std.mmfile

Read and write memory mapped files.

Memory mapped files are a mechanism in operating systems that allows file access through virtual memory. After opening a file with MmFile, the contents can be read from or written to with standard slice / pointer operations. Changes to the memory are automatically reflected in the underlying file.

Memory mapping can increase I/O performance of large files, compared to buffered read / write operations from std.file and std.stdio. However, I/O errors are not handled as safely: when for example the disk that the file is on gets removed, reading from it may result in a segfault.

Copyright

License

Boost License 1.0.

Authors

Walter Bright,

Matthew Wilson References: https://en.wikipedia.org/wiki/Memory-mapped_file Source: std/mmfile.d

class MmFile

Types 1

classMmFile

MmFile objects control the memory mapped file resource.

Fields

string filename

void[] data

ulong start

size_t window

ulong size

Mode mMode

void * address

Methods

void flush()

ulong length() @property constGives size in bytes of the memory mapped file.

Mode mode()Read-only property returning the file mode.

void[] opSlice()Returns entire file contents as an array.

void[] opSlice(ulong i1, ulong i2)Returns slice of file contents as an array.

ubyte opIndex(ulong i)Returns byte at index i in file.

ubyte opIndexAssign(ubyte value, ulong i)Sets and returns byte at index i in file to value.

private int mapped(ulong i)

private void unmap()

private void map(ulong start, size_t len)

private void ensureMapped(ulong i)

private void ensureMapped(ulong i, ulong j)

Constructors

this(string filename)Open memory mapped file filename for reading. File is closed when the object instance is deleted. Throws: - On POSIX, ErrnoException. - On Windows, WindowsException.

this(string filename,  Mode mode,  ulong  size,  void *  address,
             size_t window =  0)

Open memory mapped file filename in mode. File is closed when the object instance is deleted. Params: filename = name of the file. If null, an anonymous file mapping is created. mode = access mode ...

Destructors

~thisFlushes pending output and closes the memory mapped file.

Nested Templates

ModeThe mode the memory mapped file is opened with.