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Implement Send on Cursors so we can move them between threads #334

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Implement Send on Cursors so we can move them between threads #334

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9e24362
Implement Send on Cursors so we can move them between threads
Kerollmops May 7, 2025
62b1c53
Use NonNull ptr correctly
Kerollmops May 7, 2025
8a43f1d
Prefer using NonNull::as_ptr than NonNull::as_mut
Kerollmops Jul 16, 2025
25cacf8
Use NonNull::new_unchecked instead of unwraping a NonNull::new
Kerollmops Jul 16, 2025
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41 changes: 24 additions & 17 deletions heed/src/cursor.rs
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Original file line number Diff line number Diff line change
@@ -1,12 +1,13 @@
use std::ops::{Deref, DerefMut};
use std::ptr::NonNull;
use std::{marker, mem, ptr};

use crate::mdb::error::mdb_result;
use crate::mdb::ffi;
use crate::*;

pub struct RoCursor<'txn> {
cursor: *mut ffi::MDB_cursor,
cursor: NonNull<ffi::MDB_cursor>,
_marker: marker::PhantomData<&'txn ()>,
}

Expand All @@ -15,7 +16,7 @@ impl<'txn> RoCursor<'txn> {
let mut cursor: *mut ffi::MDB_cursor = ptr::null_mut();
let mut txn = txn.txn_ptr();
unsafe { mdb_result(ffi::mdb_cursor_open(txn.as_mut(), dbi, &mut cursor))? }
Ok(RoCursor { cursor, _marker: marker::PhantomData })
Ok(RoCursor { cursor: NonNull::new(cursor).unwrap(), _marker: marker::PhantomData })
}

pub fn current(&mut self) -> Result<Option<(&'txn [u8], &'txn [u8])>> {
Expand All @@ -25,7 +26,7 @@ impl<'txn> RoCursor<'txn> {
// Move the cursor on the first database key
let result = unsafe {
mdb_result(ffi::mdb_cursor_get(
self.cursor,
self.cursor.as_mut(),
key_val.as_mut_ptr(),
data_val.as_mut_ptr(),
ffi::cursor_op::MDB_GET_CURRENT,
Expand All @@ -52,7 +53,7 @@ impl<'txn> RoCursor<'txn> {
MoveOperation::Dup => {
unsafe {
mdb_result(ffi::mdb_cursor_get(
self.cursor,
self.cursor.as_mut(),
ptr::null_mut(),
&mut ffi::MDB_val { mv_size: 0, mv_data: ptr::null_mut() },
ffi::cursor_op::MDB_FIRST_DUP,
Expand All @@ -66,7 +67,7 @@ impl<'txn> RoCursor<'txn> {
// Move the cursor on the first database key
let result = unsafe {
mdb_result(ffi::mdb_cursor_get(
self.cursor,
self.cursor.as_mut(),
key_val.as_mut_ptr(),
data_val.as_mut_ptr(),
flag,
Expand All @@ -93,7 +94,7 @@ impl<'txn> RoCursor<'txn> {
MoveOperation::Dup => {
unsafe {
mdb_result(ffi::mdb_cursor_get(
self.cursor,
self.cursor.as_mut(),
ptr::null_mut(),
&mut ffi::MDB_val { mv_size: 0, mv_data: ptr::null_mut() },
ffi::cursor_op::MDB_LAST_DUP,
Expand All @@ -107,7 +108,7 @@ impl<'txn> RoCursor<'txn> {
// Move the cursor on the first database key
let result = unsafe {
mdb_result(ffi::mdb_cursor_get(
self.cursor,
self.cursor.as_mut(),
key_val.as_mut_ptr(),
data_val.as_mut_ptr(),
flag,
Expand All @@ -131,7 +132,7 @@ impl<'txn> RoCursor<'txn> {
// Move the cursor to the specified key
let result = unsafe {
mdb_result(ffi::mdb_cursor_get(
self.cursor,
self.cursor.as_mut(),
&mut key_val,
&mut ffi::MDB_val { mv_size: 0, mv_data: ptr::null_mut() },
ffi::cursor_op::MDB_SET,
Expand All @@ -155,7 +156,7 @@ impl<'txn> RoCursor<'txn> {
// Move the cursor to the specified key
let result = unsafe {
mdb_result(ffi::mdb_cursor_get(
self.cursor,
self.cursor.as_mut(),
&mut key_val,
data_val.as_mut_ptr(),
ffi::cursor_op::MDB_SET_RANGE,
Expand Down Expand Up @@ -186,7 +187,7 @@ impl<'txn> RoCursor<'txn> {
// Move the cursor to the previous non-dup key
let result = unsafe {
mdb_result(ffi::mdb_cursor_get(
self.cursor,
self.cursor.as_mut(),
key_val.as_mut_ptr(),
data_val.as_mut_ptr(),
flag,
Expand Down Expand Up @@ -217,7 +218,7 @@ impl<'txn> RoCursor<'txn> {
// Move the cursor to the next non-dup key
let result = unsafe {
mdb_result(ffi::mdb_cursor_get(
self.cursor,
self.cursor.as_mut(),
key_val.as_mut_ptr(),
data_val.as_mut_ptr(),
flag,
Expand All @@ -238,10 +239,12 @@ impl<'txn> RoCursor<'txn> {

impl Drop for RoCursor<'_> {
fn drop(&mut self) {
unsafe { ffi::mdb_cursor_close(self.cursor) }
unsafe { ffi::mdb_cursor_close(self.cursor.as_mut()) }
}
}

unsafe impl Send for RoCursor<'_> {}

pub struct RwCursor<'txn> {
cursor: RoCursor<'txn>,
}
Expand All @@ -266,7 +269,7 @@ impl<'txn> RwCursor<'txn> {
/// [undefined behavior]: https://doc.rust-lang.org/reference/behavior-considered-undefined.html
pub unsafe fn del_current(&mut self) -> Result<bool> {
// Delete the current entry
let result = mdb_result(ffi::mdb_cursor_del(self.cursor.cursor, 0));
let result = mdb_result(ffi::mdb_cursor_del(self.cursor.cursor.as_mut(), 0));

match result {
Ok(()) => Ok(true),
Expand Down Expand Up @@ -304,7 +307,7 @@ impl<'txn> RwCursor<'txn> {

// Modify the pointed data
let result = mdb_result(ffi::mdb_cursor_put(
self.cursor.cursor,
self.cursor.cursor.as_mut(),
&mut key_val,
&mut data_val,
ffi::MDB_CURRENT,
Expand Down Expand Up @@ -344,8 +347,12 @@ impl<'txn> RwCursor<'txn> {
let mut reserved = ffi::reserve_size_val(data_size);
let flags = ffi::MDB_RESERVE | flags.bits();

let result =
mdb_result(ffi::mdb_cursor_put(self.cursor.cursor, &mut key_val, &mut reserved, flags));
let result = mdb_result(ffi::mdb_cursor_put(
self.cursor.cursor.as_mut(),
&mut key_val,
&mut reserved,
flags,
));

let found = match result {
Ok(()) => true,
Expand Down Expand Up @@ -392,7 +399,7 @@ impl<'txn> RwCursor<'txn> {

// Modify the pointed data
let result = mdb_result(ffi::mdb_cursor_put(
self.cursor.cursor,
self.cursor.cursor.as_mut(),
&mut key_val,
&mut data_val,
flags.bits(),
Expand Down
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