oceanbase/src/sql/engine/expr/ob_expr_repeat.cpp

/**
 * 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_ENG
#include "sql/engine/expr/ob_expr_repeat.h"

#include <limits.h>
#include <string.h>

#include "sql/session/ob_sql_session_info.h"
#include "sql/engine/ob_exec_context.h"
#include "sql/engine/expr/ob_expr_lob_utils.h"

using namespace oceanbase::common;
using namespace oceanbase::sql;

namespace oceanbase
{
namespace sql
{
}
}


ObExprRepeat::ObExprRepeat(ObIAllocator &alloc)
    : ObStringExprOperator(alloc, T_FUN_SYS_REPEAT, N_REPEAT, 2, VALID_FOR_GENERATED_COL)
{
}

ObExprRepeat::~ObExprRepeat()
{
}

int ObExprRepeat::calc_result_type2(ObExprResType &type,
                                    ObExprResType &text,
                                    ObExprResType &count,
                                    ObExprTypeCtx &type_ctx) const
{
  int ret = OB_SUCCESS;
  if (GET_MIN_CLUSTER_VERSION() < CLUSTER_VERSION_4_2_0_0) {
    text.set_calc_type(common::ObVarcharType);
  } else if (!ob_is_text_tc(text.get_type()) && !text.is_null()) {
    text.set_calc_type(common::ObVarcharType);
  }
  if (!count.is_null()) {
    count.set_calc_type(common::ObIntType);
  }
  // Set cast mode for %count parameter, truncate string to integer.
  type_ctx.set_cast_mode(type_ctx.get_cast_mode() | CM_STRING_INTEGER_TRUNC);
  // repeat is mysql only epxr.
  CK(lib::is_mysql_mode());
  if (OB_SUCC(ret)) {
    ObObjType res_type = ObMaxType;
    if (text.is_null() && !count.is_null()) {
      res_type = ObVarcharType;
    } else if (count.is_literal() && !count.is_null()) {
      const ObObj &obj = count.get_param();
      ObArenaAllocator alloc(ObModIds::OB_SQL_RES_TYPE);
      const ObDataTypeCastParams dtc_params = type_ctx.get_dtc_params();
      int64_t cur_time = 0;
      ObCastMode cast_mode = CM_NONE;
      if (FALSE_IT(ObSQLUtils::get_default_cast_mode(type_ctx.get_sql_mode(), cast_mode))) {
        LOG_WARN("failed to get default cast mode", K(ret));
      } else {
        cast_mode |= CM_WARN_ON_FAIL;
        ObCastCtx cast_ctx(
            &alloc, &dtc_params, cur_time, cast_mode, CS_TYPE_INVALID);
        int64_t count_val = 0;
        EXPR_GET_INT64_V2(obj, count_val);
        res_type = get_result_type_mysql(text.get_length() * count_val);
      }
    } else {
      res_type = ObLongTextType;
    }
    type.set_type(res_type);
    type.set_collation_level(text.get_collation_level());
    type.set_collation_type(text.get_collation_type());
    if (ObVarcharType == type.get_type()) {
     /*
      * In terms of repeat(A, B), we can know the actual length when B is literal
      * constant indeed.
      * But we do not want to do this since if we did, the plan cache will not be
      * hit. So, no matter B comes from literal constant or column we just set
      * length to be  OB_MAX_VARCHAR_LENGTH here.
      */
      type.set_length(MAX_CHAR_LENGTH_FOR_VARCAHR_RESULT);
    } else if (ob_is_text_tc(type.get_type())) {
      const int32_t mbmaxlen = 4;
      const int32_t default_text_length =
        ObAccuracy::DDL_DEFAULT_ACCURACY[type.get_type()].get_length() / mbmaxlen;
      // need to set a correct length for text tc in mysql mode
      type.set_length(default_text_length);
    }
  }
  if (OB_SUCC(ret)) {
    if (OB_FAIL(aggregate_charsets_for_string_result(type, &text, 1, type_ctx))) {
      LOG_WARN("failed to aggregate charsets for string result", K(ret));
    } else {
      text.set_calc_collation_level(type.get_collation_level());
      text.set_calc_collation_type(type.get_collation_type());
    }
  }
  return ret;
}

int ObExprRepeat::calc(
    ObObj &result,
    const ObObj &text,
    const ObObj &count,
    ObIAllocator *allocator,
    ObObjType res_type,
    const int64_t max_result_size)
{
  int ret = OB_SUCCESS;
  if (text.is_null() || count.is_null()) {
    result.set_null();
  } else {
    TYPE_CHECK(text, ObVarcharType);
    TYPE_CHECK(count, ObIntType);
    ObString local_text = text.get_string();
    int64_t local_count = count.get_int();
    if (OB_FAIL(calc(result, res_type, local_text, local_count, allocator, max_result_size))) {
      LOG_WARN("Failed to cacl result");
    }
  }
  return ret;
}

int ObExprRepeat::repeat(ObString &output,
                         bool &is_null,
                         const ObString &text,
                         const int64_t count,
                         common::ObIAllocator &allocator,
                         const int64_t max_result_size)
{
  is_null = false;
  int ret = OB_SUCCESS;
  if (count <= 0 || text.length() <= 0 || max_result_size <= 0) {
    output.assign_ptr(NULL, 0);
  } else {
    int64_t length = static_cast<int64_t>(text.length());

    // Safe length check
    if ((length > max_result_size / count) || (length > INT_MAX / count)) {
      LOG_WARN("Result of repeat was larger than max_allow_packet_size",
          K(ret), K(length), K(count), K(max_result_size));
      ret = OB_ERR_FUNC_RESULT_TOO_LARGE;
      LOG_USER_ERROR(OB_ERR_FUNC_RESULT_TOO_LARGE, "repeat", static_cast<int>(max_result_size));
    } else {
      //avoid realloc
      if (1 == count) {
        output = text;
      } else {
        int64_t tot_length = length * count;
        char *buf = static_cast<char *>(allocator.alloc(tot_length));
        if (OB_ISNULL(buf)) {
          ret = OB_ALLOCATE_MEMORY_FAILED;
          LOG_ERROR("alloc memory failed", K(ret), K(tot_length));
        } else {
          int64_t tmp_count = count;
          char *tmp_buf = buf;
          while (tmp_count--) {
            MEMCPY(tmp_buf, text.ptr(), length);
            tmp_buf += length;
          }
          output.assign_ptr(buf, static_cast<int32_t>(tot_length));
        }
      }
    }
  }
  return ret;
}

int ObExprRepeat::repeat_text(ObObjType res_type,
                              bool has_lob_header,
                              ObString &output,
                              bool &is_null,
                              const ObString &text,
                              const int64_t count,
                              ObIAllocator &allocator,
                              const int64_t max_result_size)
{
  // result is text tc, but text string is varchar (), refer to calc_result_type
  is_null = false;
  int ret = OB_SUCCESS;
  if (count <= 0 || text.length() <= 0 || max_result_size <= 0) { // Notice: result is "", not null.
    ObTextStringResult result_buffer(res_type, has_lob_header, &allocator);
    if (OB_FAIL(result_buffer.init(0))) {
      LOG_WARN("init stringtextbuffer failed", K(ret));
    } else {
      result_buffer.get_result_buffer(output);
    }
  } else {
    int64_t length = static_cast<int64_t>(text.length());
    // Safe length check
    if ((length > max_result_size / count) || (length > INT_MAX / count)) {
      LOG_WARN("Result of repeat was larger than max_allow_packet_size",
          K(ret), K(length), K(count), K(max_result_size));
      ret = OB_ERR_FUNC_RESULT_TOO_LARGE;
      LOG_USER_ERROR(OB_ERR_FUNC_RESULT_TOO_LARGE, "repeat", static_cast<int>(max_result_size));
    } else {
      int64_t tot_length = length * count;
      int64_t buffer_len = 0;
      char *buf = NULL;
      if (tot_length >= MEM_WARN_THRESHOLD) {
        LOG_INFO("once repeat cost over 100M", K(ret), K(tot_length), K(length), K(count));
      }
      ObTextStringResult result_buffer(res_type, has_lob_header, &allocator);
      if (OB_FAIL(result_buffer.init(tot_length))) {
        LOG_WARN("init result failed", K(ret), K(tot_length));
      } else {
        int64_t tmp_count = count;
        while (tmp_count-- && (OB_SUCC(ret))) {
          if (OB_FAIL(result_buffer.append(text))) {
            LOG_WARN("append result failed", K(ret), K(result_buffer), K(text));
          }
        }
        if (OB_SUCC(ret)) {
          result_buffer.get_result_buffer(output);
        }
      }
    }
  }
  return ret;
}

int ObExprRepeat::calc(ObObj &result,
                       const ObObjType res_type,
                       const ObString &text,
                       const int64_t count,
                       ObIAllocator *allocator,
                       const int64_t max_result_size)
{
  int ret = OB_SUCCESS;
  ObString output;
  bool is_null = false;
  bool has_lob_header = (!IS_CLUSTER_VERSION_BEFORE_4_1_0_0 && (res_type != ObTinyTextType));
  if (OB_ISNULL(allocator)) {
    ret = OB_ERR_UNEXPECTED;
    LOG_WARN("null allocator", K(ret), K(allocator));
  } else if (false == ob_is_string_type(res_type)) {
    ret = OB_INVALID_ARGUMENT;
    // ObExprRepeat::calc_result_type2()方法中，规定返回结果的类型一定是属于某个string type
    LOG_WARN("make sure res_type is string type", K(ret), K(res_type));
  } else if (!ob_is_text_tc(res_type)) {
    ret = repeat(output, is_null, text, count, *allocator, max_result_size);
  } else {
    ret = repeat_text(res_type, has_lob_header, output, is_null,
                      text, count, *allocator, max_result_size);
  }
  if (OB_FAIL(ret)) {
    LOG_WARN("do repeat failed", K(ret));
  } else {
    if (is_null) {
      result.set_null();
    } else {
      result.set_string(res_type, output);
      if (has_lob_header) {
        result.set_has_lob_header();
      }
    }
  }
  return ret;
}

int ObExprRepeat::cg_expr(ObExprCGCtx &, const ObRawExpr &, ObExpr &rt_expr) const
{
  int ret = OB_SUCCESS;
  CK(2 == rt_expr.arg_cnt_);
  rt_expr.eval_func_ = eval_repeat;
  if (GET_MIN_CLUSTER_VERSION() >= CLUSTER_VERSION_4_3_2_0) {
    rt_expr.eval_vector_func_ = eval_repeat_vector;
  }
  return ret;
}

int ObExprRepeat::eval_repeat(const ObExpr &expr, ObEvalCtx &ctx, ObDatum &expr_datum)
{
  int ret = OB_SUCCESS;
  ObDatum *text = NULL;
  ObDatum *count = NULL;
  int64_t max_size = 0;
  ObEvalCtx::TempAllocGuard tmp_alloc_g(ctx);
  common::ObIAllocator &tmp_allocator = tmp_alloc_g.get_allocator();
  ObString text_str;
  if (OB_FAIL(expr.args_[0]->eval(ctx, text))
      || OB_FAIL(expr.args_[1]->eval(ctx, count))) {
    LOG_WARN("evaluate parameters failed", K(ret));
  } else if (text->is_null() || count->is_null()) {
    expr_datum.set_null();
  } else if (OB_FAIL(ctx.exec_ctx_.get_my_session()->get_max_allowed_packet(max_size))) {
    LOG_WARN("get max length failed", K(ret));
  } else if (OB_FAIL(ObTextStringHelper::read_real_string_data(tmp_allocator, *text,
                     expr.args_[0]->datum_meta_, expr.args_[0]->obj_meta_.has_lob_header(), text_str))) {
    LOG_WARN("fail to get real data.", K(ret), K(text_str));
  } else {
    ObExprStrResAlloc expr_res_alloc(expr, ctx);
    bool is_null = false;
    bool has_lob_header = expr.obj_meta_.has_lob_header();
    ObString output;
    if (!ob_is_text_tc(expr.datum_meta_.type_)) {
      ret = repeat(output, is_null,
                   text_str, count->get_int(), expr_res_alloc, max_size);
    } else { // text tc
      ret = repeat_text(expr.datum_meta_.type_, has_lob_header, output, is_null,
                        text_str, count->get_int(), expr_res_alloc, max_size);
    }
    if (OB_FAIL(ret)) {
      LOG_WARN("do repeat failed", K(ret));
    } else {
      if (is_null) {
        expr_datum.set_null();
      } else {
        expr_datum.set_string(output);
      }
    }
  }
  return ret;
}

template <typename Arg0Vec, typename Arg1Vec, typename ResVec>
int ObExprRepeat::repeat_vector(VECTOR_EVAL_FUNC_ARG_DECL)
{
  int ret = OB_SUCCESS;
  ResVec *res_vec = static_cast<ResVec *>(expr.get_vector(ctx));
  ObBitVector &eval_flags = expr.get_evaluated_flags(ctx);

  int64_t max_size = 0; // used for limit size of result

  if (OB_FAIL(ctx.exec_ctx_.get_my_session()->get_max_allowed_packet(max_size))) {
    LOG_WARN("get max size failed", K(ret));
  } else {
    const Arg0Vec *arg0_vec = static_cast<const Arg0Vec *>(expr.args_[0]->get_vector(ctx));
    const Arg1Vec *arg1_vec = static_cast<const Arg1Vec *>(expr.args_[1]->get_vector(ctx));

    // the count may be a variable number, repeat expr support the
    ObEvalCtx::BatchInfoScopeGuard batch_info_guard(ctx);
    batch_info_guard.set_batch_size(bound.batch_size());
    for (int64_t idx = bound.start(); OB_SUCC(ret) && idx < bound.end(); ++idx) {
      if (skip.at(idx) || eval_flags.at(idx)) {
        continue;
      }

      batch_info_guard.set_batch_idx(idx);
      if (arg0_vec->is_null(idx) || arg1_vec->is_null(idx)) {
        res_vec->set_null(idx);
        eval_flags.set(idx);
      } else {
        // prepare & init needed params
        ObEvalCtx::TempAllocGuard tmp_alloc_g(ctx);
        common::ObArenaAllocator &tmp_allocator = tmp_alloc_g.get_allocator();

        int64_t count = arg1_vec->get_int(idx);
        bool is_null = false;
        ObString text;
        ObString output;

        ObExprStrResAlloc calc_alloc(expr, ctx);

        if (OB_FAIL(ObTextStringHelper::read_real_string_data(
                tmp_allocator, arg0_vec, expr.args_[0]->datum_meta_,
                expr.args_[0]->obj_meta_.has_lob_header(), text, idx))) {
          LOG_WARN("failed to read text", K(ret), K(text));
        } else if (!ob_is_text_tc(expr.datum_meta_.type_)) {
          // 2.1 deal with string tc
          ret = repeat(output, is_null, text, count, calc_alloc, max_size);
        } else {
          // 2.2 deal with text tc
          ret = repeat_text(expr.datum_meta_.type_,
                            expr.obj_meta_.has_lob_header(), output, is_null,
                            text, count, calc_alloc, max_size);
        }
        if (OB_FAIL(ret)) {
          LOG_WARN("do repeat in vector failed", K(ret));
        } else {
          if (is_null) {
            res_vec->set_null(idx);
          } else {
            res_vec->set_string(idx, output);
          }
        }
        eval_flags.set(idx);
      }
    }
  }
  return ret;
}

int ObExprRepeat::eval_repeat_vector(VECTOR_EVAL_FUNC_ARG_DECL)
{
  int ret = OB_SUCCESS;
  // make sure that `repeat` operand should have 2 params.
  if (OB_FAIL(expr.args_[0]->eval_vector(ctx, skip, bound)) ||
      OB_FAIL(expr.args_[1]->eval_vector(ctx, skip, bound))) {
    LOG_WARN("failed to evaluate `repeat` parameters", K(ret));
  } else {
    VectorFormat arg0_format = expr.args_[0]->get_format(ctx);
    VectorFormat arg1_format = expr.args_[1]->get_format(ctx);
    VectorFormat res_format = expr.get_format(ctx);
    if (VEC_DISCRETE == arg0_format && VEC_UNIFORM_CONST == arg1_format &&
        VEC_DISCRETE == res_format) {
      ret = repeat_vector<StrDiscVec, IntegerUniCVec, StrDiscVec>(
          VECTOR_EVAL_FUNC_ARG_LIST);
    } else if (VEC_UNIFORM == arg0_format && VEC_UNIFORM_CONST == arg1_format &&
               VEC_DISCRETE == res_format) {
      ret = repeat_vector<StrUniVec, IntegerUniCVec, StrDiscVec>(
          VECTOR_EVAL_FUNC_ARG_LIST);
    } else if (VEC_CONTINUOUS == arg0_format &&
               VEC_UNIFORM_CONST == arg1_format && VEC_DISCRETE == res_format) {
      ret = repeat_vector<StrContVec, IntegerUniCVec, StrDiscVec>(
          VECTOR_EVAL_FUNC_ARG_LIST);
    } else if (VEC_DISCRETE == arg0_format &&
               VEC_UNIFORM_CONST == arg1_format && VEC_UNIFORM == res_format) {
      ret = repeat_vector<StrDiscVec, IntegerUniCVec, StrUniVec>(
          VECTOR_EVAL_FUNC_ARG_LIST);
    } else if (VEC_UNIFORM == arg0_format && VEC_UNIFORM_CONST == arg1_format &&
               VEC_UNIFORM == res_format) {
      ret = repeat_vector<StrUniVec, IntegerUniCVec, StrUniVec>(
          VECTOR_EVAL_FUNC_ARG_LIST);
    } else if (VEC_CONTINUOUS == arg0_format &&
               VEC_UNIFORM_CONST == arg1_format && VEC_UNIFORM == res_format) {
      ret = repeat_vector<StrContVec, IntegerUniCVec, StrUniVec>(
          VECTOR_EVAL_FUNC_ARG_LIST);
    } else {
      ret = repeat_vector<ObVectorBase, ObVectorBase, ObVectorBase>(
          VECTOR_EVAL_FUNC_ARG_LIST);
    }
  }
  return ret;
}

DEF_SET_LOCAL_SESSION_VARS(ObExprRepeat, raw_expr) {
  int ret = OB_SUCCESS;
  if (is_mysql_mode()) {
    SET_LOCAL_SYSVAR_CAPACITY(3);
    EXPR_ADD_LOCAL_SYSVAR(SYS_VAR_SQL_MODE);
    EXPR_ADD_LOCAL_SYSVAR(SYS_VAR_TIME_ZONE);
    EXPR_ADD_LOCAL_SYSVAR(SYS_VAR_COLLATION_CONNECTION);
  }
  return ret;
}