crypto: Use an atomic int for the key count.

src/crypto/machine.rs

@@ -18,6 +18,7 @@ use std::mem;
 #[cfg(feature = "sqlite-cryptostore")]
 use std::path::Path;
 use std::result::Result as StdResult;
+use std::sync::atomic::{AtomicU64, Ordering};
 use uuid::Uuid;
 
 use super::error::{OlmError, Result, SignatureError, VerificationResult};
@@ -70,7 +71,7 @@ pub struct OlmMachine {
     /// this is None, no action will be taken. After a sync request the client
     /// needs to set this for us, depending on the count we will suggest the
     /// client to upload new keys.
-    uploaded_signed_key_count: Option<u64>,
+    uploaded_signed_key_count: Option<AtomicU64>,
     /// Store for the encryption keys.
     /// Persists all the encrytpion keys so a client can resume the session
     /// without the need to create new keys.
@@ -170,16 +171,23 @@ impl OlmMachine {
 
         // If we have a known key count, check that we have more than
         // max_one_time_Keys() / 2, otherwise tell the client to upload more.
-        match self.uploaded_signed_key_count {
+        match &self.uploaded_signed_key_count {
             Some(count) => {
                 let max_keys = self.account.max_one_time_keys().await as u64;
-                let key_count = (max_keys / 2) - count;
+                let key_count = (max_keys / 2) - count.load(Ordering::Relaxed);
                 key_count > 0
             }
             None => false,
         }
     }
 
+    fn update_key_count(&mut self, count: u64) {
+        match &self.uploaded_signed_key_count {
+            Some(c) => c.store(count, Ordering::Relaxed),
+            None => self.uploaded_signed_key_count = Some(AtomicU64::new(count)),
+        }
+    }
+
     /// Receive a successful keys upload response.
     ///
     /// # Arguments
@@ -203,10 +211,12 @@ impl OlmMachine {
         let count: u64 = one_time_key_count.map_or(0, |c| (*c).into());
         debug!(
             "Updated uploaded one-time key count {} -> {}, marking keys as published",
-            self.uploaded_signed_key_count.as_ref().map_or(0, |c| *c),
+            self.uploaded_signed_key_count
+                .as_ref()
+                .map_or(0, |c| c.load(Ordering::Relaxed)),
             count
         );
-        self.uploaded_signed_key_count = Some(count);
+        self.update_key_count(count);
 
         self.account.mark_keys_as_published().await;
         self.store.save_account(self.account.clone()).await?;
@@ -470,8 +480,9 @@ impl OlmMachine {
     /// Returns the number of newly generated one-time keys. If no keys can be
     /// generated returns an empty error.
     async fn generate_one_time_keys(&self) -> StdResult<u64, ()> {
-        match self.uploaded_signed_key_count {
+        match &self.uploaded_signed_key_count {
             Some(count) => {
+                let count = count.load(Ordering::Relaxed);
                 let max_keys = self.account.max_one_time_keys().await as u64;
                 let max_on_server = max_keys / 2;
 
@@ -1244,7 +1255,7 @@ impl OlmMachine {
             .get(&keys::KeyAlgorithm::SignedCurve25519);
 
         let count: u64 = one_time_key_count.map_or(0, |c| (*c).into());
-        self.uploaded_signed_key_count = Some(count);
+        self.update_key_count(count);
 
         for event_result in &mut response.to_device.events {
             let event = if let Ok(e) = event_result.deserialize() {
@@ -1389,6 +1400,7 @@ mod test {
     use std::convert::TryFrom;
     use std::fs::File;
     use std::io::prelude::*;
+    use std::sync::atomic::AtomicU64;
     use std::time::SystemTime;
 
     use serde_json::json;
@@ -1463,7 +1475,7 @@ mod test {
 
     async fn get_prepared_machine() -> (OlmMachine, OneTimeKeys) {
         let mut machine = OlmMachine::new(&user_id(), DEVICE_ID).unwrap();
-        machine.uploaded_signed_key_count = Some(0);
+        machine.uploaded_signed_key_count = Some(AtomicU64::new(0));
         let (_, otk) = machine
             .keys_for_upload()
             .await
@@ -1666,7 +1678,7 @@ mod test {
     #[tokio::test]
     async fn test_one_time_key_signing() {
         let mut machine = OlmMachine::new(&user_id(), DEVICE_ID).unwrap();
-        machine.uploaded_signed_key_count = Some(49);
+        machine.uploaded_signed_key_count = Some(AtomicU64::new(49));
 
         let mut one_time_keys = machine.signed_one_time_keys().await.unwrap();
         let identity_keys = machine.account.identity_keys();
@@ -1686,7 +1698,7 @@ mod test {
     #[tokio::test]
     async fn test_keys_for_upload() {
         let mut machine = OlmMachine::new(&user_id(), DEVICE_ID).unwrap();
-        machine.uploaded_signed_key_count = Some(0);
+        machine.uploaded_signed_key_count = Some(AtomicU64::default());
 
         let identity_keys = machine.account.identity_keys();
         let ed25519_key = identity_keys.ed25519();