/src/postgres/src/port/pgsleep.c
Line | Count | Source |
1 | | /*------------------------------------------------------------------------- |
2 | | * |
3 | | * pgsleep.c |
4 | | * Portable delay handling. |
5 | | * |
6 | | * |
7 | | * Portions Copyright (c) 1996-2026, PostgreSQL Global Development Group |
8 | | * |
9 | | * src/port/pgsleep.c |
10 | | * |
11 | | *------------------------------------------------------------------------- |
12 | | */ |
13 | | #include "c.h" |
14 | | |
15 | | #include <time.h> |
16 | | |
17 | | /* |
18 | | * In a Windows backend, we don't use this implementation, but rather |
19 | | * the signal-aware version in src/backend/port/win32/signal.c. |
20 | | */ |
21 | | #if defined(FRONTEND) || !defined(WIN32) |
22 | | |
23 | | /* |
24 | | * pg_usleep --- delay the specified number of microseconds. |
25 | | * |
26 | | * NOTE: Although the delay is specified in microseconds, older Unixen and |
27 | | * Windows use periodic kernel ticks to wake up, which might increase the delay |
28 | | * time significantly. We've observed delay increases as large as 20 |
29 | | * milliseconds on supported platforms. |
30 | | * |
31 | | * On machines where "long" is 32 bits, the maximum delay is ~2000 seconds. |
32 | | * |
33 | | * CAUTION: It's not a good idea to use long sleeps in the backend. They will |
34 | | * silently return early if a signal is caught, but that doesn't include |
35 | | * latches being set on most OSes, and even signal handlers that set MyLatch |
36 | | * might happen to run before the sleep begins, allowing the full delay. |
37 | | * Better practice is to use WaitLatch() with a timeout, so that backends |
38 | | * respond to latches and signals promptly. |
39 | | */ |
40 | | void |
41 | | pg_usleep(long microsec) |
42 | 0 | { |
43 | 0 | if (microsec > 0) |
44 | 0 | { |
45 | 0 | #ifndef WIN32 |
46 | 0 | struct timespec delay; |
47 | |
|
48 | 0 | delay.tv_sec = microsec / 1000000L; |
49 | 0 | delay.tv_nsec = (microsec % 1000000L) * 1000; |
50 | 0 | (void) nanosleep(&delay, NULL); |
51 | | #else |
52 | | SleepEx((microsec < 500 ? 1 : (microsec + 500) / 1000), FALSE); |
53 | | #endif |
54 | 0 | } |
55 | 0 | } |
56 | | |
57 | | #endif /* defined(FRONTEND) || !defined(WIN32) */ |