From 6d096524f67afb4f7b598d9e99bf5cefc65fa23b Mon Sep 17 00:00:00 2001
From: Kim Altintop <kim@eagain.io>
Date: Mon, 11 Sep 2023 14:45:44 +0200
Subject: [PATCH] Remove `MessageLogIter`, use `commit_log::Iter` instead

---
 crates/core/src/db/message_log.rs   | 75 -----------------------------
 crates/core/src/db/relational_db.rs |  6 ++-
 2 files changed, 4 insertions(+), 77 deletions(-)

diff --git a/crates/core/src/db/message_log.rs b/crates/core/src/db/message_log.rs
index 91259a1698e..9e0e6fce76b 100644
--- a/crates/core/src/db/message_log.rs
+++ b/crates/core/src/db/message_log.rs
@@ -239,18 +239,6 @@ impl MessageLog {
         self.root.clone()
     }
 
-    pub fn iter(&self) -> MessageLogIter {
-        self.iter_from(0)
-    }
-
-    pub fn iter_from(&self, start_offset: u64) -> MessageLogIter {
-        MessageLogIter {
-            offset: start_offset,
-            message_log: self,
-            open_segment_file: None,
-        }
-    }
-
     /// Obtains an iterator over all segments in the log, in the order they were
     /// created.
     ///
@@ -306,19 +294,6 @@ impl MessageLog {
     fn open_segment_mut(&mut self) -> &mut Segment {
         self.segments.last_mut().expect("at least one segment must exist")
     }
-
-    fn segment_for_offset(&self, offset: u64) -> Option<Segment> {
-        let prev = self.segments[0];
-        for segment in &self.segments {
-            if segment.min_offset > offset {
-                return Some(prev);
-            }
-        }
-        if offset <= self.open_segment_max_offset {
-            return Some(*self.segments.last().unwrap());
-        }
-        None
-    }
 }
 
 /// A read-only view of an on-disk [`Segment`] of the [`MessageLog`].
@@ -439,56 +414,6 @@ impl Iterator for Segments {
     }
 }
 
-pub struct MessageLogIter<'a> {
-    offset: u64,
-    message_log: &'a MessageLog,
-    open_segment_file: Option<BufReader<File>>,
-}
-
-impl<'a> Iterator for MessageLogIter<'a> {
-    type Item = Vec<u8>;
-
-    fn next(&mut self) -> Option<Self::Item> {
-        let open_segment_file: &mut BufReader<File>;
-        if let Some(f) = &mut self.open_segment_file {
-            open_segment_file = f;
-        } else {
-            let segment = self.message_log.segment_for_offset(self.offset).unwrap();
-            let file = fs::OpenOptions::new()
-                .read(true)
-                .open(self.message_log.root.join(segment.name() + ".log"))
-                .unwrap();
-            let file = BufReader::new(file);
-            self.open_segment_file = Some(file);
-            open_segment_file = self.open_segment_file.as_mut().unwrap();
-        }
-
-        // TODO: use offset to jump to the right spot in the file
-        // open_segment_file.seek_relative(byte_offset(self.offset));
-
-        let mut buf = [0; HEADER_SIZE];
-        if let Err(err) = open_segment_file.read_exact(&mut buf) {
-            match err.kind() {
-                std::io::ErrorKind::UnexpectedEof => return None,
-                _ => panic!("MessageLogIter: {:?}", err),
-            }
-        };
-        let message_len = u32::from_le_bytes(buf);
-
-        let mut buf = vec![0; message_len as usize];
-        if let Err(err) = open_segment_file.read_exact(&mut buf) {
-            match err.kind() {
-                std::io::ErrorKind::UnexpectedEof => return None,
-                _ => panic!("MessageLogIter: {:?}", err),
-            }
-        }
-
-        self.offset += 1;
-
-        Some(buf)
-    }
-}
-
 #[cfg(test)]
 mod tests {
     use super::MessageLog;
diff --git a/crates/core/src/db/relational_db.rs b/crates/core/src/db/relational_db.rs
index e249cf49c9e..07204e54953 100644
--- a/crates/core/src/db/relational_db.rs
+++ b/crates/core/src/db/relational_db.rs
@@ -8,6 +8,7 @@ use super::message_log::MessageLog;
 use super::ostorage::memory_object_db::MemoryObjectDB;
 use super::relational_operators::Relation;
 use crate::address::Address;
+use crate::db::commit_log;
 use crate::db::db_metrics::{RDB_DELETE_BY_REL_TIME, RDB_DROP_TABLE_TIME, RDB_INSERT_TIME, RDB_ITER_TIME};
 use crate::db::messages::commit::Commit;
 use crate::db::ostorage::hashmap_object_db::HashMapObjectDB;
@@ -101,9 +102,10 @@ impl RelationalDB {
             if let Some(message_log) = &message_log {
                 let message_log = message_log.lock().unwrap();
                 let max_offset = message_log.open_segment_max_offset;
-                for message in message_log.iter() {
+                for commit in commit_log::Iter::from(message_log.segments()) {
+                    let commit = commit?;
+
                     segment_index += 1;
-                    let (commit, _) = Commit::decode(message);
                     last_hash = commit.parent_commit_hash;
                     last_commit_offset = Some(commit.commit_offset);
                     for transaction in commit.transactions {