From 1b42c652941498df006566c40001836f3b2673dd Mon Sep 17 00:00:00 2001
From: Peter Cai <peter@typeblog.net>
Date: Thu, 9 Apr 2020 17:18:52 +0800
Subject: [PATCH] blog: add more comment on PostContentCache

---
 src/blog.rs | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/src/blog.rs b/src/blog.rs
index e46c19a..ba8abbe 100644
--- a/src/blog.rs
+++ b/src/blog.rs
@@ -124,6 +124,16 @@ const CACHE_VERSION: &'static str = "0001";
 
 // Cached version of rendered blog content HTMLs
 // compiled from Markdown
+// This is needed because 
+// (1) we have to extract some information from
+//     the Markdown source code before anyone
+//     visits, e.g. pictures it refers to (
+//     for whitelisting the cache URL)
+// (2) Markdown parsing is slower than filling in
+//     HTML templates of the entire page. If these
+//     Markdown compilation results are cached,
+//     page generation can be very fast while still
+//     keeping some dynamic features available to us
 #[derive(Serialize, Deserialize)]
 pub struct PostContentCache {
     // UUID of the original post