Simultaneously read and write to buffer - julia

Question

I am in the process of learning Julia and I'd like to do some buffer manipulation.
What I want to achieve is the following:
I've got a buffer that I can write to and read from at the same time, meaning that the speed with which I add a value to the Fifo buffer approximately equals the speed with which I read from the buffer. Reading and writing will happen in separate threads so it can occur simultaneously.
Additionally, I want to be able to control the values that I write into the buffer based on user input. For now, this is just a simple console prompt asking for a number, which I then want to write into the stream continously. The prompt refreshes and asks for a new number to write into the stream, but the prompt is non-blocking, meaning that in the background, the old number is written to the buffer until I enter a new number, which is then written to the buffer continuously.
This is my preliminary code for simulatenous reading and writing of the stream:
using Causal
CreateBuffer(size...) = Buffer{Fifo}(Float32, size...)
function writetobuffer(buf::Buffer, n::Float32)
while !isfull(buf)
write!(buf, fill(n, 2, 1))
end
end
function readfrombuffer(buf::Buffer)
while true
while !isempty(buf)
#show read(buf)
end
end
end
n_channels = 2
sampling_rate = 8192
duration = 2
n_frames = sampling_rate * duration
sbuffer = CreateBuffer(n_channels, n_frames)
print("Please enter a number: ")
n = parse(Float32, readline())
s1 = Threads.#spawn writetobuffer(sbuffer, n)
s2 = Threads.#spawn readfrombuffer(sbuffer)
s1 = fetch(s1)
s2 = fetch(s2)
I am not sure how to integrate the user input in a way that it keeps writing and reading the latest number the user put in. I looked at the documentation for channels, but didn't manage to get it working in a way that was non-blocking for the stream writing. I don't know that the correct approach is (channels, events, julia's multithreading) to enable this functionality.
How would I go on about to include this?

Answer 1

I managed to get it working, but I think it could be improved:
using Causal
CreateBuffer(size...) = Buffer{Fifo}(Float32, size...)
function writeToBuffer(buf::Buffer, n::Float32)
write!(buf, fill(n, 2, 1))
end
function readFromBuffer()
global soundbuffer
println("Starting")
sleep(0.5)
while true
while !isempty(soundbuffer)
read(soundbuffer)
end
end
println("Exiting...")
end
function askForInput()::Float32
print("Please enter a number: ")
a = parse(Float32, readline())
return(a)
end
function inputAndWrite()
global soundbuffer
old_num::Float32 = 440
new_num::Float32 = 440
while true
#async new_num = askForInput()
while (new_num == old_num)
writeToBuffer(soundbuffer, new_num)
end
old_num = new_num
println("Next iteration with number " * string(new_num))
end
end
n_channels = 2
sampling_rate = 8192
duration = 2
n_frames = sampling_rate * duration
soundbuffer = CreateBuffer(n_channels, n_frames)
s1 = Threads.#spawn inputAndWrite()
s2 = Threads.#spawn readFromBuffer()
s1 = fetch(s1)
s2 = fetch(s2)