fn discard_until()

in below/store/src/lib.rs [606:664]
49 lines of code
7 McCabe index (conditional complexity)

    fn discard_until<F>(&self, f: F) -> Result<bool>
    where
        F: Fn(u64) -> bool,
    {
        let entries = get_index_files(self.dir.as_path())?;

        // Entries are sorted with increasing timestamp
        for entry in entries {
            let v: Vec<&str> = entry.split('_').collect();
            if v.len() != 2 {
                warn!(self.logger, "Invalid index file name: {}", entry);
                continue;
            }

            let entry_shard = match v[1].parse::<u64>() {
                Ok(val) => val,
                _ => {
                    warn!(self.logger, "Cannot parse index shard: {}", entry);
                    continue;
                }
            };

            if f(entry_shard) {
                return Ok(true);
            }
            if entry_shard >= self.shard {
                return Ok(false);
            }

            // Removal order doesn't matter at all, it's the
            // responsibility of the read side to handle missing files
            let mut index_path = self.dir.clone();
            index_path.push(&entry);

            match std::fs::remove_file(&index_path) {
                Err(e) if e.kind() != ErrorKind::NotFound => {
                    return Err(e).context(format!(
                        "Failed to remove index file: {}",
                        index_path.display()
                    ));
                }
                _ => {}
            };

            let mut data_path = self.dir.clone();
            data_path.push(format!("data_{:011}", entry_shard));

            match std::fs::remove_file(&data_path) {
                Err(e) if e.kind() != ErrorKind::NotFound => {
                    return Err(e).context(format!(
                        "Failed to remove data file: {}",
                        data_path.display()
                    ));
                }
                _ => {}
            };
        }
        Ok(false)
    }