Add flush functionality

Cargo.toml

@@ -3,7 +3,7 @@ authors = ["Kristoffer Ström <kristoffer@rymdkoloni.se>",
            "David Stainton <dawuud@riseup.net>"]
 edition = "2018"
 name = "appendix"
-version = "0.1.3"
+version = "0.2.0"
 description = "Append-only, on-disk key-value index"
 documentation = "https://docs.rs/appendix/"
 keywords = ["index", "datastructure"]

src/lib.rs

@@ -389,6 +389,17 @@ impl<K: Hash + Copy + PartialEq, V: Hash + Copy> Index<K, V> {
         }
     }
 
+    /// Syncronizes and flushes data to disk
+    pub fn flush(&mut self) -> std::io::Result<()> {
+        unsafe {
+            let lanes = &mut *self.lanes.get();
+            for mmap in lanes {
+                mmap.flush()?;
+            }
+        }
+        Ok(())
+    }
+
     /// Removes all data from disk
     pub fn purge(&mut self) -> std::io::Result<()> {
         for n in 0..NUM_LANES {