patch 4.0

src/sql/dblink/ob_dblink_utils.cpp

@@ -0,0 +1,100 @@
+/**
+ * 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.
+ */
+
+#define USING_LOG_PREFIX SQL_OPT
+
+#include "sql/dblink/ob_dblink_utils.h"
+
+using namespace oceanbase::sql;
+
+int GenUniqueAliasName::init()
+{
+  int ret = OB_SUCCESS;
+  if (!is_inited_) {
+    if (OB_FAIL(table_id_to_alias_name_.create(UNIQUE_NAME_BUCKETS, "DblinkAliasMap"))) {
+      LOG_WARN("failed to init hashmap table_id_to_alias_name_", K(ret));
+    } else {
+      is_inited_ = true;
+    }
+  }
+  return ret;
+}
+
+void GenUniqueAliasName::reset()
+{
+  table_id_to_alias_name_.reuse();
+  alias_name_suffix_ = 0;
+}
+
+int GenUniqueAliasName::get_unique_name(uint64_t table_id, ObString &alias_name)
+{
+  int ret = OB_SUCCESS;
+  const ObString *value = table_id_to_alias_name_.get(table_id);
+  if (NULL == value) {
+    if (OB_FAIL(set_unique_name(table_id, alias_name))) {
+      LOG_WARN("set_unique_name failed", K(ret), K(table_id), K(alias_name));
+    }
+  } else {
+    alias_name = *(const_cast<ObString *>(value));
+  }
+  return ret;
+}
+int GenUniqueAliasName::set_unique_name(uint64_t &table_id, ObString &alias_name) {
+  int ret = OB_SUCCESS;
+  CheckUnique op(alias_name);
+  if (alias_name.empty()) {
+    //do nothing
+  } else if (OB_FAIL(table_id_to_alias_name_.foreach_refactored(op))) {
+    LOG_WARN("failed to foreach table_id_to_alias_name_", K(ret));
+  } else {
+    if (op.is_unique_) {
+      if (OB_FAIL(table_id_to_alias_name_.set_refactored(table_id, alias_name))) {
+        LOG_WARN("failed to set refactored", K(ret), K(table_id), K(alias_name));
+      }
+    } else {
+      char *name_buf = NULL;
+      // Reserve MAX_LENGTH_OF_SUFFIX bytes for the suffix of new_alias_name, 
+      // and suffix is ​​a variable that increments from 0.
+      // The length of MAX_LENGTH_OF_SUFFIX bytes is completely sufficient
+      // for DBLINK to generate a unique alias_name.
+      int64_t name_buf_len = alias_name.length() + MAX_LENGTH_OF_SUFFIX;
+      if (OB_ISNULL(name_buf = static_cast<char *>(arena_allocator_.alloc(name_buf_len)))) {
+        ret = OB_ERR_UNEXPECTED;
+        LOG_WARN("failed to alloc new name", K(name_buf), K(ret));
+      } else {
+        MEMCPY(name_buf, alias_name.ptr(), alias_name.length());
+        // Every time a new alias_name is generated, 
+        // the hash_map must be traversed to confirm whether the alias_name is unique.
+        // The reason why the uniqueness of alias_name is not guaranteed by 
+        // adding an additional hash_set is because each time you reverse sql,
+        // the total number of alias_name is very small, 
+        // and this is not necessary.
+        do {
+          int64_t name_len = alias_name.length();
+          databuff_printf(name_buf, name_buf_len, name_len, "_%d", alias_name_suffix_++);
+          name_len += strlen(name_buf + name_len);
+          alias_name = ObString(name_len, name_buf);
+          op.reset(alias_name);
+          if (OB_FAIL(table_id_to_alias_name_.foreach_refactored(op))) {
+            LOG_WARN("failed to foreach table_id_to_alias_name_", K(ret));
+          }
+        } while(OB_SUCC(ret) && !op.is_unique_);
+        if (OB_SUCC(ret)) {
+          if (OB_FAIL(table_id_to_alias_name_.set_refactored(table_id, alias_name))) {
+            LOG_WARN("failed to set refactored", K(ret), K(table_id), K(alias_name));
+          }
+        }
+      }
+    }
+  }
+  return ret;
+}