1 files changed, 79 insertions, 0 deletions
diff --git a/src/mgr/Gil.cc b/src/mgr/Gil.cc
new file mode 100644
index 00000000..d476c717
--- /dev/null
+++ b/src/mgr/Gil.cc
@@ -0,0 +1,79 @@
+// -*- mode:C++; tab-width:8; c-basic-offset:2; indent-tabs-mode:t -*-
+// vim: ts=8 sw=2 smarttab
+/*
+ * Ceph - scalable distributed file system
+ *
+ * Copyright (C) 2017 SUSE LLC
+ *
+ * This is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License version 2.1, as published by the Free Software
+ * Foundation.  See file COPYING.
+ *
+ */
+
+
+#include "Python.h"
+
+#include "common/debug.h"
+
+#define dout_context g_ceph_context
+#define dout_subsys ceph_subsys_mgr
+#undef dout_prefix
+#define dout_prefix *_dout << "mgr " << __func__ << " "
+
+#include "Gil.h"
+
+SafeThreadState::SafeThreadState(PyThreadState *ts_)
+    : ts(ts_)
+{
+  ceph_assert(ts != nullptr);
+  thread = pthread_self();
+}
+
+Gil::Gil(SafeThreadState &ts, bool new_thread) : pThreadState(ts)
+{
+  // Acquire the GIL, set the current thread state
+  PyEval_RestoreThread(pThreadState.ts);
+  dout(25) << "GIL acquired for thread state " << pThreadState.ts << dendl;
+
+  //
+  // If called from a separate OS thread (i.e. a thread not created
+  // by Python, that does't already have a python thread state that
+  // was created when that thread was active), we need to manually
+  // create and switch to a python thread state specifically for this
+  // OS thread.
+  //
+  // Note that instead of requring the caller to set new_thread == true
+  // when calling this from a separate OS thread, we could figure out
+  // if this was necessary automatically, as follows:
+  //
+  //   if (pThreadState->thread_id != PyThread_get_thread_ident()) {
+  //
+  // However, this means we're accessing pThreadState->thread_id, but
+  // the Python C API docs say that "The only public data member is
+  // PyInterpreterState *interp", i.e. doing this would violate
+  // something that's meant to be a black box.
+  //
+  if (new_thread) {
+    pNewThreadState = PyThreadState_New(pThreadState.ts->interp);
+    PyThreadState_Swap(pNewThreadState);
+    dout(20) << "Switched to new thread state " << pNewThreadState << dendl;
+  } else {
+    ceph_assert(pthread_self() == pThreadState.thread);
+  }
+}
+
+Gil::~Gil()
+{
+  if (pNewThreadState != nullptr) {
+    dout(20) << "Destroying new thread state " << pNewThreadState << dendl;
+    PyThreadState_Swap(pThreadState.ts);
+    PyThreadState_Clear(pNewThreadState);
+    PyThreadState_Delete(pNewThreadState);
+  }
+  // Release the GIL, reset the thread state to NULL
+  PyEval_SaveThread();
+  dout(25) << "GIL released for thread state " << pThreadState.ts << dendl;
+}
+