Improve cancellations, randomness, and time

- Exhaustively document cancellation points
- Rename SIGCANCEL to SIGTHR just like BSDs
- Further improve POSIX thread cancellations
- Ensure asynchronous cancellations work correctly
- Elevate the quality of getrandom() and getentropy()
- Make futexes cancel correctly on OpenBSD 6.x and 7.x
- Add reboot.com and shutdown.com to examples directory
- Remove underscore prefix from awesome timespec_*() APIs
- Create assertions that help verify our cancellation points
- Remove bad timespec APIs (cmp generalizes eq/ne/gt/gte/lt/lte)

test/libc/intrin/describesigset_test.c

@@ -26,10 +26,12 @@
 TEST(DescribeSigset, full) {
   sigset_t ss;
   sigfillset(&ss);
-  if (IsXnu() || IsOpenbsd()) {
-    EXPECT_STREQ("~{ABRT,CANCEL,KILL,STOP}", DescribeSigset(0, &ss));
+  if (IsXnu()) {
+    EXPECT_STREQ("~{ABRT,THR,KILL,STOP}", DescribeSigset(0, &ss));
+  } else if (IsOpenbsd()) {
+    EXPECT_STREQ("~{ABRT,KILL,STOP,THR}", DescribeSigset(0, &ss));
   } else {
-    EXPECT_STREQ("~{ABRT,KILL,STOP,CANCEL}", DescribeSigset(0, &ss));
+    EXPECT_STREQ("~{ABRT,KILL,STOP,THR}", DescribeSigset(0, &ss));
   }
 }
 
@@ -46,11 +48,11 @@ TEST(DescribeSigset, absent) {
   sigfillset(&ss);
   sigdelset(&ss, SIGINT);
   sigdelset(&ss, SIGUSR1);
-  if (IsOpenbsd() || IsXnu()) {
-    EXPECT_STREQ("~{INT,ABRT,CANCEL,KILL,STOP,USR1}", DescribeSigset(0, &ss));
-  } else if (IsFreebsd() || IsNetbsd()) {
-    EXPECT_STREQ("~{INT,ABRT,KILL,STOP,USR1,CANCEL}", DescribeSigset(0, &ss));
+  if (IsXnu()) {
+    EXPECT_STREQ("~{INT,ABRT,THR,KILL,STOP,USR1}", DescribeSigset(0, &ss));
+  } else if (IsBsd()) {
+    EXPECT_STREQ("~{INT,ABRT,KILL,STOP,USR1,THR}", DescribeSigset(0, &ss));
   } else {
-    EXPECT_STREQ("~{INT,ABRT,KILL,USR1,STOP,CANCEL}", DescribeSigset(0, &ss));
+    EXPECT_STREQ("~{INT,ABRT,KILL,USR1,STOP,THR}", DescribeSigset(0, &ss));
   }
 }

test/libc/intrin/lock_test.c

@@ -131,7 +131,7 @@ void TestContendedLock(const char *name, int kind) {
     _Exit(1);
   }
   while (!atomic_load(&ready)) donothing;
-  t1 = _timespec_real();
+  t1 = timespec_real();
   for (i = 0; i < n; ++i) {
     ASSERT_EQ(0, pthread_mutex_lock(&mu));
     x = atomic_load_explicit(&counter, memory_order_relaxed);
@@ -139,13 +139,13 @@ void TestContendedLock(const char *name, int kind) {
     ASSERT_EQ(x - 1, atomic_load_explicit(&counter, memory_order_relaxed));
     ASSERT_EQ(0, pthread_mutex_unlock(&mu));
   }
-  t2 = _timespec_real();
+  t2 = timespec_real();
   while (tib.tib_tid) donothing;
   ASSERT_EQ(1, atomic_load(&success));
   ASSERT_EQ(0, atomic_load(&counter));
   _freestack(stk);
   ASSERT_EQ(0, pthread_mutex_destroy(&mu));
-  ns = time2dbl(_timespec_sub(t2, t1)) / n;
+  ns = time2dbl(timespec_sub(t2, t1)) / n;
   kprintf("%s contended took %s\n", name, time2str(ns));
 }
 
@@ -159,14 +159,14 @@ void TestUncontendedLock(const char *name, int kind) {
   pthread_mutexattr_settype(&attr, kind);
   pthread_mutex_init(&lock, &attr);
   pthread_mutexattr_destroy(&attr);
-  t1 = _timespec_real();
+  t1 = timespec_real();
   for (i = 0; i < n; ++i) {
     pthread_mutex_lock(&lock);
     pthread_mutex_unlock(&lock);
   }
-  t2 = _timespec_real();
+  t2 = timespec_real();
   pthread_mutex_destroy(&lock);
-  ns = time2dbl(_timespec_sub(t2, t1)) / n;
+  ns = time2dbl(timespec_sub(t2, t1)) / n;
   kprintf("%s took %s\n", name, time2str(ns));
 }
 

test/libc/intrin/lockscale_test.c

@@ -67,7 +67,7 @@ void *Waiter(void *arg) {
 BENCH(lock, scalability) {
   int i;
   struct timespec t1, t2;
-  t1 = _timespec_real();
+  t1 = timespec_real();
   pthread_mutex_init(&lock, 0);
   pthread_barrier_init(&barrier, 0, WAITERS + 1);
   for (i = 0; i < WAITERS; ++i) {
@@ -79,8 +79,8 @@ BENCH(lock, scalability) {
   }
   pthread_barrier_destroy(&barrier);
   pthread_mutex_destroy(&lock);
-  t2 = _timespec_real();
+  t2 = timespec_real();
   printf("consumed %10g seconds real time and %10g seconds cpu time\n",
-         _timespec_tonanos(_timespec_sub(t2, t1)) / 1e9,
+         timespec_tonanos(timespec_sub(t2, t1)) / 1e9,
          (double)clock() / CLOCKS_PER_SEC);
 }

test/libc/intrin/strsignal_r_test.c

@@ -34,5 +34,6 @@ TEST(strsignal, test) {
 
 TEST(strsignal, realtime) {
   if (!SIGRTMIN) return;
+  EXPECT_STREQ("SIGTHR", strsignal(SIGTHR));
   ASSERT_STREQ("SIGRTMIN+1", strsignal(SIGRTMIN + 1));
 }