Age Owner Branch data TLA Line data Source code
1 : : /*
2 : : * task.c
3 : : * framework for parallelizing pg_upgrade's once-in-each-database tasks
4 : : *
5 : : * This framework provides an efficient way of running the various
6 : : * once-in-each-database tasks required by pg_upgrade. Specifically, it
7 : : * parallelizes these tasks by managing a set of slots that follow a simple
8 : : * state machine and by using libpq's asynchronous APIs to establish the
9 : : * connections and run the queries. Callers simply need to create a callback
10 : : * function and build/execute an UpgradeTask. A simple example follows:
11 : : *
12 : : * static void
13 : : * my_process_cb(DbInfo *dbinfo, PGresult *res, void *arg)
14 : : * {
15 : : * for (int i = 0; i < PQntuples(res); i++)
16 : : * {
17 : : * ... process results ...
18 : : * }
19 : : * }
20 : : *
21 : : * void
22 : : * my_task(ClusterInfo *cluster)
23 : : * {
24 : : * UpgradeTask *task = upgrade_task_create();
25 : : *
26 : : * upgrade_task_add_step(task,
27 : : * "... query text ...",
28 : : * my_process_cb,
29 : : * true, // let the task free the PGresult
30 : : * NULL); // "arg" pointer for callback
31 : : * upgrade_task_run(task, cluster);
32 : : * upgrade_task_free(task);
33 : : * }
34 : : *
35 : : * Note that multiple steps can be added to a given task. When there are
36 : : * multiple steps, the task will run all of the steps consecutively in the same
37 : : * database connection before freeing the connection and moving on. In other
38 : : * words, it only ever initiates one connection to each database in the
39 : : * cluster for a given run.
40 : : *
41 : : * Copyright (c) 2024-2026, PostgreSQL Global Development Group
42 : : * src/bin/pg_upgrade/task.c
43 : : */
44 : :
45 : : #include "postgres_fe.h"
46 : :
47 : : #include "common/connect.h"
48 : : #include "fe_utils/string_utils.h"
49 : : #include "pg_upgrade.h"
50 : :
51 : : /*
52 : : * dbs_complete stores the number of databases that we have completed
53 : : * processing. When this value equals the number of databases in the cluster,
54 : : * the task is finished.
55 : : */
56 : : static int dbs_complete;
57 : :
58 : : /*
59 : : * dbs_processing stores the index of the next database in the cluster's array
60 : : * of databases that will be picked up for processing. It will always be
61 : : * greater than or equal to dbs_complete.
62 : : */
63 : : static int dbs_processing;
64 : :
65 : : /*
66 : : * This struct stores the information for a single step of a task. Note that
67 : : * the query string is stored in the "queries" PQExpBuffer for the UpgradeTask.
68 : : * All steps in a task are run in a single connection before moving on to the
69 : : * next database (which requires a new connection).
70 : : */
71 : : typedef struct UpgradeTaskStep
72 : : {
73 : : UpgradeTaskProcessCB process_cb; /* processes the results of the query */
74 : : bool free_result; /* should we free the result? */
75 : : void *arg; /* pointer passed to process_cb */
76 : : } UpgradeTaskStep;
77 : :
78 : : /*
79 : : * This struct is a thin wrapper around an array of steps, i.e.,
80 : : * UpgradeTaskStep, plus a PQExpBuffer for all the query strings.
81 : : */
82 : : struct UpgradeTask
83 : : {
84 : : UpgradeTaskStep *steps;
85 : : int num_steps;
86 : : PQExpBuffer queries;
87 : : };
88 : :
89 : : /*
90 : : * The different states for a parallel slot.
91 : : */
92 : : typedef enum UpgradeTaskSlotState
93 : : {
94 : : FREE, /* slot available for use in a new database */
95 : : CONNECTING, /* waiting for connection to be established */
96 : : RUNNING_QUERIES, /* running/processing queries in the task */
97 : : } UpgradeTaskSlotState;
98 : :
99 : : /*
100 : : * We maintain an array of user_opts.jobs slots to execute the task.
101 : : */
102 : : typedef struct UpgradeTaskSlot
103 : : {
104 : : UpgradeTaskSlotState state; /* state of the slot */
105 : : int db_idx; /* index of the database assigned to slot */
106 : : int step_idx; /* index of the current step of task */
107 : : PGconn *conn; /* current connection managed by slot */
108 : : bool ready; /* slot is ready for processing */
109 : : bool select_mode; /* select() mode: true->read, false->write */
110 : : int sock; /* file descriptor for connection's socket */
111 : : } UpgradeTaskSlot;
112 : :
113 : : /*
114 : : * Initializes an UpgradeTask.
115 : : */
116 : : UpgradeTask *
545 nathan@postgresql.or 117 :CBC 93 : upgrade_task_create(void)
118 : : {
16 michael@paquier.xyz 119 :GNC 93 : UpgradeTask *task = pg_malloc0_object(UpgradeTask);
120 : :
545 nathan@postgresql.or 121 :CBC 93 : task->queries = createPQExpBuffer();
122 : :
123 : : /* All tasks must first set a secure search_path. */
124 : 93 : upgrade_task_add_step(task, ALWAYS_SECURE_SEARCH_PATH_SQL, NULL, true, NULL);
125 : :
126 : 93 : return task;
127 : : }
128 : :
129 : : /*
130 : : * Frees all storage associated with an UpgradeTask.
131 : : */
132 : : void
133 : 93 : upgrade_task_free(UpgradeTask *task)
134 : : {
135 : 93 : destroyPQExpBuffer(task->queries);
136 : 93 : pg_free(task->steps);
137 : 93 : pg_free(task);
138 : 93 : }
139 : :
140 : : /*
141 : : * Adds a step to an UpgradeTask. The steps will be executed in each database
142 : : * in the order in which they are added.
143 : : *
144 : : * task: task object that must have been initialized via upgrade_task_create()
145 : : * query: the query text
146 : : * process_cb: function that processes the results of the query
147 : : * free_result: should we free the PGresult, or leave it to the caller?
148 : : * arg: pointer to task-specific data that is passed to each callback
149 : : */
150 : : void
151 : 216 : upgrade_task_add_step(UpgradeTask *task, const char *query,
152 : : UpgradeTaskProcessCB process_cb, bool free_result,
153 : : void *arg)
154 : : {
155 : : UpgradeTaskStep *new_step;
156 : :
16 michael@paquier.xyz 157 :GNC 216 : task->steps = pg_realloc_array(task->steps, UpgradeTaskStep,
158 : : ++task->num_steps);
159 : :
545 nathan@postgresql.or 160 :CBC 216 : new_step = &task->steps[task->num_steps - 1];
161 : 216 : new_step->process_cb = process_cb;
162 : 216 : new_step->free_result = free_result;
163 : 216 : new_step->arg = arg;
164 : :
165 : 216 : appendPQExpBuffer(task->queries, "%s;", query);
166 : 216 : }
167 : :
168 : : /*
169 : : * Build a connection string for the slot's current database and asynchronously
170 : : * start a new connection, but do not wait for the connection to be
171 : : * established.
172 : : */
173 : : static void
174 : 282 : start_conn(const ClusterInfo *cluster, UpgradeTaskSlot *slot)
175 : : {
176 : : PQExpBufferData conn_opts;
177 : 282 : DbInfo *dbinfo = &cluster->dbarr.dbs[slot->db_idx];
178 : :
179 : : /* Build connection string with proper quoting */
180 : 282 : initPQExpBuffer(&conn_opts);
181 : 282 : appendPQExpBufferStr(&conn_opts, "dbname=");
182 : 282 : appendConnStrVal(&conn_opts, dbinfo->db_name);
183 : 282 : appendPQExpBufferStr(&conn_opts, " user=");
184 : 282 : appendConnStrVal(&conn_opts, os_info.user);
185 : 282 : appendPQExpBuffer(&conn_opts, " port=%d", cluster->port);
186 [ + - ]: 282 : if (cluster->sockdir)
187 : : {
188 : 282 : appendPQExpBufferStr(&conn_opts, " host=");
189 : 282 : appendConnStrVal(&conn_opts, cluster->sockdir);
190 : : }
19 jchampion@postgresql 191 [ - + ]: 282 : if (!protocol_negotiation_supported(cluster))
19 jchampion@postgresql 192 :UBC 0 : appendPQExpBufferStr(&conn_opts, " max_protocol_version=3.0");
193 : :
545 nathan@postgresql.or 194 :CBC 282 : slot->conn = PQconnectStart(conn_opts.data);
195 : :
196 [ - + ]: 282 : if (!slot->conn)
272 peter@eisentraut.org 197 :UBC 0 : pg_fatal("out of memory");
198 : :
545 nathan@postgresql.or 199 :CBC 282 : termPQExpBuffer(&conn_opts);
200 : 282 : }
201 : :
202 : : /*
203 : : * Run the process_cb callback function to process the result of a query, and
204 : : * free the result if the caller indicated we should do so.
205 : : */
206 : : static void
207 : 660 : process_query_result(const ClusterInfo *cluster, UpgradeTaskSlot *slot,
208 : : const UpgradeTask *task)
209 : : {
210 : 660 : UpgradeTaskStep *steps = &task->steps[slot->step_idx];
211 : 660 : UpgradeTaskProcessCB process_cb = steps->process_cb;
212 : 660 : DbInfo *dbinfo = &cluster->dbarr.dbs[slot->db_idx];
213 : 660 : PGresult *res = PQgetResult(slot->conn);
214 : :
215 [ + - - + ]: 1320 : if (PQstatus(slot->conn) == CONNECTION_BAD ||
216 [ - - ]: 660 : (PQresultStatus(res) != PGRES_TUPLES_OK &&
545 nathan@postgresql.or 217 :UBC 0 : PQresultStatus(res) != PGRES_COMMAND_OK))
218 : 0 : pg_fatal("connection failure: %s", PQerrorMessage(slot->conn));
219 : :
220 : : /*
221 : : * We assume that a NULL process_cb callback function means there's
222 : : * nothing to process. This is primarily intended for the initial step in
223 : : * every task that sets a safe search_path.
224 : : */
545 nathan@postgresql.or 225 [ + + ]:CBC 660 : if (process_cb)
226 : 378 : (*process_cb) (dbinfo, res, steps->arg);
227 : :
228 [ + + ]: 660 : if (steps->free_result)
229 : 610 : PQclear(res);
230 : 660 : }
231 : :
232 : : /*
233 : : * Advances the state machine for a given slot as necessary.
234 : : */
235 : : static void
236 : 1260 : process_slot(const ClusterInfo *cluster, UpgradeTaskSlot *slot, const UpgradeTask *task)
237 : : {
238 : : PostgresPollingStatusType status;
239 : :
240 [ - + ]: 1260 : if (!slot->ready)
545 nathan@postgresql.or 241 :UBC 0 : return;
242 : :
545 nathan@postgresql.or 243 [ + + + - ]:CBC 1260 : switch (slot->state)
244 : : {
245 : 375 : case FREE:
246 : :
247 : : /*
248 : : * If all of the databases in the cluster have been processed or
249 : : * are currently being processed by other slots, we are done.
250 : : */
251 [ + + ]: 375 : if (dbs_processing >= cluster->dbarr.ndbs)
252 : 93 : return;
253 : :
254 : : /*
255 : : * Claim the next database in the cluster's array and initiate a
256 : : * new connection.
257 : : */
258 : 282 : slot->db_idx = dbs_processing++;
259 : 282 : slot->state = CONNECTING;
260 : 282 : start_conn(cluster, slot);
261 : :
262 : 282 : return;
263 : :
264 : 564 : case CONNECTING:
265 : :
266 : : /* Check for connection failure. */
267 : 564 : status = PQconnectPoll(slot->conn);
268 [ - + ]: 564 : if (status == PGRES_POLLING_FAILED)
545 nathan@postgresql.or 269 :UBC 0 : pg_fatal("connection failure: %s", PQerrorMessage(slot->conn));
270 : :
271 : : /* Check whether the connection is still establishing. */
545 nathan@postgresql.or 272 [ + + ]:CBC 564 : if (status != PGRES_POLLING_OK)
273 : : {
274 : 282 : slot->select_mode = (status == PGRES_POLLING_READING);
275 : 282 : return;
276 : : }
277 : :
278 : : /*
279 : : * Move on to running/processing the queries in the task.
280 : : */
281 : 282 : slot->state = RUNNING_QUERIES;
282 : 282 : slot->select_mode = true; /* wait until ready for reading */
283 [ - + ]: 282 : if (!PQsendQuery(slot->conn, task->queries->data))
545 nathan@postgresql.or 284 :UBC 0 : pg_fatal("connection failure: %s", PQerrorMessage(slot->conn));
285 : :
545 nathan@postgresql.or 286 :CBC 282 : return;
287 : :
288 : 321 : case RUNNING_QUERIES:
289 : :
290 : : /*
291 : : * Consume any available data and clear the read-ready indicator
292 : : * for the connection.
293 : : */
294 [ - + ]: 321 : if (!PQconsumeInput(slot->conn))
545 nathan@postgresql.or 295 :UBC 0 : pg_fatal("connection failure: %s", PQerrorMessage(slot->conn));
296 : :
297 : : /*
298 : : * Process any results that are ready so that we can free up this
299 : : * slot for another database as soon as possible.
300 : : */
545 nathan@postgresql.or 301 [ + + ]:CBC 981 : for (; slot->step_idx < task->num_steps; slot->step_idx++)
302 : : {
303 : : /* If no more results are available yet, move on. */
304 [ + + ]: 699 : if (PQisBusy(slot->conn))
305 : 39 : return;
306 : :
307 : 660 : process_query_result(cluster, slot, task);
308 : : }
309 : :
310 : : /*
311 : : * If we just finished processing the result of the last step in
312 : : * the task, free the slot. We recursively call this function on
313 : : * the newly-freed slot so that we can start initiating the next
314 : : * connection immediately instead of waiting for the next loop
315 : : * through the slots.
316 : : */
317 : 282 : dbs_complete++;
318 : 282 : PQfinish(slot->conn);
319 : 282 : memset(slot, 0, sizeof(UpgradeTaskSlot));
320 : 282 : slot->ready = true;
321 : :
322 : 282 : process_slot(cluster, slot, task);
323 : :
324 : 282 : return;
325 : : }
326 : : }
327 : :
328 : : /*
329 : : * Returns -1 on error, else the number of ready descriptors.
330 : : */
331 : : static int
332 : 978 : select_loop(int maxFd, fd_set *input, fd_set *output)
333 : : {
334 : 978 : fd_set save_input = *input;
335 : 978 : fd_set save_output = *output;
336 : :
337 [ + + ]: 978 : if (maxFd == 0)
338 : 93 : return 0;
339 : :
340 : : for (;;)
545 nathan@postgresql.or 341 :UBC 0 : {
342 : : int i;
343 : :
545 nathan@postgresql.or 344 :CBC 885 : *input = save_input;
345 : 885 : *output = save_output;
346 : :
347 : 885 : i = select(maxFd + 1, input, output, NULL, NULL);
348 : :
349 : : #ifndef WIN32
350 [ - + - - ]: 885 : if (i < 0 && errno == EINTR)
545 nathan@postgresql.or 351 :UBC 0 : continue;
352 : : #else
353 : : if (i == SOCKET_ERROR && WSAGetLastError() == WSAEINTR)
354 : : continue;
355 : : #endif
545 nathan@postgresql.or 356 :CBC 885 : return i;
357 : : }
358 : : }
359 : :
360 : : /*
361 : : * Wait on the slots to either finish connecting or to receive query results if
362 : : * possible. This avoids a tight loop in upgrade_task_run().
363 : : */
364 : : static void
365 : 978 : wait_on_slots(UpgradeTaskSlot *slots, int numslots)
366 : : {
367 : : fd_set input;
368 : : fd_set output;
369 : 978 : int maxFd = 0;
370 : :
371 [ + + ]: 16626 : FD_ZERO(&input);
372 [ + + ]: 16626 : FD_ZERO(&output);
373 : :
374 [ + + ]: 1956 : for (int i = 0; i < numslots; i++)
375 : : {
376 : : /*
377 : : * We assume the previous call to process_slot() handled everything
378 : : * that was marked ready in the previous call to wait_on_slots(), if
379 : : * any.
380 : : */
381 : 978 : slots[i].ready = false;
382 : :
383 : : /*
384 : : * This function should only ever see free slots as we are finishing
385 : : * processing the last few databases, at which point we don't have any
386 : : * databases left for them to process. We'll never use these slots
387 : : * again, so we can safely ignore them.
388 : : */
389 [ + + ]: 978 : if (slots[i].state == FREE)
390 : 93 : continue;
391 : :
392 : : /*
393 : : * Add the socket to the set.
394 : : */
395 : 885 : slots[i].sock = PQsocket(slots[i].conn);
396 [ - + ]: 885 : if (slots[i].sock < 0)
545 nathan@postgresql.or 397 :UBC 0 : pg_fatal("invalid socket");
545 nathan@postgresql.or 398 [ + + + + ]:CBC 885 : FD_SET(slots[i].sock, slots[i].select_mode ? &input : &output);
399 : 885 : maxFd = Max(maxFd, slots[i].sock);
400 : : }
401 : :
402 : : /*
403 : : * If we found socket(s) to wait on, wait.
404 : : */
405 [ - + ]: 978 : if (select_loop(maxFd, &input, &output) == -1)
272 peter@eisentraut.org 406 :UBC 0 : pg_fatal("%s() failed: %m", "select");
407 : :
408 : : /*
409 : : * Mark which sockets appear to be ready.
410 : : */
545 nathan@postgresql.or 411 [ + + ]:CBC 1956 : for (int i = 0; i < numslots; i++)
412 [ + + ]: 1353 : slots[i].ready |= (FD_ISSET(slots[i].sock, &input) ||
413 [ + + ]: 375 : FD_ISSET(slots[i].sock, &output));
414 : 978 : }
415 : :
416 : : /*
417 : : * Runs all the steps of the task in every database in the cluster using
418 : : * user_opts.jobs parallel slots.
419 : : */
420 : : void
421 : 93 : upgrade_task_run(const UpgradeTask *task, const ClusterInfo *cluster)
422 : : {
423 : 93 : int jobs = Max(1, user_opts.jobs);
16 michael@paquier.xyz 424 :GNC 93 : UpgradeTaskSlot *slots = pg_malloc0_array(UpgradeTaskSlot, jobs);
425 : :
545 nathan@postgresql.or 426 :CBC 93 : dbs_complete = 0;
427 : 93 : dbs_processing = 0;
428 : :
429 : : /*
430 : : * Process every slot the first time round.
431 : : */
432 [ + + ]: 186 : for (int i = 0; i < jobs; i++)
433 : 93 : slots[i].ready = true;
434 : :
435 [ + + ]: 1071 : while (dbs_complete < cluster->dbarr.ndbs)
436 : : {
437 [ + + ]: 1956 : for (int i = 0; i < jobs; i++)
438 : 978 : process_slot(cluster, &slots[i], task);
439 : :
440 : 978 : wait_on_slots(slots, jobs);
441 : : }
442 : :
443 : 93 : pg_free(slots);
444 : 93 : }
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