diff options
| -rw-r--r-- | src/db/lmdb_adapter.rs | 28 | ||||
| -rw-r--r-- | src/db/sqlite_adapter.rs | 44 |
2 files changed, 47 insertions, 25 deletions
diff --git a/src/db/lmdb_adapter.rs b/src/db/lmdb_adapter.rs index ddfb6ed5..5ce7d3e3 100644 --- a/src/db/lmdb_adapter.rs +++ b/src/db/lmdb_adapter.rs @@ -3,6 +3,7 @@ use core::ptr::NonNull; use std::collections::HashMap; use std::convert::TryInto; +use std::pin::Pin; use std::sync::{Arc, RwLock}; use heed::types::ByteSlice; @@ -319,12 +320,20 @@ where where F: FnOnce(&'a RoTxn<'a>) -> Result<I>, { - let mut res = TxAndIterator { tx, iter: None }; + let res = TxAndIterator { tx, iter: None }; + let mut boxed = Box::pin(res); - let tx = unsafe { NonNull::from(&res.tx).as_ref() }; - res.iter = Some(iterfun(tx)?); + // This unsafe allows us to bypass lifetime checks + let tx = unsafe { NonNull::from(&boxed.tx).as_ref() }; + let iter = iterfun(tx)?; - Ok(Box::new(res)) + let mut_ref = Pin::as_mut(&mut boxed); + // This unsafe allows us to write in a field of the pinned struct + unsafe { + Pin::get_unchecked_mut(mut_ref).iter = Some(iter); + } + + Ok(Box::new(TxAndIteratorPin(boxed))) } } @@ -338,14 +347,21 @@ where } } -impl<'a, I> Iterator for TxAndIterator<'a, I> +struct TxAndIteratorPin<'a, I>(Pin<Box<TxAndIterator<'a, I>>>) +where + I: Iterator<Item = IteratorItem<'a>> + 'a; + +impl<'a, I> Iterator for TxAndIteratorPin<'a, I> where I: Iterator<Item = IteratorItem<'a>> + 'a, { type Item = Result<(Value, Value)>; fn next(&mut self) -> Option<Self::Item> { - match self.iter.as_mut().unwrap().next() { + let mut_ref = Pin::as_mut(&mut self.0); + // This unsafe allows us to mutably access the iterator field + let next = unsafe { Pin::get_unchecked_mut(mut_ref).iter.as_mut()?.next() }; + match next { None => None, Some(Err(e)) => Some(Err(e.into())), Some(Ok((k, v))) => Some(Ok((k.to_vec(), v.to_vec()))), diff --git a/src/db/sqlite_adapter.rs b/src/db/sqlite_adapter.rs index 077c1f1b..2c6a4159 100644 --- a/src/db/sqlite_adapter.rs +++ b/src/db/sqlite_adapter.rs @@ -444,17 +444,23 @@ impl<'a> DbValueIterator<'a> { let mut boxed = Box::pin(res); trace!("make iterator with sql: {}", sql); - unsafe { - let db = NonNull::from(&boxed.db); - let stmt = db.as_ref().db.prepare(sql)?; + // This unsafe allows us to bypass lifetime checks + let db = unsafe { NonNull::from(&boxed.db).as_ref() }; + let stmt = db.db.prepare(sql)?; - let mut_ref: Pin<&mut DbValueIterator<'a>> = Pin::as_mut(&mut boxed); + let mut_ref = Pin::as_mut(&mut boxed); + // This unsafe allows us to write in a field of the pinned struct + unsafe { Pin::get_unchecked_mut(mut_ref).stmt = Some(stmt); + } - let mut stmt = NonNull::from(&boxed.stmt); - let iter = stmt.as_mut().as_mut().unwrap().query(args)?; + // This unsafe allows us to bypass lifetime checks + let stmt = unsafe { NonNull::from(&boxed.stmt).as_mut() }; + let iter = stmt.as_mut().unwrap().query(args)?; - let mut_ref: Pin<&mut DbValueIterator<'a>> = Pin::as_mut(&mut boxed); + let mut_ref = Pin::as_mut(&mut boxed); + // This unsafe allows us to write in a field of the pinned struct + unsafe { Pin::get_unchecked_mut(mut_ref).iter = Some(iter); } @@ -476,10 +482,9 @@ impl<'a> Iterator for DbValueIteratorPin<'a> { type Item = Result<(Value, Value)>; fn next(&mut self) -> Option<Self::Item> { - let next = unsafe { - let mut_ref: Pin<&mut DbValueIterator<'a>> = Pin::as_mut(&mut self.0); - Pin::get_unchecked_mut(mut_ref).iter.as_mut()?.next() - }; + let mut_ref = Pin::as_mut(&mut self.0); + // This unsafe allows us to mutably access the iterator field + let next = unsafe { Pin::get_unchecked_mut(mut_ref).iter.as_mut()?.next() }; let row = match next { Err(e) => return Some(Err(e.into())), Ok(None) => return None, @@ -522,11 +527,13 @@ impl<'a> TxValueIterator<'a> { let mut boxed = Box::pin(res); trace!("make iterator with sql: {}", sql); - unsafe { - let mut stmt = NonNull::from(&boxed.stmt); - let iter = stmt.as_mut().query(args)?; + // This unsafe allows us to bypass lifetime checks + let stmt = unsafe { NonNull::from(&boxed.stmt).as_mut() }; + let iter = stmt.query(args)?; - let mut_ref: Pin<&mut TxValueIterator<'a>> = Pin::as_mut(&mut boxed); + let mut_ref = Pin::as_mut(&mut boxed); + // This unsafe allows us to write in a field of the pinned struct + unsafe { Pin::get_unchecked_mut(mut_ref).iter = Some(iter); } @@ -547,10 +554,9 @@ impl<'a> Iterator for TxValueIteratorPin<'a> { type Item = TxOpResult<(Value, Value)>; fn next(&mut self) -> Option<Self::Item> { - let next = unsafe { - let mut_ref: Pin<&mut TxValueIterator<'a>> = Pin::as_mut(&mut self.0); - Pin::get_unchecked_mut(mut_ref).iter.as_mut()?.next() - }; + let mut_ref = Pin::as_mut(&mut self.0); + // This unsafe allows us to mutably access the iterator field + let next = unsafe { Pin::get_unchecked_mut(mut_ref).iter.as_mut()?.next() }; let row = match next { Err(e) => return Some(Err(e.into())), Ok(None) => return None, |