Test recursive mutex code more

libc/thread/lock.h

@@ -2,17 +2,33 @@
 #define COSMOPOLITAN_LIBC_THREAD_LOCK_H_
 COSMOPOLITAN_C_START_
 
-#define MUTEX_DEPTH_MIN 0x00000010ull
-#define MUTEX_DEPTH_MAX 0x000003f0ull
+//
+//                                                          ┌depth
+//                                                          │
+//         COSMOPOLITAN MUTEXES                             │   ┌waited
+//                                                          │   │
+//                                                          │   │┌locked
+//                                                          │   ││
+//                                                          │   ││┌pshared
+//                owner                                     │   │││
+//                 tid                                      │   │││┌type
+//                  │                                       │   ││││
+//   ┌──────────────┴───────────────┐                     ┌─┴──┐│││├┐
+// 0b0000000000000000000000000000000000000000000000000000000000000000
+
+#define MUTEX_DEPTH_MIN 0x00000020ull
+#define MUTEX_DEPTH_MAX 0x000007e0ull
 
 #define MUTEX_TYPE(word)    ((word) & 3)
 #define MUTEX_PSHARED(word) ((word) & 4)
 #define MUTEX_LOCKED(word)  ((word) & 8)
+#define MUTEX_WAITED(word)  ((word) & 16)
 #define MUTEX_DEPTH(word)   ((word) & MUTEX_DEPTH_MAX)
 #define MUTEX_OWNER(word)   ((word) >> 32)
 
 #define MUTEX_LOCK(word)                 (((word) & 7) | 8)
 #define MUTEX_UNLOCK(word)               ((word) & 7)
+#define MUTEX_SET_WAITED(word)           ((word) | 16)
 #define MUTEX_SET_TYPE(word, type)       (((word) & ~3ull) | (type))
 #define MUTEX_SET_PSHARED(word, pshared) (((word) & ~4ull) | (pshared))
 #define MUTEX_INC_DEPTH(word)            ((word) + MUTEX_DEPTH_MIN)

libc/thread/thread.h

@@ -75,6 +75,7 @@ typedef struct pthread_mutex_s {
     int32_t _pid;
     _PTHREAD_ATOMIC(int32_t) _futex;
   };
+  /* this cleverly overlaps with NSYNC struct Dll *waiters; */
   _PTHREAD_ATOMIC(uint64_t) _word;
 } pthread_mutex_t;
 

test/libc/thread/footek_test.c

@@ -1,15 +1,15 @@
 #define USE        POSIX
-#define ITERATIONS 50000
-#define THREADS    10
-// #define ITERATIONS 100000
-// #define THREADS    30
+#define ITERATIONS 100000
+#define THREADS    30
 
-#define SPIN  1
-#define FUTEX 2
-#define POSIX 3
+#define SPIN            1
+#define FUTEX           2
+#define POSIX           3
+#define POSIX_RECURSIVE 4
 
 #ifdef __COSMOPOLITAN__
 #include <cosmo.h>
+#include "libc/thread/thread.h"
 #include "third_party/nsync/futex.internal.h"
 #endif
 
@@ -278,6 +278,8 @@ void lock(atomic_int *futex) {
     pthread_setcancelstate(PTHREAD_CANCEL_DISABLE, &cs);
 #if USE == FUTEX
     nsync_futex_wait_(futex, 2, 0, 0, 0);
+#else
+    pthread_yield_np();
 #endif
     pthread_setcancelstate(cs, 0);
     word = atomic_exchange_explicit(futex, 2, memory_order_acquire);
@@ -296,11 +298,11 @@ void unlock(atomic_int *futex) {
 
 int g_chores;
 atomic_int g_lock;
-pthread_mutex_t g_locker = PTHREAD_MUTEX_INITIALIZER;
+pthread_mutex_t g_locker;
 
 void *worker(void *arg) {
   for (int i = 0; i < ITERATIONS; ++i) {
-#if USE == POSIX
+#if USE == POSIX || USE == POSIX_RECURSIVE
     pthread_mutex_lock(&g_locker);
     ++g_chores;
     pthread_mutex_unlock(&g_locker);
@@ -331,6 +333,17 @@ int main() {
   struct timeval start;
   gettimeofday(&start, 0);
 
+  pthread_mutex_t lock;
+  pthread_mutexattr_t attr;
+  pthread_mutexattr_init(&attr);
+#if USE == POSIX_RECURSIVE
+  pthread_mutexattr_settype(&attr, PTHREAD_MUTEX_RECURSIVE);
+#else
+  pthread_mutexattr_settype(&attr, PTHREAD_MUTEX_NORMAL);
+#endif
+  pthread_mutex_init(&g_locker, &attr);
+  pthread_mutexattr_destroy(&attr);
+
   pthread_t th[THREADS];
   for (int i = 0; i < THREADS; ++i)
     pthread_create(&th[i], 0, worker, 0);
@@ -349,6 +362,8 @@ int main() {
          tomicros(ru.ru_utime),      //
          tomicros(ru.ru_stime));
 
+  pthread_mutex_destroy(&lock);
+
 #ifdef __COSMOPOLITAN__
   CheckForMemoryLeaks();
 #endif

third_party/nsync/testing/mu_test.c

@@ -177,6 +177,41 @@ static void test_mutex_nthread (testing t) {
 	} while (nsync_time_cmp (nsync_time_now (NSYNC_CLOCK), deadline) < 0);
 }
 
+/* Create a few threads, each of which increments an integer a fixed
+   number of times, using a recursive pthread_mutex_t for mutual exclusion.
+   It checks that the integer is incremented the correct number of times. */
+static void test_xmutex_nthread (testing t) {
+	int loop_count = 100000;
+	nsync_time deadline;
+	deadline = nsync_time_add (nsync_time_now (NSYNC_CLOCK), nsync_time_ms (1500));
+	do {
+		int i;
+		test_data td;
+		pthread_mutexattr_t attr;
+		bzero ((void *) &td, sizeof (td));
+		td.t = t;
+		td.n_threads = 5;
+		td.loop_count = loop_count;
+		td.mu_in_use = &td.mutex;
+		td.lock = &void_pthread_mutex_lock;
+		td.unlock = &void_pthread_mutex_unlock;
+		pthread_mutexattr_init (&attr);
+		pthread_mutexattr_settype (&attr, PTHREAD_MUTEX_RECURSIVE);
+		pthread_mutex_init (&td.mutex, &attr);
+		pthread_mutexattr_destroy (&attr);
+		for (i = 0; i != td.n_threads; i++) {
+			closure_fork (closure_counting (&counting_loop, &td, i));
+		}
+		test_data_wait_for_all_threads (&td);
+		if (td.i != td.n_threads*td.loop_count) {
+			TEST_FATAL (t, ("test_mutex_nthread final count inconsistent: want %d, got %d",
+				   td.n_threads*td.loop_count, td.i));
+		}
+		pthread_mutex_destroy (&td.mutex);
+		loop_count *= 2;
+	} while (nsync_time_cmp (nsync_time_now (NSYNC_CLOCK), deadline) < 0);
+}
+
 /* void pthread_rwlock_wrlock */
 static void void_pthread_rwlock_wrlock (void *mu) {
         pthread_rwlock_wrlock ((pthread_rwlock_t *) mu);
@@ -1040,6 +1075,21 @@ static void benchmark_mutex_contended (testing t) {
 	pthread_mutex_destroy (&cs.mutex);
 }
 
+/* Measure the performance of highly contended recursive
+   pthread_mutex_t locks, with small critical sections.  */
+static void benchmark_xmutex_contended (testing t) {
+	contended_state cs;
+	pthread_mutexattr_t attr;
+	bzero ((void *) &cs, sizeof (cs));
+	pthread_mutexattr_init (&attr);
+	pthread_mutexattr_settype (&attr, PTHREAD_MUTEX_RECURSIVE);
+	pthread_mutex_init (&cs.mutex, &attr);
+	pthread_mutexattr_destroy (&attr);
+	contended_state_run_test (&cs, t, &cs.mutex, &void_pthread_mutex_lock,
+				  &void_pthread_mutex_unlock);
+	pthread_mutex_destroy (&cs.mutex);
+}
+
 /* Measure the performance of highly contended
    pthread_rwlock_t locks, with small critical sections.  */
 static void benchmark_wmutex_contended (testing t) {
@@ -1057,11 +1107,13 @@ int main (int argc, char *argv[]) {
 	TEST_RUN (tb, test_rlock);
 	TEST_RUN (tb, test_mu_nthread);
 	TEST_RUN (tb, test_mutex_nthread);
+	TEST_RUN (tb, test_xmutex_nthread);
 	TEST_RUN (tb, test_rwmutex_nthread);
 	TEST_RUN (tb, test_try_mu_nthread);
 
 	BENCHMARK_RUN (tb, benchmark_mu_contended);
 	BENCHMARK_RUN (tb, benchmark_mutex_contended);
+	BENCHMARK_RUN (tb, benchmark_xmutex_contended);
 	BENCHMARK_RUN (tb, benchmark_wmutex_contended);
 
 	BENCHMARK_RUN (tb, benchmark_mu_uncontended);