Line data Source code
1 : /*-------------------------------------------------------------------------
2 : *
3 : * walreceiverfuncs.c
4 : *
5 : * This file contains functions used by the startup process to communicate
6 : * with the walreceiver process. Functions implementing walreceiver itself
7 : * are in walreceiver.c.
8 : *
9 : * Portions Copyright (c) 2010-2017, PostgreSQL Global Development Group
10 : *
11 : *
12 : * IDENTIFICATION
13 : * src/backend/replication/walreceiverfuncs.c
14 : *
15 : *-------------------------------------------------------------------------
16 : */
17 : #include "postgres.h"
18 :
19 : #include <sys/stat.h>
20 : #include <sys/time.h>
21 : #include <time.h>
22 : #include <unistd.h>
23 : #include <signal.h>
24 :
25 : #include "access/xlog_internal.h"
26 : #include "postmaster/startup.h"
27 : #include "replication/walreceiver.h"
28 : #include "storage/pmsignal.h"
29 : #include "storage/shmem.h"
30 : #include "utils/timestamp.h"
31 :
32 : WalRcvData *WalRcv = NULL;
33 :
34 : /*
35 : * How long to wait for walreceiver to start up after requesting
36 : * postmaster to launch it. In seconds.
37 : */
38 : #define WALRCV_STARTUP_TIMEOUT 10
39 :
40 : /* Report shared memory space needed by WalRcvShmemInit */
41 : Size
42 15 : WalRcvShmemSize(void)
43 : {
44 15 : Size size = 0;
45 :
46 15 : size = add_size(size, sizeof(WalRcvData));
47 :
48 15 : return size;
49 : }
50 :
51 : /* Allocate and initialize walreceiver-related shared memory */
52 : void
53 5 : WalRcvShmemInit(void)
54 : {
55 : bool found;
56 :
57 5 : WalRcv = (WalRcvData *)
58 5 : ShmemInitStruct("Wal Receiver Ctl", WalRcvShmemSize(), &found);
59 :
60 5 : if (!found)
61 : {
62 : /* First time through, so initialize */
63 5 : MemSet(WalRcv, 0, WalRcvShmemSize());
64 5 : WalRcv->walRcvState = WALRCV_STOPPED;
65 5 : SpinLockInit(&WalRcv->mutex);
66 5 : WalRcv->latch = NULL;
67 : }
68 5 : }
69 :
70 : /* Is walreceiver running (or starting up)? */
71 : bool
72 3 : WalRcvRunning(void)
73 : {
74 3 : WalRcvData *walrcv = WalRcv;
75 : WalRcvState state;
76 : pg_time_t startTime;
77 :
78 3 : SpinLockAcquire(&walrcv->mutex);
79 :
80 3 : state = walrcv->walRcvState;
81 3 : startTime = walrcv->startTime;
82 :
83 3 : SpinLockRelease(&walrcv->mutex);
84 :
85 : /*
86 : * If it has taken too long for walreceiver to start up, give up. Setting
87 : * the state to STOPPED ensures that if walreceiver later does start up
88 : * after all, it will see that it's not supposed to be running and die
89 : * without doing anything.
90 : */
91 3 : if (state == WALRCV_STARTING)
92 : {
93 0 : pg_time_t now = (pg_time_t) time(NULL);
94 :
95 0 : if ((now - startTime) > WALRCV_STARTUP_TIMEOUT)
96 : {
97 0 : SpinLockAcquire(&walrcv->mutex);
98 :
99 0 : if (walrcv->walRcvState == WALRCV_STARTING)
100 0 : state = walrcv->walRcvState = WALRCV_STOPPED;
101 :
102 0 : SpinLockRelease(&walrcv->mutex);
103 : }
104 : }
105 :
106 3 : if (state != WALRCV_STOPPED)
107 0 : return true;
108 : else
109 3 : return false;
110 : }
111 :
112 : /*
113 : * Is walreceiver running and streaming (or at least attempting to connect,
114 : * or starting up)?
115 : */
116 : bool
117 0 : WalRcvStreaming(void)
118 : {
119 0 : WalRcvData *walrcv = WalRcv;
120 : WalRcvState state;
121 : pg_time_t startTime;
122 :
123 0 : SpinLockAcquire(&walrcv->mutex);
124 :
125 0 : state = walrcv->walRcvState;
126 0 : startTime = walrcv->startTime;
127 :
128 0 : SpinLockRelease(&walrcv->mutex);
129 :
130 : /*
131 : * If it has taken too long for walreceiver to start up, give up. Setting
132 : * the state to STOPPED ensures that if walreceiver later does start up
133 : * after all, it will see that it's not supposed to be running and die
134 : * without doing anything.
135 : */
136 0 : if (state == WALRCV_STARTING)
137 : {
138 0 : pg_time_t now = (pg_time_t) time(NULL);
139 :
140 0 : if ((now - startTime) > WALRCV_STARTUP_TIMEOUT)
141 : {
142 0 : SpinLockAcquire(&walrcv->mutex);
143 :
144 0 : if (walrcv->walRcvState == WALRCV_STARTING)
145 0 : state = walrcv->walRcvState = WALRCV_STOPPED;
146 :
147 0 : SpinLockRelease(&walrcv->mutex);
148 : }
149 : }
150 :
151 0 : if (state == WALRCV_STREAMING || state == WALRCV_STARTING ||
152 : state == WALRCV_RESTARTING)
153 0 : return true;
154 : else
155 0 : return false;
156 : }
157 :
158 : /*
159 : * Stop walreceiver (if running) and wait for it to die.
160 : * Executed by the Startup process.
161 : */
162 : void
163 3 : ShutdownWalRcv(void)
164 : {
165 3 : WalRcvData *walrcv = WalRcv;
166 3 : pid_t walrcvpid = 0;
167 :
168 : /*
169 : * Request walreceiver to stop. Walreceiver will switch to WALRCV_STOPPED
170 : * mode once it's finished, and will also request postmaster to not
171 : * restart itself.
172 : */
173 3 : SpinLockAcquire(&walrcv->mutex);
174 3 : switch (walrcv->walRcvState)
175 : {
176 : case WALRCV_STOPPED:
177 3 : break;
178 : case WALRCV_STARTING:
179 0 : walrcv->walRcvState = WALRCV_STOPPED;
180 0 : break;
181 :
182 : case WALRCV_STREAMING:
183 : case WALRCV_WAITING:
184 : case WALRCV_RESTARTING:
185 0 : walrcv->walRcvState = WALRCV_STOPPING;
186 : /* fall through */
187 : case WALRCV_STOPPING:
188 0 : walrcvpid = walrcv->pid;
189 0 : break;
190 : }
191 3 : SpinLockRelease(&walrcv->mutex);
192 :
193 : /*
194 : * Signal walreceiver process if it was still running.
195 : */
196 3 : if (walrcvpid != 0)
197 0 : kill(walrcvpid, SIGTERM);
198 :
199 : /*
200 : * Wait for walreceiver to acknowledge its death by setting state to
201 : * WALRCV_STOPPED.
202 : */
203 6 : while (WalRcvRunning())
204 : {
205 : /*
206 : * This possibly-long loop needs to handle interrupts of startup
207 : * process.
208 : */
209 0 : HandleStartupProcInterrupts();
210 :
211 0 : pg_usleep(100000); /* 100ms */
212 : }
213 3 : }
214 :
215 : /*
216 : * Request postmaster to start walreceiver.
217 : *
218 : * recptr indicates the position where streaming should begin, conninfo
219 : * is a libpq connection string to use, and slotname is, optionally, the name
220 : * of a replication slot to acquire.
221 : */
222 : void
223 0 : RequestXLogStreaming(TimeLineID tli, XLogRecPtr recptr, const char *conninfo,
224 : const char *slotname)
225 : {
226 0 : WalRcvData *walrcv = WalRcv;
227 0 : bool launch = false;
228 0 : pg_time_t now = (pg_time_t) time(NULL);
229 :
230 : /*
231 : * We always start at the beginning of the segment. That prevents a broken
232 : * segment (i.e., with no records in the first half of a segment) from
233 : * being created by XLOG streaming, which might cause trouble later on if
234 : * the segment is e.g archived.
235 : */
236 0 : if (recptr % XLogSegSize != 0)
237 0 : recptr -= recptr % XLogSegSize;
238 :
239 0 : SpinLockAcquire(&walrcv->mutex);
240 :
241 : /* It better be stopped if we try to restart it */
242 0 : Assert(walrcv->walRcvState == WALRCV_STOPPED ||
243 : walrcv->walRcvState == WALRCV_WAITING);
244 :
245 0 : if (conninfo != NULL)
246 0 : strlcpy((char *) walrcv->conninfo, conninfo, MAXCONNINFO);
247 : else
248 0 : walrcv->conninfo[0] = '\0';
249 :
250 0 : if (slotname != NULL)
251 0 : strlcpy((char *) walrcv->slotname, slotname, NAMEDATALEN);
252 : else
253 0 : walrcv->slotname[0] = '\0';
254 :
255 0 : if (walrcv->walRcvState == WALRCV_STOPPED)
256 : {
257 0 : launch = true;
258 0 : walrcv->walRcvState = WALRCV_STARTING;
259 : }
260 : else
261 0 : walrcv->walRcvState = WALRCV_RESTARTING;
262 0 : walrcv->startTime = now;
263 :
264 : /*
265 : * If this is the first startup of walreceiver (on this timeline),
266 : * initialize receivedUpto and latestChunkStart to the starting point.
267 : */
268 0 : if (walrcv->receiveStart == 0 || walrcv->receivedTLI != tli)
269 : {
270 0 : walrcv->receivedUpto = recptr;
271 0 : walrcv->receivedTLI = tli;
272 0 : walrcv->latestChunkStart = recptr;
273 : }
274 0 : walrcv->receiveStart = recptr;
275 0 : walrcv->receiveStartTLI = tli;
276 :
277 0 : SpinLockRelease(&walrcv->mutex);
278 :
279 0 : if (launch)
280 0 : SendPostmasterSignal(PMSIGNAL_START_WALRECEIVER);
281 0 : else if (walrcv->latch)
282 0 : SetLatch(walrcv->latch);
283 0 : }
284 :
285 : /*
286 : * Returns the last+1 byte position that walreceiver has written.
287 : *
288 : * Optionally, returns the previous chunk start, that is the first byte
289 : * written in the most recent walreceiver flush cycle. Callers not
290 : * interested in that value may pass NULL for latestChunkStart. Same for
291 : * receiveTLI.
292 : */
293 : XLogRecPtr
294 0 : GetWalRcvWriteRecPtr(XLogRecPtr *latestChunkStart, TimeLineID *receiveTLI)
295 : {
296 0 : WalRcvData *walrcv = WalRcv;
297 : XLogRecPtr recptr;
298 :
299 0 : SpinLockAcquire(&walrcv->mutex);
300 0 : recptr = walrcv->receivedUpto;
301 0 : if (latestChunkStart)
302 0 : *latestChunkStart = walrcv->latestChunkStart;
303 0 : if (receiveTLI)
304 0 : *receiveTLI = walrcv->receivedTLI;
305 0 : SpinLockRelease(&walrcv->mutex);
306 :
307 0 : return recptr;
308 : }
309 :
310 : /*
311 : * Returns the replication apply delay in ms or -1
312 : * if the apply delay info is not available
313 : */
314 : int
315 0 : GetReplicationApplyDelay(void)
316 : {
317 0 : WalRcvData *walrcv = WalRcv;
318 : XLogRecPtr receivePtr;
319 : XLogRecPtr replayPtr;
320 :
321 : long secs;
322 : int usecs;
323 :
324 : TimestampTz chunkReplayStartTime;
325 :
326 0 : SpinLockAcquire(&walrcv->mutex);
327 0 : receivePtr = walrcv->receivedUpto;
328 0 : SpinLockRelease(&walrcv->mutex);
329 :
330 0 : replayPtr = GetXLogReplayRecPtr(NULL);
331 :
332 0 : if (receivePtr == replayPtr)
333 0 : return 0;
334 :
335 0 : chunkReplayStartTime = GetCurrentChunkReplayStartTime();
336 :
337 0 : if (chunkReplayStartTime == 0)
338 0 : return -1;
339 :
340 0 : TimestampDifference(chunkReplayStartTime,
341 : GetCurrentTimestamp(),
342 : &secs, &usecs);
343 :
344 0 : return (((int) secs * 1000) + (usecs / 1000));
345 : }
346 :
347 : /*
348 : * Returns the network latency in ms, note that this includes any
349 : * difference in clock settings between the servers, as well as timezone.
350 : */
351 : int
352 0 : GetReplicationTransferLatency(void)
353 : {
354 0 : WalRcvData *walrcv = WalRcv;
355 :
356 : TimestampTz lastMsgSendTime;
357 : TimestampTz lastMsgReceiptTime;
358 :
359 0 : long secs = 0;
360 0 : int usecs = 0;
361 : int ms;
362 :
363 0 : SpinLockAcquire(&walrcv->mutex);
364 0 : lastMsgSendTime = walrcv->lastMsgSendTime;
365 0 : lastMsgReceiptTime = walrcv->lastMsgReceiptTime;
366 0 : SpinLockRelease(&walrcv->mutex);
367 :
368 0 : TimestampDifference(lastMsgSendTime,
369 : lastMsgReceiptTime,
370 : &secs, &usecs);
371 :
372 0 : ms = ((int) secs * 1000) + (usecs / 1000);
373 :
374 0 : return ms;
375 : }
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