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| author | Tom Lane <tgl@sss.pgh.pa.us> | 2021-11-28 21:32:36 -0500 |
|---|---|---|
| committer | Tom Lane <tgl@sss.pgh.pa.us> | 2021-11-28 21:33:07 -0500 |
| commit | 3804539e48e794781c6145c7f988f5d507418fa8 (patch) | |
| tree | 317904b43ca8c1d510b23cb8fdd7b05a75e971bc /src/bin/pg_test_fsync | |
| parent | f44ceb46ec2d8da48f6e145bf462d5620c25e079 (diff) | |
| download | postgresql-3804539e48e794781c6145c7f988f5d507418fa8.tar.gz postgresql-3804539e48e794781c6145c7f988f5d507418fa8.zip | |
Replace random(), pg_erand48(), etc with a better PRNG API and algorithm.
Standardize on xoroshiro128** as our basic PRNG algorithm, eliminating
a bunch of platform dependencies as well as fundamentally-obsolete PRNG
code. In addition, this API replacement will ease replacing the
algorithm again in future, should that become necessary.
xoroshiro128** is a few percent slower than the drand48 family,
but it can produce full-width 64-bit random values not only 48-bit,
and it should be much more trustworthy. It's likely to be noticeably
faster than the platform's random(), depending on which platform you
are thinking about; and we can have non-global state vectors easily,
unlike with random(). It is not cryptographically strong, but neither
are the functions it replaces.
Fabien Coelho, reviewed by Dean Rasheed, Aleksander Alekseev, and myself
Discussion: https://postgr.es/m/alpine.DEB.2.22.394.2105241211230.165418@pseudo
Diffstat (limited to 'src/bin/pg_test_fsync')
| -rw-r--r-- | src/bin/pg_test_fsync/pg_test_fsync.c | 5 |
1 files changed, 4 insertions, 1 deletions
diff --git a/src/bin/pg_test_fsync/pg_test_fsync.c b/src/bin/pg_test_fsync/pg_test_fsync.c index fef31844fa0..ddabf64c583 100644 --- a/src/bin/pg_test_fsync/pg_test_fsync.c +++ b/src/bin/pg_test_fsync/pg_test_fsync.c @@ -15,6 +15,7 @@ #include "access/xlogdefs.h" #include "common/logging.h" +#include "common/pg_prng.h" #include "getopt_long.h" /* @@ -117,6 +118,8 @@ main(int argc, char *argv[]) pqsignal(SIGHUP, signal_cleanup); #endif + pg_prng_seed(&pg_global_prng_state, (uint64) time(NULL)); + prepare_buf(); test_open(); @@ -233,7 +236,7 @@ prepare_buf(void) /* write random data into buffer */ for (ops = 0; ops < DEFAULT_XLOG_SEG_SIZE; ops++) - full_buf[ops] = random(); + full_buf[ops] = (char) pg_prng_int32(&pg_global_prng_state); buf = (char *) TYPEALIGN(XLOG_BLCKSZ, full_buf); } |