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use super::segment::Segment;
use crate::{Message, Result};
use std::fs;
use std::path::PathBuf;
#[derive(Debug)]
pub struct LogManager {
dir: PathBuf,
segments: Vec<Segment>,
active_segment_index: usize,
max_segment_size: u64,
}
impl LogManager {
pub async fn new(
base_dir: PathBuf,
topic: &str,
partition: u32,
max_segment_size: u64,
) -> Result<Self> {
let dir = base_dir
.join(topic)
.join(format!("partition-{}", partition));
fs::create_dir_all(&dir)?;
let mut segments = Vec::new();
// Load existing segments
// Simply look for .log files and sort them
let mut paths: Vec<_> = fs::read_dir(&dir)?
.filter_map(|entry| entry.ok())
.map(|entry| entry.path())
.filter(|path| path.extension().is_some_and(|ext| ext == "log"))
.collect();
paths.sort();
if paths.is_empty() {
// Create initial segment
segments.push(Segment::new(&dir, 0)?);
} else {
for path in paths {
// Handle malformed filenames gracefully (non-UTF8, missing stem, etc.)
let Some(stem) = path.file_stem() else {
tracing::warn!(path = ?path, "Skipping segment file with no stem");
continue;
};
let Some(filename) = stem.to_str() else {
tracing::warn!(path = ?path, "Skipping segment file with non-UTF8 name");
continue;
};
// Assumes filename is just the offset (e.g. "00000000000000000000")
if let Ok(base_offset) = filename.parse::<u64>() {
segments.push(Segment::new(&dir, base_offset)?);
} else {
tracing::warn!(filename = %filename, "Skipping segment file with unparseable offset");
}
}
}
if segments.is_empty() {
segments.push(Segment::new(&dir, 0)?);
}
let active_segment_index = segments.len() - 1;
Ok(Self {
dir,
segments,
active_segment_index,
max_segment_size,
})
}
pub async fn append(&mut self, offset: u64, message: Message) -> Result<u64> {
let segment = &mut self.segments[self.active_segment_index];
// Check if we need to roll
if segment.size() >= self.max_segment_size {
// Flush current segment before rolling
segment.flush().await?;
let new_segment = Segment::new(&self.dir, offset)?;
self.segments.push(new_segment);
self.active_segment_index += 1;
}
let segment = &mut self.segments[self.active_segment_index];
segment.append(offset, message).await
}
/// Batch append for high-throughput scenarios
/// Splits batches across segment boundaries when needed
pub async fn append_batch(&mut self, messages: Vec<(u64, Message)>) -> Result<Vec<u64>> {
if messages.is_empty() {
return Ok(Vec::new());
}
let mut all_positions = Vec::with_capacity(messages.len());
let mut remaining = messages.as_slice();
while !remaining.is_empty() {
let segment = &mut self.segments[self.active_segment_index];
// Roll if current segment is already at capacity
if segment.size() >= self.max_segment_size {
segment.flush().await?;
let new_segment = Segment::new(&self.dir, remaining[0].0)?;
self.segments.push(new_segment);
self.active_segment_index += 1;
}
let segment = &self.segments[self.active_segment_index];
let available = self.max_segment_size.saturating_sub(segment.size());
// Find how many messages fit in the remaining capacity
let mut accumulated = 0u64;
let mut split_at = 0;
for (_, m) in remaining.iter() {
let msg_size = (m.value.len() + 100) as u64;
if accumulated + msg_size > available && split_at > 0 {
break;
}
accumulated += msg_size;
split_at += 1;
// Always include at least one message to guarantee progress
if accumulated > available {
break;
}
}
let (batch, rest) = remaining.split_at(split_at);
let segment = &mut self.segments[self.active_segment_index];
let positions = segment.append_batch(batch.to_vec()).await?;
all_positions.extend(positions);
remaining = rest;
}
Ok(all_positions)
}
pub async fn read(&self, offset: u64, max_bytes: usize) -> Result<Vec<Message>> {
let mut messages = Vec::new();
let mut bytes_collected = 0;
// Optimized: Find first segment where base_offset <= offset
let start_segment_idx = self
.segments
.partition_point(|seg| seg.base_offset() <= offset)
.saturating_sub(1);
for segment in self.segments.iter().skip(start_segment_idx) {
// If we have enough data, stop
if bytes_collected >= max_bytes {
break;
}
// Read from segment
let batch = segment.read(offset, max_bytes - bytes_collected).await?;
for msg in batch {
if msg.offset < offset {
continue;
}
if messages.len() < 1000 && bytes_collected < max_bytes {
// Estimate size (header + key + val)
let size = 8 + msg.key.as_ref().map(|k| k.len()).unwrap_or(0) + msg.value.len();
bytes_collected += size;
messages.push(msg);
}
}
}
Ok(messages)
}
pub fn earliest_offset(&self) -> u64 {
self.segments.first().map(|s| s.base_offset()).unwrap_or(0)
}
pub async fn recover_next_offset(&self) -> Result<u64> {
if let Some(last_segment) = self.segments.last() {
if let Some(last_offset) = last_segment.recover_last_offset().await? {
return Ok(last_offset + 1);
}
// If last segment is empty, check `base_offset` of it?
// Usually base_offset is the next offset of previous segment.
// But if it's completely empty (newly created), next offset is `base_offset`.
return Ok(last_segment.base_offset());
}
Ok(0)
}
/// Flush all segments to disk ensuring durability
pub async fn flush(&self) -> Result<()> {
for segment in &self.segments {
segment.flush().await?;
}
Ok(())
}
/// Physically remove segments whose data is entirely below the given offset.
///
/// A segment is eligible for deletion when the *next* segment's `base_offset`
/// is ≤ `watermark`, meaning every record in the segment is before the
/// watermark. The currently-active segment is never deleted.
///
/// Returns the number of segments removed.
pub fn truncate_before(&mut self, watermark: u64) -> crate::Result<usize> {
if self.segments.len() <= 1 {
return Ok(0);
}
// Find how many segments are fully below the watermark.
// A segment at index `i` is fully below if the *next* segment's
// base_offset <= watermark (all records in segment[i] < base[i+1] <= watermark).
let mut remove_count = 0;
for i in 0..self.segments.len().saturating_sub(1) {
let next_base = self.segments[i + 1].base_offset();
if next_base <= watermark {
remove_count = i + 1;
} else {
break;
}
}
if remove_count == 0 {
return Ok(0);
}
// Delete files for removed segments
for seg in self.segments.drain(..remove_count) {
if let Err(e) = seg.delete_files() {
tracing::warn!(
"Failed to delete segment files at offset {}: {}",
seg.base_offset(),
e
);
}
}
// Adjust active segment index
self.active_segment_index = self.active_segment_index.saturating_sub(remove_count);
Ok(remove_count)
}
/// Find the first offset with timestamp >= target_timestamp (milliseconds since epoch)
/// Scans through segments to find the earliest message matching the timestamp.
/// Returns None if no matching offset is found.
pub async fn find_offset_for_timestamp(&self, target_timestamp: i64) -> Result<Option<u64>> {
// Scan segments from oldest to newest
for segment in &self.segments {
// Check timestamp bounds to skip segments that are entirely before target
if let Some((_min_ts, max_ts)) = segment.timestamp_bounds().await? {
// If the entire segment is before our target, skip it
if max_ts < target_timestamp {
continue;
}
// If the segment might contain our target, search it
if let Some(offset) = segment.find_offset_for_timestamp(target_timestamp).await? {
return Ok(Some(offset));
}
}
}
Ok(None)
}
}