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 and downloaded media 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;
27pub mod media;
28mod memory_store;
29mod traits;
30
31use matrix_sdk_common::store_locks::{
32    BackingStore, CrossProcessStoreLock, CrossProcessStoreLockGuard, LockStoreError,
33};
34pub use matrix_sdk_store_encryption::Error as StoreEncryptionError;
35use ruma::{
36    OwnedEventId,
37    events::{AnySyncTimelineEvent, relation::RelationType},
38    serde::Raw,
39};
40use tracing::trace;
41
42#[cfg(any(test, feature = "testing"))]
43pub use self::integration_tests::EventCacheStoreIntegrationTests;
44pub use self::{
45    memory_store::MemoryStore,
46    traits::{DEFAULT_CHUNK_CAPACITY, DynEventCacheStore, EventCacheStore, IntoEventCacheStore},
47};
48
49/// The high-level public type to represent an `EventCacheStore` lock.
50#[derive(Clone)]
51pub struct EventCacheStoreLock {
52    /// The inner cross process lock that is used to lock the `EventCacheStore`.
53    cross_process_lock: Arc<CrossProcessStoreLock<LockableEventCacheStore>>,
54
55    /// The store itself.
56    ///
57    /// That's the only place where the store exists.
58    store: Arc<DynEventCacheStore>,
59}
60
61#[cfg(not(tarpaulin_include))]
62impl fmt::Debug for EventCacheStoreLock {
63    fn fmt(&self, formatter: &mut fmt::Formatter<'_>) -> fmt::Result {
64        formatter.debug_struct("EventCacheStoreLock").finish_non_exhaustive()
65    }
66}
67
68impl EventCacheStoreLock {
69    /// Create a new lock around the [`EventCacheStore`].
70    ///
71    /// The `holder` argument represents the holder inside the
72    /// [`CrossProcessStoreLock::new`].
73    pub fn new<S>(store: S, holder: String) -> Self
74    where
75        S: IntoEventCacheStore,
76    {
77        let store = store.into_event_cache_store();
78
79        Self {
80            cross_process_lock: Arc::new(CrossProcessStoreLock::new(
81                LockableEventCacheStore(store.clone()),
82                "default".to_owned(),
83                holder,
84            )),
85            store,
86        }
87    }
88
89    /// Acquire a spin lock (see [`CrossProcessStoreLock::spin_lock`]).
90    pub async fn lock(&self) -> Result<EventCacheStoreLockGuard<'_>, LockStoreError> {
91        let cross_process_lock_guard = self.cross_process_lock.spin_lock(None).await?;
92
93        Ok(EventCacheStoreLockGuard { cross_process_lock_guard, store: self.store.deref() })
94    }
95}
96
97/// An RAII implementation of a “scoped lock” of an [`EventCacheStoreLock`].
98/// When this structure is dropped (falls out of scope), the lock will be
99/// unlocked.
100pub struct EventCacheStoreLockGuard<'a> {
101    /// The cross process lock guard.
102    #[allow(unused)]
103    cross_process_lock_guard: CrossProcessStoreLockGuard,
104
105    /// A reference to the store.
106    store: &'a DynEventCacheStore,
107}
108
109#[cfg(not(tarpaulin_include))]
110impl fmt::Debug for EventCacheStoreLockGuard<'_> {
111    fn fmt(&self, formatter: &mut fmt::Formatter<'_>) -> fmt::Result {
112        formatter.debug_struct("EventCacheStoreLockGuard").finish_non_exhaustive()
113    }
114}
115
116impl Deref for EventCacheStoreLockGuard<'_> {
117    type Target = DynEventCacheStore;
118
119    fn deref(&self) -> &Self::Target {
120        self.store
121    }
122}
123
124/// Event cache store specific error type.
125#[derive(Debug, thiserror::Error)]
126pub enum EventCacheStoreError {
127    /// An error happened in the underlying database backend.
128    #[error(transparent)]
129    Backend(Box<dyn std::error::Error + Send + Sync>),
130
131    /// The store is locked with a passphrase and an incorrect passphrase
132    /// was given.
133    #[error("The event cache store failed to be unlocked")]
134    Locked,
135
136    /// An unencrypted store was tried to be unlocked with a passphrase.
137    #[error("The event cache store is not encrypted but tried to be opened with a passphrase")]
138    Unencrypted,
139
140    /// The store failed to encrypt or decrypt some data.
141    #[error("Error encrypting or decrypting data from the event cache store: {0}")]
142    Encryption(#[from] StoreEncryptionError),
143
144    /// The store failed to encode or decode some data.
145    #[error("Error encoding or decoding data from the event cache store: {0}")]
146    Codec(#[from] Utf8Error),
147
148    /// The store failed to serialize or deserialize some data.
149    #[error("Error serializing or deserializing data from the event cache store: {0}")]
150    Serialization(#[from] serde_json::Error),
151
152    /// The database format has changed in a backwards incompatible way.
153    #[error(
154        "The database format of the event cache store changed in an incompatible way, \
155         current version: {0}, latest version: {1}"
156    )]
157    UnsupportedDatabaseVersion(usize, usize),
158
159    /// The store contains invalid data.
160    #[error("The store contains invalid data: {details}")]
161    InvalidData {
162        /// Details why the data contained in the store was invalid.
163        details: String,
164    },
165}
166
167impl EventCacheStoreError {
168    /// Create a new [`Backend`][Self::Backend] error.
169    ///
170    /// Shorthand for `EventCacheStoreError::Backend(Box::new(error))`.
171    #[inline]
172    pub fn backend<E>(error: E) -> Self
173    where
174        E: std::error::Error + Send + Sync + 'static,
175    {
176        Self::Backend(Box::new(error))
177    }
178}
179
180/// An `EventCacheStore` specific result type.
181pub type Result<T, E = EventCacheStoreError> = std::result::Result<T, E>;
182
183/// A type that wraps the [`EventCacheStore`] but implements [`BackingStore`] to
184/// make it usable inside the cross process lock.
185#[derive(Clone, Debug)]
186struct LockableEventCacheStore(Arc<DynEventCacheStore>);
187
188impl BackingStore for LockableEventCacheStore {
189    type LockError = EventCacheStoreError;
190
191    async fn try_lock(
192        &self,
193        lease_duration_ms: u32,
194        key: &str,
195        holder: &str,
196    ) -> std::result::Result<bool, Self::LockError> {
197        self.0.try_take_leased_lock(lease_duration_ms, key, holder).await
198    }
199}
200
201/// Helper to extract the relation information from an event.
202///
203/// If the event isn't in relation to another event, then this will return
204/// `None`. Otherwise, returns both the event id this event relates to, and the
205/// kind of relation as a string (e.g. `m.replace`).
206pub fn extract_event_relation(event: &Raw<AnySyncTimelineEvent>) -> Option<(OwnedEventId, String)> {
207    #[derive(serde::Deserialize)]
208    struct RelatesTo {
209        event_id: OwnedEventId,
210        rel_type: String,
211    }
212
213    #[derive(serde::Deserialize)]
214    struct EventContent {
215        #[serde(rename = "m.relates_to")]
216        rel: Option<RelatesTo>,
217    }
218
219    match event.get_field::<EventContent>("content") {
220        Ok(event_content) => {
221            event_content.and_then(|c| c.rel).map(|rel| (rel.event_id, rel.rel_type))
222        }
223        Err(err) => {
224            trace!("when extracting relation data from an event: {err}");
225            None
226        }
227    }
228}
229
230/// Compute the list of string filters to be applied when looking for an event's
231/// relations.
232// TODO: get Ruma fix from https://github.com/ruma/ruma/pull/2052, and get rid of this function
233// then.
234pub fn compute_filters_string(filters: Option<&[RelationType]>) -> Option<Vec<String>> {
235    filters.map(|filter| {
236        filter
237            .iter()
238            .map(|f| {
239                if *f == RelationType::Replacement { "m.replace".to_owned() } else { f.to_string() }
240            })
241            .collect()
242    })
243}
matrix_sdk_base/event_cache/store/mod.rs

matrix_sdk_base/event_cache/store/
mod.rs
