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