Import wiredtiger: a7f6fa07f90d701b73206a768ae0cc6fb50ff9b4 from branch mongodb-master

ref: 2a414fdee9..a7f6fa07f9
for: 6.3.0-rc0

WT-10338 Ensure threads get uncorrelated sequences of random values.

Author: lukech

src/third_party/wiredtiger/import.data

@@ -2,5 +2,5 @@
     "vendor": "wiredtiger",
     "github": "wiredtiger/wiredtiger.git",
     "branch": "mongodb-master",
-    "commit": "2a414fdee92400156ab05de39b6f0c2363a73469"
+    "commit": "a7f6fa07f90d701b73206a768ae0cc6fb50ff9b4"
 }

src/third_party/wiredtiger/src/support/rand.c

@@ -83,29 +83,25 @@ __wt_random_init_seed(WT_SESSION_IMPL *session, WT_RAND_STATE volatile *rnd_stat
 {
     struct timespec ts;
     WT_RAND_STATE rnd;
-    uint32_t v;
+    uintmax_t threadid;
 
     __wt_epoch(session, &ts);
+    __wt_thread_id(&threadid);
 
     /*
-     * Use this, instead of __wt_random_init if we need to vary the initial state of the RNG. This
-     * is (currently) only used by test programs, where, for example, an initial set of test data is
+     * Use this, instead of __wt_random_init, to vary the initial state of the RNG. This is
+     * (currently) only used by test programs, where, for example, an initial set of test data is
      * created by a single thread, and we want more variability in the initial state of the RNG.
      *
-     * Take the seconds and nanoseconds from the clock as seeds, and smear that value across the
-     * value space, using algorithm "xor" from Marsaglia, "Xorshift RNGs".
+     * Take the seconds and nanoseconds from the clock together with the thread ID to generate a
+     * 64-bit seed, then smear that value using algorithm "xor" from Marsaglia, "Xorshift RNGs".
      */
-    v = (uint32_t)ts.tv_sec;
-    v ^= v << 13;
-    v ^= v >> 17;
-    v ^= v << 5;
-    M_W(rnd) = v + 521288629;
-
-    v = (uint32_t)ts.tv_nsec;
-    v ^= v << 13;
-    v ^= v >> 17;
-    v ^= v << 5;
-    M_Z(rnd) = v + 362436069;
+    M_W(rnd) = (uint32_t)ts.tv_sec ^ 521288629;
+    M_Z(rnd) = (uint32_t)ts.tv_nsec ^ 362436069;
+    rnd.v ^= (uint64_t)threadid;
+    rnd.v ^= rnd.v << 13;
+    rnd.v ^= rnd.v >> 7;
+    rnd.v ^= rnd.v << 17;
 
     *rnd_state = rnd;
 }