Closed
Description
What it does
There should be a lint that gives a warning when calling File::bytes(), TcpStream::bytes(), and maybe others.
These functions (almost?) should never be called since File and TcpStream are unbuffered and will perform a syscall everytime .next() is called. This is also noted on the docs page of the function.
I'm not sure an automatic fix will be possible, since if the bytes() is used only partially, the file is only read partially. Inserting the bufreader would change this behaviour.
Advantage
- I measured the rewritten code to be ~1000x faster for large file
Drawbacks
- Theoretically a user could write
file.bytes().next(), then dropping the iterator. In this case, adding the BufReader would make no difference. I expect this to be a rare situation though.
Example
let file = File::open("./bytes.txt").unwrap();
let zero_bytes_count = file.bytes().map(|b| b.unwrap()).filter(|b| *b == 0).count();Could be written as:
let file = BufReader::new(File::open("./bytes.txt").unwrap());
let zero_bytes_count = file.bytes().map(|b| b.unwrap()).filter(|b| *b == 0).count();