PostgreSQL服务端开发学习 --- 常用结构及宏定义1

/* magic block structure */typedefstruct{
intlen;            /* sizeof(this struct) */intversion;        /* PostgreSQL major version */intfuncmaxargs;    /* FUNC_MAX_ARGS */intindexmaxkeys;   /* INDEX_MAX_KEYS */intnamedatalen;    /* NAMEDATALEN */intfloat8byval;    /* FLOAT8PASSBYVAL */charabi_extra[32];  /* see pg_config_manual.h */} Pg_magic_struct;
/* * 生成实际的数据块内容 * PG_VERSION_NUM - 在pg_config.h中定义，本例是150002* FUNC_MAX_ARGS - 在pg_config_manual.h中定义，缺省值是100* INDEX_MAX_KEYS - 在pg_config_manual.h中定义，缺省值是32* NAMEDATALEN - 在pg_config_manual.h中定义，缺省值是64* FLOAT8PASSBYVAL - 在c.h中定义，缺省值是true* FMGR_ABI_EXTRA - pg_config_manual.h中定义，缺省值是"PostgreSQL"*/#define PG_MODULE_MAGIC_DATA \{ \sizeof(Pg_magic_struct), \PG_VERSION_NUM / 100, \FUNC_MAX_ARGS, \INDEX_MAX_KEYS, \NAMEDATALEN, \FLOAT8PASSBYVAL, \FMGR_ABI_EXTRA, \}/* FMGR_ABI_EXTRA自义在pg_config_manual.h中* 内容为 "PostgreSQL"*/StaticAssertDecl(sizeof(FMGR_ABI_EXTRA) <=sizeof(((Pg_magic_struct*) 0)->abi_extra),
"FMGR_ABI_EXTRA too long");
/** Declare the module magic function.  It needs to be a function as the dlsym* in the backend is only guaranteed to work on functions, not data*/typedefconstPg_magic_struct*(*PGModuleMagicFunction) (void);
#define PG_MAGIC_FUNCTION_NAME Pg_magic_func#define PG_MAGIC_FUNCTION_NAME_STRING "Pg_magic_func"#define PG_MODULE_MAGIC \extern PGDLLEXPORT const Pg_magic_struct *PG_MAGIC_FUNCTION_NAME(void); \const Pg_magic_struct * \PG_MAGIC_FUNCTION_NAME(void) \{ \static const Pg_magic_struct Pg_magic_data = PG_MODULE_MAGIC_DATA; \return &Pg_magic_data; \} \extern int no_such_variable

externPGDLLEXPORTconstPg_magic_struct*Pg_magic_func(void);
constPg_magic_struct*Pg_magic_func(void) 
{ 
staticconstPg_magic_structPg_magic_data= {
sizeof(Pg_magic_struct),
150002/100,
100,
32,
64,
1,
"PostgreSQL",    
    }; 
return&Pg_magic_data;
} 
externintno_such_variable

typedefstruct{
intapi_version;    /* 指定调用约定版本 *//* More fields may be added later, for version numbers > 1. */} Pg_finfo_record;
/* info函数的签名 */typedefconstPg_finfo_record*(*PGFInfoFunction) (void);
#define PG_FUNCTION_INFO_V1(funcname) \extern Datum funcname(PG_FUNCTION_ARGS); \extern PGDLLEXPORT const Pg_finfo_record * CppConcat(pg_finfo_,funcname)(void); \const Pg_finfo_record * \CppConcat(pg_finfo_,funcname) (void) \{ \static const Pg_finfo_record my_finfo = { 1 }; \return &my_finfo; \} \extern int no_such_variable

/** 所有可被fmgr直接调用的函数必须有如下签名，相关struct以后讲*/typedefstructFunctionCallInfoBaseData*FunctionCallInfo;
typedefDatum (*PGFunction) (FunctionCallInfofcinfo);
externDatumpgpool_recovery(FunctionCallInfofcinfo);
externPGDLLEXPORTconstPg_finfo_record*pg_finfo_pgpool_recovery(void)
{
staticconstPg_finfo_recordmy_finfo= { 1 }; 
return&my_finfo;    
}
externintno_such_variable