fix: keep task existing when server is deleted

Author: cnstark

task/models.py

@@ -28,7 +28,7 @@ class GPUTask(models.Model):
     exclusive_gpu = models.BooleanField('独占显卡', default=False)
     memory_requirement = models.PositiveSmallIntegerField('显存需求(MB)', default=0)
     utilization_requirement = models.PositiveSmallIntegerField('利用率需求(%)', default=0)
-    assign_server = models.ForeignKey(GPUServer, verbose_name='指定服务器', on_delete=models.CASCADE, blank=True, null=True)
+    assign_server = models.ForeignKey(GPUServer, verbose_name='指定服务器', on_delete=models.SET_NULL, blank=True, null=True)
     priority = models.SmallIntegerField('优先级', default=0)
     status = models.SmallIntegerField('状态', choices=STATUS_CHOICE, default=0)
     create_at = models.DateTimeField('创建时间', auto_now_add=True)
@@ -82,7 +82,7 @@ class GPUTaskRunningLog(models.Model):
     )
     index = models.PositiveSmallIntegerField('序号')
     task = models.ForeignKey(GPUTask, verbose_name='任务', on_delete=models.CASCADE, related_name='task_logs')
-    server = models.ForeignKey(GPUServer, verbose_name='服务器', on_delete=models.CASCADE, related_name='task_logs')
+    server = models.ForeignKey(GPUServer, verbose_name='服务器', on_delete=models.SET_NULL, related_name='task_logs', null=True)
     pid = models.IntegerField('PID')
     gpus = models.CharField('GPU', max_length=20)
     log_file_path = models.FilePathField(path='running_log', match='.*\.log$', verbose_name="日志文件")