feat: make sure mithril package files are stable

Signed-off-by: jeluard <jeluard@users.noreply.github.com>

Author: jeluard

crates/amaru/src/bin/ledger/cmd/mithril.rs

@@ -13,21 +13,20 @@
 // limitations under the License.
 
 use std::{
-    collections::BTreeMap,
+    collections::{BTreeMap, BTreeSet},
     fmt,
     fs::{self, File},
     io::{self, Cursor, Write},
     path::PathBuf,
     sync::Arc,
-    time::{SystemTime, UNIX_EPOCH},
 };
 
 use amaru::{default_data_dir, default_ledger_dir};
-use amaru_kernel::{Hasher, NetworkName, cbor};
+use amaru_kernel::{Hasher, NetworkName, Point, cbor};
 use amaru_network::point::to_network_point;
 use async_trait::async_trait;
 use clap::Parser;
-use flate2::{Compression, write::GzEncoder};
+use flate2::{Compression, GzBuilder};
 use indicatif::{MultiProgress, ProgressBar, ProgressState, ProgressStyle};
 use mithril_client::{
     ClientBuilder, MessageBuilder,
@@ -37,10 +36,12 @@ use mithril_client::{
 use pallas_hardano::storage::immutable::read_blocks_from_point;
 use tar::{Builder, Header};
 use tokio::sync::RwLock;
-use tracing::info;
+use tracing::{info, warn};
 
 use crate::cmd::new_block_validator;
 
+const BLOCKS_PER_ARCHIVE: usize = 20000;
+
 #[derive(Debug, Parser)]
 pub struct Args {
     /// The target network to choose from.
@@ -161,15 +162,27 @@ impl FeedbackReceiver for IndicatifFeedbackReceiver {
 
 #[allow(clippy::expect_used)]
 fn package_blocks(network: &NetworkName, blocks: &BTreeMap<String, &Vec<u8>>) -> io::Result<String> {
-    let encoder = GzEncoder::new(Vec::new(), Compression::default());
+    let compressed = build_archive_bytes(blocks)?;
+
+    let dir = blocks_dir(*network);
+    fs::create_dir_all(&dir)?;
+    let archive_path = archive_path_for_blocks(network, blocks).expect("blocks map is non-empty here by construction");
+    let mut file = File::create(&archive_path)?;
+    file.write_all(&compressed)?;
+
+    Ok(archive_path)
+}
+
+fn build_archive_bytes(blocks: &BTreeMap<String, &Vec<u8>>) -> io::Result<Vec<u8>> {
+    let encoder = GzBuilder::new().mtime(0).write(Vec::new(), Compression::default());
     let mut tar = Builder::new(encoder);
 
     for (name, data) in blocks {
         let mut header = Header::new_gnu();
         header.set_size(data.len() as u64);
         header.set_mode(0o644);
         header.set_entry_type(tar::EntryType::Regular);
-        header.set_mtime(SystemTime::now().duration_since(UNIX_EPOCH).unwrap_or_default().as_secs());
+        header.set_mtime(0);
         header.set_uid(0);
         header.set_gid(0);
         header.set_cksum();
@@ -178,18 +191,95 @@ fn package_blocks(network: &NetworkName, blocks: &BTreeMap<String, &Vec<u8>>) ->
     }
 
     let encoder = tar.into_inner()?;
-    let compressed = encoder.finish()?;
+    encoder.finish()
+}
 
-    let dir = format!("{}/blocks", default_data_dir(*network));
-    fs::create_dir_all(&dir)?;
-    let first_block =
-        blocks.first_key_value().map(|kv| kv.0).cloned().expect("blocks map is non-empty here by construction");
-    let archive_path = format!("{}/{}.tar.gz", dir, first_block);
-    let mut f = File::create(&archive_path)?;
+fn blocks_dir(network: NetworkName) -> String {
+    format!("{}/blocks", default_data_dir(network))
+}
 
-    f.write_all(&compressed)?;
+fn archive_name_for_blocks(blocks: &BTreeMap<String, &Vec<u8>>) -> Option<String> {
+    let (first_block, _) = blocks.first_key_value()?;
+    let (last_block, _) = blocks.last_key_value()?;
+    let first_point = first_block.strip_suffix(".cbor")?;
+    let last_point = last_block.strip_suffix(".cbor")?;
 
-    Ok(archive_path)
+    Some(format!("{first_point}__{last_point}.tar.gz"))
+}
+
+fn archive_path_for_blocks(network: &NetworkName, blocks: &BTreeMap<String, &Vec<u8>>) -> Option<String> {
+    archive_name_for_blocks(blocks).map(|archive_name| format!("{}/{}", blocks_dir(*network), archive_name))
+}
+
+fn list_existing_archives(network: NetworkName) -> Result<BTreeSet<String>, io::Error> {
+    let dir = PathBuf::from(blocks_dir(network));
+    if !dir.try_exists()? {
+        return Ok(BTreeSet::new());
+    }
+
+    Ok(fs::read_dir(dir)?
+        .filter_map(Result::ok)
+        .filter_map(|entry| entry.file_name().into_string().ok())
+        .filter(|name| name.ends_with(".tar.gz"))
+        .collect())
+}
+
+fn parse_archive_point(name: &str) -> Option<Point> {
+    Point::try_from(name).ok()
+}
+
+#[derive(Debug, Clone, PartialEq, Eq)]
+struct ArchiveMetadata {
+    file_name: String,
+    first_block: Point,
+    last_block: Point,
+}
+
+fn parse_archive_metadata(archive_name: &str) -> Option<ArchiveMetadata> {
+    let archive_name = archive_name.strip_suffix(".tar.gz")?;
+    let (first_block, last_block) = archive_name.split_once("__")?;
+
+    Some(ArchiveMetadata {
+        file_name: format!("{archive_name}.tar.gz"),
+        first_block: parse_archive_point(first_block)?,
+        last_block: parse_archive_point(last_block)?,
+    })
+}
+
+#[cfg(test)]
+fn parse_archive_bounds(archive_name: &str) -> Option<(Point, Point)> {
+    let metadata = parse_archive_metadata(archive_name)?;
+
+    Some((metadata.first_block, metadata.last_block))
+}
+
+#[cfg(test)]
+fn latest_archive_end_point<'a>(archives: impl IntoIterator<Item = &'a String>) -> Option<Point> {
+    archives
+        .into_iter()
+        .filter_map(|archive_name| parse_archive_metadata(archive_name))
+        .map(|archive| archive.last_block)
+        .max()
+}
+
+fn sorted_archives<'a>(archives: impl IntoIterator<Item = &'a String>) -> Vec<ArchiveMetadata> {
+    let mut parsed: Vec<_> =
+        archives.into_iter().filter_map(|archive_name| parse_archive_metadata(archive_name)).collect();
+    parsed.sort_by_key(|archive| archive.last_block);
+    parsed
+}
+
+fn latest_archive<'a>(archives: impl IntoIterator<Item = &'a String>) -> Option<ArchiveMetadata> {
+    sorted_archives(archives).into_iter().last()
+}
+
+fn resume_point_for_archives<'a>(tip: Point, archives: impl IntoIterator<Item = &'a String>) -> Point {
+    let parsed = sorted_archives(archives);
+
+    match parsed.last() {
+        Some(_) => parsed.iter().rev().nth(1).map(|archive| archive.last_block).unwrap_or(tip),
+        None => tip,
+    }
 }
 
 /// Returns the latest chunk number present in the given immutable directory.
@@ -333,23 +423,27 @@ pub async fn run(args: Args) -> Result<(), Box<dyn std::error::Error>> {
 
     let ledger = new_block_validator(network, ledger_dir)?;
     let tip = ledger.get_tip();
+    let mut existing_archives = list_existing_archives(network)?;
+    let tail_archive = latest_archive(&existing_archives);
 
     // Determine the chunk to start from
+    let resume_point = resume_point_for_archives(tip, &existing_archives);
+
     let latest_chunk = get_latest_chunk(&immutable_dir)?;
-    let from_chunk = latest_chunk.unwrap_or(infer_chunk_from_slot(tip.slot_or_default().into()) - 1);
+    let from_chunk = latest_chunk.unwrap_or(infer_chunk_from_slot(resume_point.slot_or_default().into()) - 1);
 
     info!(
-        tip=%tip, from_chunk=%from_chunk,
+        tip=%tip, resume_point=%resume_point, from_chunk=%from_chunk,
         "Downloading mithril immutable chunks"
     );
 
     download_from_mithril(network, target_dir, from_chunk).await?;
 
     info!("Packaging blocks into .tar.gz files");
 
-    // Read blocks from the immutable storage and package them into .tar.gz files
-    const BLOCKS_PER_ARCHIVE: usize = 20000;
-    let mut iter = read_blocks_from_point(&immutable_dir, to_network_point(tip))?.map_while(Result::ok).skip(1); // Exclude the tip itself
+    // Read blocks from the immutable storage and package them into .tar.gz files.
+    let mut iter =
+        read_blocks_from_point(&immutable_dir, to_network_point(resume_point))?.map_while(Result::ok).skip(1); // Exclude the resume point itself
     loop {
         let chunk: Vec<_> = iter.by_ref().take(BLOCKS_PER_ARCHIVE).collect();
         if chunk.is_empty() {
@@ -363,11 +457,129 @@ pub async fn run(args: Args) -> Result<(), Box<dyn std::error::Error>> {
                 Ok((name, cbor))
             })
             .collect::<Result<BTreeMap<String, &Vec<u8>>, cbor::decode::Error>>()?;
+
+        #[allow(clippy::expect_used)]
+        let archive_name = archive_name_for_blocks(&map).expect("chunk map is non-empty here by construction");
+        if let Some(tail_archive) = &tail_archive {
+            let tail_first =
+                format!("{}.{}.cbor", tail_archive.first_block.slot_or_default(), tail_archive.first_block.hash());
+            let first_block = map.first_key_value().map(|(name, _)| name.as_str());
+
+            if first_block == Some(tail_first.as_str()) && archive_name == tail_archive.file_name {
+                info!(archive = %archive_name, "Retaining existing tail archive");
+                continue;
+            }
+
+            if first_block == Some(tail_first.as_str()) && archive_name != tail_archive.file_name {
+                let stale_archive_path = PathBuf::from(blocks_dir(network)).join(&tail_archive.file_name);
+                fs::remove_file(&stale_archive_path)?;
+                existing_archives.remove(&tail_archive.file_name);
+                info!(archive = %tail_archive.file_name, replacement = %archive_name, "Replacing tail archive");
+            }
+        }
+        if existing_archives.contains(&archive_name) {
+            debug_assert!(false, "encountered an already archived non-tail batch: {}", archive_name);
+            warn!(archive = %archive_name, "Encountered an already archived non-tail batch");
+            continue;
+        }
+
         let dir = package_blocks(&network, &map)?;
-        info!("Created {}", dir);
+        existing_archives.insert(archive_name);
+
+        info!(blocks = map.len(), dir, "Created archive batch");
     }
 
     info!("Done");
 
     Ok(())
 }
+
+#[cfg(test)]
+mod tests {
+    use std::collections::BTreeMap;
+
+    use amaru_kernel::Point;
+
+    use super::{
+        ArchiveMetadata, BLOCKS_PER_ARCHIVE, archive_name_for_blocks, build_archive_bytes, latest_archive,
+        latest_archive_end_point, parse_archive_bounds, parse_archive_metadata, resume_point_for_archives,
+    };
+
+    #[test]
+    fn archive_name_includes_first_and_last_blocks() {
+        let block_a = Vec::from([0x01_u8]);
+        let block_b = Vec::from([0x02_u8]);
+        let mut blocks = BTreeMap::new();
+
+        blocks.insert("10.aaaa.cbor".to_string(), &block_a);
+        blocks.insert("20.bbbb.cbor".to_string(), &block_b);
+
+        assert_eq!(archive_name_for_blocks(&blocks), Some("10.aaaa__20.bbbb.tar.gz".to_string()));
+    }
+
+    #[test]
+    fn archive_name_is_absent_for_empty_batch() {
+        let blocks: BTreeMap<String, &Vec<u8>> = BTreeMap::new();
+
+        assert_eq!(archive_name_for_blocks(&blocks), None);
+    }
+
+    #[test]
+    fn parse_archive_bounds_extracts_first_and_last_points() {
+        let bounds = parse_archive_bounds(
+            "10.aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa__20.bbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbb.tar.gz",
+        );
+
+        assert_eq!(
+            bounds,
+            Some((
+                Point::try_from("10.aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa").unwrap(),
+                Point::try_from("20.bbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbb").unwrap(),
+            ))
+        );
+    }
+
+    #[test]
+    fn latest_archive_end_point_uses_last_block_boundary() {
+        let archives = vec![
+            "10.aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa__20.bbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbb.tar.gz".to_string(),
+            "21.cccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccc__30.dddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddd.tar.gz".to_string(),
+        ];
+
+        assert_eq!(
+            latest_archive_end_point(&archives),
+            Some(Point::try_from("30.dddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddd").unwrap())
+        );
+    }
+
+    #[test]
+    fn latest_archive_picks_last_archive() {
+        let archives = vec![
+            "10.aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa__20.bbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbb.tar.gz".to_string(),
+            "21.cccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccc__25.dddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddd.tar.gz".to_string(),
+        ];
+
+        assert_eq!(
+            latest_archive(&archives),
+            Some(ArchiveMetadata {
+                file_name: "21.cccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccc__25.dddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddd.tar.gz".to_string(),
+                first_block: Point::try_from("21.cccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccc").unwrap(),
+                last_block: Point::try_from("25.dddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddd").unwrap(),
+            })
+        );
+    }
+
+    #[test]
+    fn resume_point_uses_previous_boundary_for_incomplete_tail() {
+        let tip = Point::try_from("5.eeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeee").unwrap();
+        let archives = vec![
+            "10.aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa__20.bbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbb.tar.gz".to_string(),
+            "21.cccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccc__25.dddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddd.tar.gz".to_string(),
+        ];
+
+        assert_eq!(
+            resume_point_for_archives(tip, &archives),
+            Point::try_from("20.bbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbb").unwrap()
+        );
+    }
+}