Add copy_to to io::File trait to support copying DB files

core/io/mod.rs

@@ -52,6 +52,43 @@ pub trait File: Send + Sync {
     }
     fn size(&self) -> Result<u64>;
     fn truncate(&self, len: usize, c: Completion) -> Result<Completion>;
+    fn copy_to(&self, io: &dyn IO, path: &str) -> Result<()> {
+        // Open or create the destination file
+        let dest_file = io.open_file(path, OpenFlags::Create, false)?;
+        // Get the size of the source file
+        let file_size = self.size()? as usize;
+        if file_size == 0 {
+            return Ok(());
+        }
+
+        // use 1MB chunk size
+        const BUFFER_SIZE: usize = 1024 * 1024;
+        let mut pos = 0;
+
+        while pos < file_size {
+            let chunk_size = (file_size - pos).min(BUFFER_SIZE);
+            // Read from source
+            let read_buffer = Arc::new(RefCell::new(Buffer::allocate(chunk_size, Rc::new(|_| {}))));
+            let read_completion = self.pread(
+                pos,
+                Completion::new_read(read_buffer.clone(), move |_, _| {}),
+            )?;
+
+            // Wait for read to complete
+            io.wait_for_completion(read_completion)?;
+
+            // Write to destination
+            let write_completion =
+                dest_file.pwrite(pos, read_buffer, Completion::new_write(|_| {}))?;
+            io.wait_for_completion(write_completion)?;
+
+            pos += chunk_size;
+        }
+        let sync_completion = dest_file.sync(Completion::new_sync(|_| {}))?;
+        io.wait_for_completion(sync_completion)?;
+
+        Ok(())
+    }
 }
 
 #[derive(Debug, Copy, Clone, PartialEq)]

core/lib.rs

@@ -1737,6 +1737,17 @@ impl Connection {
     pub fn get_pager(&self) -> Rc<Pager> {
         self.pager.borrow().clone()
     }
+
+    /// Copy the current Database and write out to a new file
+    pub fn copy_db(&self, file: &str) -> Result<()> {
+        let io = self._db.io.clone();
+        let disabled = false;
+        // checkpoint so everything is in the DB file before copying
+        self.pager
+            .borrow_mut()
+            .wal_checkpoint(disabled, CheckpointMode::Truncate)?;
+        self.pager.borrow_mut().db_file.copy_to(&*io, file)
+    }
 }
 
 pub struct Statement {

core/storage/database.rs

@@ -22,6 +22,7 @@ pub trait DatabaseStorage: Send + Sync {
     fn sync(&self, c: Completion) -> Result<Completion>;
     fn size(&self) -> Result<u64>;
     fn truncate(&self, len: usize, c: Completion) -> Result<Completion>;
+    fn copy_to(&self, io: &dyn crate::IO, path: &str) -> Result<()>;
 }
 
 #[cfg(feature = "fs")]
@@ -95,6 +96,11 @@ impl DatabaseStorage for DatabaseFile {
         let c = self.file.truncate(len, c)?;
         Ok(c)
     }
+
+    #[instrument(skip_all, level = Level::INFO)]
+    fn copy_to(&self, io: &dyn crate::IO, path: &str) -> Result<()> {
+        self.file.copy_to(io, path)
+    }
 }
 
 #[cfg(feature = "fs")]