    except ValueError:
-        cache.set(RUNNING_KEY, 0)
-        return 0
+    return f"sent {task_count} download_pdf tasks"
 
 
 @shared_task(base=CustomTask)
@@ -324,19 +296,18 @@ def download_pdf(paper_id):
     """
     下载单个论文的PDF
     """
+    paper = None
+    original_status = None
+    
     try:
-        try:
-            paper = Paper.objects.get(id=paper_id)
-        except Paper.DoesNotExist:
-            return f"Paper {paper_id} not found"
+        paper = Paper.objects.get(id=paper_id)
+        original_status = paper.fetch_status
+        if original_status == "downloading":
+            return f"paper {paper_id} is already downloading"
         
-        # 检查缓存，避免短时间内重复下载同一个paper
-        cache_key = f"download_pdf_{paper_id}"
-        if cache.get(cache_key):
-            return "already_processing"
-
-        # 设置处理中标记，防止并发重复处理
-        cache.set(cache_key, True, timeout=3600) 
+        # 将状态改为downloading
+        paper.fetch_status = 'downloading'
+        paper.save(update_fields=['fetch_status', 'update_time'])
         
         current_from = "oa_url"
         msg = save_pdf_from_oa_url(paper)
@@ -345,7 +316,10 @@ def download_pdf(paper_id):
             msg = save_pdf_from_openalex(paper)
         return msg, current_from
     finally:
-        decr_running()
+        # 出错时恢复到原状态
+        if paper.fetch_status == "downloading" and paper.has_fulltext_pdf is False:
+            paper.fetch_status = original_status
+            paper.save(update_fields=['fetch_status', 'update_time'])
 
 
 def save_pdf_from_oa_url(paper:Paper):