github.com/fiatjaf/generic-ristretto@v0.0.1/z/file_linux.go (about)

     1  /*
     2   * Copyright 2020 Dgraph Labs, Inc. and Contributors
     3   *
     4   * Licensed under the Apache License, Version 2.0 (the "License");
     5   * you may not use this file except in compliance with the License.
     6   * You may obtain a copy of the License at
     7   *
     8   *     http://www.apache.org/licenses/LICENSE-2.0
     9   *
    10   * Unless required by applicable law or agreed to in writing, software
    11   * distributed under the License is distributed on an "AS IS" BASIS,
    12   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    13   * See the License for the specific language governing permissions and
    14   * limitations under the License.
    15   */
    16  
    17  package z
    18  
    19  import (
    20  	"fmt"
    21  )
    22  
    23  // Truncate would truncate the mmapped file to the given size. On Linux, we truncate
    24  // the underlying file and then call mremap, but on other systems, we unmap first,
    25  // then truncate, then re-map.
    26  func (m *MmapFile) Truncate(maxSz int64) error {
    27  	if err := m.Sync(); err != nil {
    28  		return fmt.Errorf("while sync file: %s, error: %v\n", m.Fd.Name(), err)
    29  	}
    30  	if err := m.Fd.Truncate(maxSz); err != nil {
    31  		return fmt.Errorf("while truncate file: %s, error: %v\n", m.Fd.Name(), err)
    32  	}
    33  
    34  	var err error
    35  	m.Data, err = mremap(m.Data, int(maxSz)) // Mmap up to max size.
    36  	return err
    37  }