1/*-------------------------------------------------------------------------
2 *
3 * spi_priv.h
4 * Server Programming Interface private declarations
5 *
6 * Portions Copyright (c) 1996-2019, PostgreSQL Global Development Group
7 * Portions Copyright (c) 1994, Regents of the University of California
8 *
9 * src/include/executor/spi_priv.h
10 *
11 *-------------------------------------------------------------------------
12 */
13#ifndef SPI_PRIV_H
14#define SPI_PRIV_H
15
16#include "executor/spi.h"
17#include "utils/queryenvironment.h"
18
19
20#define _SPI_PLAN_MAGIC 569278163
21
22typedef struct
23{
24 /* current results */
25 uint64 processed; /* by Executor */
26 SPITupleTable *tuptable; /* tuptable currently being built */
27
28 /* subtransaction in which current Executor call was started */
29 SubTransactionId execSubid;
30
31 /* resources of this execution context */
32 slist_head tuptables; /* list of all live SPITupleTables */
33 MemoryContext procCxt; /* procedure context */
34 MemoryContext execCxt; /* executor context */
35 MemoryContext savedcxt; /* context of SPI_connect's caller */
36 SubTransactionId connectSubid; /* ID of connecting subtransaction */
37 QueryEnvironment *queryEnv; /* query environment setup for SPI level */
38
39 /* transaction management support */
40 bool atomic; /* atomic execution context, does not allow
41 * transactions */
42 bool internal_xact; /* SPI-managed transaction boundary, skip
43 * cleanup */
44
45 /* saved values of API global variables for previous nesting level */
46 uint64 outer_processed;
47 SPITupleTable *outer_tuptable;
48 int outer_result;
49} _SPI_connection;
50
51/*
52 * SPI plans have three states: saved, unsaved, or temporary.
53 *
54 * Ordinarily, the _SPI_plan struct itself as well as the argtypes array
55 * are in a dedicated memory context identified by plancxt (which can be
56 * really small). All the other subsidiary state is in plancache entries
57 * identified by plancache_list (note: the list cells themselves are in
58 * plancxt).
59 *
60 * In an unsaved plan, the plancxt as well as the plancache entries' contexts
61 * are children of the SPI procedure context, so they'll all disappear at
62 * function exit. plancache.c also knows that the plancache entries are
63 * "unsaved", so it doesn't link them into its global list; hence they do
64 * not respond to inval events. This is OK since we are presumably holding
65 * adequate locks to prevent other backends from messing with the tables.
66 *
67 * For a saved plan, the plancxt is made a child of CacheMemoryContext
68 * since it should persist until explicitly destroyed. Likewise, the
69 * plancache entries will be under CacheMemoryContext since we tell
70 * plancache.c to save them. We rely on plancache.c to keep the cache
71 * entries up-to-date as needed in the face of invalidation events.
72 *
73 * There are also "temporary" SPI plans, in which the _SPI_plan struct is
74 * not even palloc'd but just exists in some function's local variable.
75 * The plancache entries are unsaved and exist under the SPI executor context,
76 * while additional data such as argtypes and list cells is loose in the SPI
77 * executor context. Such plans can be identified by having plancxt == NULL.
78 *
79 * We can also have "one-shot" SPI plans (which are typically temporary,
80 * as described above). These are meant to be executed once and discarded,
81 * and various optimizations are made on the assumption of single use.
82 * Note in particular that the CachedPlanSources within such an SPI plan
83 * are not "complete" until execution.
84 *
85 * Note: if the original query string contained only whitespace and comments,
86 * the plancache_list will be NIL and so there is no place to store the
87 * query string. We don't care about that, but we do care about the
88 * argument type array, which is why it's seemingly-redundantly stored.
89 */
90typedef struct _SPI_plan
91{
92 int magic; /* should equal _SPI_PLAN_MAGIC */
93 bool saved; /* saved or unsaved plan? */
94 bool oneshot; /* one-shot plan? */
95 bool no_snapshots; /* let the caller handle the snapshots */
96 List *plancache_list; /* one CachedPlanSource per parsetree */
97 MemoryContext plancxt; /* Context containing _SPI_plan and data */
98 int cursor_options; /* Cursor options used for planning */
99 int nargs; /* number of plan arguments */
100 Oid *argtypes; /* Argument types (NULL if nargs is 0) */
101 ParserSetupHook parserSetup; /* alternative parameter spec method */
102 void *parserSetupArg;
103} _SPI_plan;
104
105#endif /* SPI_PRIV_H */
106