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
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
|
/*-------------------------------------------------------------------------
*
* memnodes.h
* POSTGRES memory context node definitions.
*
*
* Portions Copyright (c) 1996-2025, 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
{
/*
* Function to handle memory allocation requests of 'size' to allocate
* memory into the given 'context'. The function must handle flags
* MCXT_ALLOC_HUGE and MCXT_ALLOC_NO_OOM. MCXT_ALLOC_ZERO is handled by
* the calling function.
*/
void *(*alloc) (MemoryContext context, Size size, int flags);
/* call this free_p in case someone #define's free() */
void (*free_p) (void *pointer);
/*
* Function to handle a size change request for an existing allocation.
* The implementation must handle flags MCXT_ALLOC_HUGE and
* MCXT_ALLOC_NO_OOM. MCXT_ALLOC_ZERO is handled by the calling function.
*/
void *(*realloc) (void *pointer, Size size, int flags);
/*
* Invalidate all previous allocations in the given memory context and
* prepare the context for a new set of allocations. Implementations may
* optionally free() excess memory back to the OS during this time.
*/
void (*reset) (MemoryContext context);
/* Free all memory consumed by the given MemoryContext. */
void (*delete_context) (MemoryContext context);
/* Return the MemoryContext that the given pointer belongs to. */
MemoryContext (*get_chunk_context) (void *pointer);
/*
* Return the number of bytes consumed by the given pointer within its
* memory context, including the overhead of alignment and chunk headers.
*/
Size (*get_chunk_space) (void *pointer);
/*
* Return true if the given MemoryContext has not had any allocations
* since it was created or last reset.
*/
bool (*is_empty) (MemoryContext context);
void (*stats) (MemoryContext context,
MemoryStatsPrintFunc printfunc, void *passthru,
MemoryContextCounters *totals,
bool print_to_stderr);
#ifdef MEMORY_CONTEXT_CHECKING
/*
* Perform validation checks on the given context and raise any discovered
* anomalies as WARNINGs.
*/
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 */
const char *ident; /* context ID if any */
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) || \
IsA((context), BumpContext)))
#endif /* MEMNODES_H */
|
