go.chromium.org/luci@v0.0.0-20240309015107-7cdc2e660f33/cv/internal/rpc/pagination/size.go (about)

     1  // Copyright 2021 The LUCI Authors.
     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 pagination
    16  
    17  import (
    18  	"fmt"
    19  
    20  	"google.golang.org/grpc/codes"
    21  
    22  	"go.chromium.org/luci/grpc/appstatus"
    23  )
    24  
    25  // InvalidPageSize annotates the error with InvalidArgument appstatus.
    26  func InvalidPageSize(err error) error {
    27  	return appstatus.Attachf(err, codes.InvalidArgument, "invalid page size, must be >= 0")
    28  }
    29  
    30  type requestWithPageSize interface {
    31  	GetPageSize() int32
    32  }
    33  
    34  // ValidatePageSize validates and caps page size from the given request.
    35  func ValidatePageSize(req requestWithPageSize, defaultValue, maxValue int32) (int32, error) {
    36  	if defaultValue > maxValue {
    37  		panic(fmt.Errorf("invalid use: defaultValue %d must be <= maxValue %d", defaultValue, maxValue))
    38  	}
    39  	switch v := req.GetPageSize(); {
    40  	case v < 0:
    41  		return 0, InvalidPageSize(fmt.Errorf("page_size %d", v))
    42  	case v == 0:
    43  		return defaultValue, nil
    44  	case v < maxValue:
    45  		return v, nil
    46  	default:
    47  		return maxValue, nil
    48  	}
    49  }