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// Copyright Materialize, Inc. and contributors. All rights reserved.
//
// Use of this software is governed by the Business Source License
// included in the LICENSE file.
//
// As of the Change Date specified in that file, in accordance with
// the Business Source License, use of this software will be governed
// by the Apache License, Version 2.0.
// BEGIN LINT CONFIG
// DO NOT EDIT. Automatically generated by bin/gen-lints.
// Have complaints about the noise? See the note in misc/python/materialize/cli/gen-lints.py first.
#![allow(unknown_lints)]
#![allow(clippy::style)]
#![allow(clippy::complexity)]
#![allow(clippy::large_enum_variant)]
#![allow(clippy::mutable_key_type)]
#![allow(clippy::stable_sort_primitive)]
#![allow(clippy::map_entry)]
#![allow(clippy::box_default)]
#![allow(clippy::drain_collect)]
#![warn(clippy::bool_comparison)]
#![warn(clippy::clone_on_ref_ptr)]
#![warn(clippy::no_effect)]
#![warn(clippy::unnecessary_unwrap)]
#![warn(clippy::dbg_macro)]
#![warn(clippy::todo)]
#![warn(clippy::wildcard_dependencies)]
#![warn(clippy::zero_prefixed_literal)]
#![warn(clippy::borrowed_box)]
#![warn(clippy::deref_addrof)]
#![warn(clippy::double_must_use)]
#![warn(clippy::double_parens)]
#![warn(clippy::extra_unused_lifetimes)]
#![warn(clippy::needless_borrow)]
#![warn(clippy::needless_question_mark)]
#![warn(clippy::needless_return)]
#![warn(clippy::redundant_pattern)]
#![warn(clippy::redundant_slicing)]
#![warn(clippy::redundant_static_lifetimes)]
#![warn(clippy::single_component_path_imports)]
#![warn(clippy::unnecessary_cast)]
#![warn(clippy::useless_asref)]
#![warn(clippy::useless_conversion)]
#![warn(clippy::builtin_type_shadow)]
#![warn(clippy::duplicate_underscore_argument)]
#![warn(clippy::double_neg)]
#![warn(clippy::unnecessary_mut_passed)]
#![warn(clippy::wildcard_in_or_patterns)]
#![warn(clippy::crosspointer_transmute)]
#![warn(clippy::excessive_precision)]
#![warn(clippy::overflow_check_conditional)]
#![warn(clippy::as_conversions)]
#![warn(clippy::match_overlapping_arm)]
#![warn(clippy::zero_divided_by_zero)]
#![warn(clippy::must_use_unit)]
#![warn(clippy::suspicious_assignment_formatting)]
#![warn(clippy::suspicious_else_formatting)]
#![warn(clippy::suspicious_unary_op_formatting)]
#![warn(clippy::mut_mutex_lock)]
#![warn(clippy::print_literal)]
#![warn(clippy::same_item_push)]
#![warn(clippy::useless_format)]
#![warn(clippy::write_literal)]
#![warn(clippy::redundant_closure)]
#![warn(clippy::redundant_closure_call)]
#![warn(clippy::unnecessary_lazy_evaluations)]
#![warn(clippy::partialeq_ne_impl)]
#![warn(clippy::redundant_field_names)]
#![warn(clippy::transmutes_expressible_as_ptr_casts)]
#![warn(clippy::unused_async)]
#![warn(clippy::disallowed_methods)]
#![warn(clippy::disallowed_macros)]
#![warn(clippy::disallowed_types)]
#![warn(clippy::from_over_into)]
// END LINT CONFIG
//! Durable metadata storage.
use std::collections::btree_map::Entry;
use std::collections::{BTreeMap, BTreeSet};
use std::error::Error;
use std::fmt::{self, Debug};
use std::marker::PhantomData;
use std::sync::Arc;
use mz_ore::soft_assert;
use mz_proto::{RustType, TryFromProtoError};
use serde::{Deserialize, Serialize};
use timely::progress::Antichain;
use tokio_postgres::error::SqlState;
pub mod objects;
mod postgres;
mod transaction;
// TODO(parkmycar): This shouldn't be public, but it is for now to prevent dead code warnings.
pub mod upgrade;
#[cfg(test)]
mod tests;
pub use crate::postgres::{DebugStashFactory, Stash, StashFactory};
pub use crate::transaction::{Transaction, INSERT_BATCH_SPLIT_SIZE};
/// The current version of the [`Stash`].
///
/// We will initialize new [`Stash`]es with this version, and migrate existing [`Stash`]es to this
/// version. Whenever the [`Stash`] changes, e.g. the protobufs we serialize in the [`Stash`]
/// change, we need to bump this version.
pub const STASH_VERSION: u64 = 37;
/// The minimum [`Stash`] version number that we support migrating from.
///
/// After bumping this we can delete the old migrations.
pub(crate) const MIN_STASH_VERSION: u64 = 25;
// TODO(jkosh44) There's some circular logic going on with this key across crates.
// mz_catalog::stash initializes uses this value to initialize
// `CONFIG_COLLECTION: mz_stash::TypedCollection`. Then `mz_stash::postgres::Stash` uses this value
// to check if the stash has been initialized.
/// The key within the Config Collection that stores the version of the Stash.
pub const USER_VERSION_KEY: &str = "user_version";
pub const COLLECTION_CONFIG: TypedCollection<
objects::proto::ConfigKey,
objects::proto::ConfigValue,
> = TypedCollection::new("config");
pub type Diff = i64;
pub type Timestamp = i64;
pub(crate) type Id = i64;
/// A common trait for uses of K and V to express in a single place all of the
/// traits required by async_trait and StashCollection.
pub trait Data:
prost::Message + Default + Ord + Send + Sync + Serialize + for<'de> Deserialize<'de>
{
}
impl<T: prost::Message + Default + Ord + Send + Sync + Serialize + for<'de> Deserialize<'de>> Data
for T
{
}
/// `StashCollection` is like a differential dataflow [`Collection`], but the
/// state of the collection is durable.
///
/// A `StashCollection` stores `(key, value, timestamp, diff)` entries. The key
/// and value types are chosen by the caller; they must implement [`Ord`] and
/// they must be serializable to and deserializable via serde. The timestamp and
/// diff types are fixed to `i64`.
///
/// A `StashCollection` maintains a since frontier and an upper frontier, as
/// described in the [correctness vocabulary document].
///
/// [correctness vocabulary document]: https://github.com/MaterializeInc/materialize/blob/main/doc/developer/design/20210831_correctness.md
/// [`Collection`]: differential_dataflow::collection::Collection
#[derive(Debug)]
pub struct StashCollection<K, V> {
pub id: Id,
_kv: PhantomData<(K, V)>,
}
impl<K, V> StashCollection<K, V> {
fn new(id: Id) -> Self {
Self {
id,
_kv: PhantomData,
}
}
}
impl<K, V> Clone for StashCollection<K, V> {
fn clone(&self) -> Self {
*self
}
}
impl<K, V> Copy for StashCollection<K, V> {}
struct AntichainFormatter<'a, T>(&'a [T]);
impl<T> fmt::Display for AntichainFormatter<'_, T>
where
T: fmt::Display,
{
fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
f.write_str("{")?;
for (i, element) in self.0.iter().enumerate() {
if i > 0 {
f.write_str(", ")?;
}
element.fmt(f)?;
}
f.write_str("}")
}
}
impl<'a, T> From<&'a Antichain<T>> for AntichainFormatter<'a, T> {
fn from(antichain: &Antichain<T>) -> AntichainFormatter<T> {
AntichainFormatter(antichain.elements())
}
}
/// An error that can occur while interacting with a [`Stash`].
///
/// Stash errors are deliberately opaque. They generally indicate unrecoverable
/// conditions, like running out of disk space.
#[derive(Debug)]
pub struct StashError {
// Internal to avoid leaking implementation details.
inner: InternalStashError,
}
impl StashError {
/// Reports whether the error is unrecoverable (retrying will never succeed,
/// or a retry is not safe due to an indeterminate state).
pub fn is_unrecoverable(&self) -> bool {
match &self.inner {
InternalStashError::Fence(_) | InternalStashError::StashNotWritable(_) => true,
_ => false,
}
}
/// Reports whether the error can be recovered if we opened the stash in writeable
pub fn can_recover_with_write_mode(&self) -> bool {
match &self.inner {
InternalStashError::StashNotWritable(_) => true,
_ => false,
}
}
/// The underlying transaction failed in a way that must be resolved by retrying
pub fn should_retry(&self) -> bool {
match &self.inner {
InternalStashError::Postgres(e) => {
matches!(e.code(), Some(&SqlState::T_R_SERIALIZATION_FAILURE))
}
_ => false,
}
}
}
#[derive(Debug)]
enum InternalStashError {
Postgres(::tokio_postgres::Error),
Fence(String),
PeekSinceUpper(String),
IncompatibleVersion(u64),
Proto(TryFromProtoError),
Decoding(prost::DecodeError),
Uninitialized,
StashNotWritable(String),
Other(String),
}
impl fmt::Display for StashError {
fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
f.write_str("stash error: ")?;
match &self.inner {
InternalStashError::Postgres(e) => write!(f, "postgres: {e}"),
InternalStashError::Proto(e) => write!(f, "proto: {e}"),
InternalStashError::Decoding(e) => write!(f, "prost decoding: {e}"),
InternalStashError::Fence(e) => f.write_str(e),
InternalStashError::PeekSinceUpper(e) => f.write_str(e),
InternalStashError::IncompatibleVersion(v) => {
write!(f, "incompatible Stash version {v}, minimum: {MIN_STASH_VERSION}, current: {STASH_VERSION}")
}
InternalStashError::Uninitialized => write!(f, "uninitialized"),
InternalStashError::StashNotWritable(e) => f.write_str(e),
InternalStashError::Other(e) => f.write_str(e),
}
}
}
impl Error for StashError {}
impl From<InternalStashError> for StashError {
fn from(inner: InternalStashError) -> StashError {
StashError { inner }
}
}
impl From<prost::DecodeError> for StashError {
fn from(e: prost::DecodeError) -> Self {
StashError {
inner: InternalStashError::Decoding(e),
}
}
}
impl From<TryFromProtoError> for StashError {
fn from(e: TryFromProtoError) -> Self {
StashError {
inner: InternalStashError::Proto(e),
}
}
}
impl From<String> for StashError {
fn from(e: String) -> StashError {
StashError {
inner: InternalStashError::Other(e),
}
}
}
impl From<&str> for StashError {
fn from(e: &str) -> StashError {
StashError {
inner: InternalStashError::Other(e.into()),
}
}
}
impl From<std::io::Error> for StashError {
fn from(e: std::io::Error) -> StashError {
StashError {
inner: InternalStashError::Other(e.to_string()),
}
}
}
impl From<anyhow::Error> for StashError {
fn from(e: anyhow::Error) -> Self {
StashError {
inner: InternalStashError::Other(e.to_string()),
}
}
}
/// An [`AppendBatch`] describes a set of changes to append to a stash collection.
#[derive(Clone, Debug)]
pub struct AppendBatch {
/// Id of stash collection.
pub(crate) collection_id: Id,
/// Current upper of the collection. The collection will also be compacted to `lower`.
pub(crate) lower: Antichain<Timestamp>,
/// The collection will be sealed to `upper`.
pub(crate) upper: Antichain<Timestamp>,
/// The timestamp of all entries in `entries`.
pub(crate) timestamp: Timestamp,
/// Entries to append to a collection. Each entry is of the form
/// ((key [in bytes], value [in bytes]), timestamp, diff).
pub(crate) entries: Vec<((Vec<u8>, Vec<u8>), Timestamp, Diff)>,
}
impl<K, V> StashCollection<K, V> {
/// Returns whether the collection is initialized, i.e. has been written to at least once.
/// Collections that haven't been written to at least once cannot be read.
pub async fn is_initialized(&self, tx: &Transaction<'_>) -> Result<bool, StashError> {
let upper = tx.upper(self.id).await?;
Ok(upper.elements() != [Timestamp::MIN])
}
/// Create a new AppendBatch for this collection from its current upper.
pub async fn make_batch_tx(&self, tx: &Transaction<'_>) -> Result<AppendBatch, StashError> {
let id = self.id;
let lower = tx.upper(id).await?;
self.make_batch_lower(lower)
}
/// Create a new AppendBatch for this collection from its current upper.
pub(crate) fn make_batch_lower(
&self,
lower: Antichain<Timestamp>,
) -> Result<AppendBatch, StashError> {
let timestamp: Timestamp = match lower.elements() {
[ts] => *ts,
_ => return Err("cannot determine batch timestamp".into()),
};
let upper = match timestamp.checked_add(1) {
Some(ts) => Antichain::from_elem(ts),
None => return Err("cannot determine new upper".into()),
};
Ok(AppendBatch {
collection_id: self.id,
lower,
upper,
timestamp,
entries: Vec::new(),
})
}
}
impl<K, V> StashCollection<K, V>
where
K: Data,
V: Data,
{
/// Append `key`, `value`, `diff` to `batch`.
pub fn append_to_batch(&self, batch: &mut AppendBatch, key: &K, value: &V, diff: Diff) {
let key = key.encode_to_vec();
let val = value.encode_to_vec();
batch.entries.push(((key, val), batch.timestamp, diff));
}
}
impl<K, V> From<Id> for StashCollection<K, V> {
fn from(id: Id) -> Self {
Self {
id,
_kv: PhantomData,
}
}
}
/// A helper struct to prevent mistyping of a [`StashCollection`]'s name and
/// k,v types.
pub struct TypedCollection<K, V> {
name: &'static str,
typ: PhantomData<(K, V)>,
}
impl<K, V> TypedCollection<K, V> {
/// Creates a new [`TypedCollection`] with `name`.
pub const fn new(name: &'static str) -> Self {
Self {
name,
typ: PhantomData,
}
}
/// Returns the name of this [`TypedCollection`].
pub const fn name(&self) -> &'static str {
self.name
}
}
impl<K, V> TypedCollection<K, V>
where
K: Data,
V: Data,
{
/// Returns a [`StashCollection`] corresponding to this [`TypedCollection`].
pub async fn from_tx(&self, tx: &Transaction<'_>) -> Result<StashCollection<K, V>, StashError> {
tx.collection(self.name).await
}
/// Returns all ((key, value), timestamp, diff) tuples in this [`TypedCollection`].
pub async fn iter(
&self,
stash: &mut Stash,
) -> Result<Vec<((K, V), Timestamp, Diff)>, StashError> {
let name = self.name;
stash
.with_transaction(move |tx| {
Box::pin(async move {
let collection = tx.collection::<K, V>(name).await?;
tx.iter(collection).await
})
})
.await
}
/// Returns all key, value pairs in this [`TypedCollection`].
pub async fn peek_one(&self, stash: &mut Stash) -> Result<BTreeMap<K, V>, StashError> {
let name = self.name;
stash
.with_transaction(move |tx| {
Box::pin(async move {
let collection = tx.collection::<K, V>(name).await?;
tx.peek_one(collection).await
})
})
.await
}
/// Returns the value of `key` in this [`TypedCollection`].
#[tracing::instrument(level = "trace", skip_all)]
pub async fn peek_key_one(&self, stash: &mut Stash, key: K) -> Result<Option<V>, StashError>
where
// TODO: Is it possible to remove the 'static?
K: 'static,
{
let name = self.name;
let key = Arc::new(key);
stash
.with_transaction(move |tx| {
Box::pin(async move {
let collection = tx.collection::<K, V>(name).await?;
tx.peek_key_one(collection, &key).await
})
})
.await
}
/// Sets the given k,v pair, if not already set.
///
/// Returns the new value stored in stash after this operations.
#[tracing::instrument(level = "debug", skip_all)]
pub async fn insert_key_without_overwrite(
&self,
stash: &mut Stash,
key: K,
value: V,
) -> Result<V, StashError>
where
// TODO: Is it possible to remove the 'statics?
K: 'static,
V: Clone + 'static,
{
let name = self.name;
let key = Arc::new(key);
let value = Arc::new(value);
stash
.with_transaction(move |tx| {
Box::pin(async move {
let collection = tx.collection::<K, V>(name).await?;
let lower = tx.upper(collection.id).await?;
let mut batch = collection.make_batch_lower(lower)?;
let prev = match tx.peek_key_one(collection, &key).await {
Ok(prev) => prev,
Err(err) => match err.inner {
InternalStashError::PeekSinceUpper(_) => {
// If the upper isn't > since, bump the upper and try again to find a sealed
// entry. Do this by appending the empty batch which will advance the upper.
tx.append(vec![batch]).await?;
let lower = tx.upper(collection.id).await?;
batch = collection.make_batch_lower(lower)?;
tx.peek_key_one(collection, &key).await?
}
_ => return Err(err),
},
};
match prev {
Some(prev) => Ok(prev),
None => {
collection.append_to_batch(&mut batch, &key, &value, 1);
tx.append(vec![batch]).await?;
Ok((*value).clone())
}
}
})
})
.await
}
/// Sets the given key value pairs, if not already set. If a new key appears
/// multiple times in `entries`, its value will be from the first occurrence
/// in `entries`.
#[tracing::instrument(level = "debug", skip_all)]
pub async fn insert_without_overwrite<I>(
&self,
stash: &mut Stash,
entries: I,
) -> Result<(), StashError>
where
I: IntoIterator<Item = (K, V)>,
// TODO: Figure out if it's possible to remove the 'static bounds.
K: Clone + 'static,
V: Clone + 'static,
{
let name = self.name;
let entries: Vec<_> = entries.into_iter().collect();
let entries = Arc::new(entries);
stash
.with_transaction(move |tx| {
Box::pin(async move {
let collection = tx.collection::<K, V>(name).await?;
let lower = tx.upper(collection.id).await?;
let mut batch = collection.make_batch_lower(lower)?;
let mut prev = match tx.peek_one(collection).await {
Ok(prev) => prev,
Err(err) => match err.inner {
InternalStashError::PeekSinceUpper(_) => {
// If the upper isn't > since, bump the upper and try again to find a sealed
// entry. Do this by appending the empty batch which will advance the upper.
tx.append(vec![batch]).await?;
let lower = tx.upper(collection.id).await?;
batch = collection.make_batch_lower(lower)?;
tx.peek_one(collection).await?
}
_ => return Err(err),
},
};
for (k, v) in entries.iter() {
if !prev.contains_key(k) {
collection.append_to_batch(&mut batch, k, v, 1);
prev.insert(k.clone(), v.clone());
}
}
tx.append(vec![batch]).await?;
Ok(())
})
})
.await
}
/// Sets a value for a key to the result of `f`. `f` is passed the
/// previous value, if any.
///
/// Returns the previous value if one existed and the value returned from
/// `f`.
#[tracing::instrument(level = "debug", skip_all)]
pub async fn upsert_key<F, R>(
&self,
stash: &mut Stash,
key: K,
f: F,
) -> Result<Result<(Option<V>, V), R>, StashError>
where
F: FnOnce(Option<&V>) -> Result<V, R> + Clone + Send + Sync + 'static,
K: 'static,
{
let name = self.name;
let key = Arc::new(key);
stash
.with_transaction(move |tx| {
Box::pin(async move {
let collection = tx.collection::<K, V>(name).await?;
let lower = tx.upper(collection.id).await?;
let mut batch = collection.make_batch_lower(lower)?;
let prev = match tx.peek_key_one(collection, &key).await {
Ok(prev) => prev,
Err(err) => match err.inner {
InternalStashError::PeekSinceUpper(_) => {
// If the upper isn't > since, bump the upper and try again to find a sealed
// entry. Do this by appending the empty batch which will advance the upper.
tx.append(vec![batch]).await?;
let lower = tx.upper(collection.id).await?;
batch = collection.make_batch_lower(lower)?;
tx.peek_key_one(collection, &key).await?
}
_ => return Err(err),
},
};
let next = match f(prev.as_ref()) {
Ok(v) => v,
Err(e) => return Ok(Err(e)),
};
// Do nothing if the values are the same.
if Some(&next) != prev.as_ref() {
if let Some(prev) = &prev {
collection.append_to_batch(&mut batch, &key, prev, -1);
}
collection.append_to_batch(&mut batch, &key, &next, 1);
tx.append(vec![batch]).await?;
}
Ok(Ok((prev, next)))
})
})
.await
}
/// Sets the given key value pairs, removing existing entries match any key.
#[tracing::instrument(level = "debug", skip_all)]
pub async fn upsert<I>(&self, stash: &mut Stash, entries: I) -> Result<(), StashError>
where
I: IntoIterator<Item = (K, V)>,
K: 'static,
V: 'static,
{
let name = self.name;
let entries: Vec<_> = entries.into_iter().collect();
let entries = Arc::new(entries);
stash
.with_transaction(move |tx| {
Box::pin(async move {
let collection = tx.collection::<K, V>(name).await?;
let lower = tx.upper(collection.id).await?;
let mut batch = collection.make_batch_lower(lower)?;
let prev = match tx.peek_one(collection).await {
Ok(prev) => prev,
Err(err) => match err.inner {
InternalStashError::PeekSinceUpper(_) => {
// If the upper isn't > since, bump the upper and try again to find a sealed
// entry. Do this by appending the empty batch which will advance the upper.
tx.append(vec![batch]).await?;
let lower = tx.upper(collection.id).await?;
batch = collection.make_batch_lower(lower)?;
tx.peek_one(collection).await?
}
_ => return Err(err),
},
};
for (k, v) in entries.iter() {
if let Some(prev_v) = prev.get(k) {
collection.append_to_batch(&mut batch, k, prev_v, -1);
}
collection.append_to_batch(&mut batch, k, v, 1);
}
tx.append(vec![batch]).await?;
Ok(())
})
})
.await
}
/// Transactionally deletes any kv pair from `self` whose key is in `keys`.
///
/// Note that:
/// - Unlike `delete`, this operation operates in time O(keys), and not
/// O(set), however does so by parallelizing a number of point queries so
/// is likely not performant for more than 10-or-so keys.
/// - This operation runs in a single transaction and cannot be combined
/// with other transactions.
#[tracing::instrument(level = "debug", skip_all)]
pub async fn delete_keys(&self, stash: &mut Stash, keys: BTreeSet<K>) -> Result<(), StashError>
where
K: Clone + 'static,
V: Clone,
{
use futures::StreamExt;
let name = self.name.to_string();
stash
.with_transaction(move |tx| {
Box::pin(async move {
let collection = tx.collection::<K, V>(&name).await?;
let lower = tx.upper(collection.id).await?;
let mut batch = collection.make_batch_lower(lower)?;
let tx = &tx;
let kv_results: Vec<(K, Result<Option<V>, StashError>)> =
futures::stream::iter(keys.into_iter())
.map(|key| async move {
(key.clone(), tx.peek_key_one(collection.clone(), &key).await)
})
.buffer_unordered(10)
.collect()
.await;
for (key, val) in kv_results {
if let Some(v) = val? {
collection.append_to_batch(&mut batch, &key, &v, -1);
}
}
tx.append(vec![batch]).await?;
Ok(())
})
})
.await
}
}
/// TableTransaction emulates some features of a typical SQL transaction over
/// table for a [`StashCollection`].
///
/// It supports:
/// - uniqueness constraints
/// - transactional reads and writes (including read-your-writes before commit)
///
/// `K` is the primary key type. Multiple entries with the same key are disallowed.
/// `V` is the an arbitrary value type.
///
/// To finalize, add the results of [`TableTransaction::pending()`] to an
/// [`AppendBatch`].
pub struct TableTransaction<K, V> {
initial: BTreeMap<K, V>,
// The desired state of keys after commit. `None` means the value will be
// deleted.
pending: BTreeMap<K, Option<V>>,
uniqueness_violation: fn(a: &V, b: &V) -> bool,
}
impl<K, V> TableTransaction<K, V>
where
K: Ord + Eq + Clone,
V: Ord + Clone,
{
/// Create a new TableTransaction with initial data. `uniqueness_violation` is a function
/// whether there is a uniqueness violation among two values.
///
/// Internally the [`Stash`] serializes data as protobuf. All fields in a proto message are
/// optional, which makes using them in Rust cumbersome. Generic parameters `KP` and `VP` are
/// protobuf types which deserialize to `K` and `V` that a [`TableTransaction`] is generic
/// over.
pub fn new<KP, VP>(
initial: BTreeMap<KP, VP>,
uniqueness_violation: fn(a: &V, b: &V) -> bool,
) -> Result<Self, TryFromProtoError>
where
K: RustType<KP>,
V: RustType<VP>,
{
let initial = initial
.into_iter()
.map(RustType::from_proto)
.collect::<Result<_, _>>()?;
Ok(Self {
initial,
pending: BTreeMap::new(),
uniqueness_violation,
})
}
/// Consumes and returns the pending changes and their diffs. `Diff` is
/// guaranteed to be 1 or -1.
pub fn pending<KP, VP>(self) -> Vec<(KP, VP, Diff)>
where
K: RustType<KP>,
V: RustType<VP>,
{
soft_assert!(self.verify().is_ok());
// Pending describes the desired final state for some keys. K,V pairs should be
// retracted if they already exist and were deleted or are being updated.
self.pending
.into_iter()
.map(|(k, v)| match self.initial.get(&k) {
Some(initial_v) => {
let mut diffs = vec![(k.clone(), initial_v.clone(), -1)];
if let Some(v) = v {
diffs.push((k, v, 1));
}
diffs
}
None => {
if let Some(v) = v {
vec![(k, v, 1)]
} else {
vec![]
}
}
})
.flatten()
.map(|(key, val, diff)| (key.into_proto(), val.into_proto(), diff))
.collect()
}
fn verify(&self) -> Result<(), StashError> {
// Compare each value to each other value and ensure they are unique.
let items = self.items();
for (i, vi) in items.values().enumerate() {
for (j, vj) in items.values().enumerate() {
if i != j && (self.uniqueness_violation)(vi, vj) {
return Err("uniqueness violation".into());
}
}
}
Ok(())
}
/// Iterates over the items viewable in the current transaction in arbitrary
/// order and applies `f` on all key, value pairs.
pub fn for_values<F: FnMut(&K, &V)>(&self, mut f: F) {
let mut seen = BTreeSet::new();
for (k, v) in self.pending.iter() {
seen.insert(k);
// Deleted items don't exist so shouldn't be visited, but still suppress
// visiting the key later.
if let Some(v) = v {
f(k, v);
}
}
for (k, v) in self.initial.iter() {
// Add on initial items that don't have updates.
if !seen.contains(k) {
f(k, v);
}
}
}
/// Returns the current value of `k`.
pub fn get(&self, k: &K) -> Option<&V> {
if let Some(v) = self.pending.get(k) {
v.as_ref()
} else if let Some(v) = self.initial.get(k) {
Some(v)
} else {
None
}
}
/// Returns the items viewable in the current transaction.
pub fn items(&self) -> BTreeMap<K, V> {
let mut items = BTreeMap::new();
self.for_values(|k, v| {
items.insert(k.clone(), v.clone());
});
items
}
/// Iterates over the items viewable in the current transaction, and provides a
/// map where additional pending items can be inserted, which will be appended
/// to current pending items. Does not verify uniqueness.
fn for_values_mut<F: FnMut(&mut BTreeMap<K, Option<V>>, &K, &V)>(&mut self, mut f: F) {
let mut pending = BTreeMap::new();
self.for_values(|k, v| f(&mut pending, k, v));
self.pending.extend(pending);
}
/// Inserts a new k,v pair.
///
/// Returns an error if the uniqueness check failed or the key already exists.
pub fn insert(&mut self, k: K, v: V) -> Result<(), StashError> {
let mut violation = None;
self.for_values(|for_k, for_v| {
if &k == for_k {
violation = Some("duplicate key".to_string());
}
if (self.uniqueness_violation)(for_v, &v) {
violation = Some("uniqueness violation".to_string());
}
});
if let Some(violation) = violation {
return Err(violation.into());
}
self.pending.insert(k, Some(v));
soft_assert!(self.verify().is_ok());
Ok(())
}
/// Updates k, v pairs. `f` is a function that can return `Some(V)` if the
/// value should be updated, otherwise `None`. Returns the number of changed
/// entries.
///
/// Returns an error if the uniqueness check failed.
pub fn update<F: Fn(&K, &V) -> Option<V>>(&mut self, f: F) -> Result<Diff, StashError> {
let mut changed = 0;
// Keep a copy of pending in case of uniqueness violation.
let pending = self.pending.clone();
self.for_values_mut(|p, k, v| {
if let Some(next) = f(k, v) {
changed += 1;
p.insert(k.clone(), Some(next));
}
});
// Check for uniqueness violation.
if let Err(err) = self.verify() {
self.pending = pending;
Err(err)
} else {
Ok(changed)
}
}
/// Set the value for a key. Returns the previous entry if the key existed,
/// otherwise None.
///
/// Returns an error if the uniqueness check failed.
pub fn set(&mut self, k: K, v: Option<V>) -> Result<Option<V>, StashError> {
// Save the pending value for the key so we can restore it in case of
// uniqueness violation.
let restore = self.pending.get(&k).cloned();
let prev = match self.pending.entry(k.clone()) {
// key hasn't been set in this txn yet. Set it and return the
// initial txn's value of k.
Entry::Vacant(e) => {
e.insert(v);
self.initial.get(&k).cloned()
}
// key has been set in this txn. Set it and return the previous
// pending value.
Entry::Occupied(mut e) => e.insert(v),
};
// Check for uniqueness violation.
if let Err(err) = self.verify() {
// Revert self.pending to the state it was in before calling this
// function.
match restore {
Some(v) => {
self.pending.insert(k, v);
}
None => {
self.pending.remove(&k);
}
}
Err(err)
} else {
Ok(prev)
}
}
/// Deletes items for which `f` returns true. Returns the keys and values of
/// the deleted entries.
pub fn delete<F: Fn(&K, &V) -> bool>(&mut self, f: F) -> Vec<(K, V)> {
let mut deleted = Vec::new();
self.for_values_mut(|p, k, v| {
if f(k, v) {
deleted.push((k.clone(), v.clone()));
p.insert(k.clone(), None);
}
});
soft_assert!(self.verify().is_ok());
deleted
}
}