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/*------------------------------------------------------------------------- * * buf.h * Basic buffer manager data types. * * * Portions Copyright (c) 1996-2012, PostgreSQL Global Development Group * Portions Copyright (c) 1994, Regents of the University of California * * src/include/storage/buf.h * *------------------------------------------------------------------------- */ #ifndef BUF_H #define BUF_H /* * Buffer identifiers. * * Zero is invalid, positive is the index of a shared buffer (1..NBuffers), * negative is the index of a local buffer (-1 .. -NLocBuffer). */ typedef int Buffer; #define InvalidBuffer 0 /* * BufferIsInvalid * True iff the buffer is invalid. */ #define BufferIsInvalid(buffer) ((buffer) == InvalidBuffer) /* * BufferIsLocal * True iff the buffer is local (not visible to other backends). */ #define BufferIsLocal(buffer) ((buffer) < 0) /* * Buffer access strategy objects. * * BufferAccessStrategyData is private to freelist.c */ typedef struct BufferAccessStrategyData *BufferAccessStrategy; #endif /* BUF_H */