docs

storage/blockchain/src/ops/alt_block/chain.rs

@@ -28,10 +28,10 @@ pub fn update_alt_chain_info(
         Err(e) => return Err(e),
     };
 
-    // try update the info if one exists for this chain.
+    tables
-    let update = tables
         .alt_chain_infos_mut()
-        .update(&alt_block_height.chain_id, |mut info| {
+        .entry(&alt_block_height.chain_id)?
+        .and_update(|info| {
             if info.chain_height < alt_block_height.height + 1 {
                 // If the chain height is increasing we only need to update the chain height.
                 info.chain_height = alt_block_height.height + 1;
@@ -43,25 +43,12 @@ pub fn update_alt_chain_info(
             }
 
             info.chain_height = alt_block_height.height + 1;
-            Some(info)
+        })?
-        });
+        .or_insert_with(|| AltChainInfo {
-
-    match update {
-        Ok(()) => return Ok(()),
-        Err(RuntimeError::KeyNotFound) => (),
-        Err(e) => return Err(e),
-    }
-
-    // If one doesn't already exist add it.
-
-    tables.alt_chain_infos_mut().put(
-        &alt_block_height.chain_id,
-        &AltChainInfo {
             parent_chain: parent_chain.into(),
             common_ancestor_height: alt_block_height.height.checked_sub(1).unwrap(),
             chain_height: alt_block_height.height + 1,
-        },
+        })
-    )
 }
 
 /// Get the height history of an alt-chain in reverse chronological order.

storage/blockchain/src/ops/output.rs

@@ -62,19 +62,12 @@ pub fn remove_output(
     pre_rct_output_id: &PreRctOutputId,
     tables: &mut impl TablesMut,
 ) -> DbResult<()> {
-    // Decrement the amount index by 1, or delete the entry out-right.
+    // INVARIANT: `num_outputs` should never be 0.
-    // FIXME: this would be much better expressed with a
-    // `btree_map::Entry`-like API, fix `trait DatabaseRw`.
     tables
         .num_outputs_mut()
-        .update(&pre_rct_output_id.amount, |num_outputs| {
+        .entry(&pre_rct_output_id.amount)?
-            // INVARIANT: Should never be 0.
+        .remove_if(|num_outputs| *num_outputs == 1)?
-            if num_outputs == 1 {
+        .and_update(|num_outputs| *num_outputs -= 1)?;
-                None
-            } else {
-                Some(num_outputs - 1)
-            }
-        })?;
 
     // Delete the output data itself.
     tables.outputs_mut().delete(pre_rct_output_id)

storage/database/src/backend/tests.rs

@@ -263,17 +263,17 @@ fn db_read_write() {
         }
     }
 
-    // Assert `update()` works.
+    // Assert `Entry` works.
     {
         const NEW_VALUE: u64 = 999;
 
         assert_ne!(table.get(&KEY).unwrap(), NEW_VALUE);
 
-        #[expect(unused_assignments)]
         table
-            .update(&KEY, |mut value| {
+            .entry(&KEY)
-                value = NEW_VALUE;
+            .unwrap()
-                Some(value)
+            .and_update(|value| {
+                *value = NEW_VALUE;
             })
             .unwrap();
 

storage/database/src/database.rs

@@ -179,30 +179,6 @@ pub trait DatabaseRw<T: Table>: DatabaseRo<T> + Sized {
     #[doc = doc_database!()]
     fn take(&mut self, key: &T::Key) -> DbResult<T::Value>;
 
-    /// Fetch the value, and apply a function to it - or delete the entry.
-    ///
-    /// This will call [`DatabaseRo::get`] and call your provided function `f` on it.
-    ///
-    /// The [`Option`] `f` returns will dictate whether `update()`:
-    /// - Updates the current value OR
-    /// - Deletes the `(key, value)` pair
-    ///
-    /// - If `f` returns `Some(value)`, that will be [`DatabaseRw::put`] as the new value
-    /// - If `f` returns `None`, the entry will be [`DatabaseRw::delete`]d
-    ///
-    #[doc = doc_database!()]
-    fn update<F>(&mut self, key: &T::Key, mut f: F) -> DbResult<()>
-    where
-        F: FnMut(T::Value) -> Option<T::Value>,
-    {
-        let value = DatabaseRo::get(self, key)?;
-
-        match f(value) {
-            Some(value) => DatabaseRw::put(self, key, &value),
-            None => DatabaseRw::delete(self, key),
-        }
-    }
-
     /// Removes and returns the first `(key, value)` pair in the database.
     ///
     #[doc = doc_database!()]
@@ -213,6 +189,8 @@ pub trait DatabaseRw<T: Table>: DatabaseRo<T> + Sized {
     #[doc = doc_database!()]
     fn pop_last(&mut self) -> DbResult<(T::Key, T::Value)>;
 
-    /// TODO
+    /// Gets the given key's corresponding entry for in-place manipulation.
+    ///
+    #[doc = doc_database!()]
     fn entry<'a>(&'a mut self, key: &'a T::Key) -> DbResult<Entry<'a, T, Self>>;
 }

storage/database/src/entry.rs

@@ -0,0 +1,315 @@
+//! Entry API for [`DatabaseRw`].
+//!
+//! This module provides a [`std::collections::btree_map::Entry`]-like API for [`DatabaseRw`].
+//!
+//! ## Example
+//! ```rust
+//! use cuprate_database::{
+//!     ConcreteEnv,
+//!     config::ConfigBuilder,
+//!     Env, EnvInner,
+//!     DatabaseRo, DatabaseRw, TxRo, TxRw, RuntimeError,
+//! };
+//!
+//! # fn main() -> Result<(), Box<dyn std::error::Error>> {
+//! # let tmp_dir = tempfile::tempdir()?;
+//! # let db_dir = tmp_dir.path().to_owned();
+//! # let config = ConfigBuilder::new(db_dir.into()).build();
+//! #
+//! # let env = ConcreteEnv::open(config)?;
+//! #
+//! # struct Table;
+//! # impl cuprate_database::Table for Table {
+//! #     const NAME: &'static str = "table";
+//! #     type Key = u8;
+//! #     type Value = u64;
+//! # }
+//! #
+//! # let env_inner = env.env_inner();
+//! # let tx_rw = env_inner.tx_rw()?;
+//! #
+//! # env_inner.create_db::<Table>(&tx_rw)?;
+//! # let mut table = env_inner.open_db_rw::<Table>(&tx_rw)?;
+//! /// The key to use.
+//! const KEY: u8 = u8::MAX;
+//!
+//! /// The update function applied if the value already exists.
+//! fn f(value: &mut u64) {
+//!     *value += 1;
+//! }
+//!
+//! // No entry exists.
+//! assert!(matches!(table.first(), Err(RuntimeError::KeyNotFound)));
+//!
+//! // Increment the value by `1` or insert a `0` if it doesn't exist.
+//! table.entry(&KEY)?.and_update(f)?.or_insert(&0)?;
+//! assert_eq!(table.first()?, (KEY, 0));
+//! table.entry(&KEY)?.and_update(f)?.or_insert(&0)?;
+//! assert_eq!(table.first()?, (KEY, 1));
+//!
+//! // Conditionally remove the entry.
+//! table.entry(&KEY)?.remove_if(|v| *v == 0);
+//! assert_eq!(table.first()?, (KEY, 1));
+//! table.entry(&KEY)?.remove_if(|v| *v == 1);
+//! assert!(matches!(table.first(), Err(RuntimeError::KeyNotFound)));
+//! # Ok(()) }
+//! ```
+
+use crate::{DatabaseRw, DbResult, RuntimeError, Table};
+
+//---------------------------------------------------------------------------------------------------- Entry
+/// A view into a single entry in a [`DatabaseRw`], which may either be a [`VacantEntry`] or [`OccupiedEntry`].
+///
+/// This enum is constructed from the [`DatabaseRw::entry`] method.
+pub enum Entry<'a, T, D>
+where
+    T: Table,
+    D: DatabaseRw<T>,
+{
+    /// A vacant entry; this key did not exist.
+    ///
+    /// [`RuntimeError::KeyExists`] will never be returned from this type's operations.
+    Vacant(VacantEntry<'a, T, D>),
+
+    /// An occupied entry; this key already exists.
+    ///
+    /// [`RuntimeError::KeyNotFound`] will never be returned from this type's operations.
+    Occupied(OccupiedEntry<'a, T, D>),
+}
+
+impl<'a, T, D> Entry<'a, T, D>
+where
+    T: Table,
+    D: DatabaseRw<T>,
+{
+    /// Returns [`true`] if [`Self::Occupied`].
+    pub const fn is_occupied(&self) -> bool {
+        matches!(self, Self::Occupied(_))
+    }
+
+    /// Returns [`true`] if [`Self::Vacant`].
+    pub const fn is_vacant(&self) -> bool {
+        matches!(self, Self::Vacant(_))
+    }
+
+    /// Ensures a value is in the entry by inserting the `default` if empty.
+    ///
+    /// This only inserts if the entry is [`VacantEntry`].
+    pub fn or_insert(self, default: &T::Value) -> DbResult<()> {
+        match self {
+            Self::Occupied(_) => Ok(()),
+            Self::Vacant(entry) => entry.insert(default),
+        }
+    }
+
+    /// Ensures a value is in the entry by inserting the result of the `default` function.
+    ///
+    /// This only inserts if the entry is [`VacantEntry`].
+    pub fn or_insert_with<F>(self, default: F) -> DbResult<()>
+    where
+        F: FnOnce() -> T::Value,
+    {
+        match self {
+            Self::Occupied(_) => Ok(()),
+            Self::Vacant(entry) => entry.insert(&default()),
+        }
+    }
+
+    /// Same as [`Self::or_insert_with`] but gives access to the key.
+    pub fn or_insert_with_key<F>(self, default: F) -> DbResult<()>
+    where
+        F: FnOnce(&'a T::Key) -> T::Value,
+    {
+        match self {
+            Self::Occupied(_) => Ok(()),
+            Self::Vacant(entry) => {
+                let key = entry.key;
+                entry.insert(&default(key))
+            }
+        }
+    }
+
+    /// Returns a reference to this entry's key.
+    pub const fn key(&self) -> &T::Key {
+        match self {
+            Self::Occupied(entry) => entry.key(),
+            Self::Vacant(entry) => entry.key(),
+        }
+    }
+
+    /// Returns a reference to this entry's value (if the entry is [`OccupiedEntry`]).
+    ///
+    /// # Errors
+    /// This returns [`RuntimeError::KeyNotFound`] if the entry is [`VacantEntry`].
+    pub const fn value(&self) -> DbResult<&T::Value> {
+        match self {
+            Self::Occupied(entry) => Ok(entry.value()),
+            Self::Vacant(_) => Err(RuntimeError::KeyNotFound),
+        }
+    }
+
+    /// Take ownership of entry's value (if the entry is [`OccupiedEntry`]).
+    ///
+    /// # Errors
+    /// This returns [`RuntimeError::KeyNotFound`] if the entry is [`VacantEntry`].
+    pub fn into_value(self) -> DbResult<T::Value> {
+        match self {
+            Self::Occupied(entry) => Ok(entry.into_value()),
+            Self::Vacant(_) => Err(RuntimeError::KeyNotFound),
+        }
+    }
+
+    /// Conditionally remove the value if it already exists.
+    ///
+    /// If `f` returns `true`, the entry will be removed if it exists.
+    ///
+    /// This functions does nothing if the entry is [`VacantEntry`].
+    pub fn remove_if<F>(self, f: F) -> DbResult<Self>
+    where
+        F: FnOnce(&T::Value) -> bool,
+    {
+        Ok(match self {
+            Self::Occupied(entry) => {
+                if f(&entry.value) {
+                    Self::Vacant(entry.remove()?.0)
+                } else {
+                    Self::Occupied(entry)
+                }
+            }
+            Self::Vacant(entry) => Self::Vacant(entry),
+        })
+    }
+
+    /// Update the value if it already exists.
+    ///
+    /// This functions does nothing if the entry is [`VacantEntry`].
+    pub fn and_update<F>(self, f: F) -> DbResult<Self>
+    where
+        F: FnOnce(&mut T::Value),
+    {
+        Ok(match self {
+            Self::Occupied(mut entry) => {
+                entry.update(f)?;
+                Self::Occupied(entry)
+            }
+            Self::Vacant(entry) => Self::Vacant(entry),
+        })
+    }
+}
+
+impl<T, D> Entry<'_, T, D>
+where
+    T: Table,
+    <T as Table>::Value: Default,
+    D: DatabaseRw<T>,
+{
+    /// Ensures a value is in the entry by inserting a [`Default`] value if empty.
+    ///
+    /// This only inserts if the entry is [`VacantEntry`].
+    pub fn or_default(self) -> DbResult<()> {
+        match self {
+            Self::Occupied(_) => Ok(()),
+            Self::Vacant(entry) => entry.insert(&Default::default()),
+        }
+    }
+}
+
+//---------------------------------------------------------------------------------------------------- VacantEntry
+/// A view into a vacant [`Entry`] in a [`DatabaseRw`].
+pub struct VacantEntry<'a, T, D>
+where
+    T: Table,
+    D: DatabaseRw<T>,
+{
+    pub(crate) db: &'a mut D,
+    pub(crate) key: &'a T::Key,
+}
+
+impl<T, D> VacantEntry<'_, T, D>
+where
+    T: Table,
+    D: DatabaseRw<T>,
+{
+    /// Gets a reference to the key that is used when [`Self::insert`]ing a value.
+    pub const fn key(&self) -> &T::Key {
+        self.key
+    }
+
+    /// [`DatabaseRw::put`] a new value with [`Self::key`] as the key.
+    pub fn insert(self, value: &T::Value) -> DbResult<()> {
+        match DatabaseRw::put(self.db, self.key, value) {
+            Ok(()) => Ok(()),
+            Err(RuntimeError::KeyExists) => {
+                unreachable!("this error popping up while VacantEntry exists is a logical error")
+            }
+            Err(e) => Err(e),
+        }
+    }
+}
+
+//---------------------------------------------------------------------------------------------------- OccupiedEntry
+/// A view into an occupied [`Entry`] in a [`DatabaseRw`].
+pub struct OccupiedEntry<'a, T, D>
+where
+    T: Table,
+    D: DatabaseRw<T>,
+{
+    pub(crate) db: &'a mut D,
+    pub(crate) key: &'a T::Key,
+    pub(crate) value: T::Value,
+}
+
+impl<'a, T, D> OccupiedEntry<'a, T, D>
+where
+    T: Table,
+    D: DatabaseRw<T>,
+{
+    /// Gets a reference to the key that is used when [`Self::insert`]ing a value.
+    pub const fn key(&self) -> &T::Key {
+        self.key
+    }
+
+    /// Gets a reference to the current value.
+    ///
+    /// [`Self::update`] will modify this value.
+    pub const fn value(&self) -> &T::Value {
+        &self.value
+    }
+
+    /// Take ownership of the current value.
+    pub fn into_value(self) -> T::Value {
+        self.value
+    }
+
+    /// Modify the current value and insert it.
+    ///
+    /// Calling [`Self::value`] after this will return the modified value.
+    pub fn update<F>(&mut self, f: F) -> DbResult<()>
+    where
+        F: FnOnce(&mut T::Value),
+    {
+        f(&mut self.value);
+        DatabaseRw::put(self.db, self.key, &self.value)
+    }
+
+    /// Replace the current value with a new value.
+    pub fn insert(self, value: &T::Value) -> DbResult<()> {
+        DatabaseRw::put(self.db, self.key, value)
+    }
+
+    /// Remove this entry.
+    ///
+    /// The returned values are:
+    /// - A [`VacantEntry`]
+    /// - The value that was removed
+    pub fn remove(self) -> DbResult<(VacantEntry<'a, T, D>, T::Value)> {
+        DatabaseRw::delete(self.db, self.key)?;
+        Ok((
+            VacantEntry {
+                db: self.db,
+                key: self.key,
+            },
+            self.value,
+        ))
+    }
+}

storage/database/src/entry/entry.rs

@@ -1,96 +0,0 @@
-//! TODO
-
-use crate::{
-    entry::{OccupiedEntry, VacantEntry},
-    DatabaseRw, DbResult, Table,
-};
-
-pub enum Entry<'a, T, D>
-where
-    T: Table,
-    D: DatabaseRw<T>,
-{
-    Vacant(VacantEntry<'a, T, D>),
-    Occupied(OccupiedEntry<'a, T, D>),
-}
-
-impl<'a, T, D> Entry<'a, T, D>
-where
-    T: Table,
-    D: DatabaseRw<T>,
-{
-    /// TODO
-    pub fn or_insert(self, default: &T::Value) -> DbResult<()> {
-        match self {
-            Self::Occupied(_) => Ok(()),
-            Self::Vacant(entry) => entry.insert(default),
-        }
-    }
-
-    /// TODO
-    pub fn or_insert_with<F>(self, default: F) -> DbResult<()>
-    where
-        F: FnOnce() -> &'a T::Value,
-    {
-        match self {
-            Self::Occupied(_) => Ok(()),
-            Self::Vacant(entry) => entry.insert(default()),
-        }
-    }
-
-    /// TODO
-    pub fn or_insert_with_key<F>(self, default: F) -> DbResult<()>
-    where
-        F: FnOnce(&'a T::Key) -> &'a T::Value,
-    {
-        match self {
-            Self::Occupied(_) => Ok(()),
-            Self::Vacant(entry) => {
-                let key = entry.key;
-                entry.insert(default(key))
-            }
-        }
-    }
-
-    /// TODO
-    pub const fn key(&self) -> &T::Key {
-        match self {
-            Self::Occupied(entry) => entry.key(),
-            Self::Vacant(entry) => entry.key(),
-        }
-    }
-
-    /// TODO
-    pub const fn value(&self) -> Option<&T::Value> {
-        match self {
-            Self::Occupied(entry) => Some(entry.value()),
-            Self::Vacant(_) => None,
-        }
-    }
-
-    /// TODO
-    pub fn and_update<F>(self, f: F) -> DbResult<Self>
-    where
-        F: FnOnce(&mut T::Value),
-    {
-        Ok(match self {
-            Self::Occupied(mut entry) => {
-                entry.update(f)?;
-                Self::Occupied(entry)
-            }
-            Self::Vacant(entry) => Self::Vacant(entry),
-        })
-    }
-}
-
-impl<'a, T, D> Entry<'a, T, D>
-where
-    T: Table,
-    <T as Table>::Value: Default,
-    D: DatabaseRw<T>,
-{
-    /// TODO
-    pub fn or_default(self) -> &'a mut T::Value {
-        todo!()
-    }
-}

storage/database/src/entry/mod.rs

@@ -1,10 +0,0 @@
-//! TODO
-
-#[expect(clippy::module_inception)]
-mod entry;
-mod occupied_entry;
-mod vacant_entry;
-
-pub use entry::Entry;
-pub use occupied_entry::OccupiedEntry;
-pub use vacant_entry::VacantEntry;

storage/database/src/entry/occupied_entry.rs

@@ -1,58 +0,0 @@
-//! TODO
-
-use crate::{DatabaseRw, DbResult, Table};
-
-pub struct OccupiedEntry<'a, T, D>
-where
-    T: Table,
-    D: DatabaseRw<T>,
-{
-    pub(crate) db: &'a mut D,
-    pub(crate) key: &'a T::Key,
-    pub(crate) value: T::Value,
-}
-
-impl<T, D> OccupiedEntry<'_, T, D>
-where
-    T: Table,
-    D: DatabaseRw<T>,
-{
-    /// TODO
-    pub const fn key(&self) -> &T::Key {
-        self.key
-    }
-
-    /// TODO
-    pub const fn value(&self) -> &T::Value {
-        &self.value
-    }
-
-    /// TODO
-    pub fn update<F>(&mut self, f: F) -> DbResult<()>
-    where
-        F: FnOnce(&mut T::Value),
-    {
-        f(&mut self.value);
-        DatabaseRw::put(self.db, self.key, &self.value)
-    }
-
-    /// TODO
-    pub fn insert(&mut self, value: &T::Value) -> DbResult<()> {
-        DatabaseRw::put(self.db, self.key, value)
-    }
-
-    /// TODO
-    pub fn remove(self) -> DbResult<T::Value> {
-        DatabaseRw::delete(self.db, self.key).map(|()| Ok(self.value))?
-    }
-
-    /// TODO
-    pub const fn get(&self) -> &T::Value {
-        &self.value
-    }
-
-    /// TODO
-    pub fn into_value(self) -> T::Value {
-        self.value
-    }
-}

storage/database/src/entry/vacant_entry.rs

@@ -1,34 +0,0 @@
-//! TODO
-
-use crate::{DatabaseRw, DbResult, RuntimeError, Table};
-
-pub struct VacantEntry<'a, T, D>
-where
-    T: Table,
-    D: DatabaseRw<T>,
-{
-    pub(crate) db: &'a mut D,
-    pub(crate) key: &'a T::Key,
-}
-
-impl<T, D> VacantEntry<'_, T, D>
-where
-    T: Table,
-    D: DatabaseRw<T>,
-{
-    /// TODO
-    pub const fn key(&self) -> &T::Key {
-        self.key
-    }
-
-    /// TODO
-    pub fn insert(self, value: &T::Value) -> DbResult<()> {
-        match DatabaseRw::put(self.db, self.key, value) {
-            Ok(()) => Ok(()),
-            Err(RuntimeError::KeyExists) => {
-                unreachable!("this error popping up while VacantEntry exists is a logical error")
-            }
-            Err(e) => Err(e),
-        }
-    }
-}

storage/txpool/src/service/write.rs

@@ -114,10 +114,11 @@ fn promote(env: &ConcreteEnv, tx_hash: &TransactionHash) -> DbResult<TxpoolWrite
     let res = || {
         let mut tx_infos = env_inner.open_db_rw::<TransactionInfos>(&tx_rw)?;
 
-        tx_infos.update(tx_hash, |mut info| {
+        tx_infos.entry(tx_hash)?.and_update(|info| {
             info.flags.remove(TxStateFlags::STATE_STEM);
-            Some(info)
+        })?;
-        })
+
+        Ok(())
     };
 
     if let Err(e) = res() {