feat: [#1539] save global downloads counter in DB

The total number of dowloads (for all torrents) is saved in the DB, but
not loaded yet.

todo: load the initial value when the tracker starts.

Author: josecelano

packages/tracker-core/src/statistics/event/handler.rs

@@ -41,17 +41,7 @@ pub async fn handle_event(
         Event::PeerDownloadCompleted { info_hash, peer } => {
             tracing::debug!(info_hash = ?info_hash, peer = ?peer, "Peer download completed", );
 
-            // Increment the number of downloads for the torrent
-            match db_torrent_repository.increase_number_of_downloads(&info_hash) {
-                Ok(()) => {
-                    tracing::debug!(info_hash = ?info_hash, "Number of downloads increased");
-                }
-                Err(err) => {
-                    tracing::error!(info_hash = ?info_hash, error = ?err, "Failed to increase number of downloads");
-                }
-            }
-
-            // Increment the number of downloads for all the torrents
+            // Increment the number of downloads for all the torrents in memory
             let _unused = stats_repository
                 .increment_counter(
                     &metric_name!(TRACKER_CORE_PERSISTENT_TORRENTS_DOWNLOADS_TOTAL),
@@ -60,9 +50,25 @@ pub async fn handle_event(
                 )
                 .await;
 
-            // todo:
-            //   - Persist the metric into the database.
-            //   - Load the metric from the database.
+            // Increment the number of downloads for the torrent in the database
+            match db_torrent_repository.increase_number_of_downloads(&info_hash) {
+                Ok(()) => {
+                    tracing::debug!(info_hash = ?info_hash, "Number of torrent downloads increased");
+                }
+                Err(err) => {
+                    tracing::error!(info_hash = ?info_hash, error = ?err, "Failed to increase number of downloads for the torrent");
+                }
+            }
+
+            // Increment the global number of downloads (for all torrents) in the database
+            match db_torrent_repository.increase_global_number_of_downloads() {
+                Ok(()) => {
+                    tracing::debug!("Global number of downloads increased");
+                }
+                Err(err) => {
+                    tracing::error!(error = ?err, "Failed to increase global number of downloads");
+                }
+            }
         }
     }
 }

packages/tracker-core/src/torrent/repository/persisted.rs

@@ -67,6 +67,22 @@ impl DatabasePersistentTorrentRepository {
         }
     }
 
+    /// Increases the global number of downloads for all torrent.
+    ///
+    /// If the metric is not found, it creates it.
+    ///
+    /// # Errors
+    ///
+    /// Returns an [`Error`] if the database operation fails.
+    pub(crate) fn increase_global_number_of_downloads(&self) -> Result<(), Error> {
+        let torrent = self.database.load_global_number_of_downloads()?;
+
+        match torrent {
+            Some(_number_of_downloads) => self.database.increase_global_number_of_downloads(),
+            None => self.database.save_global_number_of_downloads(1),
+        }
+    }
+
     /// Loads all persistent torrent metrics from the database.
     ///
     /// This function retrieves the torrent metrics (e.g., download counts) from the persistent store