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mmap_util.go
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mmap_util.go
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// Copyright (c) 2019 Uber Technologies, Inc.
//
// Permission is hereby granted, free of charge, to any person obtaining a copy
// of this software and associated documentation files (the "Software"), to deal
// in the Software without restriction, including without limitation the rights
// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
// copies of the Software, and to permit persons to whom the Software is
// furnished to do so, subject to the following conditions:
//
// The above copyright notice and this permission notice shall be included in
// all copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
// THE SOFTWARE.
package fs
import (
"fmt"
"github.com/m3db/m3/src/dbnode/digest"
"github.com/m3db/m3/src/x/mmap"
)
func validateAndMmap(
fdWithDigest digest.FdWithDigestReader,
expectedDigest uint32,
forceMmapMemory bool,
reporterOptions mmap.ReporterOptions,
) (mmap.Descriptor, error) {
if forceMmapMemory {
return validateAndMmapMemory(fdWithDigest, expectedDigest, reporterOptions)
}
return validateAndMmapFile(fdWithDigest, expectedDigest, reporterOptions)
}
func validateAndMmapMemory(
fdWithDigest digest.FdWithDigestReader,
expectedDigest uint32,
reporterOptions mmap.ReporterOptions,
) (mmap.Descriptor, error) {
fd := fdWithDigest.Fd()
stat, err := fd.Stat()
if err != nil {
return mmap.Descriptor{}, err
}
numBytes := stat.Size()
// Request an anonymous (non-file-backed) mmap region. Note that we're going
// to use the mmap'd region to store the read-only summaries data, but the mmap
// region itself needs to be writable so we can copy the bytes from disk
// into it.
mmapDescriptor, err := mmap.Bytes(numBytes, mmap.Options{Read: true, Write: true, ReporterOptions: reporterOptions})
if err != nil {
return mmap.Descriptor{}, err
}
// Validate the bytes on disk using the digest, and read them into
// the mmap'd region
_, err = fdWithDigest.ReadAllAndValidate(mmapDescriptor.Bytes, expectedDigest)
if err != nil {
mmap.Munmap(mmapDescriptor)
return mmap.Descriptor{}, err
}
return mmapDescriptor, nil
}
func validateAndMmapFile(
fdWithDigest digest.FdWithDigestReader,
expectedDigest uint32,
reporterOptions mmap.ReporterOptions,
) (mmap.Descriptor, error) {
fd := fdWithDigest.Fd()
mmapDescriptor, err := mmap.File(fd, mmap.Options{Read: true, Write: false, ReporterOptions: reporterOptions})
if err != nil {
return mmap.Descriptor{}, err
}
if calculatedDigest := digest.Checksum(mmapDescriptor.Bytes); calculatedDigest != expectedDigest {
mmap.Munmap(mmapDescriptor)
return mmap.Descriptor{}, fmt.Errorf("expected %s file digest was: %d, but got: %d",
fd.Name(), expectedDigest, calculatedDigest)
}
return mmapDescriptor, nil
}