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

     1  // +build !linux
     2  
     3  /*
     4   * Copyright 2020 Dgraph Labs, Inc. and Contributors
     5   *
     6   * Licensed under the Apache License, Version 2.0 (the "License");
     7   * you may not use this file except in compliance with the License.
     8   * You may obtain a copy of the License at
     9   *
    10   *     http://www.apache.org/licenses/LICENSE-2.0
    11   *
    12   * Unless required by applicable law or agreed to in writing, software
    13   * distributed under the License is distributed on an "AS IS" BASIS,
    14   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    15   * See the License for the specific language governing permissions and
    16   * limitations under the License.
    17   */
    18  
    19  package z
    20  
    21  import "fmt"
    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 := Munmap(m.Data); err != nil {
    31  		return fmt.Errorf("while munmap file: %s, error: %v\n", m.Fd.Name(), err)
    32  	}
    33  	if err := m.Fd.Truncate(maxSz); err != nil {
    34  		return fmt.Errorf("while truncate file: %s, error: %v\n", m.Fd.Name(), err)
    35  	}
    36  	var err error
    37  	m.Data, err = Mmap(m.Fd, true, maxSz) // Mmap up to max size.
    38  	return err
    39  }