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db_include/utils/resowner.h

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+/*-------------------------------------------------------------------------
+ *
+ * resowner.h
+ *	  POSTGRES resource owner definitions.
+ *
+ * Query-lifespan resources are tracked by associating them with
+ * ResourceOwner objects.  This provides a simple mechanism for ensuring
+ * that such resources are freed at the right time.
+ * See utils/resowner/README for more info.
+ *
+ *
+ * Portions Copyright (c) 1996-2021, PostgreSQL Global Development Group
+ * Portions Copyright (c) 1994, Regents of the University of California
+ *
+ * src/include/utils/resowner.h
+ *
+ *-------------------------------------------------------------------------
+ */
+#ifndef RESOWNER_H
+#define RESOWNER_H
+
+
+/*
+ * ResourceOwner objects are an opaque data structure known only within
+ * resowner.c.
+ */
+typedef struct ResourceOwnerData *ResourceOwner;
+
+
+/*
+ * Globally known ResourceOwners
+ */
+extern PGDLLIMPORT ResourceOwner CurrentResourceOwner;
+extern PGDLLIMPORT ResourceOwner CurTransactionResourceOwner;
+extern PGDLLIMPORT ResourceOwner TopTransactionResourceOwner;
+extern PGDLLIMPORT ResourceOwner AuxProcessResourceOwner;
+
+/*
+ * Resource releasing is done in three phases: pre-locks, locks, and
+ * post-locks.  The pre-lock phase must release any resources that are
+ * visible to other backends (such as pinned buffers); this ensures that
+ * when we release a lock that another backend may be waiting on, it will
+ * see us as being fully out of our transaction.  The post-lock phase
+ * should be used for backend-internal cleanup.
+ */
+typedef enum
+{
+	RESOURCE_RELEASE_BEFORE_LOCKS,
+	RESOURCE_RELEASE_LOCKS,
+	RESOURCE_RELEASE_AFTER_LOCKS
+} ResourceReleasePhase;
+
+/*
+ *	Dynamically loaded modules can get control during ResourceOwnerRelease
+ *	by providing a callback of this form.
+ */
+typedef void (*ResourceReleaseCallback) (ResourceReleasePhase phase,
+										 bool isCommit,
+										 bool isTopLevel,
+										 void *arg);
+
+
+/*
+ * Functions in resowner.c
+ */
+
+/* generic routines */
+extern ResourceOwner ResourceOwnerCreate(ResourceOwner parent,
+										 const char *name);
+extern void ResourceOwnerRelease(ResourceOwner owner,
+								 ResourceReleasePhase phase,
+								 bool isCommit,
+								 bool isTopLevel);
+extern void ResourceOwnerReleaseAllPlanCacheRefs(ResourceOwner owner);
+extern void ResourceOwnerDelete(ResourceOwner owner);
+extern ResourceOwner ResourceOwnerGetParent(ResourceOwner owner);
+extern void ResourceOwnerNewParent(ResourceOwner owner,
+								   ResourceOwner newparent);
+extern void RegisterResourceReleaseCallback(ResourceReleaseCallback callback,
+											void *arg);
+extern void UnregisterResourceReleaseCallback(ResourceReleaseCallback callback,
+											  void *arg);
+extern void CreateAuxProcessResourceOwner(void);
+extern void ReleaseAuxProcessResources(bool isCommit);
+
+#endif							/* RESOWNER_H */