ref(sync): promote shared spinlock helper

src/CMakeLists.txt

@@ -54,6 +54,7 @@ sentry_target_sources_cwd(sentry
 	sentry_session.h
 	sentry_slice.c
 	sentry_slice.h
+	sentry_spinlock.h
 	sentry_string.c
 	sentry_string.h
 	sentry_symbolizer.h
@@ -98,7 +99,6 @@ if(WIN32)
 	)
 elseif(NX OR PROSPERO)
 	sentry_target_sources_cwd(sentry
-		sentry_unix_spinlock.h
 		path/sentry_path_unix.c
 		process/sentry_process_none.c
 	)
@@ -108,7 +108,6 @@ else()
 		sentry_random.h
 		sentry_unix_pageallocator.c
 		sentry_unix_pageallocator.h
-		sentry_unix_spinlock.h
 		symbolizer/sentry_symbolizer_unix.c
 		path/sentry_path_unix.c
 		process/sentry_process_unix.c

src/sentry_spinlock.h

@@ -0,0 +1,63 @@
+#ifndef SENTRY_SPINLOCK_H_INCLUDED
+#define SENTRY_SPINLOCK_H_INCLUDED
+
+#include "sentry_boot.h"
+#include "sentry_cpu_relax.h"
+
+typedef volatile long sentry_spinlock_t;
+typedef bool (*sentry_spinlock_wait_func_t)(int attempt, void *data);
+
+#define SENTRY__SPINLOCK_INIT 0
+
+static inline bool
+sentry__spinlock_try_lock(sentry_spinlock_t *spinlock)
+{
+#ifdef SENTRY_PLATFORM_WINDOWS
+#    if SIZEOF_LONG == 8
+    return InterlockedCompareExchange64((volatile LONG64 *)spinlock, 1, 0) == 0;
+#    else
+    return InterlockedCompareExchange((volatile LONG *)spinlock, 1, 0) == 0;
+#    endif
+#else
+    long unlocked = 0;
+    return __atomic_compare_exchange_n(
+        spinlock, &unlocked, 1, false, __ATOMIC_ACQUIRE, __ATOMIC_RELAXED);
+#endif
+}
+
+static inline void
+sentry__spinlock_lock(sentry_spinlock_t *spinlock)
+{
+    while (!sentry__spinlock_try_lock(spinlock)) {
+        sentry__cpu_relax();
+    }
+}
+
+static inline bool
+sentry__spinlock_wait(sentry_spinlock_t *spinlock,
+    sentry_spinlock_wait_func_t wait_func, void *data)
+{
+    int attempts = 0;
+    while (!sentry__spinlock_try_lock(spinlock)) {
+        if (!wait_func || !wait_func(++attempts, data)) {
+            return false;
+        }
+    }
+    return true;
+}
+
+static inline void
+sentry__spinlock_unlock(sentry_spinlock_t *spinlock)
+{
+#ifdef SENTRY_PLATFORM_WINDOWS
+#    if SIZEOF_LONG == 8
+    InterlockedExchange64((volatile LONG64 *)spinlock, 0);
+#    else
+    InterlockedExchange((volatile LONG *)spinlock, 0);
+#    endif
+#else
+    __atomic_store_n(spinlock, 0, __ATOMIC_RELEASE);
+#endif
+}
+
+#endif

src/sentry_unix_pageallocator.c

@@ -1,6 +1,6 @@
 #include "sentry_unix_pageallocator.h"
 #include "sentry_core.h"
-#include "sentry_unix_spinlock.h"
+#include "sentry_spinlock.h"
 
 #include <sys/mman.h>
 #include <unistd.h>

tests/unit/test_sync.c

@@ -1,4 +1,5 @@
 #include "sentry_core.h"
+#include "sentry_spinlock.h"
 #include "sentry_sync.h"
 #include "sentry_testsupport.h"
 #include "sentry_utils.h"
@@ -669,3 +670,34 @@ SENTRY_TEST(cond_wait_timeout_overflow)
     pthread_cond_destroy(&cond);
 #endif
 }
+
+static long g_spin_waits = 0;
+
+static bool
+spin_wait(int UNUSED(attempt), void *UNUSED(data))
+{
+    sentry__atomic_fetch_and_add(&g_spin_waits, 1);
+    return sentry__atomic_fetch(&g_spin_waits) < 2;
+}
+
+SENTRY_TEST(spinlock)
+{
+    sentry_spinlock_t lock = SENTRY__SPINLOCK_INIT;
+    sentry__atomic_store(&g_spin_waits, 0);
+
+    TEST_CHECK(sentry__spinlock_try_lock(&lock));
+    TEST_CHECK_INT_EQUAL(sentry__atomic_fetch(&lock), 1);
+    TEST_CHECK(!sentry__spinlock_try_lock(&lock));
+    sentry__spinlock_unlock(&lock);
+    TEST_CHECK_INT_EQUAL(sentry__atomic_fetch(&lock), 0);
+
+    sentry__spinlock_lock(&lock);
+    TEST_CHECK_INT_EQUAL(sentry__atomic_fetch(&lock), 1);
+    TEST_CHECK(!sentry__spinlock_wait(&lock, spin_wait, NULL));
+    TEST_CHECK_INT_EQUAL(sentry__atomic_fetch(&g_spin_waits), 2);
+    sentry__spinlock_unlock(&lock);
+    TEST_CHECK_INT_EQUAL(sentry__atomic_fetch(&lock), 0);
+    TEST_CHECK(sentry__spinlock_wait(&lock, spin_wait, NULL));
+    TEST_CHECK_INT_EQUAL(sentry__atomic_fetch(&g_spin_waits), 2);
+    sentry__spinlock_unlock(&lock);
+}

tests/unit/tests.inc

@@ -372,6 +372,7 @@ XX(span_data_n)
 XX(span_tagging)
 XX(span_tagging_n)
 XX(spans_on_scope)
+XX(spinlock)
 XX(stack_guarantee)
 XX(stack_guarantee_auto_init)
 XX(strict_continuation_asymmetric_lenient_continues)