Trait FileBufRead

Source

pub trait FileBufRead<'a>: BufRead {
    // Required methods
    fn set_file(&mut self, file: &'a File, read_limit: FileSize) -> Result<()>;
    fn add_file_to_prefetch(
        &mut self,
        file: &'a File,
        read_limit: FileSize,
    ) -> Result<()>;
    fn get_file_offset(&self) -> FileSize;
    fn consume_or_skip(&mut self, n: usize);
}

Expand description

An extension of the BufRead trait for file readers that allow tracking file read position offset.

Required Methods§

Source

fn set_file(&mut self, file: &'a File, read_limit: FileSize) -> Result<()>

Activate the given file as source of reads of this reader.

Resets the internal buffer to an empty state and sets the file offset to 0.

read_limit provides a pre-defined limit on the number of bytes that can be read from the file (unless EOF is reached).

If the file was previously queued via add_file_to_prefetch, the reader advances to that file (validating identity / read_limit) rather than re-queueing it.

Source

fn add_file_to_prefetch( &mut self, file: &'a File, read_limit: FileSize, ) -> Result<()>

Queue file for read-ahead (prefetch). Files are processed in FIFO order by subsequent set_file calls.

This is a hint to keep the read pipeline saturated for readers that support concurrent read-ahead. Implementations without read-ahead may ignore the call. Callers must still invoke set_file to switch the active file.

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fn get_file_offset(&self) -> FileSize

Returns the current file offset corresponding to the start of the buffer that will be returned by the next call to fill_buf.

This offset represents the position within the underlying file where data will be consumed from.

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fn consume_or_skip(&mut self, n: usize)

Advance the offset by amt bytes, potentially skipping past the current buffer into the underlying file.

Unlike BufRead::consume, amt is not constrained by the size of the buffer returned by fill_buf — any bytes beyond what is currently buffered are skipped by advancing the file read offset, so the next fill_buf starts at the correct position.