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e00912e11a
An AllocSet doubles the size of allocated blocks (up to maxBlockSize), which means that the current block can represent half of the total allocated space for the memory context. But the free space in the current block may never have been touched, so don't count the untouched memory as allocated for the purposes of MemoryContextMemAllocated(). Discussion: https://postgr.es/m/ec63d70b668818255486a83ffadc3aec492c1f57.camel@j-davis.com
109 lines
3.9 KiB
C
109 lines
3.9 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) 1996-2020, 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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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) (MemoryContext context, void *pointer);
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void *(*realloc) (MemoryContext context, 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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Size (*get_chunk_space) (MemoryContext context, void *pointer);
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Size (*mem_allocated) (MemoryContext context);
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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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#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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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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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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