github.com/dolthub/dolt/go@v0.40.5-0.20240520175717-68db7794bea6/store/nbs/quota.go (about)

     1  // Copyright 2022 Dolthub, Inc.
     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 nbs
    16  
    17  import (
    18  	"context"
    19  	"sync"
    20  )
    21  
    22  type MemoryQuotaProvider interface {
    23  	AcquireQuotaBytes(ctx context.Context, sz int) ([]byte, error)
    24  	ReleaseQuotaBytes(sz int)
    25  	Usage() uint64
    26  }
    27  
    28  type UnlimitedQuotaProvider struct {
    29  	mu   sync.Mutex
    30  	used uint64
    31  }
    32  
    33  func NewUnlimitedMemQuotaProvider() *UnlimitedQuotaProvider {
    34  	return &UnlimitedQuotaProvider{}
    35  }
    36  
    37  func (q *UnlimitedQuotaProvider) AcquireQuotaBytes(ctx context.Context, sz int) ([]byte, error) {
    38  	buf := make([]byte, sz)
    39  	q.mu.Lock()
    40  	defer q.mu.Unlock()
    41  	q.used += uint64(sz)
    42  	return buf, nil
    43  }
    44  
    45  func (q *UnlimitedQuotaProvider) ReleaseQuotaBytes(sz int) {
    46  	if sz < 0 {
    47  		panic("tried to release negative bytes")
    48  	}
    49  	q.mu.Lock()
    50  	defer q.mu.Unlock()
    51  	if uint64(sz) > q.used {
    52  		panic("tried to release too much quota")
    53  	}
    54  	q.used -= uint64(sz)
    55  }
    56  
    57  func (q *UnlimitedQuotaProvider) Usage() uint64 {
    58  	q.mu.Lock()
    59  	defer q.mu.Unlock()
    60  	return q.used
    61  }