rgw_sal_motr, motr_gc: [CORTX-33148] Add MotrGC class

For Garbage Collection, cortx-rgw needs a MotrGC thread which
works concurrently to delete all the stale objects.
Added the MotrGC class and the interface to configure and start
GC workers.

Signed-off-by: Sumedh A. Kulkarni <sumedh.a.kulkarni@seagate.com>

src/rgw/CMakeLists.txt

@@ -177,7 +177,7 @@ if(WITH_RADOSGW_DBSTORE)
   list(APPEND librgw_common_srcs rgw_sal_dbstore.cc)
 endif()
 if(WITH_RADOSGW_MOTR)
-  list(APPEND librgw_common_srcs rgw_sal_motr.cc)
+  list(APPEND librgw_common_srcs rgw_sal_motr.cc motr/gc/gc.cc)
 endif()
 if(WITH_JAEGER)
   list(APPEND librgw_common_srcs rgw_tracer.cc)

src/rgw/motr/gc/gc.cc

@@ -0,0 +1,31 @@
+// -*- mode:C++; tab-width:8; c-basic-offset:2; indent-tabs-mode:t -*-
+// vim: ts=2 sw=2 expandtab ft=cpp
+
+/*
+ * Garbage Collector implementation for the CORTX Motr backend
+ *
+ * Copyright (C) 2022 Seagate Technology LLC and/or its Affiliates
+ *
+ * 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 "gc.h"
+
+void *MotrGC::entry() {
+  std::unique_lock<std::mutex> lk(mtx);
+  ldpp_dout(dpp, 10) << __func__ << ": Motr GC started" << dendl;
+
+  do {
+    ldpp_dout(dpp, 10) << __func__ << ": In a Motr GC loop." << dendl;
+    cv.wait_for(lk, std::chrono::milliseconds(gc_interval * 10));
+  } while (! stop_signalled);
+
+  ldpp_dout(dpp, 0) << __func__ << ": Stop signalled called.#" 
+    << stop_signalled << dendl;
+  return nullptr;
+}
+

src/rgw/motr/gc/gc.h

@@ -0,0 +1,47 @@
+// -*- mode:C++; tab-width:8; c-basic-offset:2; indent-tabs-mode:t -*-
+// vim: ts=2 sw=2 expandtab ft=cpp
+
+/*
+ * Garbage Collector Classes for the CORTX Motr backend
+ *
+ * Copyright (C) 2022 Seagate Technology LLC and/or its Affiliates
+ *
+ * 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.
+ *
+ */
+
+#ifndef __MOTR_GC_H__
+#define __MOTR_GC_H__
+
+#include "rgw_sal_motr.h"
+#include "common/Thread.h"
+#include <mutex>
+#include <condition_variable>
+
+class MotrGC : public Thread {
+ private: 
+  const DoutPrefixProvider *dpp;
+  rgw::sal::Store *store;
+  std::mutex mtx;
+  std::condition_variable cv;
+  bool stop_signalled = false;
+  uint32_t gc_interval = 60*60;  // default: 24*60*60 sec
+  uint32_t gc_obj_min_wait = 60*60;  // 60*60sec default
+
+ public:
+  MotrGC(const DoutPrefixProvider *_dpp, rgw::sal::Store* _store) :
+         dpp(_dpp), store(_store) {}
+
+  void *entry() override;
+
+  void signal_stop() {
+    std::lock_guard<std::mutex> lk_guard(mtx);
+    stop_signalled = true;
+    cv.notify_all();  
+  }
+};
+
+#endif

src/rgw/rgw_sal.cc

@@ -117,7 +117,13 @@ rgw::sal::Store* StoreManager::init_storage_provider(const DoutPrefixProvider* d
       ldpp_dout(dpp, 0) << "newMotrStore() failed!" << dendl;
       return store;
     }
-    ((rgw::sal::MotrStore *)store)->init_metadata_cache(dpp, cct, use_cache);
+
+    if ((*(rgw::sal::MotrStore*)store).set_use_cache(use_cache)
+                                      .set_run_gc_thread(use_gc_thread)
+                                      .initialize(cct, dpp) < 0) {
+      delete store;
+      return nullptr;
+    }
 
     return store;
   }

src/rgw/rgw_sal_motr.cc

@@ -1454,12 +1454,58 @@ int MotrBucket::abort_multiparts(const DoutPrefixProvider *dpp, CephContext *cct
   return 0;
 }
 
-void MotrStore::finalize(void)
-{
+void MotrStore::finalize(void) {
+  // stop gc worker threads
+  stop_gc();
   // close connection with motr
   m0_client_fini(this->instance, true);
 }
 
+MotrStore& MotrStore::set_run_gc_thread(bool _use_gc_thread) {
+  use_gc_thread = _use_gc_thread;
+  return *this;
+}
+
+MotrStore& MotrStore::set_use_cache(bool _use_cache) {
+  use_cache = _use_cache;
+  return *this;
+}
+
+int MotrStore::initialize(CephContext *cct, const DoutPrefixProvider *dpp) {
+  int rc = 0;
+  if (use_cache) {
+    int rc = init_metadata_cache(dpp, cct);
+    if (rc != 0) {
+      ldpp_dout(dpp, 0) << __func__ << ": Metadata cache init failed " <<
+        "with rc = " << rc << dendl;
+      return rc;
+    }
+  }
+
+  if (use_gc_thread) {
+    int rc = create_gc(dpp);
+    if (rc != 0)
+      ldpp_dout(dpp, 0) << __func__ << ": Metadata cache init failed " <<
+        "with rc = " << rc << dendl;
+  }
+  return rc;
+}
+
+int MotrStore::create_gc(const DoutPrefixProvider *dpp) {
+  int ret = 0;
+  // [TODO] Create multiple GC threads as per config
+  gc_worker = std::make_unique<MotrGC>(dpp, this);
+  gc_worker->create("motr_gc");
+  return ret;
+}
+
+void MotrStore::stop_gc() {
+  if (gc_worker) {
+    gc_worker->signal_stop();
+    gc_worker->join();
+  }
+}
+
 uint64_t MotrStore::get_new_req_id()
 {
   uint64_t req_id = ceph::util::generate_random_number<uint64_t>();
@@ -5362,7 +5408,7 @@ std::string MotrStore::get_cluster_id(const DoutPrefixProvider* dpp,  optional_y
 }
 
 int MotrStore::init_metadata_cache(const DoutPrefixProvider *dpp,
-                                   CephContext *cct, bool use_cache)
+                                   CephContext *cct)
 {
   this->obj_meta_cache = new MotrMetaCache(dpp, cct);
   this->get_obj_meta_cache()->set_enabled(use_cache);

src/rgw/rgw_sal_motr.h

@@ -32,8 +32,11 @@ extern "C" {
 #include "rgw_role.h"
 #include "rgw_multi.h"
 #include "rgw_putobj_processor.h"
+#include "motr/gc/gc.h"
 typedef void (*progress_cb)(off_t, void*);
 
+class MotrGC;
+
 namespace rgw::sal {
 
 class MotrStore;
@@ -982,6 +985,12 @@ class MotrStore : public Store {
     MotrMetaCache* user_cache;
     MotrMetaCache* bucket_inst_cache;
 
+    // [TODO] Create vector of gc_workers
+    //        size is input from `rgw_gc_max_concurrent_io`
+    std::unique_ptr<MotrGC> gc_worker;
+    bool use_gc_thread;
+    bool use_cache;
+
   public:
     CephContext *cctx;
     struct m0_client   *instance;
@@ -1097,7 +1106,12 @@ class MotrStore : public Store {
         uint64_t olh_epoch,
         const std::string& unique_tag) override;
 
+    virtual int initialize(CephContext *cct, const DoutPrefixProvider *dpp);
     virtual void finalize(void) override;
+    int create_gc(const DoutPrefixProvider *dpp);
+    void stop_gc();
+    MotrStore& set_run_gc_thread(bool _use_gc_thread);
+    MotrStore& set_use_cache(bool _use_cache);
 
     virtual CephContext *ctx(void) override {
       return cctx;
@@ -1133,7 +1147,7 @@ class MotrStore : public Store {
     int delete_access_key(const DoutPrefixProvider *dpp, optional_yield y, std::string access_key);
     int store_email_info(const DoutPrefixProvider *dpp, optional_yield y, MotrEmailInfo& email_info);
 
-    int init_metadata_cache(const DoutPrefixProvider *dpp, CephContext *cct, bool use_cache);
+    int init_metadata_cache(const DoutPrefixProvider *dpp, CephContext *cct);
     MotrMetaCache* get_obj_meta_cache() {return obj_meta_cache;}
     MotrMetaCache* get_user_cache() {return user_cache;}
     MotrMetaCache* get_bucket_inst_cache() {return bucket_inst_cache;}