neorados: build new RADOS client using legacy librados::Rados

Client libraries like librbd cannot force the adaptation to neorados
and it would not be ideal to have two effective RADOS cluster
connections for librados and neorados.

The new neorados::RADOS::make_with_librados helper method will
allow neorados to re-use the existing thread pool, MGR, MON, and
objecter already created for librados::Rados.

Signed-off-by: Jason Dillaman <dillaman@redhat.com>

src/include/neorados/RADOS.hpp

@@ -55,6 +55,7 @@
 #include "include/common_fwd.h"
 
 #include "include/buffer.h"
+#include "include/rados/librados_fwd.hpp"
 
 #include "common/ceph_time.h"
 
@@ -531,6 +532,8 @@ public:
     return init.result.get();
   }
 
+  static RADOS make_with_librados(librados::Rados& rados);
+
   RADOS(const RADOS&) = delete;
   RADOS& operator =(const RADOS&) = delete;
 

src/include/rados/librados.hpp

@@ -19,6 +19,8 @@ namespace libradosstriper
   class RadosStriper;
 }
 
+namespace neorados { class RADOS; }
+
 namespace librados {
 
 using ceph::bufferlist;
@@ -1503,9 +1505,11 @@ inline namespace v14_2_0 {
 						callback_t cb_safe)
       __attribute__ ((deprecated));
     static AioCompletion *aio_create_completion(void *cb_arg, callback_t cb_complete);
-    
+
     friend std::ostream& operator<<(std::ostream &oss, const Rados& r);
   private:
+    friend class neorados::RADOS;
+
     // We don't allow assignment or copying
     Rados(const Rados& rhs);
     const Rados& operator=(const Rados& rhs);

src/librados/RadosClient.h

@@ -40,9 +40,12 @@ class MLog;
 class Messenger;
 class AioCompletionImpl;
 
+namespace neorados { namespace detail { class RadosClient; }}
+
 class librados::RadosClient : public Dispatcher,
 			      public md_config_obs_t
 {
+  friend neorados::detail::RadosClient;
 public:
   using Dispatcher::cct;
 private:

src/neorados/RADOS.cc

@@ -759,6 +759,9 @@ void RADOS::make_with_cct(CephContext* cct,
   }
 }
 
+RADOS RADOS::make_with_librados(librados::Rados& rados) {
+  return RADOS{std::make_unique<detail::RadosClient>(rados.client)};
+}
 
 RADOS::RADOS() = default;
 

src/neorados/RADOSImpl.h

@@ -11,8 +11,8 @@
  * Foundation.  See file COPYING.
  *
  */
-#ifndef CEPH_LIBRADOS_RADOSCLIENT_H
-#define CEPH_LIBRADOS_RADOSCLIENT_H
+#ifndef CEPH_NEORADOS_RADOSIMPL_H
+#define CEPH_NEORADOS_RADOSIMPL_H
 
 #include <functional>
 #include <memory>
@@ -24,6 +24,8 @@
 #include "common/ceph_context.h"
 #include "common/ceph_mutex.h"
 
+#include "librados/RadosClient.h"
+
 #include "mon/MonClient.h"
 
 #include "mgr/MgrClient.h"
@@ -68,9 +70,6 @@ public:
   mon_feature_t get_required_monitor_features() const {
     return monclient.with_monmap(std::mem_fn(&MonMap::get_required_features));
   }
-  int get_instance_id() const {
-    return instance_id;
-  }
 };
 
 class Client {
@@ -107,13 +106,29 @@ public:
   }
 
   int get_instance_id() const override {
-    return rados->get_instance_id();
+    return rados->instance_id;
   }
 
 private:
   std::unique_ptr<RADOS> rados;
 };
 
+class RadosClient : public Client {
+public:
+  RadosClient(librados::RadosClient* rados_client)
+    : Client(rados_client->poolctx, {rados_client->cct},
+             rados_client->monclient, rados_client->objecter),
+      rados_client(rados_client) {
+  }
+
+  int get_instance_id() const override {
+    return rados_client->instance_id;
+  }
+
+public:
+  librados::RadosClient* rados_client;
+};
+
 } // namespace detail
 } // namespace neorados
 

src/test/neorados/CMakeLists.txt

@@ -1,3 +1,12 @@
+
+add_executable(ceph_test_neorados test_neorados.cc)
+target_link_libraries(ceph_test_neorados global libneorados
+  ${unittest_libs}
+  radostest
+  radostest-cxx
+  librados
+  GTest::GTest)
+
 add_executable(ceph_test_neorados_start_stop start_stop.cc)
 target_link_libraries(ceph_test_neorados_start_stop global libneorados
   ${unittest_libs})

src/test/neorados/test_neorados.cc

@@ -0,0 +1,47 @@
+// -*- mode:C++; tab-width:8; c-basic-offset:2; indent-tabs-mode:t -*-
+// vim: ts=8 sw=2 smarttab
+
+#include "include/rados/librados.hpp"
+#include "include/neorados/RADOS.hpp"
+#include "common/async/blocked_completion.h"
+#include "test/librados/test_cxx.h"
+#include "gtest/gtest.h"
+#include <iostream>
+
+namespace neorados {
+
+class TestNeoRADOS : public ::testing::Test {
+public:
+  TestNeoRADOS() {
+  }
+};
+
+TEST_F(TestNeoRADOS, MakeWithLibRADOS) {
+  librados::Rados paleo_rados;
+  auto result = connect_cluster_pp(paleo_rados);
+  ASSERT_EQ("", result);
+
+  auto rados = RADOS::make_with_librados(paleo_rados);
+
+  ReadOp op;
+  bufferlist bl;
+  op.read(0, 0, &bl);
+
+  // provide pool that doesn't exists -- just testing round-trip
+  ASSERT_THROW(
+    rados.execute({"dummy-obj"}, std::numeric_limits<int64_t>::max(),
+                  std::move(op), nullptr, ceph::async::use_blocked),
+    boost::system::system_error);
+}
+
+} // namespace neorados
+
+int main(int argc, char **argv) {
+  ::testing::InitGoogleTest(&argc, argv);
+
+  int seed = getpid();
+  std::cout << "seed " << seed << std::endl;
+  srand(seed);
+
+  return RUN_ALL_TESTS();
+}