76 lines
2.4 KiB
C++
76 lines
2.4 KiB
C++
/**
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* Copyright (c) 2021 OceanBase
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* OceanBase CE is licensed under Mulan PubL v2.
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* You can use this software according to the terms and conditions of the Mulan PubL v2.
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* You may obtain a copy of Mulan PubL v2 at:
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* http://license.coscl.org.cn/MulanPubL-2.0
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* THIS SOFTWARE IS PROVIDED ON AN "AS IS" BASIS, WITHOUT WARRANTIES OF ANY KIND,
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* EITHER EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO NON-INFRINGEMENT,
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* MERCHANTABILITY OR FIT FOR A PARTICULAR PURPOSE.
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* See the Mulan PubL v2 for more details.
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*/
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#define USING_LOG_PREFIX SQL_RESV
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#include "sql/engine/expr/ob_expr_uuid_short.h"
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#include "observer/ob_server_struct.h"
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#include "lib/time/ob_time_utility.h"
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using namespace oceanbase::common;
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namespace oceanbase
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{
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namespace sql
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{
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ObExprUuidShort::ObExprUuidShort(ObIAllocator &alloc)
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: ObFuncExprOperator(alloc, T_FUN_SYS_UUID_SHORT, N_UUID_SHORT, 0, NOT_VALID_FOR_GENERATED_COL, NOT_ROW_DIMENSION)
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{
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}
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ObExprUuidShort::~ObExprUuidShort()
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{
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}
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/**
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* Note:
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* The total number of serverids over(>=) 256 will not guarantee uniqueness,
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* but we will not report an error, because this is a undefined behavior in mysql.
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* In short, users should need to know this.
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*/
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uint64_t ObExprUuidShort::generate_uuid_short()
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{
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// uuid_short
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// | <8> | <32> | <24>
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// server_id server_start_time incremented_variable
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static volatile uint64_t server_id_and_server_startup_time = ((GCTX.server_id_ & 255) << 56) |
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((static_cast<uint64_t>(common::ObTimeUtility::current_time() / 1000000) << 24) &
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((static_cast<uint64_t>(1) << 56) - 1));
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uint64_t uuid_short = ATOMIC_AAF(&server_id_and_server_startup_time, 1);
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LOG_DEBUG("uuid_short generated.", K(uuid_short));
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return uuid_short;
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}
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int ObExprUuidShort::cg_expr(ObExprCGCtx &expr_cg_ctx,
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const ObRawExpr &raw_expr,
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ObExpr &rt_expr) const
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{
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UNUSED(raw_expr);
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UNUSED(expr_cg_ctx);
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rt_expr.eval_func_ = ObExprUuidShort::eval_uuid_short;
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return OB_SUCCESS;
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}
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int ObExprUuidShort::eval_uuid_short(const ObExpr &expr,
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ObEvalCtx &ctx,
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ObDatum &expr_datum)
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{
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int ret = OB_SUCCESS;
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UNUSED(expr);
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UNUSED(ctx);
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expr_datum.set_uint(generate_uuid_short());
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return ret;
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}
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} // namespace sql
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} // namespace oceanbase
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