diff options
| -rw-r--r-- | src/common.rs | 16 | ||||
| -rw-r--r-- | src/forward_log_reader.rs | 124 | ||||
| -rw-r--r-- | src/lib.rs | 7 | ||||
| -rw-r--r-- | src/reverse_log_reader.rs (renamed from src/log_reader.rs) | 135 |
4 files changed, 147 insertions, 135 deletions
diff --git a/src/common.rs b/src/common.rs index 9ea43aa..ea179ab 100644 --- a/src/common.rs +++ b/src/common.rs @@ -39,6 +39,22 @@ pub const SEQ_LIT_FIELD_SEP: &[u8] = &[ ESCAPE_CHARACTER, ]; +/// There are three special sequences that need to be handled: +/// Here: SC = escape char, FS = field separator. +/// - SC FS FS SC -> actual record separator +/// - SC SC FS SC -> literal FS +/// - SC SC SC SC -> literal SC +/// +/// Returns SpecialSequence or None if not valid. +pub fn validate_special(buf: &[u8]) -> Option<SpecialSequence> { + match buf { + SEQ_RECORD_SEP => Some(SpecialSequence::RecordSeparator), + SEQ_LIT_FIELD_SEP => Some(SpecialSequence::LiteralFieldSeparator), + SEQ_LIT_ESCAPE => Some(SpecialSequence::LiteralEscape), + _ => None, + } +} + #[derive(Debug, Eq, PartialEq)] pub enum SpecialSequence { RecordSeparator, diff --git a/src/forward_log_reader.rs b/src/forward_log_reader.rs new file mode 100644 index 0000000..10788a7 --- /dev/null +++ b/src/forward_log_reader.rs @@ -0,0 +1,124 @@ +use super::common::*; +use std::fs::{self}; +use std::io::{self, BufRead, Read}; + +pub struct ForwardLogReader<'a> { + reader: io::BufReader<&'a mut fs::File>, +} + +impl<'a> ForwardLogReader<'a> { + pub fn new(file: &mut fs::File) -> ForwardLogReader { + let reader = io::BufReader::new(file); + ForwardLogReader { reader } + } + + fn read_record(&mut self) -> Result<Option<Record>, io::Error> { + // The buffer that stores the bytes read from the file. + let mut read_buf: Vec<u8> = Vec::new(); + // The buffer that stores all the bytes of the record read so far in reverse order. + let mut result_buf: Vec<u8> = Vec::new(); + + // Try reading a byte from the file. + // If we've reached the end of the file, return None. + let mut peek_buf = vec![0]; + match self.reader.read_exact(&mut peek_buf) { + Ok(_) => { + // Go back one byte + self.reader.seek_relative(-1)?; + } + Err(ref e) if e.kind() == io::ErrorKind::UnexpectedEof => { + return Ok(None); + } + Err(e) => { + return Err(e); + } + } + + loop { + read_buf.clear(); + self.reader.read_until(ESCAPE_CHARACTER, &mut read_buf)?; + self.reader.seek_relative(-1)?; + result_buf.extend(&read_buf[..read_buf.len() - 1]); + + // Otherwise, we must have encountered an escape character. + match self.read_special_sequence()? { + SpecialSequence::RecordSeparator => { + // The record is complete, so we can break out of the loop. + break; + } + SpecialSequence::LiteralFieldSeparator => { + // The field separator is escaped, so we need to add it to the result buffer. + result_buf.push(FIELD_SEPARATOR); + } + SpecialSequence::LiteralEscape => { + // The escape character is escaped, so we need to add it to the result buffer. + result_buf.push(ESCAPE_CHARACTER); + } + } + } + + let record = Record::deserialize(&result_buf); + Ok(Some(record)) + } + + fn read_special_sequence(&mut self) -> Result<SpecialSequence, io::Error> { + let mut special_buf: Vec<u8> = vec![0; SEQ_RECORD_SEP.len()]; + self.reader.read_exact(&mut special_buf)?; + + match validate_special(&special_buf.as_slice()) { + Some(special) => Ok(special), + None => Err(io::Error::new( + io::ErrorKind::InvalidData, + "Not a special sequence", + )), + } + } +} + +impl Iterator for ForwardLogReader<'_> { + type Item = Record; + + fn next(&mut self) -> Option<Self::Item> { + match self.read_record() { + Ok(Some(record)) => Some(record), + Ok(None) => None, + Err(err) => panic!("Error reading record: {:?}", err), + } + } +} + +#[cfg(test)] +mod reverse_reader_tests { + use super::*; + use std::path::Path; + + #[test] + fn test_forward_log_reader_fixture_db1() { + let db_path = Path::new(TEST_RESOURCES_DIR).join("test_db1"); + let mut file = fs::OpenOptions::new() + .read(true) + .open(&db_path) + .expect("Failed to open file"); + let mut forward_log_reader = ForwardLogReader::new(&mut file); + + // There are two records in the log with "schema": Int, Null + + let first_record = forward_log_reader + .next() + .expect("Failed to read the first record"); + assert!(match first_record.values.as_slice() { + [RecordValue::Int(0x1D), RecordValue::Null] => true, + _ => false, + }); + + let last_record = forward_log_reader + .next() + .expect("Failed to read the last record"); + assert!(match last_record.values.as_slice() { + [RecordValue::Int(10), RecordValue::Null] => true, + _ => false, + }); + + assert!(forward_log_reader.next().is_none()); + } +} @@ -2,16 +2,17 @@ extern crate log; mod common; -mod log_reader; +mod forward_log_reader; mod primary_memtable; +mod reverse_log_reader; mod secondary_memtable; pub use common::*; +pub use forward_log_reader::ForwardLogReader; use fs2::lock_contended_error; use fs2::FileExt; -pub use log_reader::ForwardLogReader; -pub use log_reader::ReverseLogReader; use primary_memtable::PrimaryMemtable; +pub use reverse_log_reader::ReverseLogReader; use secondary_memtable::SecondaryMemtable; use std::fmt::Debug; use std::fs::{self}; diff --git a/src/log_reader.rs b/src/reverse_log_reader.rs index d07326a..778d1b4 100644 --- a/src/log_reader.rs +++ b/src/reverse_log_reader.rs @@ -1,21 +1,6 @@ use super::common::*; use std::fs::{self}; -use std::io::{self, BufRead, Read, Seek, SeekFrom}; -use std::path::Path; - -/// There are three special sequences that need to be handled: -/// Here: SC = escape char, FS = field separator. -/// - SC FS FS SC -> actual record separator -/// - SC SC FS SC -> literal FS -/// - SC SC SC SC -> literal SC -fn validate_special(buf: &[u8]) -> Option<SpecialSequence> { - match buf { - SEQ_RECORD_SEP => Some(SpecialSequence::RecordSeparator), - SEQ_LIT_FIELD_SEP => Some(SpecialSequence::LiteralFieldSeparator), - SEQ_LIT_ESCAPE => Some(SpecialSequence::LiteralEscape), - _ => None, - } -} +use std::io::{self, Read, Seek, SeekFrom}; pub struct ReverseLogReader<'a> { file: &'a mut fs::File, @@ -78,7 +63,7 @@ impl<'a> ReverseLogReader<'a> { let mut result_buf: Vec<u8> = vec![]; loop { let mut read_buf = vec![]; - let read = self.read_until(ESCAPE_CHARACTER, &mut read_buf)?; + let _read = self.read_until(ESCAPE_CHARACTER, &mut read_buf)?; result_buf.extend(&read_buf); @@ -195,6 +180,7 @@ impl<'a> ReverseLogReader<'a> { mod reverse_reader_tests { use super::*; use std::io::Write; + use std::path::Path; #[test] fn test_read_until_found() { @@ -305,36 +291,6 @@ mod reverse_reader_tests { } #[test] - fn test_forward_log_reader_fixture_db1() { - let db_path = Path::new(TEST_RESOURCES_DIR).join("test_db1"); - let mut file = fs::OpenOptions::new() - .read(true) - .open(&db_path) - .expect("Failed to open file"); - let mut forward_log_reader = ForwardLogReader::new(&mut file); - - // There are two records in the log with "schema": Int, Null - - let first_record = forward_log_reader - .next() - .expect("Failed to read the first record"); - assert!(match first_record.values.as_slice() { - [RecordValue::Int(0x1D), RecordValue::Null] => true, - _ => false, - }); - - let last_record = forward_log_reader - .next() - .expect("Failed to read the last record"); - assert!(match last_record.values.as_slice() { - [RecordValue::Int(10), RecordValue::Null] => true, - _ => false, - }); - - assert!(forward_log_reader.next().is_none()); - } - - #[test] fn test_read_exact() { let mut file = tempfile::tempfile().unwrap(); file.write_all(b"hello,world").unwrap(); @@ -378,88 +334,3 @@ impl Iterator for ReverseLogReader<'_> { } } } - -pub struct ForwardLogReader<'a> { - reader: io::BufReader<&'a mut fs::File>, -} - -impl<'a> ForwardLogReader<'a> { - pub fn new(file: &mut fs::File) -> ForwardLogReader { - let reader = io::BufReader::new(file); - ForwardLogReader { reader } - } - - fn read_record(&mut self) -> Result<Option<Record>, io::Error> { - // The buffer that stores the bytes read from the file. - let mut read_buf: Vec<u8> = Vec::new(); - // The buffer that stores all the bytes of the record read so far in reverse order. - let mut result_buf: Vec<u8> = Vec::new(); - - // Try reading a byte from the file. - // If we've reached the end of the file, return None. - let mut peek_buf = vec![0]; - match self.reader.read_exact(&mut peek_buf) { - Ok(_) => { - // Go back one byte - self.reader.seek_relative(-1)?; - } - Err(ref e) if e.kind() == io::ErrorKind::UnexpectedEof => { - return Ok(None); - } - Err(e) => { - return Err(e); - } - } - - loop { - read_buf.clear(); - self.reader.read_until(ESCAPE_CHARACTER, &mut read_buf)?; - self.reader.seek_relative(-1)?; - result_buf.extend(&read_buf[..read_buf.len() - 1]); - - // Otherwise, we must have encountered an escape character. - match self.read_special_sequence()? { - SpecialSequence::RecordSeparator => { - // The record is complete, so we can break out of the loop. - break; - } - SpecialSequence::LiteralFieldSeparator => { - // The field separator is escaped, so we need to add it to the result buffer. - result_buf.push(FIELD_SEPARATOR); - } - SpecialSequence::LiteralEscape => { - // The escape character is escaped, so we need to add it to the result buffer. - result_buf.push(ESCAPE_CHARACTER); - } - } - } - - let record = Record::deserialize(&result_buf); - Ok(Some(record)) - } - - fn read_special_sequence(&mut self) -> Result<SpecialSequence, io::Error> { - let mut special_buf: Vec<u8> = vec![0; SEQ_RECORD_SEP.len()]; - self.reader.read_exact(&mut special_buf)?; - - match validate_special(&special_buf.as_slice()) { - Some(special) => Ok(special), - None => Err(io::Error::new( - io::ErrorKind::InvalidData, - "Not a special sequence", - )), - } - } -} - -impl Iterator for ForwardLogReader<'_> { - type Item = Record; - - fn next(&mut self) -> Option<Self::Item> { - match self.read_record() { - Ok(Some(record)) => Some(record), - Ok(None) => None, - Err(err) => panic!("Error reading record: {:?}", err), - } - } -} |