From f46581288f093168e3bc13478d783af318085cb2 Mon Sep 17 00:00:00 2001
From: Alexandre Archambault <alexandre.archambault@gmail.com>
Date: Mon, 25 Jul 2016 00:19:03 +0200
Subject: [PATCH] Enable TTL for changing artifacts by default

---
 cache/src/main/scala/coursier/CachePolicy.scala | 12 ++++++++++++
 1 file changed, 12 insertions(+)

diff --git a/cache/src/main/scala/coursier/CachePolicy.scala b/cache/src/main/scala/coursier/CachePolicy.scala
index da83b4e6a..a9ec3445e 100644
--- a/cache/src/main/scala/coursier/CachePolicy.scala
+++ b/cache/src/main/scala/coursier/CachePolicy.scala
@@ -13,6 +13,8 @@ object CachePolicy {
     *
     * If no local file is found, *don't* try download it. Updates are only checked for files already
     * in cache.
+    *
+    * Follows the TTL parameter (assumes no update is needed if the last one is recent enough).
     */
   case object LocalUpdateChanging extends CachePolicy
 
@@ -22,6 +24,8 @@ object CachePolicy {
     * If no local file is found, *don't* try download it. Updates are only checked for files already
     * in cache.
     *
+    * Follows the TTL parameter (assumes no update is needed if the last one is recent enough).
+    *
     * Unlike `LocalUpdateChanging`, all found local files are checked for updates, not just the
     * changing ones.
     */
@@ -31,12 +35,16 @@ object CachePolicy {
     * Pick local files, and download the missing ones.
     *
     * For changing ones, check for updates, and download those if any.
+    *
+    * Follows the TTL parameter (assumes no update is needed if the last one is recent enough).
     */
   case object UpdateChanging extends CachePolicy
 
   /**
     * Pick local files, download the missing ones, check for updates and download those if any.
     *
+    * Follows the TTL parameter (assumes no update is needed if the last one is recent enough).
+    *
     * Unlike `UpdateChanging`, all found local files are checked for updates, not just the changing
     * ones.
     */
@@ -58,7 +66,11 @@ object CachePolicy {
 
 
   private val baseDefault = Seq(
+    // first, try to update changing artifacts that were previously downloaded (follows TTL)
+    CachePolicy.LocalUpdateChanging,
+    // then, use what's available locally
     CachePolicy.LocalOnly,
+    // lastly, try to download what's missing
     CachePolicy.FetchMissing
   )