add Background Fetch method

deltachat-ffi/deltachat.h

@@ -3151,6 +3151,23 @@ void           dc_accounts_maybe_network        (dc_accounts_t* accounts);
 void           dc_accounts_maybe_network_lost    (dc_accounts_t* accounts);
 
 
+/**
+ * Perform a background fetch for all accounts in parallel with a timeout.
+ * Pauses the scheduler, fetches messages from imap and then resumes the scheduler.
+ *
+ * dc_accounts_background_fetch() was created for the iOS Background fetch.
+ *
+ * The `DC_EVENT_ACCOUNTS_BACKGROUND_FETCH_DONE` event is emitted at the end
+ * even in case of timeout, unless the function fails and returns 0.
+ * Process all events until you get this one and you can safely return to the background
+ * without forgetting to create notifications caused by timing race conditions.
+ *
+ * @memberof dc_accounts_t
+ * @param timeout The timeout in seconds
+ * @return Return 1 if DC_EVENT_ACCOUNTS_BACKGROUND_FETCH_DONE was emitted and 0 otherwise.
+ */
+int            dc_accounts_background_fetch    (dc_accounts_t* accounts, uint64_t timeout);
+
 /**
  * Create the event emitter that is used to receive events.
  *
@@ -6255,6 +6272,16 @@ void dc_event_unref(dc_event_t* event);
 
 #define DC_EVENT_WEBXDC_INSTANCE_DELETED          2121
 
+/**
+ * Tells that the Background fetch was completed (or timed out).
+ *
+ * This event acts as a marker, when you reach this event you can be sure
+ * that all events emitted during the background fetch were processed.
+ * 
+ * This event is only emitted by the account manager
+ */
+
+#define DC_EVENT_ACCOUNTS_BACKGROUND_FETCH_DONE  2200
 
 /**
  * @}

deltachat-ffi/src/lib.rs

@@ -559,6 +559,7 @@ pub unsafe extern "C" fn dc_event_get_id(event: *mut dc_event_t) -> libc::c_int
         EventType::ConfigSynced { .. } => 2111,
         EventType::WebxdcStatusUpdate { .. } => 2120,
         EventType::WebxdcInstanceDeleted { .. } => 2121,
+        EventType::AccountsBackgroundFetchDone => 2200,
     }
 }
 
@@ -586,7 +587,8 @@ pub unsafe extern "C" fn dc_event_get_data1_int(event: *mut dc_event_t) -> libc:
         | EventType::SelfavatarChanged
         | EventType::ConfigSynced { .. }
         | EventType::IncomingMsgBunch { .. }
-        | EventType::ErrorSelfNotInGroup(_) => 0,
+        | EventType::ErrorSelfNotInGroup(_)
+        | EventType::AccountsBackgroundFetchDone => 0,
         EventType::MsgsChanged { chat_id, .. }
         | EventType::ReactionsChanged { chat_id, .. }
         | EventType::IncomingMsg { chat_id, .. }
@@ -646,6 +648,7 @@ pub unsafe extern "C" fn dc_event_get_data2_int(event: *mut dc_event_t) -> libc:
         | EventType::WebxdcInstanceDeleted { .. }
         | EventType::IncomingMsgBunch { .. }
         | EventType::SelfavatarChanged
+        | EventType::AccountsBackgroundFetchDone
         | EventType::ConfigSynced { .. } => 0,
         EventType::ChatModified(_) => 0,
         EventType::MsgsChanged { msg_id, .. }
@@ -708,6 +711,7 @@ pub unsafe extern "C" fn dc_event_get_data2_str(event: *mut dc_event_t) -> *mut
         | EventType::SelfavatarChanged
         | EventType::WebxdcStatusUpdate { .. }
         | EventType::WebxdcInstanceDeleted { .. }
+        | EventType::AccountsBackgroundFetchDone
         | EventType::ChatEphemeralTimerModified { .. } => ptr::null_mut(),
         EventType::ConfigureProgress { comment, .. } => {
             if let Some(comment) = comment {
@@ -4898,6 +4902,26 @@ pub unsafe extern "C" fn dc_accounts_maybe_network_lost(accounts: *mut dc_accoun
     block_on(async move { accounts.write().await.maybe_network_lost().await });
 }
 
+#[no_mangle]
+pub unsafe extern "C" fn dc_accounts_background_fetch(
+    accounts: *mut dc_accounts_t,
+    timeout_in_seconds: u64,
+) -> libc::c_int {
+    if accounts.is_null() || timeout_in_seconds <= 2 {
+        eprintln!("ignoring careless call to dc_accounts_background_fetch()");
+        return 0;
+    }
+
+    let accounts = &*accounts;
+    block_on(async move {
+        let accounts = accounts.read().await;
+        accounts
+            .background_fetch(Duration::from_secs(timeout_in_seconds))
+            .await;
+    });
+    1
+}
+
 #[no_mangle]
 pub unsafe extern "C" fn dc_accounts_get_event_emitter(
     accounts: *mut dc_accounts_t,

deltachat-jsonrpc/src/api.rs

@@ -231,6 +231,20 @@ impl CommandApi {
         Ok(())
     }
 
+    /// Performs a background fetch for all accounts in parallel with a timeout.
+    ///
+    /// The `AccountsBackgroundFetchDone` event is emitted at the end even in case of timeout.
+    /// Process all events until you get this one and you can safely return to the background
+    /// without forgetting to create notifications caused by timing race conditions.
+    async fn accounts_background_fetch(&self, timeout_in_seconds: f64) -> Result<()> {
+        self.accounts
+            .write()
+            .await
+            .background_fetch(std::time::Duration::from_secs_f64(timeout_in_seconds))
+            .await;
+        Ok(())
+    }
+
     // ---------------------------------------------
     // Methods that work on individual accounts
     // ---------------------------------------------

deltachat-jsonrpc/src/api/types/events.rs

@@ -245,6 +245,13 @@ pub enum EventType {
     /// Inform that a message containing a webxdc instance has been deleted
     #[serde(rename_all = "camelCase")]
     WebxdcInstanceDeleted { msg_id: u32 },
+
+    /// Tells that the Background fetch was completed (or timed out).
+    /// This event acts as a marker, when you reach this event you can be sure
+    /// that all events emitted during the background fetch were processed.
+    ///
+    /// This event is only emitted by the account manager
+    AccountsBackgroundFetchDone,
 }
 
 impl From<CoreEventType> for EventType {
@@ -353,6 +360,7 @@ impl From<CoreEventType> for EventType {
             CoreEventType::WebxdcInstanceDeleted { msg_id } => WebxdcInstanceDeleted {
                 msg_id: msg_id.to_u32(),
             },
+            CoreEventType::AccountsBackgroundFetchDone => AccountsBackgroundFetchDone,
         }
     }
 }

node/constants.js

@@ -29,6 +29,7 @@ module.exports = {
   DC_DOWNLOAD_FAILURE: 20,
   DC_DOWNLOAD_IN_PROGRESS: 1000,
   DC_DOWNLOAD_UNDECIPHERABLE: 30,
+  DC_EVENT_ACCOUNTS_BACKGROUND_FETCH_DONE: 2200,
   DC_EVENT_CHAT_EPHEMERAL_TIMER_MODIFIED: 2021,
   DC_EVENT_CHAT_MODIFIED: 2020,
   DC_EVENT_CONFIGURE_PROGRESS: 2041,

node/events.js

@@ -36,5 +36,6 @@ module.exports = {
   2110: 'DC_EVENT_SELFAVATAR_CHANGED',
   2111: 'DC_EVENT_CONFIG_SYNCED',
   2120: 'DC_EVENT_WEBXDC_STATUS_UPDATE',
-  2121: 'DC_EVENT_WEBXDC_INSTANCE_DELETED'
+  2121: 'DC_EVENT_WEBXDC_INSTANCE_DELETED',
+  2200: 'DC_EVENT_ACCOUNTS_BACKGROUND_FETCH_DONE'
 }

node/lib/constants.ts

@@ -29,6 +29,7 @@ export enum C {
   DC_DOWNLOAD_FAILURE = 20,
   DC_DOWNLOAD_IN_PROGRESS = 1000,
   DC_DOWNLOAD_UNDECIPHERABLE = 30,
+  DC_EVENT_ACCOUNTS_BACKGROUND_FETCH_DONE = 2200,
   DC_EVENT_CHAT_EPHEMERAL_TIMER_MODIFIED = 2021,
   DC_EVENT_CHAT_MODIFIED = 2020,
   DC_EVENT_CONFIGURE_PROGRESS = 2041,
@@ -326,4 +327,5 @@ export const EventId2EventName: { [key: number]: string } = {
   2111: 'DC_EVENT_CONFIG_SYNCED',
   2120: 'DC_EVENT_WEBXDC_STATUS_UPDATE',
   2121: 'DC_EVENT_WEBXDC_INSTANCE_DELETED',
+  2200: 'DC_EVENT_ACCOUNTS_BACKGROUND_FETCH_DONE',
 }

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 +292,42 @@ impl Accounts {
         }
     }
 
+    /// Performs a background fetch for all accounts in parallel.
+    ///
+    /// This is an auxiliary function and not part of public API.
+    /// Use [Accounts::background_fetch] instead.
+    async fn background_fetch_without_timeout(&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.
+    ///
+    /// The `AccountsBackgroundFetchDone` event is emitted at the end,
+    /// process all events until you get this one and you can safely return to the background
+    /// without forgetting to create notifications caused by timing race conditions.
+    pub async fn background_fetch(&self, timeout: std::time::Duration) {
+        if let Err(_err) =
+            tokio::time::timeout(timeout, self.background_fetch_without_timeout()).await
+        {
+            self.emit_event(EventType::Warning(
+                "Background fetch timed out.".to_string(),
+            ));
+        }
+        self.emit_event(EventType::AccountsBackgroundFetchDone);
+    }
+
     /// Emits a single event.
     pub fn emit_event(&self, event: EventType) {
         self.events.emit(Event { id: 0, typ: event })

src/constants.rs

@@ -214,6 +214,9 @@ pub(crate) const DC_FOLDERS_CONFIGURED_VERSION: i32 = 4;
 // `max_smtp_rcpt_to` in the provider db.
 pub(crate) const DEFAULT_MAX_SMTP_RCPT_TO: usize = 50;
 
+/// How far the last quota check needs to be in the past to be checked by the background function (in seconds).
+pub(crate) const DC_BACKGROUND_FETCH_QUOTA_CHECK_RATELIMIT: i64 = 12 * 60 * 60; // 12 hours
+
 #[cfg(test)]
 mod tests {
     use num_traits::FromPrimitive;

src/context.rs

@@ -15,16 +15,16 @@ use tokio::sync::{Mutex, Notify, RwLock};
 
 use crate::chat::{get_chat_cnt, ChatId};
 use crate::config::Config;
-use crate::constants::DC_VERSION_STR;
+use crate::constants::{DC_BACKGROUND_FETCH_QUOTA_CHECK_RATELIMIT, 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 +441,55 @@ impl Context {
         self.scheduler.maybe_network().await;
     }
 
+    /// Does 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 address = self.get_primary_self_addr().await?;
+        let time_start = std::time::SystemTime::now();
+        info!(self, "background_fetch started fetching {address}");
+
+        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) - but only check it once in a while
+        let quota_needs_update = {
+            let quota = self.quota.read().await;
+            quota
+                .as_ref()
+                .filter(|quota| quota.modified + DC_BACKGROUND_FETCH_QUOTA_CHECK_RATELIMIT > time())
+                .is_none()
+        };
+
+        if quota_needs_update {
+            if let Err(err) = self.update_recent_quota(&mut connection).await {
+                warn!(self, "Failed to update quota: {err:#}.");
+            }
+        }
+
+        info!(
+            self,
+            "background_fetch done for {address} took {:?}",
+            time_start.elapsed().unwrap_or_default()
+        );
+
+        Ok(())
+    }
+
     pub(crate) async fn schedule_resync(&self) -> Result<()> {
         self.resync_request.store(true, Ordering::Relaxed);
         self.scheduler.interrupt_inbox().await;

src/events/payload.rs

@@ -287,4 +287,11 @@ pub enum EventType {
         /// ID of the deleted message.
         msg_id: MsgId,
     },
+
+    /// Tells that the Background fetch was completed (or timed out).
+    /// This event acts as a marker, when you reach this event you can be sure
+    /// that all events emitted during the background fetch were processed.
+    ///
+    /// This event is only emitted by the account manager
+    AccountsBackgroundFetchDone,
 }