Prevent c++ istream from locking when calling 'get' and 'peek'

Question

I'm currently reading a text file in c++ using an istream, and I noticed that there's significant overhead from the istream locking the file after every read (istream get and peek methods, specifically).

If I understand correctly, this locking occurs for thread safety, but I'm only planning on using a single thread, so it feels unnecessary.

Is there any way to prevent this thread locking when reading from the istream?

Thanks in advance!

P.S.: I attached a VTune results image containing an overview of where the time is being spent.

Answer 1

While it's not supported, there appear to be some hacker-y ways of doing this:

for char = in.get(), or in.get(char&), use std::sbumpc.

for char = in.peek(), use std::sgetc.

So:

// Old:
char c = in.get();
char p = in.peek();

// New:
char c = in.rdbuf()->sbumpc();
char p = in.rdbuf()->sgetc();

Note that these methods will not be thread safe, and will not automatically detect eof. Only use when performance is critical, and be aware of checks yourself.