matrix_sdk_base/event_cache/store/
mod.rs

1// Copyright 2024 The Matrix.org Foundation C.I.C.
2//
3// Licensed under the Apache License, Version 2.0 (the "License");
4// you may not use this file except in compliance with the License.
5// You may obtain a copy of the License at
6//
7//     http://www.apache.org/licenses/LICENSE-2.0
8//
9// Unless required by applicable law or agreed to in writing, software
10// distributed under the License is distributed on an "AS IS" BASIS,
11// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
12// See the License for the specific language governing permissions and
13// limitations under the License.
14
15//! The event cache stores holds events when the cache was
16//! activated to save bandwidth at the cost of increased storage space usage.
17//!
18//! Implementing the `EventCacheStore` trait, you can plug any storage backend
19//! into the event cache for the actual storage. By default this brings an
20//! in-memory store.
21
22use std::{fmt, ops::Deref, str::Utf8Error, sync::Arc};
23
24#[cfg(any(test, feature = "testing"))]
25#[macro_use]
26pub mod integration_tests;
27mod memory_store;
28mod traits;
29
30use matrix_sdk_common::cross_process_lock::{
31    CrossProcessLock, CrossProcessLockError, CrossProcessLockGuard, TryLock,
32};
33pub use matrix_sdk_store_encryption::Error as StoreEncryptionError;
34use ruma::{OwnedEventId, events::AnySyncTimelineEvent, serde::Raw};
35use tracing::trace;
36
37#[cfg(any(test, feature = "testing"))]
38pub use self::integration_tests::EventCacheStoreIntegrationTests;
39pub use self::{
40    memory_store::MemoryStore,
41    traits::{DEFAULT_CHUNK_CAPACITY, DynEventCacheStore, EventCacheStore, IntoEventCacheStore},
42};
43
44/// The high-level public type to represent an `EventCacheStore` lock.
45#[derive(Clone)]
46pub struct EventCacheStoreLock {
47    /// The inner cross process lock that is used to lock the `EventCacheStore`.
48    cross_process_lock: Arc<CrossProcessLock<LockableEventCacheStore>>,
49
50    /// The store itself.
51    ///
52    /// That's the only place where the store exists.
53    store: Arc<DynEventCacheStore>,
54}
55
56#[cfg(not(tarpaulin_include))]
57impl fmt::Debug for EventCacheStoreLock {
58    fn fmt(&self, formatter: &mut fmt::Formatter<'_>) -> fmt::Result {
59        formatter.debug_struct("EventCacheStoreLock").finish_non_exhaustive()
60    }
61}
62
63impl EventCacheStoreLock {
64    /// Create a new lock around the [`EventCacheStore`].
65    ///
66    /// The `holder` argument represents the holder inside the
67    /// [`CrossProcessLock::new`].
68    pub fn new<S>(store: S, holder: String) -> Self
69    where
70        S: IntoEventCacheStore,
71    {
72        let store = store.into_event_cache_store();
73
74        Self {
75            cross_process_lock: Arc::new(CrossProcessLock::new(
76                LockableEventCacheStore(store.clone()),
77                "default".to_owned(),
78                holder,
79            )),
80            store,
81        }
82    }
83
84    /// Acquire a spin lock (see [`CrossProcessLock::spin_lock`]).
85    pub async fn lock(&self) -> Result<EventCacheStoreLockGuard<'_>, CrossProcessLockError> {
86        let cross_process_lock_guard = self.cross_process_lock.spin_lock(None).await?;
87
88        Ok(EventCacheStoreLockGuard { cross_process_lock_guard, store: self.store.deref() })
89    }
90}
91
92/// An RAII implementation of a “scoped lock” of an [`EventCacheStoreLock`].
93/// When this structure is dropped (falls out of scope), the lock will be
94/// unlocked.
95pub struct EventCacheStoreLockGuard<'a> {
96    /// The cross process lock guard.
97    #[allow(unused)]
98    cross_process_lock_guard: CrossProcessLockGuard,
99
100    /// A reference to the store.
101    store: &'a DynEventCacheStore,
102}
103
104#[cfg(not(tarpaulin_include))]
105impl fmt::Debug for EventCacheStoreLockGuard<'_> {
106    fn fmt(&self, formatter: &mut fmt::Formatter<'_>) -> fmt::Result {
107        formatter.debug_struct("EventCacheStoreLockGuard").finish_non_exhaustive()
108    }
109}
110
111impl Deref for EventCacheStoreLockGuard<'_> {
112    type Target = DynEventCacheStore;
113
114    fn deref(&self) -> &Self::Target {
115        self.store
116    }
117}
118
119/// Event cache store specific error type.
120#[derive(Debug, thiserror::Error)]
121pub enum EventCacheStoreError {
122    /// An error happened in the underlying database backend.
123    #[error(transparent)]
124    Backend(Box<dyn std::error::Error + Send + Sync>),
125
126    /// The store is locked with a passphrase and an incorrect passphrase
127    /// was given.
128    #[error("The event cache store failed to be unlocked")]
129    Locked,
130
131    /// An unencrypted store was tried to be unlocked with a passphrase.
132    #[error("The event cache store is not encrypted but tried to be opened with a passphrase")]
133    Unencrypted,
134
135    /// The store failed to encrypt or decrypt some data.
136    #[error("Error encrypting or decrypting data from the event cache store: {0}")]
137    Encryption(#[from] StoreEncryptionError),
138
139    /// The store failed to encode or decode some data.
140    #[error("Error encoding or decoding data from the event cache store: {0}")]
141    Codec(#[from] Utf8Error),
142
143    /// The store failed to serialize or deserialize some data.
144    #[error("Error serializing or deserializing data from the event cache store: {0}")]
145    Serialization(#[from] serde_json::Error),
146
147    /// The database format has changed in a backwards incompatible way.
148    #[error(
149        "The database format of the event cache store changed in an incompatible way, \
150         current version: {0}, latest version: {1}"
151    )]
152    UnsupportedDatabaseVersion(usize, usize),
153
154    /// The store contains invalid data.
155    #[error("The store contains invalid data: {details}")]
156    InvalidData {
157        /// Details why the data contained in the store was invalid.
158        details: String,
159    },
160}
161
162impl EventCacheStoreError {
163    /// Create a new [`Backend`][Self::Backend] error.
164    ///
165    /// Shorthand for `EventCacheStoreError::Backend(Box::new(error))`.
166    #[inline]
167    pub fn backend<E>(error: E) -> Self
168    where
169        E: std::error::Error + Send + Sync + 'static,
170    {
171        Self::Backend(Box::new(error))
172    }
173}
174
175/// An `EventCacheStore` specific result type.
176pub type Result<T, E = EventCacheStoreError> = std::result::Result<T, E>;
177
178/// A type that wraps the [`EventCacheStore`] but implements [`TryLock`] to
179/// make it usable inside the cross process lock.
180#[derive(Clone, Debug)]
181struct LockableEventCacheStore(Arc<DynEventCacheStore>);
182
183impl TryLock for LockableEventCacheStore {
184    type LockError = EventCacheStoreError;
185
186    async fn try_lock(
187        &self,
188        lease_duration_ms: u32,
189        key: &str,
190        holder: &str,
191    ) -> std::result::Result<bool, Self::LockError> {
192        self.0.try_take_leased_lock(lease_duration_ms, key, holder).await
193    }
194}
195
196/// Helper to extract the relation information from an event.
197///
198/// If the event isn't in relation to another event, then this will return
199/// `None`. Otherwise, returns both the event id this event relates to, and the
200/// kind of relation as a string (e.g. `m.replace`).
201pub fn extract_event_relation(event: &Raw<AnySyncTimelineEvent>) -> Option<(OwnedEventId, String)> {
202    #[derive(serde::Deserialize)]
203    struct RelatesTo {
204        event_id: OwnedEventId,
205        rel_type: String,
206    }
207
208    #[derive(serde::Deserialize)]
209    struct EventContent {
210        #[serde(rename = "m.relates_to")]
211        rel: Option<RelatesTo>,
212    }
213
214    match event.get_field::<EventContent>("content") {
215        Ok(event_content) => {
216            event_content.and_then(|c| c.rel).map(|rel| (rel.event_id, rel.rel_type))
217        }
218        Err(err) => {
219            trace!("when extracting relation data from an event: {err}");
220            None
221        }
222    }
223}
matrix_sdk_base/event_cache/store/mod.rs

matrix_sdk_base/event_cache/store/
mod.rs
