adding compaction from lib

src/lib.rs

@@ -167,9 +167,47 @@ impl<'a> From<(Bound<Cow<'a, str>>, Bound<Cow<'a, str>>)> for CowStringRange<'a>
 	}
 }
 
+/// Perform a compaction of the DB.
+///
+/// For use with downstream crates needing periodic
+/// compactions. Returns the number of records compacted.
+pub fn compact(dir: &std::path::Path, major: bool) -> std::io::Result<u64> {
+	use fs2::FileExt;
+	let lock = std::fs::File::create(dir.join(".compact"))?;
+	lock.try_lock_exclusive()?;
+
+	let db = if major {
+		DatabaseReader::new(dir)?
+	} else {
+		DatabaseReader::without_main_db(dir)?
+	};
+
+	{
+		let ps = db.transaction_paths();
+		if db.num_txes() <= 1 || (ps.len() == 1 && ps[0].file_name().expect("filename") == "main") {
+			return Ok(0);
+		}
+	}
+	// println!("Processing {} .txes", db.num_txes());
+	let db = std::sync::Arc::new(db);
+	let mut compacted = CreateTx::new(dir)?;
+
+	// create the new transaction after opening the database reader
+	let reader = db.get_range(..);
+	let mut n = 0u64;
+	for record in reader {
+		compacted
+			.add_record_raw(record.key(), record.format(), record.raw())
+			.expect("Error adding record");
+		n += 1;
+	}
+	_purge_compacted_files(compacted, dir, &db, major)?;
+
+	Ok(n)
+}
+
 // not part of public api
 #[doc(hidden)]
-#[cfg(feature = "bin")]
 pub fn _purge_compacted_files(
 	compacted: CreateTx,
 	dir: &std::path::Path,