Public Documentation

mmap(file::Union{IO,AbstractString}[, ::Type{Array{T}}, dims]; kws...)
mmap(::Type{Array{T}}, dims; kws...)

Memory maps an Array from a file file of size dims (either a scalar Integer or a tuple of dimension lengths), or creates an anonymous mapping not backed by a file if no file is given.

If not specified, the array type defaults to Array{UInt8}, and dim defaults to a vector with length equal to the number of elements remaining in the file (accounting for a non-zero position in the file stream io).

Extended help

This function provides a relatively simple wrapper around the underlying mmap system call. In particular, it is the user's responsibility to ensure the combination(s) of stream state (e.g. read/write or read-only, file length), protection flags, and memory map flags must form a valid mmap request, as they are not validated here.

See your system mmap man page for details on the behaviors of each flag.

Keywords

The following keywords are available:

• flags::MmapFlags — any of the MAP_* system-specific constants. For files, this defaults to MAP_SHARED, and anonymous mappings default to MAP_SHARED | MAP_ANONYMOUS.

• prot::MmapProtection — any of the PROT_* flags. The default is PROT_READ | PROT_WRITE for all anonymous maps and memory maps of non-existent files (in which case the file will be created). If the file already exists, it is opened read-only and the default is PROT_READ only.

• offset::Integer — offset in bytes from the beginning of the file, defaulting to the current stream position. This keyword is not valid for anonymous maps.

• grow::Bool — Whether to grow a file to accomodate the memory map, if the file is writable. Defaults to true. This keyword is not valid for anonymous maps.

mincore(array::Array)

Returns a boolean array (of length fld1(sizeof(m), PAGESIZE)) indicating whether the pages of the memory-mapped array are resident in RAM. Pages corresponding to false values will cause a fault if referenced.

madvise!(array, flag::AdviseFlags = MADV_NORMAL)

Advises the kernel on the intended usage of the memory-mapped array, with the intent flag being one of the available MADV_* constants.

msync!(array, flag::SyncFlags = MS_SYNC)

Synchronizes the memory-mapped array and its backing file on disk.