nginx-0.0.7-2004-06-30-19:30:41 import

src/core/ngx_spinlock.c

diff --git a/src/core/ngx_spinlock.c b/src/core/ngx_spinlock.c
new file mode 100644
index 0000000..c3c65d3
--- /dev/null
+++ b/src/core/ngx_spinlock.c
@@ -0,0 +1,29 @@
+
+#include <ngx_config.h>
+#include <ngx_core.h>
+
+
+void ngx_spinlock(ngx_atomic_t *lock, ngx_uint_t spin)
+{
+    ngx_uint_t  tries;
+
+    tries = 0;
+
+    for ( ;; ) {
+
+        if (*lock) {
+            if (ngx_ncpu > 1 && tries++ < spin) {
+                continue;
+            }
+
+            ngx_sched_yield();
+
+            tries = 0;
+
+        } else {
+            if (ngx_atomic_cmp_set(lock, 0, 1)) {
+                return;
+            }
+        }
+    }
+}