Line data Source code
1 : /*-------------------------------------------------------------------------
2 : *
3 : * explain_state.c
4 : * Code for initializing and accessing ExplainState objects
5 : *
6 : * Portions Copyright (c) 1996-2025, PostgreSQL Global Development Group
7 : * Portions Copyright (c) 1994-5, Regents of the University of California
8 : *
9 : * In-core options have hard-coded fields inside ExplainState; e.g. if
10 : * the user writes EXPLAIN (BUFFERS) then ExplainState's "buffers" member
11 : * will be set to true. Extensions can also register options using
12 : * RegisterExtensionExplainOption; so that e.g. EXPLAIN (BICYCLE 'red')
13 : * will invoke a designated handler that knows what the legal values are
14 : * for the BICYCLE option. However, it's not enough for an extension to be
15 : * able to parse new options: it also needs a place to store the results
16 : * of that parsing, and an ExplainState has no 'bicycle' field.
17 : *
18 : * To solve this problem, an ExplainState can contain an array of opaque
19 : * pointers, one per extension. An extension can use GetExplainExtensionId
20 : * to acquire an integer ID to acquire an offset into this array that is
21 : * reserved for its exclusive use, and then use GetExplainExtensionState
22 : * and SetExplainExtensionState to read and write its own private state
23 : * within an ExplainState.
24 : *
25 : * Note that there is no requirement that the name of the option match
26 : * the name of the extension; e.g. a pg_explain_conveyance extension could
27 : * implement options for BICYCLE, MONORAIL, etc.
28 : *
29 : * IDENTIFICATION
30 : * src/backend/commands/explain_state.c
31 : *
32 : *-------------------------------------------------------------------------
33 : */
34 : #include "postgres.h"
35 :
36 : #include "commands/defrem.h"
37 : #include "commands/explain.h"
38 : #include "commands/explain_state.h"
39 :
40 : /* Hook to perform additional EXPLAIN options validation */
41 : explain_validate_options_hook_type explain_validate_options_hook = NULL;
42 :
43 : typedef struct
44 : {
45 : const char *option_name;
46 : ExplainOptionHandler option_handler;
47 : } ExplainExtensionOption;
48 :
49 : static const char **ExplainExtensionNameArray = NULL;
50 : static int ExplainExtensionNamesAssigned = 0;
51 : static int ExplainExtensionNamesAllocated = 0;
52 :
53 : static ExplainExtensionOption *ExplainExtensionOptionArray = NULL;
54 : static int ExplainExtensionOptionsAssigned = 0;
55 : static int ExplainExtensionOptionsAllocated = 0;
56 :
57 : /*
58 : * Create a new ExplainState struct initialized with default options.
59 : */
60 : ExplainState *
61 23502 : NewExplainState(void)
62 : {
63 23502 : ExplainState *es = (ExplainState *) palloc0(sizeof(ExplainState));
64 :
65 : /* Set default options (most fields can be left as zeroes). */
66 23502 : es->costs = true;
67 : /* Prepare output buffer. */
68 23502 : es->str = makeStringInfo();
69 :
70 23502 : return es;
71 : }
72 :
73 : /*
74 : * Parse a list of EXPLAIN options and update an ExplainState accordingly.
75 : */
76 : void
77 23482 : ParseExplainOptionList(ExplainState *es, List *options, ParseState *pstate)
78 : {
79 : ListCell *lc;
80 23482 : bool timing_set = false;
81 23482 : bool buffers_set = false;
82 23482 : bool summary_set = false;
83 :
84 : /* Parse options list. */
85 45430 : foreach(lc, options)
86 : {
87 21956 : DefElem *opt = (DefElem *) lfirst(lc);
88 :
89 21956 : if (strcmp(opt->defname, "analyze") == 0)
90 3436 : es->analyze = defGetBoolean(opt);
91 18520 : else if (strcmp(opt->defname, "verbose") == 0)
92 2404 : es->verbose = defGetBoolean(opt);
93 16116 : else if (strcmp(opt->defname, "costs") == 0)
94 13076 : es->costs = defGetBoolean(opt);
95 3040 : else if (strcmp(opt->defname, "buffers") == 0)
96 : {
97 928 : buffers_set = true;
98 928 : es->buffers = defGetBoolean(opt);
99 : }
100 2112 : else if (strcmp(opt->defname, "wal") == 0)
101 0 : es->wal = defGetBoolean(opt);
102 2112 : else if (strcmp(opt->defname, "settings") == 0)
103 12 : es->settings = defGetBoolean(opt);
104 2100 : else if (strcmp(opt->defname, "generic_plan") == 0)
105 18 : es->generic = defGetBoolean(opt);
106 2082 : else if (strcmp(opt->defname, "timing") == 0)
107 : {
108 852 : timing_set = true;
109 852 : es->timing = defGetBoolean(opt);
110 : }
111 1230 : else if (strcmp(opt->defname, "summary") == 0)
112 : {
113 828 : summary_set = true;
114 828 : es->summary = defGetBoolean(opt);
115 : }
116 402 : else if (strcmp(opt->defname, "memory") == 0)
117 30 : es->memory = defGetBoolean(opt);
118 372 : else if (strcmp(opt->defname, "serialize") == 0)
119 : {
120 30 : if (opt->arg)
121 : {
122 12 : char *p = defGetString(opt);
123 :
124 12 : if (strcmp(p, "off") == 0 || strcmp(p, "none") == 0)
125 0 : es->serialize = EXPLAIN_SERIALIZE_NONE;
126 12 : else if (strcmp(p, "text") == 0)
127 6 : es->serialize = EXPLAIN_SERIALIZE_TEXT;
128 6 : else if (strcmp(p, "binary") == 0)
129 6 : es->serialize = EXPLAIN_SERIALIZE_BINARY;
130 : else
131 0 : ereport(ERROR,
132 : (errcode(ERRCODE_INVALID_PARAMETER_VALUE),
133 : errmsg("unrecognized value for EXPLAIN option \"%s\": \"%s\"",
134 : opt->defname, p),
135 : parser_errposition(pstate, opt->location)));
136 : }
137 : else
138 : {
139 : /* SERIALIZE without an argument is taken as 'text' */
140 18 : es->serialize = EXPLAIN_SERIALIZE_TEXT;
141 : }
142 : }
143 342 : else if (strcmp(opt->defname, "format") == 0)
144 : {
145 312 : char *p = defGetString(opt);
146 :
147 312 : if (strcmp(p, "text") == 0)
148 12 : es->format = EXPLAIN_FORMAT_TEXT;
149 300 : else if (strcmp(p, "xml") == 0)
150 8 : es->format = EXPLAIN_FORMAT_XML;
151 292 : else if (strcmp(p, "json") == 0)
152 280 : es->format = EXPLAIN_FORMAT_JSON;
153 12 : else if (strcmp(p, "yaml") == 0)
154 12 : es->format = EXPLAIN_FORMAT_YAML;
155 : else
156 0 : ereport(ERROR,
157 : (errcode(ERRCODE_INVALID_PARAMETER_VALUE),
158 : errmsg("unrecognized value for EXPLAIN option \"%s\": \"%s\"",
159 : opt->defname, p),
160 : parser_errposition(pstate, opt->location)));
161 : }
162 30 : else if (!ApplyExtensionExplainOption(es, opt, pstate))
163 8 : ereport(ERROR,
164 : (errcode(ERRCODE_SYNTAX_ERROR),
165 : errmsg("unrecognized EXPLAIN option \"%s\"",
166 : opt->defname),
167 : parser_errposition(pstate, opt->location)));
168 : }
169 :
170 : /* check that WAL is used with EXPLAIN ANALYZE */
171 23474 : if (es->wal && !es->analyze)
172 0 : ereport(ERROR,
173 : (errcode(ERRCODE_INVALID_PARAMETER_VALUE),
174 : errmsg("EXPLAIN option %s requires ANALYZE", "WAL")));
175 :
176 : /* if the timing was not set explicitly, set default value */
177 23474 : es->timing = (timing_set) ? es->timing : es->analyze;
178 :
179 : /* if the buffers was not set explicitly, set default value */
180 23474 : es->buffers = (buffers_set) ? es->buffers : es->analyze;
181 :
182 : /* check that timing is used with EXPLAIN ANALYZE */
183 23474 : if (es->timing && !es->analyze)
184 0 : ereport(ERROR,
185 : (errcode(ERRCODE_INVALID_PARAMETER_VALUE),
186 : errmsg("EXPLAIN option %s requires ANALYZE", "TIMING")));
187 :
188 : /* check that serialize is used with EXPLAIN ANALYZE */
189 23474 : if (es->serialize != EXPLAIN_SERIALIZE_NONE && !es->analyze)
190 0 : ereport(ERROR,
191 : (errcode(ERRCODE_INVALID_PARAMETER_VALUE),
192 : errmsg("EXPLAIN option %s requires ANALYZE", "SERIALIZE")));
193 :
194 : /* check that GENERIC_PLAN is not used with EXPLAIN ANALYZE */
195 23474 : if (es->generic && es->analyze)
196 6 : ereport(ERROR,
197 : (errcode(ERRCODE_INVALID_PARAMETER_VALUE),
198 : errmsg("EXPLAIN options ANALYZE and GENERIC_PLAN cannot be used together")));
199 :
200 : /* if the summary was not set explicitly, set default value */
201 23468 : es->summary = (summary_set) ? es->summary : es->analyze;
202 :
203 : /* plugin specific option validation */
204 23468 : if (explain_validate_options_hook)
205 0 : (*explain_validate_options_hook) (es, options, pstate);
206 23468 : }
207 :
208 : /*
209 : * Map the name of an EXPLAIN extension to an integer ID.
210 : *
211 : * Within the lifetime of a particular backend, the same name will be mapped
212 : * to the same ID every time. IDs are not stable across backends. Use the ID
213 : * that you get from this function to call GetExplainExtensionState and
214 : * SetExplainExtensionState.
215 : *
216 : * extension_name is assumed to be a constant string or allocated in storage
217 : * that will never be freed.
218 : */
219 : int
220 2 : GetExplainExtensionId(const char *extension_name)
221 : {
222 : /* Search for an existing extension by this name; if found, return ID. */
223 2 : for (int i = 0; i < ExplainExtensionNamesAssigned; ++i)
224 0 : if (strcmp(ExplainExtensionNameArray[i], extension_name) == 0)
225 0 : return i;
226 :
227 : /* If there is no array yet, create one. */
228 2 : if (ExplainExtensionNameArray == NULL)
229 : {
230 2 : ExplainExtensionNamesAllocated = 16;
231 2 : ExplainExtensionNameArray = (const char **)
232 2 : MemoryContextAlloc(TopMemoryContext,
233 : ExplainExtensionNamesAllocated
234 : * sizeof(char *));
235 : }
236 :
237 : /* If there's an array but it's currently full, expand it. */
238 2 : if (ExplainExtensionNamesAssigned >= ExplainExtensionNamesAllocated)
239 : {
240 0 : int i = pg_nextpower2_32(ExplainExtensionNamesAssigned + 1);
241 :
242 0 : ExplainExtensionNameArray = (const char **)
243 0 : repalloc(ExplainExtensionNameArray, i * sizeof(char *));
244 0 : ExplainExtensionNamesAllocated = i;
245 : }
246 :
247 : /* Assign and return new ID. */
248 2 : ExplainExtensionNameArray[ExplainExtensionNamesAssigned] = extension_name;
249 2 : return ExplainExtensionNamesAssigned++;
250 : }
251 :
252 : /*
253 : * Get extension-specific state from an ExplainState.
254 : *
255 : * See comments for SetExplainExtensionState, below.
256 : */
257 : void *
258 100 : GetExplainExtensionState(ExplainState *es, int extension_id)
259 : {
260 : Assert(extension_id >= 0);
261 :
262 100 : if (extension_id >= es->extension_state_allocated)
263 18 : return NULL;
264 :
265 82 : return es->extension_state[extension_id];
266 : }
267 :
268 : /*
269 : * Store extension-specific state into an ExplainState.
270 : *
271 : * To use this function, first obtain an integer extension_id using
272 : * GetExplainExtensionId. Then use this function to store an opaque pointer
273 : * in the ExplainState. Later, you can retrieve the opaque pointer using
274 : * GetExplainExtensionState.
275 : */
276 : void
277 18 : SetExplainExtensionState(ExplainState *es, int extension_id, void *opaque)
278 : {
279 : Assert(extension_id >= 0);
280 :
281 : /* If there is no array yet, create one. */
282 18 : if (es->extension_state == NULL)
283 : {
284 18 : es->extension_state_allocated = 16;
285 18 : es->extension_state =
286 18 : palloc0(es->extension_state_allocated * sizeof(void *));
287 : }
288 :
289 : /* If there's an array but it's currently full, expand it. */
290 18 : if (extension_id >= es->extension_state_allocated)
291 : {
292 : int i;
293 :
294 0 : i = pg_nextpower2_32(es->extension_state_allocated + 1);
295 0 : es->extension_state = (void **)
296 0 : repalloc0(es->extension_state,
297 0 : es->extension_state_allocated * sizeof(void *),
298 : i * sizeof(void *));
299 0 : es->extension_state_allocated = i;
300 : }
301 :
302 18 : es->extension_state[extension_id] = opaque;
303 18 : }
304 :
305 : /*
306 : * Register a new EXPLAIN option.
307 : *
308 : * When option_name is used as an EXPLAIN option, handler will be called and
309 : * should update the ExplainState passed to it. See comments at top of file
310 : * for a more detailed explanation.
311 : *
312 : * option_name is assumed to be a constant string or allocated in storage
313 : * that will never be freed.
314 : */
315 : void
316 4 : RegisterExtensionExplainOption(const char *option_name,
317 : ExplainOptionHandler handler)
318 : {
319 : ExplainExtensionOption *exopt;
320 :
321 : /* Search for an existing option by this name; if found, update handler. */
322 6 : for (int i = 0; i < ExplainExtensionOptionsAssigned; ++i)
323 : {
324 2 : if (strcmp(ExplainExtensionOptionArray[i].option_name,
325 : option_name) == 0)
326 : {
327 0 : ExplainExtensionOptionArray[i].option_handler = handler;
328 0 : return;
329 : }
330 : }
331 :
332 : /* If there is no array yet, create one. */
333 4 : if (ExplainExtensionOptionArray == NULL)
334 : {
335 2 : ExplainExtensionOptionsAllocated = 16;
336 2 : ExplainExtensionOptionArray = (ExplainExtensionOption *)
337 2 : MemoryContextAlloc(TopMemoryContext,
338 : ExplainExtensionOptionsAllocated
339 : * sizeof(char *));
340 : }
341 :
342 : /* If there's an array but it's currently full, expand it. */
343 4 : if (ExplainExtensionOptionsAssigned >= ExplainExtensionOptionsAllocated)
344 : {
345 0 : int i = pg_nextpower2_32(ExplainExtensionOptionsAssigned + 1);
346 :
347 0 : ExplainExtensionOptionArray = (ExplainExtensionOption *)
348 0 : repalloc(ExplainExtensionOptionArray, i * sizeof(char *));
349 0 : ExplainExtensionOptionsAllocated = i;
350 : }
351 :
352 : /* Assign and return new ID. */
353 4 : exopt = &ExplainExtensionOptionArray[ExplainExtensionOptionsAssigned++];
354 4 : exopt->option_name = option_name;
355 4 : exopt->option_handler = handler;
356 : }
357 :
358 : /*
359 : * Apply an EXPLAIN option registered by an extension.
360 : *
361 : * If no extension has registered the named option, returns false. Otherwise,
362 : * calls the appropriate handler function and then returns true.
363 : */
364 : bool
365 30 : ApplyExtensionExplainOption(ExplainState *es, DefElem *opt, ParseState *pstate)
366 : {
367 44 : for (int i = 0; i < ExplainExtensionOptionsAssigned; ++i)
368 : {
369 36 : if (strcmp(ExplainExtensionOptionArray[i].option_name,
370 36 : opt->defname) == 0)
371 : {
372 22 : ExplainExtensionOptionArray[i].option_handler(es, opt, pstate);
373 22 : return true;
374 : }
375 : }
376 :
377 8 : return false;
378 : }
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