go.chromium.org/luci@v0.0.0-20240309015107-7cdc2e660f33/analysis/internal/pagination/page_size.go (about)

     1  // Copyright 2022 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  	"go.chromium.org/luci/common/errors"
    19  )
    20  
    21  type PageSizeLimiter struct {
    22  	Max     int32
    23  	Default int32
    24  }
    25  
    26  // Adjust the requested pageSize according to PageSizeLimiter.Max and
    27  // PageSizeLimiter.Default as necessary.
    28  func (psl *PageSizeLimiter) Adjust(pageSize int32) int32 {
    29  	switch {
    30  	case pageSize >= psl.Max:
    31  		return psl.Max
    32  	case pageSize > 0:
    33  		return pageSize
    34  	default:
    35  		return psl.Default
    36  	}
    37  }
    38  
    39  // ValidatePageSize returns a non-nil error if pageSize is invalid.
    40  // Returns nil if pageSize is 0.
    41  func ValidatePageSize(pageSize int32) error {
    42  	if pageSize < 0 {
    43  		return errors.Reason("negative").Err()
    44  	}
    45  	return nil
    46  }