1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
|
/*-------------------------------------------------------------------------
*
* memnodes.h
* POSTGRES memory context node definitions.
*
*
* Portions Copyright (c) 1996-2000, PostgreSQL, Inc
* Portions Copyright (c) 1994, Regents of the University of California
*
* $Id: memnodes.h,v 1.18 2000/07/11 14:30:34 momjian Exp $
*
*-------------------------------------------------------------------------
*/
#ifndef MEMNODES_H
#define MEMNODES_H
#include "nodes/nodes.h"
/*
* MemoryContext
* A logical context in which memory allocations occur.
*
* MemoryContext itself is an abstract type that can have multiple
* implementations, though for now we have only AllocSetContext.
* 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 MemoryContext.
*
* Note: for largely historical reasons, typedef MemoryContext is a pointer
* to the context struct rather than the struct type itself.
*/
typedef struct MemoryContextMethods
{
void *(*alloc) (MemoryContext context, Size size);
/* call this free_p in case someone #define's free() */
void (*free_p) (MemoryContext context, void *pointer);
void *(*realloc) (MemoryContext context, void *pointer, Size size);
void (*init) (MemoryContext context);
void (*reset) (MemoryContext context);
void (*delete) (MemoryContext context);
#ifdef MEMORY_CONTEXT_CHECKING
void (*check) (MemoryContext context);
#endif
void (*stats) (MemoryContext context);
} MemoryContextMethods;
typedef struct MemoryContextData
{
NodeTag type; /* identifies exact kind of context */
MemoryContextMethods *methods; /* virtual function table */
MemoryContext parent; /* NULL if no parent (toplevel context) */
MemoryContext firstchild; /* head of linked list of children */
MemoryContext nextchild; /* next child of same parent */
char *name; /* context name (just for debugging) */
} MemoryContextData;
/* utils/palloc.h contains typedef struct MemoryContextData *MemoryContext */
/*
* AllocSetContext is our standard implementation of MemoryContext.
*/
typedef struct AllocBlockData *AllocBlock; /* internal to aset.c */
typedef struct AllocChunkData *AllocChunk;
typedef struct AllocSetContext
{
MemoryContextData header; /* Standard memory-context fields */
/* Info about storage allocated in this context: */
AllocBlock blocks; /* head of list of blocks in this set */
#define ALLOCSET_NUM_FREELISTS 8
AllocChunk freelist[ALLOCSET_NUM_FREELISTS]; /* free chunk lists */
/* Allocation parameters for this context: */
Size initBlockSize; /* initial block size */
Size maxBlockSize; /* maximum block size */
AllocBlock keeper; /* if not NULL, keep this block
* over resets */
} AllocSetContext;
/*
* 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)))
#endif /* MEMNODES_H */
|
