Revert "SERVER-21542 Optimize spinlock on non-windows systems"

This reverts commit 18600ed909f739ab1bc3032c2a230aeac1abe1c2.

1 files changed, 64 insertions, 8 deletions

diff --git a/src/mongo/util/concurrency/spin_lock.cpp b/src/mongo/util/concurrency/spin_lock.cpp
index 7f01b9d491b..cb66ad2abc5 100644
--- a/src/mongo/util/concurrency/spin_lock.cpp
+++ b/src/mongo/util/concurrency/spin_lock.cpp
@@ -27,20 +27,45 @@
  *    then also delete it in the license file.
  */
 
-#if !defined(_WIN32)
-
 #include "mongo/platform/basic.h"
+#undef MONGO_PCH_WHITELISTED  // todo eliminate this include
 
 #include "mongo/util/concurrency/spin_lock.h"
 
 #include <sched.h>
 #include <time.h>
 
+#include "mongo/bson/inline_decls.h"
 
 namespace mongo {
 
+SpinLock::~SpinLock() {
+#if defined(_WIN32)
+    DeleteCriticalSection(&_cs);
+#elif defined(__USE_XOPEN2K)
+    pthread_spin_destroy(&_lock);
+#endif
+}
+
+SpinLock::SpinLock()
+#if defined(_WIN32)
+{
+    InitializeCriticalSectionAndSpinCount(&_cs, 4000);
+}
+#elif defined(__USE_XOPEN2K)
+{
+    pthread_spin_init(&_lock, 0);
+}
+#elif defined(__GCC_HAVE_SYNC_COMPARE_AND_SWAP_4)
+    : _locked(false) {
+}
+#else
+    : _mutex("SpinLock") {
+}
+#endif
 
-void SpinLock::_lockSlowPath() {
+#if defined(__USE_XOPEN2K)
+NOINLINE_DECL void SpinLock::_lk() {
     /**
      * this is designed to perform close to the default spin lock
      * the reason for the mild insanity is to prevent horrible performance
@@ -50,15 +75,15 @@ void SpinLock::_lockSlowPath() {
      */
 
     for (int i = 0; i < 1000; i++) {
-        if (_tryLock())
+        if (pthread_spin_trylock(&_lock) == 0)
             return;
 #if defined(__i386__) || defined(__x86_64__)
-        asm volatile("pause");
+        asm volatile("pause");  // maybe trylock does this; just in case.
 #endif
     }
 
     for (int i = 0; i < 1000; i++) {
-        if (_tryLock())
+        if (pthread_spin_trylock(&_lock) == 0)
             return;
         sched_yield();
     }
@@ -67,11 +92,42 @@ void SpinLock::_lockSlowPath() {
     t.tv_sec = 0;
     t.tv_nsec = 5000000;
 
-    while (!_tryLock()) {
+    while (pthread_spin_trylock(&_lock) != 0) {
         nanosleep(&t, NULL);
     }
 }
+#elif defined(__GCC_HAVE_SYNC_COMPARE_AND_SWAP_4)
+void SpinLock::lock() {
+    // fast path
+    if (!_locked && !__sync_lock_test_and_set(&_locked, true)) {
+        return;
+    }
 
-}  // namespace mongo
+    // wait for lock
+    int wait = 1000;
+    while ((wait-- > 0) && (_locked)) {
+#if defined(__i386__) || defined(__x86_64__)
+        asm volatile("pause");
+#endif
+    }
+
+    // if failed to grab lock, sleep
+    struct timespec t;
+    t.tv_sec = 0;
+    t.tv_nsec = 5000000;
+    while (__sync_lock_test_and_set(&_locked, true)) {
+        nanosleep(&t, NULL);
+    }
+}
+#endif
 
+bool SpinLock::isfast() {
+#if defined(_WIN32) || defined(__USE_XOPEN2K) || defined(__GCC_HAVE_SYNC_COMPARE_AND_SWAP_4)
+    return true;
+#else
+    return false;
 #endif
+}
+
+
+}  // namespace mongo