1 files changed, 166 insertions, 0 deletions
diff --git a/src/common/shared_mutex_debug.cc b/src/common/shared_mutex_debug.cc
new file mode 100644
index 000000000..258cf4039
--- /dev/null
+++ b/src/common/shared_mutex_debug.cc
@@ -0,0 +1,166 @@
+#include "shared_mutex_debug.h"
+
+#include <system_error>
+
+#include "acconfig.h"
+#include "common/valgrind.h"
+
+namespace ceph {
+
+shared_mutex_debug::shared_mutex_debug(std::string group,
+                                       bool track_lock,
+                                       bool enable_lock_dep,
+                                       bool prioritize_write)
+  : mutex_debugging_base{std::move(group),
+                         enable_lock_dep,
+                         false /* backtrace */},
+    track(track_lock)
+{
+#ifdef HAVE_PTHREAD_RWLOCKATTR_SETKIND_NP
+  if (prioritize_write) {
+    pthread_rwlockattr_t attr;
+    pthread_rwlockattr_init(&attr);
+    // PTHREAD_RWLOCK_PREFER_WRITER_NONRECURSIVE_NP
+    //   Setting the lock kind to this avoids writer starvation as long as
+    //   long as any read locking is not done in a recursive fashion.
+    pthread_rwlockattr_setkind_np(&attr,
+                                  PTHREAD_RWLOCK_PREFER_WRITER_NONRECURSIVE_NP);
+    pthread_rwlock_init(&rwlock, &attr);
+    pthread_rwlockattr_destroy(&attr);
+  } else
+#endif
+  // Next block is in {} to possibly connect to the above if when code is used.
+  {
+    pthread_rwlock_init(&rwlock, NULL);
+  }
+  ANNOTATE_BENIGN_RACE_SIZED(&id, sizeof(id), "shared_mutex_debug lockdep id");
+  ANNOTATE_BENIGN_RACE_SIZED(&nlock, sizeof(nlock), "shared_mutex_debug nwlock");
+  ANNOTATE_BENIGN_RACE_SIZED(&nrlock, sizeof(nrlock), "shared_mutex_debug nrlock");
+}
+
+// exclusive
+void shared_mutex_debug::lock()
+{
+  if (_enable_lockdep()) {
+    _will_lock();
+  }
+  if (int r = pthread_rwlock_wrlock(&rwlock); r != 0) {
+    throw std::system_error(r, std::generic_category());
+  }
+  if (_enable_lockdep()) {
+    _locked();
+  }
+  _post_lock();
+}
+
+bool shared_mutex_debug::try_lock()
+{
+  int r = pthread_rwlock_trywrlock(&rwlock);
+  switch (r) {
+  case 0:
+    if (_enable_lockdep()) {
+      _locked();
+    }
+    _post_lock();
+    return true;
+  case EBUSY:
+    return false;
+  default:
+    throw std::system_error(r, std::generic_category());
+  }
+}
+
+void shared_mutex_debug::unlock()
+{
+  _pre_unlock();
+  if (_enable_lockdep()) {
+    _will_unlock();
+  }
+  if (int r = pthread_rwlock_unlock(&rwlock); r != 0) {
+    throw std::system_error(r, std::generic_category());
+  }
+}
+
+// shared locking
+void shared_mutex_debug::lock_shared()
+{
+  if (_enable_lockdep()) {
+    _will_lock();
+  }
+  if (int r = pthread_rwlock_rdlock(&rwlock); r != 0) {
+    throw std::system_error(r, std::generic_category());
+  }
+  if (_enable_lockdep()) {
+    _locked();
+  }
+  _post_lock_shared();
+}
+
+bool shared_mutex_debug::try_lock_shared()
+{
+  if (_enable_lockdep()) {
+    _will_unlock();
+  }
+  switch (int r = pthread_rwlock_rdlock(&rwlock); r) {
+  case 0:
+    if (_enable_lockdep()) {
+      _locked();
+    }
+    _post_lock_shared();
+    return true;
+  case EBUSY:
+    return false;
+  default:
+    throw std::system_error(r, std::generic_category());
+  }
+}
+
+void shared_mutex_debug::unlock_shared()
+{
+  _pre_unlock_shared();
+  if (_enable_lockdep()) {
+    _will_unlock();
+  }
+  if (int r = pthread_rwlock_unlock(&rwlock); r != 0) {
+    throw std::system_error(r, std::generic_category());
+  }
+}
+
+// exclusive locking
+void shared_mutex_debug::_pre_unlock()
+{
+  if (track) {
+    ceph_assert(nlock > 0);
+    --nlock;
+    ceph_assert(locked_by == std::this_thread::get_id());
+    ceph_assert(nlock == 0);
+    locked_by = std::thread::id();
+  }
+}
+
+void shared_mutex_debug::_post_lock()
+{
+  if (track) {
+    ceph_assert(nlock == 0);
+    locked_by = std::this_thread::get_id();
+    ++nlock;
+  }
+}
+
+// shared locking
+void shared_mutex_debug::_pre_unlock_shared()
+{
+  if (track) {
+    ceph_assert(nrlock > 0);
+    nrlock--;
+  }
+}
+
+void shared_mutex_debug::_post_lock_shared()
+{
+  if (track) {
+    ++nrlock;
+  }
+}
+
+} // namespace ceph