FastIOBuffers

FastIOBuffers aims to provide faster alternatives to Base.IOBuffer, which as of time of writing allocates memory even when e.g. a Float64 is written to or read from it.

FastWriteBuffer

FastWriteBuffer solves the allocation problem for the write use case. On 1.1.0, using IOBuffer:

using BenchmarkTools
const N = 1000
@btime write(buf, x) evals = N setup = begin
    x = rand(Float64)
    buf = IOBuffer(Vector{UInt8}(undef, N * Core.sizeof(x)), read=false, write=true)
end

results in 15.582 ns (1 allocation: 16 bytes), while

using BenchmarkTools
using FastIOBuffers
const N = 1000
@btime write(buf, x) evals = N setup = begin
    x = rand(Float64)
    buf = FastWriteBuffer(Vector{UInt8}(undef, N * Core.sizeof(x)))
end

results in 10.759 ns (0 allocations: 0 bytes)

FastReadBuffer

Similarly, FastReadBuffer can be used in place of IOBuffer for reading. On 1.1.0, using IOBuffer:

using BenchmarkTools, Random
const N = 1000
@btime read(buf, Float64) evals = N setup = begin
    rng = MersenneTwister(1)
    writebuf = IOBuffer()
    map(1 : N) do _
        write(writebuf, rand(rng, Float64))
    end
    buf = IOBuffer(take!(writebuf))
end

results in 3.368 ns (0 allocations: 0 bytes), while replacing IOBuffer with FastReadBuffer results in 1.344 ns (0 allocations: 0 bytes).