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src/storage/ob_i_sample_iterator.cpp

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+/**
+ * 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 "storage/ob_i_sample_iterator.h"
+
+namespace oceanbase {
+using namespace common;
+namespace storage {
+
+ObISampleIterator::ObISampleIterator(const SampleInfo& sample_info) : sample_info_(&sample_info)
+{}
+
+ObISampleIterator::~ObISampleIterator()
+{
+  sample_info_ = nullptr;
+}
+
+bool ObISampleIterator::return_this_sample(const int64_t num) const
+{
+  bool bret = false;
+  int64_t seed = sample_info_->seed_;
+  if (seed == -1) {
+    // seed is not specified, generate random seed
+    seed = ObTimeUtility::current_time();
+  }
+  uint64_t hash_value = murmurhash(&num, sizeof(num), static_cast<uint64_t>(seed));
+  uint64_t cut_off = static_cast<uint64_t>(static_cast<double>(UINT64_MAX) * sample_info_->percent_ / 100.0);
+  bret = hash_value <= cut_off;
+  return bret;
+}
+
+}  // namespace storage
+}  // namespace oceanbase