Move downloads to queue for better performance (#367)

src/queue/download.rs

@@ -0,0 +1,58 @@
+use crate::database::models::{DatabaseError, ProjectId, VersionId};
+use sqlx::PgPool;
+use tokio::sync::Mutex;
+
+pub struct DownloadQueue {
+    queue: Mutex<Vec<(ProjectId, VersionId)>>,
+}
+
+// Batches download transactions every thirty seconds
+impl DownloadQueue {
+    pub fn new() -> Self {
+        DownloadQueue {
+            queue: Mutex::new(Vec::with_capacity(1000)),
+        }
+    }
+    pub async fn add(&self, project_id: ProjectId, version_id: VersionId) {
+        self.queue.lock().await.push((project_id, version_id));
+    }
+
+    pub async fn take(&self) -> Vec<(ProjectId, VersionId)> {
+        let mut queue = self.queue.lock().await;
+        let len = queue.len();
+
+        std::mem::replace(&mut queue, Vec::with_capacity(len))
+    }
+
+    pub async fn index(&self, pool: &PgPool) -> Result<(), DatabaseError> {
+        let queue = self.take().await;
+
+        if queue.len() > 0 {
+            let mut transaction = pool.begin().await?;
+
+            for (project_id, version_id) in queue {
+                sqlx::query!(
+                    "UPDATE versions
+                    SET downloads = downloads + 1
+                    WHERE (id = $1)",
+                    version_id as VersionId
+                )
+                .execute(&mut *transaction)
+                .await?;
+
+                sqlx::query!(
+                    "UPDATE mods
+                    SET downloads = downloads + 1
+                    WHERE (id = $1)",
+                    project_id as ProjectId
+                )
+                .execute(&mut *transaction)
+                .await?;
+            }
+
+            transaction.commit().await?;
+        }
+
+        Ok(())
+    }
+}

src/queue/mod.rs

@@ -0,0 +1 @@
+pub mod download;