fix(ext/node): implement SQLite Session API (#27909)

https://nodejs.org/api/sqlite.html#class-session

---------

Signed-off-by: Divy Srivastava <[email protected]>

Cargo.toml

@@ -184,7 +184,7 @@ rand = "=0.8.5"
 regex = "^1.7.0"
 reqwest = { version = "=0.12.5", default-features = false, features = ["rustls-tls", "stream", "gzip", "brotli", "socks", "json", "http2"] } # pinned because of https://github.com/seanmonstar/reqwest/pull/1955
 ring = "^0.17.0"
-rusqlite = { version = "0.32.0", features = ["unlock_notify", "bundled"] }
+rusqlite = { version = "0.32.0", features = ["unlock_notify", "bundled", "session"] }
 rustls = { version = "0.23.11", default-features = false, features = ["logging", "std", "tls12", "ring"] }
 rustls-pemfile = "2"
 rustls-tokio-stream = "=0.3.0"

ext/node/lib.rs

@@ -443,6 +443,7 @@ deno_core::extension!(deno_node,
   objects = [
     ops::perf_hooks::EldHistogram,
     ops::sqlite::DatabaseSync,
+    ops::sqlite::Session,
     ops::sqlite::StatementSync
   ],
   esm_entry_point = "ext:deno_node/02_init.js",

ext/node/ops/sqlite/database.rs

@@ -2,6 +2,8 @@
 
 use std::cell::Cell;
 use std::cell::RefCell;
+use std::ffi::CString;
+use std::ptr::null;
 use std::rc::Rc;
 
 use deno_core::op2;
@@ -10,6 +12,8 @@ use deno_core::OpState;
 use deno_permissions::PermissionsContainer;
 use serde::Deserialize;
 
+use super::session::SessionOptions;
+use super::Session;
 use super::SqliteError;
 use super::StatementSync;
 
@@ -192,4 +196,62 @@ impl DatabaseSync {
       use_big_ints: Cell::new(false),
     })
   }
+
+  // Creates and attaches a session to the database.
+  //
+  // This method is a wrapper around `sqlite3session_create()` and
+  // `sqlite3session_attach()`.
+  #[cppgc]
+  fn create_session(
+    &self,
+    #[serde] options: Option<SessionOptions>,
+  ) -> Result<Session, SqliteError> {
+    let db = self.conn.borrow();
+    let db = db.as_ref().ok_or(SqliteError::AlreadyClosed)?;
+
+    // SAFETY: lifetime of the connection is guaranteed by reference
+    // counting.
+    let raw_handle = unsafe { db.handle() };
+
+    let mut raw_session = std::ptr::null_mut();
+    let mut options = options;
+
+    let z_db = options
+      .as_mut()
+      .and_then(|options| options.db.take())
+      .map(|db| CString::new(db).unwrap())
+      .unwrap_or_else(|| CString::new("main").unwrap());
+    // SAFETY: `z_db` points to a valid c-string.
+    let r = unsafe {
+      libsqlite3_sys::sqlite3session_create(
+        raw_handle,
+        z_db.as_ptr() as *const _,
+        &mut raw_session,
+      )
+    };
+
+    if r != libsqlite3_sys::SQLITE_OK {
+      return Err(SqliteError::SessionCreateFailed);
+    }
+
+    let table = options
+      .as_mut()
+      .and_then(|options| options.table.take())
+      .map(|table| CString::new(table).unwrap());
+    let z_table = table.as_ref().map(|table| table.as_ptr()).unwrap_or(null());
+    let r =
+      // SAFETY: `z_table` points to a valid c-string and `raw_session`
+      // is a valid session handle.
+      unsafe { libsqlite3_sys::sqlite3session_attach(raw_session, z_table) };
+
+    if r != libsqlite3_sys::SQLITE_OK {
+      return Err(SqliteError::SessionCreateFailed);
+    }
+
+    Ok(Session {
+      inner: raw_session,
+      freed: Cell::new(false),
+      _db: self.conn.clone(),
+    })
+  }
 }

ext/node/ops/sqlite/mod.rs

@@ -1,17 +1,18 @@
 // Copyright 2018-2025 the Deno authors. MIT license.
 
 mod database;
+mod session;
 mod statement;
 
 pub use database::DatabaseSync;
-use deno_permissions::PermissionCheckError;
+pub use session::Session;
 pub use statement::StatementSync;
 
 #[derive(Debug, thiserror::Error, deno_error::JsError)]
 pub enum SqliteError {
   #[class(inherit)]
   #[error(transparent)]
-  Permission(#[from] PermissionCheckError),
+  Permission(#[from] deno_permissions::PermissionCheckError),
   #[class(generic)]
   #[error(transparent)]
   SqliteError(#[from] rusqlite::Error),
@@ -40,6 +41,15 @@ pub enum SqliteError {
   #[error("Failed to prepare statement")]
   PrepareFailed,
   #[class(generic)]
+  #[error("Failed to create session")]
+  SessionCreateFailed,
+  #[class(generic)]
+  #[error("Failed to retrieve changeset")]
+  SessionChangesetFailed,
+  #[class(generic)]
+  #[error("Session is already closed")]
+  SessionClosed,
+  #[class(generic)]
   #[error("Invalid constructor")]
   InvalidConstructor,
   #[class(generic)]

ext/node/ops/sqlite/session.rs

@@ -0,0 +1,124 @@
+// Copyright 2018-2025 the Deno authors. MIT license.
+
+use std::cell::Cell;
+use std::cell::RefCell;
+use std::ffi::c_void;
+use std::rc::Rc;
+
+use deno_core::op2;
+use deno_core::GarbageCollected;
+use libsqlite3_sys as ffi;
+use serde::Deserialize;
+
+use super::SqliteError;
+
+#[derive(Deserialize)]
+#[serde(rename_all = "camelCase")]
+pub struct SessionOptions {
+  pub table: Option<String>,
+  pub db: Option<String>,
+}
+
+pub struct Session {
+  pub(crate) inner: *mut ffi::sqlite3_session,
+  pub(crate) freed: Cell<bool>,
+
+  // Hold a strong reference to the database.
+  pub(crate) _db: Rc<RefCell<Option<rusqlite::Connection>>>,
+}
+
+impl GarbageCollected for Session {}
+
+impl Drop for Session {
+  fn drop(&mut self) {
+    let _ = self.delete();
+  }
+}
+
+impl Session {
+  fn delete(&self) -> Result<(), SqliteError> {
+    if self.freed.get() {
+      return Err(SqliteError::SessionClosed);
+    }
+
+    self.freed.set(true);
+    // Safety: `self.inner` is a valid session. double free is
+    // prevented by `freed` flag.
+    unsafe {
+      ffi::sqlite3session_delete(self.inner);
+    }
+
+    Ok(())
+  }
+}
+
+#[op2]
+impl Session {
+  // Closes the session.
+  #[fast]
+  fn close(&self) -> Result<(), SqliteError> {
+    self.delete()
+  }
+
+  // Retrieves a changeset containing all changes since the changeset
+  // was created. Can be called multiple times.
+  //
+  // This method is a wrapper around `sqlite3session_changeset()`.
+  #[buffer]
+  fn changeset(&self) -> Result<Box<[u8]>, SqliteError> {
+    if self.freed.get() {
+      return Err(SqliteError::SessionClosed);
+    }
+
+    session_buffer_op(self.inner, ffi::sqlite3session_changeset)
+  }
+
+  // Similar to the method above, but generates a more compact patchset.
+  //
+  // This method is a wrapper around `sqlite3session_patchset()`.
+  #[buffer]
+  fn patchset(&self) -> Result<Box<[u8]>, SqliteError> {
+    if self.freed.get() {
+      return Err(SqliteError::SessionClosed);
+    }
+
+    session_buffer_op(self.inner, ffi::sqlite3session_patchset)
+  }
+}
+
+fn session_buffer_op(
+  s: *mut ffi::sqlite3_session,
+  f: unsafe extern "C" fn(
+    *mut ffi::sqlite3_session,
+    *mut i32,
+    *mut *mut c_void,
+  ) -> i32,
+) -> Result<Box<[u8]>, SqliteError> {
+  let mut n_buffer = 0;
+  let mut p_buffer = std::ptr::null_mut();
+
+  // Safety: `s` is a valid session and the buffer is allocated
+  // by sqlite3 and will be freed later.
+  let r = unsafe { f(s, &mut n_buffer, &mut p_buffer) };
+  if r != ffi::SQLITE_OK {
+    return Err(SqliteError::SessionChangesetFailed);
+  }
+
+  if n_buffer == 0 {
+    return Ok(Default::default());
+  }
+
+  // Safety: n_buffer is the size of the buffer.
+  let buffer = unsafe {
+    std::slice::from_raw_parts(p_buffer as *const u8, n_buffer as usize)
+  }
+  .to_vec()
+  .into_boxed_slice();
+
+  // Safety: free sqlite allocated buffer, we copied it into the JS buffer.
+  unsafe {
+    ffi::sqlite3_free(p_buffer);
+  }
+
+  Ok(buffer)
+}

tests/unit_node/sqlite_test.ts

@@ -77,6 +77,27 @@ Deno.test("[node/sqlite] StatementSync read bigints are supported", () => {
   assertEquals(stmt.expandedSQL, "SELECT * FROM data");
 });
 
+Deno.test("[node/sqlite] createSession and changesets", () => {
+  const db = new DatabaseSync(":memory:");
+  const session = db.createSession();
+
+  db.exec("CREATE TABLE test (id INTEGER PRIMARY KEY, name TEXT)");
+  db.exec("INSERT INTO test (name) VALUES ('foo')");
+
+  assert(session.changeset() instanceof Uint8Array);
+  assert(session.patchset() instanceof Uint8Array);
+
+  assert(session.changeset().byteLength > 0);
+  assert(session.patchset().byteLength > 0);
+
+  session.close();
+
+  // Use after close shoud throw.
+  assertThrows(() => session.changeset(), Error, "Session is already closed");
+  // Close after close should throw.
+  assertThrows(() => session.close(), Error, "Session is already closed");
+});
+
 Deno.test("[node/sqlite] StatementSync integer too large", () => {
   const db = new DatabaseSync(":memory:");
   db.exec("CREATE TABLE data(key INTEGER PRIMARY KEY);");