1 /*-------------------------------------------------------------------------
2  *
3  * resowner.h
4  *	  POSTGRES resource owner definitions.
5  *
6  * Query-lifespan resources are tracked by associating them with
7  * ResourceOwner objects.  This provides a simple mechanism for ensuring
8  * that such resources are freed at the right time.
9  * See utils/resowner/README for more info.
10  *
11  *
12  * Portions Copyright (c) 1996-2021, PostgreSQL Global Development Group
13  * Portions Copyright (c) 1994, Regents of the University of California
14  *
15  * src/include/utils/resowner.h
16  *
17  *-------------------------------------------------------------------------
18  */
19 #ifndef RESOWNER_H
20 #define RESOWNER_H
21 
22 
23 /*
24  * ResourceOwner objects are an opaque data structure known only within
25  * resowner.c.
26  */
27 typedef struct ResourceOwnerData *ResourceOwner;
28 
29 
30 /*
31  * Globally known ResourceOwners
32  */
33 extern PGDLLIMPORT ResourceOwner CurrentResourceOwner;
34 extern PGDLLIMPORT ResourceOwner CurTransactionResourceOwner;
35 extern PGDLLIMPORT ResourceOwner TopTransactionResourceOwner;
36 extern PGDLLIMPORT ResourceOwner AuxProcessResourceOwner;
37 
38 /*
39  * Resource releasing is done in three phases: pre-locks, locks, and
40  * post-locks.  The pre-lock phase must release any resources that are
41  * visible to other backends (such as pinned buffers); this ensures that
42  * when we release a lock that another backend may be waiting on, it will
43  * see us as being fully out of our transaction.  The post-lock phase
44  * should be used for backend-internal cleanup.
45  */
46 typedef enum
47 {
48 	RESOURCE_RELEASE_BEFORE_LOCKS,
49 	RESOURCE_RELEASE_LOCKS,
50 	RESOURCE_RELEASE_AFTER_LOCKS
51 } ResourceReleasePhase;
52 
53 /*
54  *	Dynamically loaded modules can get control during ResourceOwnerRelease
55  *	by providing a callback of this form.
56  */
57 typedef void (*ResourceReleaseCallback) (ResourceReleasePhase phase,
58 										 bool isCommit,
59 										 bool isTopLevel,
60 										 void *arg);
61 
62 
63 /*
64  * Functions in resowner.c
65  */
66 
67 /* generic routines */
68 extern ResourceOwner ResourceOwnerCreate(ResourceOwner parent,
69 										 const char *name);
70 extern void ResourceOwnerRelease(ResourceOwner owner,
71 								 ResourceReleasePhase phase,
72 								 bool isCommit,
73 								 bool isTopLevel);
74 extern void ResourceOwnerReleaseAllPlanCacheRefs(ResourceOwner owner);
75 extern void ResourceOwnerDelete(ResourceOwner owner);
76 extern ResourceOwner ResourceOwnerGetParent(ResourceOwner owner);
77 extern void ResourceOwnerNewParent(ResourceOwner owner,
78 								   ResourceOwner newparent);
79 extern void RegisterResourceReleaseCallback(ResourceReleaseCallback callback,
80 											void *arg);
81 extern void UnregisterResourceReleaseCallback(ResourceReleaseCallback callback,
82 											  void *arg);
83 extern void CreateAuxProcessResourceOwner(void);
84 extern void ReleaseAuxProcessResources(bool isCommit);
85 
86 #endif							/* RESOWNER_H */
87