greenplumn backend_cancel 代码
文件路径：/src/include/utils/backend_cancel.h
/*-------------------------------------------------------------------------
*
* backend_cancel.h
* Declarations for backend cancellation messaging
*
* Portions Copyright (c) 1996-2017, PostgreSQL Global Development Group
*
* src/include/utils/backend_cancel.h
*
*-------------------------------------------------------------------------
*/
#ifndef BACKEND_CANCEL_H
#define BACKEND_CANCEL_H
#define MAX_CANCEL_MSG 128
extern Size CancelBackendMsgShmemSize(void);
extern void BackendCancelShmemInit(void);
extern void BackendCancelInit(int backend_id);
extern int SetBackendCancelMessage(pid_t backend, char *message);
extern bool HasCancelMessage(void);
extern int GetCancelMessage(char **msg, size_t len);
#endif /* BACKEND_CANCEL_H */