mdbx: add mdbx_osal_jitter() and mdbx_jitter4testing().

src/bits.h

@@ -799,6 +799,14 @@ void mdbx_panic(const char *fmt, ...)
 
 /*----------------------------------------------------------------------------*/
 
+static __inline void mdbx_jitter4testing(bool tiny) {
+#ifndef NDEBUG
+  mdbx_osal_jitter(tiny);
+#else
+  (void)tiny;
+#endif
+}
+
 int mdbx_reader_check0(MDB_env *env, int rlocked, int *dead);
 
 #define METAPAGE_1(env) (&((MDB_metabuf *)(env)->me_map)->mb_metabuf.mm_meta)

src/lck-windows.c

@@ -24,19 +24,6 @@
  * LY
  */
 
-static __inline void jitter4testing(void) {
-#ifndef NDEBUG
-  for (;;) {
-    unsigned coin = ((unsigned)__rdtsc() * 277u) % 43u;
-    if (coin < 43 / 3)
-      break;
-    SwitchToThread();
-    if (coin > 43 * 2 / 3)
-      Sleep(1);
-  }
-#endif
-}
-
 /*----------------------------------------------------------------------------*/
 /* rthc */
 

src/osal.c

@@ -626,3 +626,29 @@ int mdbx_mlock(const void *address, size_t length) {
   return (mlock(address, length) == 0) ? MDB_SUCCESS : errno;
 #endif
 }
+
+/*----------------------------------------------------------------------------*/
+
+__cold void mdbx_osal_jitter(bool tiny) {
+  for (;;) {
+#if defined(_M_IX86) || defined(_M_X64) || defined(__i386__) ||                \
+    defined(__x86_64__)
+    const unsigned salt = 277u * (unsigned)__rdtsc();
+#else
+    const unsigned salt = rand();
+#endif
+
+    const unsigned coin = salt % (tiny ? 29u : 43u);
+    if (coin < 43 / 3)
+      break;
+#if defined(_WIN32) || defined(_WIN64)
+    SwitchToThread();
+    if (coin > 43 * 2 / 3)
+      Sleep(1);
+#else
+    sched_yield();
+    if (coin > 43 * 2 / 3)
+      usleep(coin);
+#endif
+  }
+}

src/osal.h

@@ -383,6 +383,8 @@ static __inline mdbx_pid_t mdbx_getpid(void) {
 #endif
 }
 
+void mdbx_osal_jitter(bool tiny);
+
 /*----------------------------------------------------------------------------*/
 
 #ifndef mdbx_assert_fail