granicus.if.org Git - postgresql/blob - src/include/utils/resowner.h

   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) 1996-2014, 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
  37 /*
  38  * Resource releasing is done in three phases: pre-locks, locks, and
  39  * post-locks.  The pre-lock phase must release any resources that are
  40  * visible to other backends (such as pinned buffers); this ensures that
  41  * when we release a lock that another backend may be waiting on, it will
  42  * see us as being fully out of our transaction.  The post-lock phase
  43  * should be used for backend-internal cleanup.
  44  */
  45 typedef enum
  46 {
  47         RESOURCE_RELEASE_BEFORE_LOCKS,
  48         RESOURCE_RELEASE_LOCKS,
  49         RESOURCE_RELEASE_AFTER_LOCKS
  50 } ResourceReleasePhase;
  51
  52 /*
  53  *      Dynamically loaded modules can get control during ResourceOwnerRelease
  54  *      by providing a callback of this form.
  55  */
  56 typedef void (*ResourceReleaseCallback) (ResourceReleasePhase phase,
  57                                                                                                          bool isCommit,
  58                                                                                                          bool isTopLevel,
  59                                                                                                          void *arg);
  60
  61
  62 /*
  63  * Functions in resowner.c
  64  */
  65
  66 /* generic routines */
  67 extern ResourceOwner ResourceOwnerCreate(ResourceOwner parent,
  68                                         const char *name);
  69 extern void ResourceOwnerRelease(ResourceOwner owner,
  70                                          ResourceReleasePhase phase,
  71                                          bool isCommit,
  72                                          bool isTopLevel);
  73 extern void ResourceOwnerDelete(ResourceOwner owner);
  74 extern ResourceOwner ResourceOwnerGetParent(ResourceOwner owner);
  75 extern void ResourceOwnerNewParent(ResourceOwner owner,
  76                                            ResourceOwner newparent);
  77 extern void RegisterResourceReleaseCallback(ResourceReleaseCallback callback,
  78                                                                 void *arg);
  79 extern void UnregisterResourceReleaseCallback(ResourceReleaseCallback callback,
  80                                                                   void *arg);
  81
  82 #endif   /* RESOWNER_H */