moved cache stream config to constants at top of file

src/data.rs

@@ -7,8 +7,18 @@ use tokio::sync::{
     mpsc,
     watch,
 };
+use tokio::time::Duration;
 use std::fs::Metadata;
 
+/// How many unprocessed insertion requests are allowed in the backlog before the insertion stream backpressures?
+pub const CACHE_SEND_BUFFER_SIZE: usize = 30;
+/// How many insertion requests should be grouped before emitting them all as blocks downstream.
+pub const CACHE_GATE_BUFFER_SIZE: usize = 80;
+/// How long should a partial block be kept in the gate buffer with an open upstream before being sent by force.
+pub const CACHE_GATE_TIMEOUT: Duration = duration!(100 ms);
+/// How long should the insertion stream be forced to wait before accepting new blocks to insert.
+pub const CACHE_GATED_LAG: Duration = duration!(10 ms);
+
 /// A raw file or directory inode number
 ///
 /// Ususally created from the `.inode()` extension method on `fs::Metadata` found in prelude.
@@ -99,7 +109,7 @@ impl Cache
 	let inner = Arc::new(INodeCache {
 	    cache: RwLock::new(HashMap::new()),
 	});
-	let (tx, rx) = mpsc::channel(24);
+	let (tx, rx) = mpsc::channel(CACHE_SEND_BUFFER_SIZE);
 	let (e_tx, e_rx) = watch::channel(true);
 	
 	tokio::spawn({
@@ -108,8 +118,8 @@ impl Cache
 		use futures::prelude::*;
 		{
 		    let mut rx = rx
-			.gate_with_timeout(60, duration!(100 ms))
-			.lag(duration!(10 ms));
+			.gate_with_timeout(CACHE_GATE_BUFFER_SIZE, CACHE_GATE_TIMEOUT)
+			.lag(CACHE_GATED_LAG);
 		    while let Some(elements) = rx.next().await
 		    {
 			let mut writer = cache.cache.write().await;