Sketch out indexes in Store

storage_engine/src/cursor.rs

@@ -14,10 +14,14 @@ use crate::entry::{Entry, EntryDetailed};
 use crate::entry_header::{EntryHeaderWithDataSize, EntryHeader};
 use crate::store_header::StoreHeader;
 use crate::storage_engine::{Store, FilePosition, Column, Result, ROWS_FILE_NAME, GARBAGE_COLLECTION_INTERMEDIATE_ROWS_FILE_NAME};
+use crate::index::Index;
+
+
 
 // ===Concrete Cursors===
-pub struct ReadCursor<T> {
+pub struct ReadCursor<'a, T> {
     header: StoreHeader,
+    indexes: Vec<Option<&'a Index<T, FilePosition>>>,
     file: File,
     data_type: PhantomData<T>,
 
@@ -26,6 +30,7 @@ pub struct ReadCursor<T> {
 
 pub struct WriteCursor<'a, T> {
     header: &'a mut StoreHeader,
+    indexes: Vec<Option<&'a Index<T, FilePosition>>>,
     file: File,
     data_type: PhantomData<T>,
 
@@ -224,9 +229,20 @@ pub trait CursorWithStoreHeader<T>: PrimitiveCursor<T> {
     }
 }
 
+#[async_trait]
+pub trait CursorWithAccessToIndex<T>: CursorWithStoreHeader<T> {
+    fn indexes(&mut self) -> &[Option<&Index<T, FilePosition>>];
+
+    async fn find_in_index(&mut self, k: &T) -> Result<Option<FilePosition>> 
+        where T: Encode + Decode + Ord + Send + Sync
+    {
+        // let x = self.primary_index().lookup(k).await?;
+        todo!()
+    }
+}
 
 // ===PrimitiveCursor===
-impl <T>PrimitiveCursor<T> for ReadCursor<T> {
+impl <T>PrimitiveCursor<T> for ReadCursor<'_, T> {
     fn file(&mut self) -> &mut File {
         &mut self.file
     }
@@ -247,7 +263,7 @@ impl <T>PrimitiveCursor<T> for WriteCursor<'_, T> {
 }
 
 // ===CursorWithStoreHeader===
-impl <T>CursorWithStoreHeader<T> for ReadCursor<T> {
+impl <T>CursorWithStoreHeader<T> for ReadCursor<'_, T> {
     fn header(&self) -> &StoreHeader {
         &self.header
     }
@@ -259,9 +275,23 @@ impl <T>CursorWithStoreHeader<T> for WriteCursor<'_, T> {
     }
 }
 
-impl <T> ReadCursor<T> {
-    pub async fn new(store: &Store<T>) -> Result<Self> 
-        where T: Send
+// ===CursorWithAccessToIndex===
+impl <T>CursorWithAccessToIndex<T> for ReadCursor<'_, T> {
+    fn indexes(&mut self) -> &[Option<&Index<T, FilePosition>>] {
+        &self.indexes
+    }
+}
+
+impl <T>CursorWithAccessToIndex<T> for WriteCursor<'_, T> {
+    fn indexes(&mut self) -> &[Option<&Index<T, FilePosition>>] {
+        &self.indexes
+    }
+}
+
+
+impl <'cursor, T> ReadCursor<'cursor, T> {
+    pub async fn new<'store: 'cursor>(store: &'store Store<T>) -> Result<Self> 
+        where T: Send + Sync
     {
             let path_to_rows = Path::new(&store.header.table_folder).join(ROWS_FILE_NAME);
             let file: File =
@@ -274,6 +304,7 @@ impl <T> ReadCursor<T> {
                 header: store.header.clone(),
                 file,
                 data_type: store.data_type,
+                indexes: todo!(),
 
                 eof_file_position: 0,
             };
@@ -284,13 +315,12 @@ impl <T> ReadCursor<T> {
 
             Ok(cursor)
     }
-
-    pub async fn less_than_eq(&mut self, file_position0: FilePosition, file_position1: FilePosition) -> Result<bool> {
-        todo!()
-    }
 }
 
-impl <'cursor, T> WriteCursor<'cursor, T> {
+impl <'cursor, T> WriteCursor<'cursor, T> 
+// TODO: Consider adding this manually to wher eit is really needed
+    where T: Sync
+{
     // 'store lives atleast as long as 'cursor
     pub async fn new<'store: 'cursor>(store: &'store mut Store<T>) -> Result<Self> 
         where T: Send
@@ -307,6 +337,7 @@ impl <'cursor, T> WriteCursor<'cursor, T> {
                 header: &mut store.header,
                 file,
                 data_type: store.data_type,
+                indexes: todo!(),
 
                 eof_file_position: 0,
             };
@@ -332,6 +363,7 @@ impl <'cursor, T> WriteCursor<'cursor, T> {
                 header,
                 file,
                 data_type: PhantomData::<T>,
+                indexes: todo!(),
 
                 eof_file_position: 0,
             };
@@ -478,4 +510,20 @@ impl <'cursor, T> WriteCursor<'cursor, T> {
         // Afterwards we swap the files, and delete the garbage.
         todo!()
     }
+
+    // ===Indexing===
+    async fn insert_to_index(&mut self, t: T, file_position: FilePosition) -> Result<Option<FilePosition>> 
+        where T: Encode + Decode + Ord + Send + Sync
+    {
+        // let x = self.primary_index.insert(t, file_position).await?;
+        todo!()
+    }
+
+    async fn delete_from_index(&mut self, t: T, file_position: FilePosition) -> Result<Option<FilePosition>> 
+        where T: Encode + Decode + Ord + Send + Sync
+    {
+        // let x = self.primary_index.delete(t, file_position).await?;
+        todo!()
+    }
 }
+