Updated pager.rs

Cargo.lock

@@ -8,14 +8,81 @@ version = "1.0.72"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "3b13c32d80ecc7ab747b80c3784bce54ee8a7a0cc4fbda9bf4cda2cf6fe90854"
 
+[[package]]
+name = "bitflags"
+version = "1.3.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "bef38d45163c2f1dde094a7dfd33ccf595c92905c8f8f4fdc18d06fb1037718a"
+
+[[package]]
+name = "bitflags"
+version = "2.4.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "b4682ae6287fcf752ecaabbfcc7b6f9b72aa33933dc23a554d853aea8eea8635"
+
+[[package]]
+name = "cc"
+version = "1.0.82"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "305fe645edc1442a0fa8b6726ba61d422798d37a52e12eaecf4b022ebbb88f01"
+dependencies = [
+ "libc",
+]
+
+[[package]]
+name = "cfg-if"
+version = "1.0.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "baf1de4339761588bc0619e3cbc0120ee582ebb74b53b4efbf79117bd2da40fd"
+
 [[package]]
 name = "dbonk"
 version = "0.1.0"
 dependencies = [
  "anyhow",
+ "tempfile",
  "thiserror",
 ]
 
+[[package]]
+name = "errno"
+version = "0.3.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "6b30f669a7961ef1631673d2766cc92f52d64f7ef354d4fe0ddfd30ed52f0f4f"
+dependencies = [
+ "errno-dragonfly",
+ "libc",
+ "windows-sys",
+]
+
+[[package]]
+name = "errno-dragonfly"
+version = "0.1.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "aa68f1b12764fab894d2755d2518754e71b4fd80ecfb822714a1206c2aab39bf"
+dependencies = [
+ "cc",
+ "libc",
+]
+
+[[package]]
+name = "fastrand"
+version = "2.0.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "6999dc1837253364c2ebb0704ba97994bd874e8f195d665c50b7548f6ea92764"
+
+[[package]]
+name = "libc"
+version = "0.2.147"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "b4668fb0ea861c1df094127ac5f1da3409a82116a4ba74fca2e58ef927159bb3"
+
+[[package]]
+name = "linux-raw-sys"
+version = "0.4.5"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "57bcfdad1b858c2db7c38303a6d2ad4dfaf5eb53dfeb0910128b2c26d6158503"
+
 [[package]]
 name = "proc-macro2"
 version = "1.0.66"
@@ -34,6 +101,28 @@ dependencies = [
  "proc-macro2",
 ]
 
+[[package]]
+name = "redox_syscall"
+version = "0.3.5"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "567664f262709473930a4bf9e51bf2ebf3348f2e748ccc50dea20646858f8f29"
+dependencies = [
+ "bitflags 1.3.2",
+]
+
+[[package]]
+name = "rustix"
+version = "0.38.8"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "19ed4fa021d81c8392ce04db050a3da9a60299050b7ae1cf482d862b54a7218f"
+dependencies = [
+ "bitflags 2.4.0",
+ "errno",
+ "libc",
+ "linux-raw-sys",
+ "windows-sys",
+]
+
 [[package]]
 name = "syn"
 version = "2.0.28"
@@ -45,6 +134,19 @@ dependencies = [
  "unicode-ident",
 ]
 
+[[package]]
+name = "tempfile"
+version = "3.7.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "dc02fddf48964c42031a0b3fe0428320ecf3a73c401040fc0096f97794310651"
+dependencies = [
+ "cfg-if",
+ "fastrand",
+ "redox_syscall",
+ "rustix",
+ "windows-sys",
+]
+
 [[package]]
 name = "thiserror"
 version = "1.0.44"
@@ -70,3 +172,69 @@ name = "unicode-ident"
 version = "1.0.11"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "301abaae475aa91687eb82514b328ab47a211a533026cb25fc3e519b86adfc3c"
+
+[[package]]
+name = "windows-sys"
+version = "0.48.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "677d2418bec65e3338edb076e806bc1ec15693c5d0104683f2efe857f61056a9"
+dependencies = [
+ "windows-targets",
+]
+
+[[package]]
+name = "windows-targets"
+version = "0.48.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "05d4b17490f70499f20b9e791dcf6a299785ce8af4d709018206dc5b4953e95f"
+dependencies = [
+ "windows_aarch64_gnullvm",
+ "windows_aarch64_msvc",
+ "windows_i686_gnu",
+ "windows_i686_msvc",
+ "windows_x86_64_gnu",
+ "windows_x86_64_gnullvm",
+ "windows_x86_64_msvc",
+]
+
+[[package]]
+name = "windows_aarch64_gnullvm"
+version = "0.48.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "91ae572e1b79dba883e0d315474df7305d12f569b400fcf90581b06062f7e1bc"
+
+[[package]]
+name = "windows_aarch64_msvc"
+version = "0.48.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "b2ef27e0d7bdfcfc7b868b317c1d32c641a6fe4629c171b8928c7b08d98d7cf3"
+
+[[package]]
+name = "windows_i686_gnu"
+version = "0.48.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "622a1962a7db830d6fd0a69683c80a18fda201879f0f447f065a3b7467daa241"
+
+[[package]]
+name = "windows_i686_msvc"
+version = "0.48.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "4542c6e364ce21bf45d69fdd2a8e455fa38d316158cfd43b3ac1c5b1b19f8e00"
+
+[[package]]
+name = "windows_x86_64_gnu"
+version = "0.48.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "ca2b8a661f7628cbd23440e50b05d705db3686f894fc9580820623656af974b1"
+
+[[package]]
+name = "windows_x86_64_gnullvm"
+version = "0.48.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "7896dbc1f41e08872e9d5e8f8baa8fdd2677f29468c4e156210174edc7f7b953"
+
+[[package]]
+name = "windows_x86_64_msvc"
+version = "0.48.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "1a515f5799fe4961cb532f983ce2b23082366b898e52ffbce459c86f67c8378a"

Cargo.toml

@@ -6,3 +6,6 @@ edition = "2021"
 [dependencies]
 anyhow = "1.0.72"
 thiserror = "1.0.44"
+
+[dev-dependencies]
+tempfile = "3.7.1"

src/cursor.rs

@@ -0,0 +1,40 @@
+use crate::table::Table;
+
+pub type Position = (usize, usize);
+
+pub struct Cursor<'a> {
+    pub table: &'a mut Table,
+    pub row_num: usize,
+    pub end_of_table: bool,
+}
+
+impl<'a> Cursor<'a> {
+    pub fn at_table_start(table: &'a mut Table) -> Self {
+        let end_of_table = table.row_count == 0;
+        Self {
+            table,
+            row_num: 0,
+            end_of_table,
+        }
+    }
+
+    pub fn at_table_end(table: &'a mut Table) -> Self {
+        let row_count = table.row_count;
+        Self {
+            table,
+            row_num: row_count,
+            end_of_table: true,
+        }
+    }
+
+    pub fn position(&self) -> Position {
+        self.table.row_slot(self.row_num)
+    }
+
+    pub fn advance(&mut self) {
+        self.row_num += 1;
+        if self.row_num >= self.table.row_count {
+            self.end_of_table = true;
+        }
+    }
+}

src/lib.rs

@@ -1,3 +1,4 @@
+pub mod cursor;
 pub mod layout;
 pub mod pager;
 pub mod row;

src/pager.rs

@@ -1,9 +1,10 @@
 use std::{
     fs::{File, OpenOptions},
     os::unix::prelude::FileExt,
+    path::Path,
 };
 
-use crate::layout::*;
+use crate::{cursor::Position, layout::*};
 use anyhow::Result;
 use thiserror::Error;
 
@@ -23,7 +24,7 @@ pub struct Pager {
 }
 
 impl Pager {
-    pub fn new(file_path: &str) -> Result<Self> {
+    pub fn new<T: AsRef<Path>>(file_path: T) -> Result<Self> {
         let file = OpenOptions::new()
             .read(true)
             .write(true)
@@ -41,7 +42,7 @@ impl Pager {
         metadata.len() as usize
     }
 
-    pub fn row_location(&self, row_num: usize) -> (usize, usize) {
+    pub fn row_location(&self, row_num: usize) -> Position {
         let page_num = row_num / ROWS_PER_PAGE;
         let row_offset = row_num % ROWS_PER_PAGE;
         let byte_offset = row_offset * ROW_SIZE;
@@ -61,12 +62,12 @@ impl Pager {
                 num_pages += 1
             }
 
+            let mut page: Page = [0; PAGE_SIZE];
             if page_num <= num_pages {
-                let mut page: Page = [0; PAGE_SIZE];
                 let offset: u64 = (page_num * PAGE_SIZE).try_into()?;
                 self.file.read_at(&mut page, offset)?;
-                self.pages[page_num] = Some(page);
             }
+            self.pages[page_num] = Some(page);
         }
 
         Ok(self.pages[page_num].as_mut().unwrap())

src/statement.rs

@@ -1,4 +1,5 @@
 use crate::{
+    cursor::Cursor,
     layout::{ROW_SIZE, TABLE_MAX_ROWS},
     row::{Row, RowBytes},
     table::Table,
@@ -6,8 +7,6 @@ use crate::{
 use anyhow::Result;
 use thiserror::Error;
 
-type FilteredRows = Vec<Row>;
-
 #[derive(Debug)]
 pub enum StatementType {
     Insert(Box<Row>),
@@ -73,23 +72,69 @@ pub fn execute_insert(row: Row, table: &mut Table) -> Result<()> {
         return Err(ExecutionError::TableFull.into());
     }
 
+    let cursor = Cursor::at_table_end(table);
     let bytes: RowBytes = row.into();
-    let (page_num, offset) = table.row_slot(table.row_count);
+
+    let (page_num, offset) = cursor.position();
     let page = table.pager.page(page_num)?;
-    // let page = table.pager.pages[page_num].as_mut().unwrap();
     page[offset..offset + ROW_SIZE].copy_from_slice(&bytes);
     table.row_count += 1;
     Ok(())
 }
 
-pub fn execute_select(table: &mut Table) -> Result<FilteredRows> {
-    let mut rows: FilteredRows = vec![];
-    for i in 0..table.row_count {
-        let (page_num, offset) = table.row_slot(i);
-        let page = table.pager.page(page_num)?;
+pub fn execute_select(table: &mut Table) -> Result<Vec<Row>> {
+    let mut rows: Vec<Row> = vec![];
+    let mut cursor = Cursor::at_table_start(table);
+    while !cursor.end_of_table {
+        let (page_num, offset) = cursor.position();
+        let page = cursor.table.pager.page(page_num)?;
         let row: RowBytes = page[offset..offset + ROW_SIZE].try_into()?;
         rows.push(row.into());
+        cursor.advance();
     }
 
     Ok(rows)
 }
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use crate::{pager::Pager, row::Row, table::Table};
+    use tempfile::NamedTempFile;
+
+    #[test]
+    fn execute_select_with_data_succeeds() {
+        let file = NamedTempFile::new_in("target").unwrap();
+        let pager = Pager::new(file.path()).unwrap();
+        let mut table = Table::new(pager);
+        for _ in 0..5 {
+            execute_insert(Row::default(), &mut table).unwrap();
+        }
+        let rows = execute_select(&mut table).unwrap();
+        assert_eq!(rows.len(), 5);
+    }
+
+    #[test]
+    fn execute_insert_exceeding_row_limit_fails() {
+        let file = NamedTempFile::new_in("target").unwrap();
+        let pager = Pager::new(file.path()).unwrap();
+        let mut table = Table::new(pager);
+        for _ in 0..TABLE_MAX_ROWS {
+            let row = Row::new(u16::MAX, "a".repeat(32).as_str(), "a".repeat(255).as_str());
+            execute_insert(row, &mut table).unwrap();
+        }
+        let result = execute_insert(Row::default(), &mut table);
+        assert!(result.is_err());
+    }
+
+    #[test]
+    #[should_panic]
+    fn execute_insert_input_exceeding_length_fails() {
+        let file = NamedTempFile::new_in("target").unwrap();
+        let pager = Pager::new(file.path()).unwrap();
+        let mut table = Table::new(pager);
+        let row = Row::new(u16::MAX, "a".repeat(33).as_str(), "a".repeat(256).as_str());
+        let result = execute_insert(row, &mut table);
+        assert!(result.is_err());
+    }
+}

src/table.rs

@@ -1,4 +1,4 @@
-use crate::{layout::*, pager::Pager};
+use crate::{cursor::Position, layout::*, pager::Pager};
 
 pub struct Table {
     pub row_count: usize,
@@ -11,7 +11,7 @@ impl Table {
         Self { row_count, pager }
     }
 
-    pub fn row_slot(&self, index: usize) -> (usize, usize) {
+    pub fn row_slot(&self, index: usize) -> Position {
         self.pager.row_location(index)
     }