Fix delete bug

storage_engine/src/cursor.rs

@@ -10,12 +10,13 @@ use bincode::{Decode, Encode};
 use crate::binary_coding::encode;
 
 use crate::entry::{Entry, EntryDetailed};
-use crate::entry_header::EntryHeaderWithDataSize;
+use crate::entry_header::{EntryHeaderWithDataSize, EntryHeader};
 use crate::store_header::StoreHeader;
 use crate::storage_engine::{Store, FilePosition, Result, ROWS_FILE_NAME};
 
 #[async_trait]
-trait PrimitiveCursor<T> {
+// TODO: Make this private
+pub trait PrimitiveCursor<T> {
     fn file(&mut self) -> &mut File;
     fn eof_file_position(&self) -> FilePosition;
 
@@ -30,22 +31,23 @@ trait PrimitiveCursor<T> {
         Ok(result)
     }
 
-    async fn seek_to(&mut self, file_position: FilePosition) -> Result<()> {
+    async fn seek_to(&mut self, file_position: FilePosition) -> Result<FilePosition> {
-        self.file().seek(SeekFrom::Start(file_position)).await?;
+        let file_position = self.file().seek(SeekFrom::Start(file_position)).await?;
-        Ok(())
+        Ok(file_position)
     }
 
-    async fn seek_to_start(&mut self) -> Result<()> {
+    // Start of the file i.e. the Header, not the entries.
-        self.file().seek(SeekFrom::Start(0)).await?;
+    async fn seek_to_start(&mut self) -> Result<FilePosition> {
-        Ok(())
+        let file_position = self.file().seek(SeekFrom::Start(0)).await?;
+        Ok(file_position)
     }
 
-    async fn seek_to_end(&mut self) -> Result<()> {
+    async fn seek_to_end(&mut self) -> Result<FilePosition> {
-        self.file().seek(SeekFrom::End(0)).await?;
+        let file_position = self.file().seek(SeekFrom::End(0)).await?;
-        Ok(())
+        Ok(file_position)
     }
 
-    async fn seek_to_start_of_data(&mut self) -> Result<()> {
+    async fn seek_to_start_of_data(&mut self) -> Result<FilePosition> {
         self.seek_to(StoreHeader::SIZE as u64).await
     }
 
@@ -55,7 +57,10 @@ trait PrimitiveCursor<T> {
     }
 
     async fn is_at_eof(&mut self) -> Result<bool> {
-        Ok(self.current_file_position().await? == self.eof_file_position())
+        let current_file_position = self.current_file_position().await?;
+        let eof_file_position = self.eof_file_position();
+        println!("IN EOF: current={}, eof_file_position={}", current_file_position, eof_file_position);
+        Ok(current_file_position == eof_file_position)
     }
 }
 
@@ -90,9 +95,12 @@ pub trait CursorWithStoreHeader<T>: PrimitiveCursor<T> {
     async fn next(&mut self) -> Result<Option<EntryDetailed<T>>> 
         where T: Decode
     {
+        println!("are we at eof?");
         if self.is_at_eof().await? {
+            println!("YES");
             return Ok(None)
         }
+        println!("NO");
 
         let entry_header = self.read_entry_header().await?;
 
@@ -118,6 +126,7 @@ pub trait CursorWithStoreHeader<T>: PrimitiveCursor<T> {
 
     async fn read_all_bytes(&mut self) -> std::result::Result<Vec<u8>, std::io::Error> {
         let mut bytes: Vec<u8> = vec![];
+        self.seek_to_start().await.map_err(|e| e.to_io_or_panic())?;
         self.file().read_to_end(&mut bytes).await?;
         Ok(bytes)
     }
@@ -191,8 +200,11 @@ impl <T> ReadCursor<T> {
                 file,
                 data_type: store.data_type,
 
-                eof_file_position: 0, // This will be overwriten by the seek_to_start_of_data
+                eof_file_position: 0,
             };
+            let eof_file_position: FilePosition = cursor.seek_to_end().await?;
+            cursor.eof_file_position = eof_file_position;
+
             cursor.seek_to_start_of_data().await?;
 
             Ok(cursor)
@@ -221,8 +233,11 @@ impl <'cursor, T> WriteCursor<'cursor, T> {
                 file,
                 data_type: store.data_type,
 
-                eof_file_position: 0, // This will be overwriten by the seek_to_start_of_data
+                eof_file_position: 0,
             };
+            let eof_file_position: FilePosition = cursor.seek_to_end().await?;
+            cursor.eof_file_position = eof_file_position;
+
             cursor.seek_to_start_of_data().await?;
 
             Ok(cursor)
@@ -255,12 +270,10 @@ impl <'cursor, T> WriteCursor<'cursor, T> {
     }
 
     // ===Entry Header Manipulation===
-    // assumes we are at the start of the valid entry.
+    // assumes we are at the start of valid entry.
-    async fn set_entry_is_deleted_to(&mut self, is_deleted: bool) -> Result<()> 
+    async fn set_new_entry_header(&mut self, entry_header: EntryHeader) -> Result<()> {
-        where T: Send
+        let bytes: Vec<u8> = entry_header.encode()?;
-    {
+        self.write_bytes(&bytes).await?;
-        self.seek_to(EntryHeaderWithDataSize::IS_DELETED_OFFSET as u64).await?;
-        self.write_bytes(&encode::<bool>(&is_deleted)?).await?;
         Ok(())
     }
 
@@ -274,8 +287,7 @@ impl <'cursor, T> WriteCursor<'cursor, T> {
         self.increment_total_count().await?;
 
         let encoded_entry: Vec<u8> = entry.encode()?;
-        self.seek_to_end().await?;
+        let file_position = self.seek_to_end().await?;
-        let file_position: FilePosition = self.current_file_position().await?;
         self.write_bytes(&encoded_entry).await?;
 
         let eof_file_position: FilePosition = self.current_file_position().await?;
@@ -289,13 +301,19 @@ impl <'cursor, T> WriteCursor<'cursor, T> {
         where T: Send
     {
         self.seek_to(file_position).await?;
-        let entry_header = self.read_entry_header().await?;
+        println!("Attempting to read the entry");
+        let mut entry_header = self.read_entry_header().await?;
+        println!("Entry Header == {:?}", entry_header);
         if entry_header.is_deleted {
+            println!("Already deleted");
             Ok(())
         } else {
+            println!("Marking as deleted");
             self.increment_deleted_count().await?;
             self.seek_to(file_position).await?;
-            self.set_entry_is_deleted_to(true).await?;
+
+            entry_header.is_deleted = true;
+            self.set_new_entry_header(entry_header.into()).await?;
 
             self.attempt_garbage_collection_if_necessary().await?;
             Ok(())

storage_engine/src/entry.rs

@@ -1,6 +1,6 @@
 use bincode::{Decode, Encode};
 
-use crate::binary_coding::{encode, encode_sequence, encode_sequence_with_sizes, decode_sequence};
+use crate::binary_coding::{encode_sequence, encode_sequence_with_sizes, decode_sequence};
 use crate::storage_engine::Result;
 use crate::error::{Error, DecodeErrorKind};
 use crate::entry_header::{EntryHeader, EntryHeaderWithDataSize};
@@ -17,13 +17,6 @@ pub struct EntryDetailed<T> {
     data: Vec<T>,
 }
 
-impl EntryHeader {
-    fn encode(self: &EntryHeader) -> Result<Vec<u8>> {
-        let result: Vec<u8> = encode(&self.is_deleted)?;
-        Ok(result)
-    }
-}
-
 impl <T>Entry<T> {
     pub fn new(data: Vec<T>) -> Self {
         Self { header: EntryHeader { is_deleted: false }, data }

storage_engine/src/entry_header.rs

@@ -1,4 +1,4 @@
-use crate::binary_coding::{decode, decode_sequence};
+use crate::binary_coding::{decode, encode, decode_sequence};
 use crate::storage_engine::Result;
 use crate::error::{Error, DecodeErrorKind};
 use std::mem::size_of;
@@ -14,6 +14,20 @@ pub struct EntryHeaderWithDataSize {
     pub data_sizes: Vec<usize>, // vec![5, 6, 20] means that column 0 stores 5 bytes, column 1 stores 6
                            // bytes etc
 }
+
+impl EntryHeader {
+    pub fn encode(self: &EntryHeader) -> Result<Vec<u8>> {
+        let result: Vec<u8> = encode(&self.is_deleted)?;
+        Ok(result)
+    }
+}
+
+impl From<EntryHeaderWithDataSize> for EntryHeader {
+    fn from(entry: EntryHeaderWithDataSize) -> Self {
+        Self { is_deleted: entry.is_deleted, }
+    }
+}
+
 impl EntryHeaderWithDataSize {
     pub const IS_DELETED_OFFSET: usize = 0;
     pub const IS_DELETED_SIZE: usize = size_of::<bool>();

storage_engine/src/main.rs

@@ -9,7 +9,7 @@ mod store_header;
 
 use crate::entry::{Entry, EntryDetailed};
 use crate::storage_engine::{Store, FilePosition};
-use crate::cursor::{ReadCursor, WriteCursor};
+use crate::cursor::{ReadCursor, WriteCursor, CursorWithStoreHeader, PrimitiveCursor};
 
 type Data = u32;
 
@@ -20,8 +20,8 @@ type Result<T> = std::result::Result<T, std::io::Error>;
 async fn create_store() -> Result<Store<Data>> {
     let mut store: Store<Data> = Store::new(TABLE_PATH, 5, 0).await.map_err(|e| e.to_io_or_panic())?;
     println!("CREATED");
-    println!("THE STORE: {:?}", store);
+    // println!("THE STORE: {:?}", store);
-    println!("THE BYTES: {:?}", store.read_all_bytes().await?);
+    // println!("THE BYTES: {:?}", store.read_all_bytes().await?);
 
     Ok(store)
 }
@@ -29,8 +29,8 @@ async fn create_store() -> Result<Store<Data>> {
 async fn connect_store() -> Result<Store<Data>> {
     let mut store: Store<Data> = Store::connect(TABLE_PATH).await.map_err(|e| e.to_io_or_panic())?;
     println!("CONNECTED");
-    println!("THE STORE: {:?}", store);
+    // println!("THE STORE: {:?}", store);
-    println!("THE BYTES: {:?}", store.read_all_bytes().await?);
+    // println!("THE BYTES: {:?}", store.read_all_bytes().await?);
     Ok(store)
 }
 
@@ -60,14 +60,7 @@ async fn read_entry(cursor: &mut ReadCursor<Data>, file_position: FilePosition)
     todo!()
 }
 
-
+async fn append_bunch_of_entries(store: &mut Store<Data>) -> Result<()> {
-#[tokio::main]
-async fn main() -> Result<()> {
-    println!("STOOOOOOOOOOOORAAAAAAAAAAAGE");
-
-    let mut store: Store<Data> = create_or_connect().await?;
-
-    {
     let mut cursor = store.write_cursor().await.map_err(|e| e.to_io_or_panic())?;
     let entry0: Entry<u32> = Entry::new(vec![1, 2, 3, 4, 5]);
     append_entry(&mut cursor, &entry0).await?;
@@ -81,28 +74,55 @@ async fn main() -> Result<()> {
 
     let entry3: Entry<u32> = Entry::new(vec![50,50,50,50,50]);
     append_entry(&mut cursor, &entry3).await?;
+    Ok(())
+}
+
+#[tokio::main]
+async fn main() -> Result<()> {
+    println!("STOOOOOOOOOOOORAAAAAAAAAAAGE");
+
+    let mut store: Store<Data> = create_or_connect().await?;
+
+    if store.header.total_count == 0 {
+        println!("INSERTING!");
+        append_bunch_of_entries(&mut store).await?;
+    }
+
+    {
+        let mut cursor = store.write_cursor().await.map_err(|e| e.to_io_or_panic())?;
+
+        let entry: Entry<u32> = Entry::new(vec![60, 50, 40, 30, 20]);
+        // let file_position = append_entry(&mut cursor, &entry).await?;
+        // let file_position = 215;
+        // cursor.seek_to(file_position).await.map_err(|e| e.to_io_or_panic())?;
+
+        // let entry_header = cursor.read_entry_header().await.map_err(|e| e.to_io_or_panic())?;
+        // println!("entry header = {:?}", entry_header);
+
+        // println!("FILE POSITION == {}", file_position);
+        // cursor.mark_deleted_at(file_position).await.map_err(|e| e.to_io_or_panic())?;
+        // let entry_header = cursor.read_entry_header().await.map_err(|e| e.to_io_or_panic())?;
+        // println!("entry header after delete = {:?}", entry_header);
     }
 
     // println!("{:?}", store);
     // println!("{:?}", store.read_all_bytes().await?);
 
-    // let entry0: Entry<u32> = Entry::new(vec![99, 98, 97, 96, 95]);
+    let mut cursor = store.read_cursor().await.map_err(|e| e.to_io_or_panic())?;
-    // append_entry(&mut cursor, &entry0).await?;
 
-    // let entry1: Entry<u32> = Entry::new(vec![50,50,50,50,50]);
+    // let x = cursor.next().await.map_err(|e| e.to_io_or_panic())?;
-    // let file_position = append_entry(&mut cursor, &entry1).await?;
+    // println!("{:?}", x);
-    // println!("CURRENT FILE_POSITION = {}", file_position);
+    // let x = cursor.next().await.map_err(|e| e.to_io_or_panic())?;
+    // println!("{:?}", x);
+    // let x = cursor.next().await.map_err(|e| e.to_io_or_panic())?;
+    // println!("{:?}", x);
+    // let x = cursor.next().await.map_err(|e| e.to_io_or_panic())?;
+    // println!("{:?}", x);
+    // let x = cursor.next().await.map_err(|e| e.to_io_or_panic())?;
+    // println!("{:?}", x);
 
-    // Now file_position point to entry1.
+    cursor.read_entries().await.map_err(|e| e.to_io_or_panic())?;
-    // cursor.mark_deleted_at(file_position).await.map_err(|e| e.to_io_or_panic())?;
-    // cursor.seek_to(file_position).await.map_err(|e| e.to_io_or_panic())?;
 
-    // let entry2: StoreEntry<u32> = StoreEntry::new_deleted(vec![3, 2, 1]);
-    // let cursor2 = store.append_entry(&entry2).await.map_err(|e| e.to_io_or_panic())?;
-    // println!("cursor2 = {}", cursor2);
-
-    println!("{:?}", store);
-    println!("{:?}", store.read_all_bytes().await?);
 
 
     println!("DONE");