github.com/matrixorigin/matrixone@v0.7.0/pkg/container/types/bytes.go (about)

     1  // Copyright 2021 Matrix Origin
     2  //
     3  // Licensed under the Apache License, Version 2.0 (the "License");
     4  // you may not use this file except in compliance with the License.
     5  // You may obtain a copy of the License at
     6  //
     7  //      http://www.apache.org/licenses/LICENSE-2.0
     8  //
     9  // Unless required by applicable law or agreed to in writing, software
    10  // distributed under the License is distributed on an "AS IS" BASIS,
    11  // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    12  // See the License for the specific language governing permissions and
    13  // limitations under the License.
    14  
    15  package types
    16  
    17  import (
    18  	"unsafe"
    19  
    20  	"github.com/matrixorigin/matrixone/pkg/common/mpool"
    21  )
    22  
    23  const (
    24  	VarlenaInlineSize = 23
    25  	VarlenaSize       = 24
    26  	MaxStringSize     = 10485760
    27  	VarlenaBigHdr     = 0xffffffff
    28  	MaxVarcharLen     = 65535
    29  	MaxCharLen        = 255
    30  )
    31  
    32  func (v *Varlena) UnsafePtr() unsafe.Pointer {
    33  	return unsafe.Pointer(&v[0])
    34  }
    35  
    36  func (v *Varlena) ByteSlice() []byte {
    37  	svlen := (*v)[0]
    38  	ptr := unsafe.Add(unsafe.Pointer(&v[0]), 1)
    39  	return unsafe.Slice((*byte)(ptr), svlen)
    40  }
    41  
    42  func (v *Varlena) U32Slice() []uint32 {
    43  	ptr := (*uint32)(v.UnsafePtr())
    44  	return unsafe.Slice(ptr, 6)
    45  }
    46  
    47  func (v *Varlena) OffsetLen() (uint32, uint32) {
    48  	s := v.U32Slice()
    49  	return s[1], s[2]
    50  }
    51  func (v *Varlena) SetOffsetLen(voff, vlen uint32) {
    52  	s := v.U32Slice()
    53  	s[0] = VarlenaBigHdr
    54  	s[1] = voff
    55  	s[2] = vlen
    56  }
    57  
    58  func BuildVarlena(bs []byte, area []byte, m *mpool.MPool) (Varlena, []byte, error) {
    59  	var err error
    60  	var v Varlena
    61  	vlen := len(bs)
    62  	if vlen <= VarlenaInlineSize {
    63  		v[0] = byte(vlen)
    64  		copy(v[1:1+vlen], bs)
    65  		return v, area, nil
    66  	} else {
    67  		voff := len(area)
    68  		if voff+vlen < cap(area) || m == nil {
    69  			area = append(area, bs...)
    70  		} else {
    71  			area, err = m.Grow2(area, bs, voff+vlen)
    72  			if err != nil {
    73  				return v, nil, err
    74  			}
    75  		}
    76  		v.SetOffsetLen(uint32(voff), uint32(vlen))
    77  		return v, area, nil
    78  	}
    79  }
    80  
    81  func (v *Varlena) IsSmall() bool {
    82  	return (*v)[0] <= VarlenaInlineSize
    83  }
    84  
    85  // For short slice, this one will return a slice stored internal
    86  // in the varlena.   Caller must ensure that v has a longer life
    87  // span than the returned byte slice.
    88  //
    89  // Main user of Varlena is vector.  v that comes from vector.Data
    90  // will be fine.
    91  func (v *Varlena) GetByteSlice(area []byte) []byte {
    92  	svlen := (*v)[0]
    93  	if svlen <= VarlenaInlineSize {
    94  		return v.ByteSlice()
    95  	}
    96  	voff, vlen := v.OffsetLen()
    97  	return area[voff : voff+vlen]
    98  }
    99  
   100  // See the lifespan comment above.
   101  func (v *Varlena) GetString(area []byte) string {
   102  	return string(v.GetByteSlice(area))
   103  }
   104  
   105  func (v *Varlena) Reset() {
   106  	var vzero Varlena
   107  	*v = vzero
   108  }