Renaming

storage_engine/src/cursor_capabilities/entry_modification.rs

@@ -0,0 +1,67 @@
+use async_trait::async_trait;
+
+use bincode;
+use bincode::Encode;
+use crate::binary_coding::encode;
+
+use crate::segments::entry::Entry;
+use crate::segments::store_header::StoreHeader;
+use crate::store::{FilePosition, Result};
+use crate::cursor_capabilities::primitive::{CursorCanRead, CursorCanWrite};
+use crate::cursor_capabilities::traversal::CursorCanTraverse;
+
+#[async_trait]
+pub trait CursorCanModifyEntries<T>: CursorCanTraverse<T> + CursorCanWrite<T> {
+    fn header_mut(&mut self) -> &mut StoreHeader;
+    fn set_eof_file_position(&mut self, new_file_position: FilePosition);
+
+    // ===Store Header Manipulation===
+    async fn increment_total_count(&mut self) -> Result<()> 
+        where T: Send
+    {
+        self.seek_to_start().await?;
+        self.seek_to(StoreHeader::TOTAL_COUNT_OFFSET as u64).await?;
+        let new_count = self.header_mut().increment_total_count();
+        self.write_bytes(&encode::<usize>(&new_count)?).await?;
+        Ok(())
+    }
+
+    async fn increment_deleted_count(&mut self) -> Result<()> 
+        where T: Send
+    {
+        self.seek_to_start().await?;
+        self.seek_to(StoreHeader::DELETED_COUNT_OFFSET as u64).await?;
+        let new_count = self.header_mut().increment_deleted_count();
+        self.write_bytes(&encode::<usize>(&new_count)?).await?;
+        Ok(())
+    }
+
+    async fn set_header(&mut self, header: &StoreHeader) -> Result<()> 
+        where T: Send
+    {
+        self.seek_to_start().await?;
+        let encoded_header: Vec<u8> = header.encode()?;
+        self.write_bytes(&encoded_header).await?;
+
+        Ok(())
+    }
+
+    // ===Append Entry===
+
+    // Moves cursor to the end.
+    // Returns file position to the start of the new entry.
+    async fn append_entry_no_indexing(&mut self, entry: &Entry<T>) -> Result<FilePosition> 
+        where T: Encode + Send + Sync
+    {
+        self.increment_total_count().await?;
+
+        let encoded_entry: Vec<u8> = entry.encode()?;
+        let file_position = self.seek_to_end().await?;
+        self.write_bytes(&encoded_entry).await?;
+
+        let eof_file_position: FilePosition = self.current_file_position().await?;
+        self.set_eof_file_position(eof_file_position);
+
+        Ok(file_position)
+    }
+}