kitchen-freezer/src/provider.rs
2021-04-20 00:22:09 +02:00

314 lines
13 KiB
Rust

//! This modules abstracts data sources and merges them in a single virtual one
use std::error::Error;
use std::collections::HashSet;
use std::marker::PhantomData;
use std::sync::{Arc, Mutex};
use crate::traits::{CalDavSource, DavCalendar};
use crate::traits::CompleteCalendar;
use crate::item::SyncStatus;
use crate::calendar::SupportedComponents;
/// A data source that combines two `CalDavSource`s (usually a server and a local cache), which is able to sync both sources.
/// This can be used for integration tests, where the remote source is mocked by a `Cache`.
pub struct Provider<L, T, R, U>
where
L: CalDavSource<T>,
T: CompleteCalendar + Sync + Send,
R: CalDavSource<U>,
U: DavCalendar + Sync + Send,
{
/// The remote source (usually a server)
remote: R,
/// The local cache
local: L,
phantom_t: PhantomData<T>,
phantom_u: PhantomData<U>,
}
impl<L, T, R, U> Provider<L, T, R, U>
where
L: CalDavSource<T>,
T: CompleteCalendar + Sync + Send,
R: CalDavSource<U>,
U: DavCalendar + Sync + Send,
{
/// Create a provider.
///
/// `remote` is usually a [`Client`](crate::client::Client), `local` is usually a [`Cache`](crate::cache::Cache).
/// However, both can be interchangeable. The only difference is that `remote` always wins in case of a sync conflict
pub fn new(remote: R, local: L) -> Self {
Self { remote, local,
phantom_t: PhantomData, phantom_u: PhantomData,
}
}
/// Returns the data source described as the `remote`
pub fn remote(&self) -> &R { &self.remote }
/// Returns the data source described as the `local`
pub fn local(&self) -> &L { &self.local }
/// Performs a synchronisation between `local` and `remote`.
///
/// This bidirectional sync applies additions/deletions made on a source to the other source.
/// In case of conflicts (the same item has been modified on both ends since the last sync, `remote` always wins)
pub async fn sync(&mut self) -> Result<(), Box<dyn Error>> {
log::info!("Starting a sync.");
let cals_remote = self.remote.get_calendars().await?;
for (cal_id, cal_remote) in cals_remote {
let cal_local = loop {
if let Some(cal) = self.local.get_calendar(&cal_id).await {
break cal;
}
// This calendar does not exist locally yet, let's add it
log::error!("TODO: what name/SP should we choose?");
let new_calendar = T::new(String::from("new calendar"), cal_id.clone(), SupportedComponents::TODO);
if let Err(err) = self.local.insert_calendar(new_calendar).await {
log::warn!("Unable to create local calendar {}: {}. Skipping it.", cal_id, err);
continue;
}
};
if let Err(err) = Self::sync_calendar_pair(cal_local, cal_remote).await {
log::warn!("Unable to sync calendar {}: {}, skipping this time.", cal_id, err);
}
}
Ok(())
}
async fn sync_calendar_pair(cal_local: Arc<Mutex<T>>, cal_remote: Arc<Mutex<U>>) -> Result<(), Box<dyn Error>> {
let mut cal_remote = cal_remote.lock().unwrap();
let mut cal_local = cal_local.lock().unwrap();
// Step 1 - find the differences
log::debug!("Finding the differences to sync...");
let mut local_del = HashSet::new();
let mut remote_del = HashSet::new();
let mut local_changes = HashSet::new();
let mut remote_changes = HashSet::new();
let mut local_additions = HashSet::new();
let mut remote_additions = HashSet::new();
let remote_items = cal_remote.get_item_version_tags().await?;
let mut local_items_to_handle = cal_local.get_item_ids().await?;
for (id, remote_tag) in remote_items {
log::trace!("***** Considering remote item {}...", id);
match cal_local.get_item_by_id_ref(&id).await {
None => {
// This was created on the remote
log::debug!("* {} is a remote addition", id);
remote_additions.insert(id);
},
Some(local_item) => {
if local_items_to_handle.remove(&id) == false {
log::error!("Inconsistent state: missing task {} from the local tasks", id);
}
match local_item.sync_status() {
SyncStatus::NotSynced => {
log::error!("ID reuse between remote and local sources ({}). Ignoring this item in the sync", id);
continue;
},
SyncStatus::Synced(local_tag) => {
if &remote_tag != local_tag {
// This has been modified on the remote
log::debug!("* {} is a remote change", id);
remote_changes.insert(id);
}
},
SyncStatus::LocallyModified(local_tag) => {
if &remote_tag == local_tag {
// This has been changed locally
log::debug!("* {} is a local change", id);
local_changes.insert(id);
} else {
log::info!("Conflict: task {} has been modified in both sources. Using the remote version.", id);
log::debug!("* {} is considered a remote change", id);
remote_changes.insert(id);
}
},
SyncStatus::LocallyDeleted(local_tag) => {
if &remote_tag == local_tag {
// This has been locally deleted
log::debug!("* {} is a local deletion", id);
local_del.insert(id);
} else {
log::info!("Conflict: task {} has been locally deleted and remotely modified. Reverting to the remote version.", id);
log::debug!("* {} is a considered a remote change", id);
remote_changes.insert(id);
}
},
}
}
}
}
// Also iterate on the local tasks that are not on the remote
for id in local_items_to_handle {
log::trace!("##### Considering local item {}...", id);
let local_item = match cal_local.get_item_by_id_ref(&id).await {
None => {
log::error!("Inconsistent state: missing task {} from the local tasks", id);
continue;
},
Some(item) => item,
};
match local_item.sync_status() {
SyncStatus::Synced(_) => {
// This item has been removed from the remote
log::debug!("# {} is a deletion from the server", id);
remote_del.insert(id);
},
SyncStatus::NotSynced => {
// This item has just been locally created
log::debug!("# {} has been locally created", id);
local_additions.insert(id);
},
SyncStatus::LocallyDeleted(_) => {
// This item has been deleted from both sources
log::debug!("# {} has been deleted from both sources", id);
remote_del.insert(id);
},
SyncStatus::LocallyModified(_) => {
log::info!("Conflict: item {} has been deleted from the server and locally modified. Deleting the local copy", id);
remote_del.insert(id);
},
}
}
// Step 2 - commit changes
log::trace!("Committing changes...");
for id_del in local_del {
log::debug!("> Pushing local deletion {} to the server", id_del);
match cal_remote.delete_item(&id_del).await {
Err(err) => {
log::warn!("Unable to delete remote item {}: {}", id_del, err);
},
Ok(()) => {
// Change the local copy from "marked to deletion" to "actually deleted"
if let Err(err) = cal_local.immediately_delete_item(&id_del).await {
log::error!("Unable to permanently delete local item {}: {}", id_del, err);
}
},
}
}
for id_del in remote_del {
log::debug!("> Applying remote deletion {} locally", id_del);
if let Err(err) = cal_local.immediately_delete_item(&id_del).await {
log::warn!("Unable to delete local item {}: {}", id_del, err);
}
}
for id_add in remote_additions {
log::debug!("> Applying remote addition {} locally", id_add);
match cal_remote.get_item_by_id(&id_add).await {
Err(err) => {
log::warn!("Unable to get remote item {}: {}. Skipping it.", id_add, err);
continue;
},
Ok(item) => match item {
None => {
log::error!("Inconsistency: new item {} has vanished from the remote end", id_add);
continue;
},
Some(new_item) => {
if let Err(err) = cal_local.add_item(new_item.clone()).await {
log::error!("Not able to add item {} to local calendar: {}", id_add, err);
}
},
},
}
}
for id_change in remote_changes {
log::debug!("> Applying remote change {} locally", id_change);
match cal_remote.get_item_by_id(&id_change).await {
Err(err) => {
log::warn!("Unable to get remote item {}: {}. Skipping it", id_change, err);
continue;
},
Ok(item) => match item {
None => {
log::error!("Inconsistency: modified item {} has vanished from the remote end", id_change);
continue;
},
Some(item) => {
//
//
//
//
// TODO: implement update_item (maybe only create_item also updates it?)
//
if let Err(err) = cal_local.immediately_delete_item(&id_change).await {
log::error!("Unable to delete item {} from local calendar: {}", id_change, err);
}
if let Err(err) = cal_local.add_item(item.clone()).await {
log::error!("Unable to add item {} to local calendar: {}", id_change, err);
}
},
}
}
}
for id_add in local_additions {
log::debug!("> Pushing local addition {} to the server", id_add);
match cal_local.get_item_by_id_mut(&id_add).await {
None => {
log::error!("Inconsistency: created item {} has been marked for upload but is locally missing", id_add);
continue;
},
Some(item) => {
match cal_remote.add_item(item.clone()).await {
Err(err) => log::error!("Unable to add item {} to remote calendar: {}", id_add, err),
Ok(new_ss) => {
// Update local sync status
item.set_sync_status(new_ss);
},
}
},
};
}
for id_change in local_changes {
log::debug!("> Pushing local change {} to the server", id_change);
match cal_local.get_item_by_id_mut(&id_change).await {
None => {
log::error!("Inconsistency: modified item {} has been marked for upload but is locally missing", id_change);
continue;
},
Some(item) => {
//
//
//
//
// TODO: implement update_item (maybe only create_item also updates it?)
//
if let Err(err) = cal_remote.delete_item(&id_change).await {
log::error!("Unable to delete item {} from remote calendar: {}", id_change, err);
}
match cal_remote.add_item(item.clone()).await {
Err(err) => log::error!("Unable to add item {} to remote calendar: {}", id_change, err),
Ok(new_ss) => {
// Update local sync status
item.set_sync_status(new_ss);
},
};
}
};
}
Ok(())
}
}