Add basic memory

Cargo.lock

@@ -11,6 +11,24 @@ dependencies = [
  "memchr",
 ]
 
+[[package]]
+name = "bincode"
+version = "2.0.0-rc.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "f609ceb2c41b0d0277314a789ef0e7eb14593d5485f7c67320bed3924ebb1b33"
+dependencies = [
+ "bincode_derive",
+]
+
+[[package]]
+name = "bincode_derive"
+version = "2.0.0-rc.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "913287a8f3e00db4c7ae1b87e9b9b8cebd6b89217eaadfc281fa5c897da35dc3"
+dependencies = [
+ "virtue",
+]
+
 [[package]]
 name = "const_format"
 version = "0.2.22"
@@ -78,10 +96,32 @@ version = "0.6.25"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "f497285884f3fcff424ffc933e56d7cbca511def0c9831a7f9b5f6153e3cc89b"
 
+[[package]]
+name = "serde"
+version = "1.0.136"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "ce31e24b01e1e524df96f1c2fdd054405f8d7376249a5110886fb4b658484789"
+dependencies = [
+ "serde_derive",
+]
+
+[[package]]
+name = "serde_derive"
+version = "1.0.136"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "08597e7152fcd306f41838ed3e37be9eaeed2b61c42e2117266a554fab4662f9"
+dependencies = [
+ "proc-macro2",
+ "quote",
+ "syn",
+]
+
 [[package]]
 name = "sqlite_clone"
 version = "0.1.0"
 dependencies = [
+ "bincode",
+ "serde",
  "sscanf",
 ]
 
@@ -125,3 +165,9 @@ name = "unicode-xid"
 version = "0.2.2"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "8ccb82d61f80a663efe1f787a51b16b5a51e3314d6ac365b08639f52387b33f3"
+
+[[package]]
+name = "virtue"
+version = "0.0.7"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "757cfbfe0d17ee6f22fe97e536d463047d451b47cf9d11e2b7d1398b0ef274dd"

Cargo.toml

@@ -7,3 +7,5 @@ edition = "2021"
 
 [dependencies]
 sscanf = {version="0.2.1"}
+bincode = "2.0.0-rc.1"
+serde = {version="1.0.136", features=["derive"]}

src/main.rs

@@ -1,18 +1,25 @@
+mod page;
+mod pager;
+mod row;
 mod statement;
+mod table;
 
+use crate::statement::ExecuteResult;
+use crate::table::Table;
 use std::io;
 use std::io::Write;
 use std::process::exit;
 
 struct InputBuffer {
     buffer: Option<String>,
+    table: Table,
 }
 
-
 impl InputBuffer {
     pub fn new() -> Self {
         return Self {
-            buffer: None
+            buffer: None,
+            table: Table::new(),
         };
     }
 
@@ -34,11 +41,11 @@ impl InputBuffer {
                     Err(String::from("could not handle input"))
                 }
             }
-            _ => { Err(String::from("Could not initialize buffer")) }
+            _ => Err(String::from("Could not initialize buffer")),
         }
     }
 
-    pub(crate) fn parse(&self) {
+    pub(crate) fn parse(&mut self) {
         match &self.buffer {
             Some(command) => {
                 if command.starts_with(".") {
@@ -46,7 +53,15 @@ impl InputBuffer {
                 } else {
                     match Self::prepare_statement(&command.replace("\n", "")) {
                         Ok(statement) => {
-                            statement.execute()
+                            let execution_result = statement.execute(&mut self.table);
+                            match execution_result {
+                                ExecuteResult::Success => {
+                                    println!("success")
+                                }
+                                _ => {
+                                    println!("failure")
+                                }
+                            }
                         }
                         Err(e) => {
                             println!("{}", e);
@@ -74,14 +89,10 @@ impl InputBuffer {
     }
 }
 
-
 fn main() -> Result<(), String> {
     let mut input_buffer = InputBuffer::new();
 
     loop {
-        input_buffer
-            .print_prompt()
-            .read_input()?
-            .parse()
+        input_buffer.print_prompt().read_input()?.parse()
     }
 }

src/page.rs

@@ -0,0 +1,28 @@
+use std::ops::{Deref, DerefMut};
+
+#[derive(Debug, Clone)]
+pub struct Page {
+    buffer: Vec<u8>,
+}
+
+impl Page {
+    pub fn new(buffer: Vec<u8>) -> Self {
+        Self {
+            buffer,
+        }
+    }
+}
+
+impl Deref for Page {
+    type Target = Vec<u8>;
+
+    fn deref(&self) -> &Self::Target {
+        &self.buffer
+    }
+}
+
+impl DerefMut for Page {
+    fn deref_mut(&mut self) -> &mut Self::Target {
+        &mut self.buffer
+    }
+}

src/pager.rs

@@ -0,0 +1,35 @@
+use crate::page::Page;
+
+pub struct Pager {
+    pages: Vec<Option<Page>>,
+    page_size: usize,
+}
+
+impl Pager {
+    pub fn new(page_size: usize) -> Self {
+        Self {
+            page_size,
+            pages: Vec::new(),
+        }
+    }
+
+    pub fn get_mut_or_alloc(&mut self, page_num: usize) -> &mut Page {
+        if page_num >= self.pages.len() {
+            self.grow_pages(page_num)
+        }
+
+        if self.pages[page_num].is_none() {
+            let buf = vec![0; self.page_size];
+            let page = Page::new(buf);
+            self.pages[page_num] = Some(page)
+        }
+
+        self.pages[page_num].as_mut().unwrap()
+    }
+
+    #[inline]
+    fn grow_pages(&mut self, index: usize) {
+        println!("debug: Growing pages");
+        self.pages.resize(index + 1, None)
+    }
+}

src/row.rs

@@ -0,0 +1,84 @@
+use std::{iter, slice};
+use std::io::Write;
+
+use bincode::{Decode, Encode};
+use bincode::config::Configuration;
+use bincode::error::{DecodeError, EncodeError};
+
+const COLUMN_USERNAME_SIZE: usize = 32;
+const COLUMN_EMAIL_SIZE: usize = 255;
+
+#[derive(Encode, Decode)]
+pub struct Row {
+    pub id: u32,
+    pub username: [u8; COLUMN_USERNAME_SIZE],
+    pub email: [u8; COLUMN_EMAIL_SIZE],
+}
+
+pub trait Serialize {
+    fn serialize(&self) -> Result<Vec<u8>, EncodeError>;
+    fn deserialize(buffer: &[u8]) -> Result<Self, DecodeError>
+        where
+            Self: Sized;
+}
+
+impl Serialize for Row {
+    fn serialize(&self) -> Result<Vec<u8>, EncodeError> {
+        bincode::encode_to_vec(self, bincode::config::standard())
+    }
+
+    fn deserialize(buffer: &[u8]) -> Result<Self, DecodeError> {
+        match bincode::decode_from_slice::<Self, Configuration>(buffer, bincode::config::standard())
+        {
+            Ok((row, _)) => Ok(row),
+            Err(e) => Err(e),
+        }
+    }
+}
+
+impl Row {
+    pub fn new(id: u32, username: String, email: String) -> Result<Self, String> {
+        let username_bytes = username.as_bytes();
+        let email_bytes = email.as_bytes();
+        if username_bytes.len() > COLUMN_USERNAME_SIZE {
+            Err(String::from("username is too long"))
+        } else if email_bytes.len() > COLUMN_EMAIL_SIZE {
+            Err(String::from("email is too long"))
+        } else {
+            let username_buffer = &mut [0; COLUMN_USERNAME_SIZE];
+            if let Err(_) = pad_buffer(username_buffer, username_bytes) {
+                panic!("could not pad username buffer")
+            }
+            let email_buffer = &mut [0; COLUMN_EMAIL_SIZE];
+            if let Err(_) = pad_buffer(email_buffer, username_bytes) {
+                panic!("could not pad username buffer")
+            }
+            Ok(Self {
+                id,
+                username: *username_buffer,
+                email: *email_buffer,
+            })
+        }
+    }
+
+
+    pub(crate) fn print(&self) {
+        println!("({}, {}, {})", self.id, String::from_utf8(self.email.to_vec()).unwrap(), String::from_utf8(self.username.to_vec()).unwrap())
+    }
+}
+
+fn pad_buffer(mut bytes: &mut [u8], source: &[u8]) -> std::io::Result<usize> {
+    bytes.write(source)
+}
+
+pub struct RowIter<'a> {
+    inner: slice::Iter<'a, Row>,
+}
+
+impl<'a> iter::Iterator for RowIter<'a> {
+    type Item = &'a Row;
+
+    fn next(&mut self) -> Option<Self::Item> {
+        self.inner.next()
+    }
+}

src/statement.rs

@@ -1,50 +1,16 @@
-use std::io::Write;
-use std::mem::size_of;
+use crate::row::Serialize;
+use crate::table::Table;
+use crate::{row};
+
 
 pub enum StatementType {
-    Insert {
-        row: Row
-    },
+    Insert { row: row::Row },
     Select,
 }
 
-const COLUMN_USERNAME_SIZE: usize = 32;
-const COLUMN_EMAIL_SIZE: usize = 255;
-
-pub struct Row {
-    id: u32,
-    username: [u8; COLUMN_USERNAME_SIZE],
-    email: [u8; COLUMN_EMAIL_SIZE],
-}
-
-impl Row {
-    fn new(id: u32, username: String, email: String) -> Result<Self, String> {
-        let username_bytes = username.as_bytes();
-        let email_bytes = email.as_bytes();
-        if username_bytes.len() > COLUMN_USERNAME_SIZE {
-            Err(String::from("username is too long"))
-        } else if email_bytes.len() > COLUMN_EMAIL_SIZE {
-            Err(String::from("email is too long"))
-        } else {
-            let username_buffer = &mut [0; COLUMN_USERNAME_SIZE];
-            if let Err(_) = pad_buffer(username_buffer, username_bytes) {
-                panic!("could not pad username buffer")
-            }
-            let email_buffer = &mut [0; COLUMN_EMAIL_SIZE];
-            if let Err(_) = pad_buffer(email_buffer, username_bytes) {
-                panic!("could not pad username buffer")
-            }
-            Ok(Self {
-                id,
-                username: *username_buffer,
-                email: *email_buffer,
-            })
-        }
-    }
-}
-
-fn pad_buffer(mut bytes: &mut [u8], source: &[u8]) -> std::io::Result<usize> {
-    bytes.write(source)
+pub enum ExecuteResult {
+    Error { error: String },
+    Success,
 }
 
 pub struct Statement {
@@ -53,43 +19,50 @@ pub struct Statement {
 
 impl Statement {
     pub fn new(statement_type: StatementType) -> Self {
-        Self {
-            statement_type,
-        }
+        Self { statement_type }
     }
 
     pub fn parse_statement(command: &String) -> Result<Self, String> {
         if command.starts_with("insert") {
             match sscanf::scanf!(command, "insert {} {} {}", usize, str, str) {
                 Ok((id, username, email)) => {
-                    match Row::new(u32::try_from(id).unwrap(), username.to_string(), email.to_string()) {
-                        Ok(row) => {
-                            Ok(Statement::new(StatementType::Insert { row: row }))
-                        }
-                        Err(e) => { Err(e) }
+                    match row::Row::new(
+                        u32::try_from(id).unwrap(),
+                        username.to_string(),
+                        email.to_string(),
+                    ) {
+                        Ok(row) => Ok(Statement::new(StatementType::Insert { row })),
+                        Err(e) => Err(e),
                     }
                 }
-                _ => {
-                    Err(String::from("could not parse insert statement"))
-                }
+                _ => Err(String::from("could not parse insert statement")),
             }
         } else if command.starts_with("select") {
             Ok(Statement::new(StatementType::Select))
         } else {
-            return Err(String::from("Could not parse command"));
+            Err(String::from("Could not parse command"))
         }
     }
 
-    pub(crate) fn execute(&self) {
+    pub(crate) fn execute(&self, table: &mut Table) -> ExecuteResult {
         match &self.statement_type {
-            StatementType::Insert { row } => {
-                println!("This is where you do an insert {}", row.id)
-            }
+            StatementType::Insert { row } => match row.serialize() {
+                Err(e) => ExecuteResult::Error {
+                    error: e.to_string(),
+                },
+                Ok(serialization) => {
+                    table.append_row(serialization);
+                    ExecuteResult::Success
+                }
+            },
             StatementType::Select => {
-                println!("This is where you do an select")
+                let rows = table.get_rows();
+                for row in rows {
+                    row.print()
+                }
+
+                return ExecuteResult::Success;
             }
         }
     }
 }
-
-

src/table.rs

@@ -0,0 +1,61 @@
+use crate::pager::Pager;
+use crate::row;
+use std::mem::size_of;
+use std::ops::DerefMut;
+use crate::row::Row;
+use crate::row::Serialize;
+
+const PAGE_SIZE: usize = 4096;
+
+pub struct Table {
+    num_rows: usize,
+    pager: Pager,
+}
+
+impl Table {
+    pub fn new() -> Self {
+        Self {
+            num_rows: 0,
+            pager: Pager::new(PAGE_SIZE),
+        }
+    }
+
+    pub(crate) fn append_row(&mut self, row: Vec<u8>) {
+        let row_size = size_of::<row::Row>();
+        let page_num = self.num_rows / self.rows_per_page(row_size);
+        let row_offset = self.num_rows % self.rows_per_page(row_size);
+
+        let page = self.pager.get_mut_or_alloc(page_num);
+
+        let byte_offset = row_offset * row_size;
+
+        page.deref_mut()
+            .splice(byte_offset..byte_offset + row_size, row);
+        self.num_rows += 1;
+    }
+
+    pub fn row(&mut self, row_num: usize) -> Row {
+        let row_size = size_of::<row::Row>();
+        let page_num = row_num / self.rows_per_page(row_size);
+        let row_offset = row_num % self.rows_per_page(row_size);
+        let byte_offset = row_offset * row_size;
+
+        let page = self.pager.get_mut_or_alloc(page_num);
+
+        Row::deserialize(&page[byte_offset..byte_offset + row_size]).unwrap()
+    }
+
+    #[inline]
+    fn rows_per_page(&self, row_size: usize) -> usize {
+        PAGE_SIZE / row_size
+    }
+
+    pub(crate) fn get_rows(&mut self) -> Vec<Row> {
+        let mut rows: Vec<Row> = Vec::with_capacity(self.num_rows);
+        for i in 0..self.num_rows {
+            rows.push(self.row(i))
+        }
+
+        rows
+    }
+}