Output feed trimming policy when starting server

Author: wezm

README.md

@@ -130,11 +130,16 @@ does not exist it will be created. When the server starts the path on the
 server for the feed is printed. This is what you would use to subscribe to the
 feed in your feed reader.
 
-**Note:** The feed is capped to 50 items, with older items dropped when a new
-item is added. The limit was added to stop the feed growing forever since there
-is no way for Feedlynx to know when an item has been read. RSS readers need to
-download and process the whole feed whenever there are new items, so imposing a
-cap helps limit the size and scope of that work.
+**Feed Trimming**
+
+When a new link is added links older than 30 days are considered for removal.
+Feedlynx will retain up to 50 entries. Entries older than 30 days in excess of
+50 entries will be removed, oldest first.
+
+The limit was added to stop the feed growing forever since there is no way for
+Feedlynx to know when an item has been read. RSS readers need to download and
+process the whole feed whenever there are new items, so imposing a cap helps
+limit the size and scope of that work.
 
 ### Example
 

src/feed.rs

@@ -11,8 +11,8 @@ use uriparse::URI;
 use crate::webpage::WebPage;
 use crate::{base62, Error};
 
-const MIN_ENTRIES: usize = 50;
-const TRIM_AGE: TimeDelta = TimeDelta::days(30);
+pub const MIN_ENTRIES: usize = 50;
+pub const TRIM_AGE: TimeDelta = TimeDelta::days(30);
 
 pub struct Feed {
     path: PathBuf,

src/server.rs

@@ -15,7 +15,7 @@ use tiny_http::{Header, HeaderField, Method, Request, Response, StatusCode};
 use tinyjson::JsonValue;
 use uriparse::URI;
 
-use crate::feed::Feed;
+use crate::feed::{self, Feed};
 use crate::webpage::WebPage;
 use crate::{embed, webpage, FeedToken, PrivateToken};
 
@@ -85,6 +85,11 @@ impl Server {
         let _ = HTML_CONTENT_TYPE.set("Content-type: text/html; charset=utf-8".parse().unwrap());
         let _ = JSON_CONTENT_TYPE.set("Content-type: application/json".parse().unwrap());
 
+        info!(
+            "Feed trimming policy: Min entries: {}, trim age: {} days",
+            feed::MIN_ENTRIES,
+            feed::TRIM_AGE.num_days()
+        );
         info!(
             "Feed available at: http://{}{}",
             self.server.server_addr(),