Report latency at server startup (#551) (#562)

- Measure the `[time]` taken to get the `.parseable.json` object from 
the store at server startup
- Print `[time]` on the banner

This is useful to display current latency at server startup time and
will help the user decide if latency is higher than expected in their
deployment.

Author: theteachr

server/src/banner.rs

@@ -27,7 +27,7 @@ pub async fn print(config: &Config, meta: &StorageMetadata) {
     print_ascii_art();
     let scheme = config.parseable.get_scheme();
     status_info(config, &scheme, meta.deployment_id);
-    storage_info(config);
+    storage_info(config).await;
     about::print(config, meta).await;
     println!();
 }
@@ -79,16 +79,26 @@ fn status_info(config: &Config, scheme: &str, id: Uid) {
     );
 }
 
-fn storage_info(config: &Config) {
+/// Prints information about the `ObjectStorage`.
+/// - Mode (`Local drive`, `S3 bucket`)
+/// - Staging (temporary landing point for incoming events)
+/// - Store (path where the data is stored)
+/// - Latency
+async fn storage_info(config: &Config) {
+    let storage = config.storage();
+    let latency = storage.get_object_store().get_latency().await;
+
     eprintln!(
         "
     {}
         Mode:               \"{}\"
         Staging:            \"{}\"
-        Store:              \"{}\"",
+        Store:              \"{}\"
+        Latency:            \"{:?}\"",
         "Storage:".to_string().bold(),
         config.mode_string(),
         config.staging_dir().to_string_lossy(),
-        config.storage().get_endpoint(),
+        storage.get_endpoint(),
+        latency
     )
 }

server/src/storage/object_storage.rs

@@ -38,7 +38,13 @@ use relative_path::RelativePath;
 use relative_path::RelativePathBuf;
 use serde_json::Value;
 
-use std::{collections::HashMap, fs, path::Path, sync::Arc};
+use std::{
+    collections::HashMap,
+    fs,
+    path::Path,
+    sync::Arc,
+    time::{Duration, Instant},
+};
 
 // metadata file names in a Stream prefix
 pub(super) const STREAM_METADATA_FILE_NAME: &str = ".stream.json";
@@ -67,6 +73,19 @@ pub trait ObjectStorage: Sync + 'static {
     async fn list_streams(&self) -> Result<Vec<LogStream>, ObjectStorageError>;
     async fn list_dates(&self, stream_name: &str) -> Result<Vec<String>, ObjectStorageError>;
     async fn upload_file(&self, key: &str, path: &Path) -> Result<(), ObjectStorageError>;
+
+    /// Returns the amount of time taken by the `ObjectStore` to perform a get
+    /// call.
+    async fn get_latency(&self) -> Duration {
+        // It's Ok to `unwrap` here. The hardcoded value will always Result in
+        // an `Ok`.
+        let path = RelativePathBuf::from_path(".parseable.json").unwrap();
+
+        let start = Instant::now();
+        let _ = self.get_object(&path).await;
+        start.elapsed()
+    }
+
     fn normalize_prefixes(&self, prefixes: Vec<String>) -> Vec<String>;
     fn query_prefixes(&self, prefixes: Vec<String>) -> Vec<ListingTableUrl>;
     fn store_url(&self) -> url::Url;