1 files changed, 113 insertions, 0 deletions
diff --git a/src/include/nodes/memnodes.h b/src/include/nodes/memnodes.h
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+/*-------------------------------------------------------------------------
+ *
+ * memnodes.h
+ *	  POSTGRES memory context node definitions.
+ *
+ *
+ * Portions Copyright (c) 1996-2023, PostgreSQL Global Development Group
+ * Portions Copyright (c) 1994, Regents of the University of California
+ *
+ * src/include/nodes/memnodes.h
+ *
+ *-------------------------------------------------------------------------
+ */
+#ifndef MEMNODES_H
+#define MEMNODES_H
+
+#include "nodes/nodes.h"
+
+/*
+ * MemoryContextCounters
+ *		Summarization state for MemoryContextStats collection.
+ *
+ * The set of counters in this struct is biased towards AllocSet; if we ever
+ * add any context types that are based on fundamentally different approaches,
+ * we might need more or different counters here.  A possible API spec then
+ * would be to print only nonzero counters, but for now we just summarize in
+ * the format historically used by AllocSet.
+ */
+typedef struct MemoryContextCounters
+{
+	Size		nblocks;		/* Total number of malloc blocks */
+	Size		freechunks;		/* Total number of free chunks */
+	Size		totalspace;		/* Total bytes requested from malloc */
+	Size		freespace;		/* The unused portion of totalspace */
+} MemoryContextCounters;
+
+/*
+ * MemoryContext
+ *		A logical context in which memory allocations occur.
+ *
+ * MemoryContext itself is an abstract type that can have multiple
+ * implementations.
+ * The function pointers in MemoryContextMethods define one specific
+ * implementation of MemoryContext --- they are a virtual function table
+ * in C++ terms.
+ *
+ * Node types that are actual implementations of memory contexts must
+ * begin with the same fields as MemoryContextData.
+ *
+ * Note: for largely historical reasons, typedef MemoryContext is a pointer
+ * to the context struct rather than the struct type itself.
+ */
+
+typedef void (*MemoryStatsPrintFunc) (MemoryContext context, void *passthru,
+									  const char *stats_string,
+									  bool print_to_stderr);
+
+typedef struct MemoryContextMethods
+{
+	void	   *(*alloc) (MemoryContext context, Size size);
+	/* call this free_p in case someone #define's free() */
+	void		(*free_p) (void *pointer);
+	void	   *(*realloc) (void *pointer, Size size);
+	void		(*reset) (MemoryContext context);
+	void		(*delete_context) (MemoryContext context);
+	MemoryContext (*get_chunk_context) (void *pointer);
+	Size		(*get_chunk_space) (void *pointer);
+	bool		(*is_empty) (MemoryContext context);
+	void		(*stats) (MemoryContext context,
+						  MemoryStatsPrintFunc printfunc, void *passthru,
+						  MemoryContextCounters *totals,
+						  bool print_to_stderr);
+#ifdef MEMORY_CONTEXT_CHECKING
+	void		(*check) (MemoryContext context);
+#endif
+} MemoryContextMethods;
+
+
+typedef struct MemoryContextData
+{
+	pg_node_attr(abstract)		/* there are no nodes of this type */
+
+	NodeTag		type;			/* identifies exact kind of context */
+	/* these two fields are placed here to minimize alignment wastage: */
+	bool		isReset;		/* T = no space alloced since last reset */
+	bool		allowInCritSection; /* allow palloc in critical section */
+	Size		mem_allocated;	/* track memory allocated for this context */
+	const MemoryContextMethods *methods;	/* virtual function table */
+	MemoryContext parent;		/* NULL if no parent (toplevel context) */
+	MemoryContext firstchild;	/* head of linked list of children */
+	MemoryContext prevchild;	/* previous child of same parent */
+	MemoryContext nextchild;	/* next child of same parent */
+	const char *name;			/* context name (just for debugging) */
+	const char *ident;			/* context ID if any (just for debugging) */
+	MemoryContextCallback *reset_cbs;	/* list of reset/delete callbacks */
+} MemoryContextData;
+
+/* utils/palloc.h contains typedef struct MemoryContextData *MemoryContext */
+
+
+/*
+ * MemoryContextIsValid
+ *		True iff memory context is valid.
+ *
+ * Add new context types to the set accepted by this macro.
+ */
+#define MemoryContextIsValid(context) \
+	((context) != NULL && \
+	 (IsA((context), AllocSetContext) || \
+	  IsA((context), SlabContext) || \
+	  IsA((context), GenerationContext)))
+
+#endif							/* MEMNODES_H */