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Data tree parser: only read more data when needed.

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Before this, it would eagerly load more data on every call, which
defeats the whole point.
This commit is contained in:
Nathan Vegdahl 2020-01-05 15:58:51 +09:00
parent ccd7e141fb
commit 1f4947e895
1 changed files with 19 additions and 3 deletions
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22
sub_crates/data_tree/src/lib.rs
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@ -89,6 +89,7 @@ pub struct Parser<R: Read> {
buf_consumed_idx: usize,
total_bytes_processed: usize,
inner_opens: usize,
eof: bool,
}
impl<R: Read> Parser<R> {
@ -100,6 +101,7 @@ impl<R: Read> Parser<R> {
buf_consumed_idx: 0,
total_bytes_processed: 0,
inner_opens: 0,
eof: false,
}
}
@ -113,8 +115,13 @@ impl<R: Read> Parser<R> {
}
loop {
// Read in new data and make a string from the valid prefix.
let (read_count, valid_count) = self.do_read()?;
// Determine how much of the buffer is valid utf8.
let valid_count = match std::str::from_utf8(&self.buffer[..self.buf_fill_idx]) {
Ok(_) => self.buf_fill_idx,
Err(e) => e.valid_up_to(),
};
// Make a str slice out of the valid prefix.
let buffer_text = std::str::from_utf8(&self.buffer[..valid_count]).unwrap();
// Try to parse an event from the valid prefix.
@ -157,7 +164,7 @@ impl<R: Read> Parser<R> {
EventParse::IncompleteData => {
// If we're at the end, it's a problem.
// Otherwise, wait for more data.
if read_count == 0 {
if self.eof {
return Err(Error::UnexpectedEOF(
self.total_bytes_processed + valid_count,
));
@ -186,6 +193,15 @@ impl<R: Read> Parser<R> {
));
}
}
// If we couldn't parse a complete event, and if there were
// no errors, read in more data and loop back to try again.
if !self.eof {
let (read_count, _valid_count) = self.do_read()?;
if read_count == 0 {
self.eof = true;
}
}
}
}