feat: add background fetch method

src/accounts.rs

@@ -5,6 +5,7 @@ use std::future::Future;
 use std::path::{Path, PathBuf};
 
 use anyhow::{ensure, Context as _, Result};
+use futures::future::join_all;
 use serde::{Deserialize, Serialize};
 use tokio::fs;
 use tokio::io::AsyncWriteExt;
@@ -291,6 +292,33 @@ impl Accounts {
         }
     }
 
+    /// Performs a background fetch for all accounts in parallel.
+    ///
+    /// If you need a timeout, then use [Accounts::background_fetch_with_timeout] instead.
+    pub async fn background_fetch(&self) {
+        async fn background_fetch_and_log_error(account: Context) {
+            if let Err(error) = account.background_fetch().await {
+                warn!(account, "{error:#}");
+            }
+        }
+
+        join_all(
+            self.accounts
+                .values()
+                .cloned()
+                .map(background_fetch_and_log_error),
+        )
+        .await;
+    }
+
+    /// Performs a background fetch for all accounts in parallel with a timeout.
+    ///
+    /// If you want no timeout, then use [Accounts::background_fetch] instead.
+    pub async fn background_fetch_with_timeout(&self, timeout: Duration) -> Result<()> {
+        tokio::time::timeout(timeout, self.background_fetch()).await?;
+        Ok(())
+    }
+
     /// Emits a single event.
     pub fn emit_event(&self, event: EventType) {
         self.events.emit(Event { id: 0, typ: event })

src/context.rs

@@ -19,12 +19,12 @@ use crate::constants::DC_VERSION_STR;
 use crate::contact::Contact;
 use crate::debug_logging::DebugLogging;
 use crate::events::{Event, EventEmitter, EventType, Events};
-use crate::imap::ServerMetadata;
+use crate::imap::{FolderMeaning, Imap, ServerMetadata};
 use crate::key::{load_self_public_key, DcKey as _};
 use crate::login_param::LoginParam;
 use crate::message::{self, MessageState, MsgId};
 use crate::quota::QuotaInfo;
-use crate::scheduler::SchedulerState;
+use crate::scheduler::{convert_folder_meaning, SchedulerState};
 use crate::sql::Sql;
 use crate::stock_str::StockStrings;
 use crate::timesmearing::SmearedTimestamp;
@@ -441,6 +441,35 @@ impl Context {
         self.scheduler.maybe_network().await;
     }
 
+    /// Do a background fetch
+    /// pauses the scheduler and does one imap fetch, then unpauses and returns
+    pub async fn background_fetch(&self) -> Result<()> {
+        if !(self.is_configured().await?) {
+            return Ok(());
+        }
+
+        let _pause_guard = self.scheduler.pause(self.clone()).await?;
+
+        // connection
+        let mut connection = Imap::new_configured(self, channel::bounded(1).1).await?;
+        connection.prepare(self).await?;
+
+        // fetch imap folders
+        for folder_meaning in [FolderMeaning::Inbox, FolderMeaning::Mvbox] {
+            let (_, watch_folder) = convert_folder_meaning(self, folder_meaning).await?;
+            connection
+                .fetch_move_delete(self, &watch_folder, folder_meaning)
+                .await?;
+        }
+
+        // update quota (to send warning if full)
+        if let Err(err) = self.update_recent_quota(&mut connection).await {
+            warn!(self, "Failed to update quota: {:#}.", err);
+        }
+
+        Ok(())
+    }
+
     pub(crate) async fn schedule_resync(&self) -> Result<()> {
         self.resync_request.store(true, Ordering::Relaxed);
         self.scheduler.interrupt_inbox().await;