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buf.h
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1 /*-------------------------------------------------------------------------
2  *
3  * buf.h
4  * Basic buffer manager data types.
5  *
6  *
7  * Portions Copyright (c) 1996-2024, PostgreSQL Global Development Group
8  * Portions Copyright (c) 1994, Regents of the University of California
9  *
10  * src/include/storage/buf.h
11  *
12  *-------------------------------------------------------------------------
13  */
14 #ifndef BUF_H
15 #define BUF_H
16 
17 /*
18  * Buffer identifiers.
19  *
20  * Zero is invalid, positive is the index of a shared buffer (1..NBuffers),
21  * negative is the index of a local buffer (-1 .. -NLocBuffer).
22  */
23 typedef int Buffer;
24 
25 #define InvalidBuffer 0
26 
27 /*
28  * BufferIsInvalid
29  * True iff the buffer is invalid.
30  */
31 #define BufferIsInvalid(buffer) ((buffer) == InvalidBuffer)
32 
33 /*
34  * BufferIsLocal
35  * True iff the buffer is local (not visible to other backends).
36  */
37 #define BufferIsLocal(buffer) ((buffer) < 0)
38 
39 /*
40  * Buffer access strategy objects.
41  *
42  * BufferAccessStrategyData is private to freelist.c
43  */
44 typedef struct BufferAccessStrategyData *BufferAccessStrategy;
45 
46 #endif /* BUF_H */
Buffer
int Buffer
Definition: buf.h:23
BufferAccessStrategy
struct BufferAccessStrategyData * BufferAccessStrategy
Definition: buf.h:44