[liboblog] support storage work mode

tools/obcdc/src/ob_log_ref_state.cpp

@@ -0,0 +1,95 @@
+/**
+ * Copyright (c) 2021 OceanBase
+ * OceanBase CE is licensed under Mulan PubL v2.
+ * You can use this software according to the terms and conditions of the Mulan PubL v2.
+ * You may obtain a copy of Mulan PubL v2 at:
+ *          http://license.coscl.org.cn/MulanPubL-2.0
+ * THIS SOFTWARE IS PROVIDED ON AN "AS IS" BASIS, WITHOUT WARRANTIES OF ANY KIND,
+ * EITHER EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO NON-INFRINGEMENT,
+ * MERCHANTABILITY OR FIT FOR A PARTICULAR PURPOSE.
+ * See the Mulan PubL v2 for more details.
+ */
+
+#include "ob_log_ref_state.h"
+
+#include "lib/atomic/ob_atomic.h"     // ATOMIC_*
+
+namespace oceanbase
+{
+namespace liboblog
+{
+
+bool RefState::inc_ref(const int64_t target_state, int64_t &new_state, int64_t &new_ref)
+{
+  bool succ = false;
+  RefState cur_st(ATOMIC_LOAD(&value_));
+
+  while (! succ && cur_st.state_ == target_state) {
+    RefState old_st = cur_st;
+    RefState new_st = cur_st;
+    new_st.ref_cnt_++;   // Status unchanged, reference count +1
+
+    cur_st.value_ = ATOMIC_CAS(&value_, old_st.value_, new_st.value_);
+
+    if (cur_st.value_ == old_st.value_) {
+      succ = true;
+      // The reference count is successfully increased, returning the new state and the new reference count
+      new_state = new_st.state_;
+      new_ref = new_st.ref_cnt_;
+    } else {
+      // Reference count increase failed, return current state and current reference count
+      new_state = cur_st.state_;
+      new_ref = cur_st.ref_cnt_;
+    }
+  }
+
+  return succ;
+}
+
+void RefState::dec_ref(int64_t &new_state, int64_t &new_ref_cnt)
+{
+  RefState cur_st(ATOMIC_LOAD(&value_));
+
+  bool done = false;
+  while (!done) {
+    RefState old_st = cur_st;
+    RefState new_st = cur_st;
+    new_st.ref_cnt_--; // No change in status, number of transactions minus 1
+
+    cur_st.value_ = ATOMIC_CAS(&value_, old_st.value_, new_st.value_);
+
+    if (old_st.value_ == cur_st.value_) {
+      done = true;
+      // Returns the state value and reference count after the reference count has been subtracted successfully
+      new_state = new_st.state_;
+      new_ref_cnt = new_st.ref_cnt_;
+    }
+  }
+}
+
+bool RefState::change_state(const int64_t target_state, int64_t &old_state, int64_t &ref_cnt)
+{
+  bool succ = false;
+  RefState cur_st(ATOMIC_LOAD(&value_));
+
+  while (! succ && cur_st.state_ != target_state) {
+    RefState old_st = cur_st;
+    RefState new_st = cur_st;
+    new_st.state_ = target_state;   // No change in reference count, change in status
+
+    cur_st.value_ = ATOMIC_CAS(&value_, old_st.value_, new_st.value_);
+
+    if (cur_st.value_ == old_st.value_) {
+      succ = true;
+    }
+  }
+
+  // cur_st holds the old state values
+  old_state = cur_st.state_;
+  ref_cnt = cur_st.ref_cnt_;
+
+  return succ;
+}
+
+}
+}