Cache fetched sources

.gitignore

@@ -13,6 +13,7 @@ listings/lp-output/*
 
 # Server-side cache
 cache
+cache-lt
 
 # Local tests
 .test

.phpenv

@@ -11,6 +11,8 @@
 	$ROOM_ICONS_CACHE="$CACHE_ROOT/icons";
 	$ROOM_ICONS="$DOCUMENT_ROOT/icons";
 	$ROOM_ICONS_RELATIVE="icons";
+	$LONG_TERM_CACHE_ROOT="$PROJECT_ROOT/cache-lt";
+	$SOURCES_CACHE="$LONG_TERM_CACHE_ROOT/sources";
 
 	$LISTING_PROVIDER_ROOT="$PROJECT_ROOT/listings";
 	$LISTINGS_INI="$LISTING_PROVIDER_ROOT/listings.ini";

CONTRIBUTING.md

@@ -5,7 +5,7 @@
 ### Prerequisites
 
 - PHP 8.1+
-- `make`
+- `make`, `awk`, `xargs`
 - `entr` to watch for file changes
 - `xdg-open` link handler to invoke browser
 - `libgd` (`php-gd`, `phpX.Y-gd`) for downsizing images

Makefile

@@ -68,7 +68,11 @@ watchdog:
 
 # Remove artefacts
 clean:
-	-git clean -dfX
+	-awk '/^[^#]/ { printf " -e \"!%s\"", $$0 }' <etc/.gitpreserve | xargs git clean -Xdf $(CLEANFLAGS)
+
+# Display files affected by artefact removal.
+would-clean: CLEANFLAGS="-n"
+would-clean: clean
 
 # Build everything from scratch and test functionality.
 test: FLAGS = --verbose

etc/.gitpreserve

@@ -0,0 +1,10 @@
+# Preserve the following files when cleaning the directory:
+
+# Long-term cache
+cache-lt
+
+# Visual Studio Code
+.vscode
+
+# Kate
+.kate-swp

php/servers/sources.php

@@ -242,20 +242,33 @@
 				str_replace("\\/", "/", $this->contents_sdir);
 		}
 
+		private static function source_cache_file(string $source_key) {
+			global $SOURCES_CACHE;
+			return "$SOURCES_CACHE/$source_key";
+		}
+
 		private static function fetch_source(string $source_key) {
 			$url = CommunitySources::SOURCES[$source_key];
 
 			$contents = file_get_contents($url);
 			log_debug($http_response_header[0]);
+			$cache_file = CommunitySources::source_cache_file($source_key);
 
-			if (!$contents) {
+			if ($contents) {
-				log_error("Could not fetch source from $url.");
+				file_put_contents($cache_file, $contents);
-				return "";
+				return $contents;
 			}
 
+			$contents = file_get_contents($cache_file);
+			if ($contents) {
+				log_warning("Could not fetch source from $url, using cache");
 				return $contents;
 			}
 
+			log_error("Could not fetch source from $url.");
+			return "";
+		}
+
 		/**
 		 * @param string[][] $tags Array associating room IDs to tag arrays
 		 */
@@ -315,4 +328,6 @@
 			return $this->room_tags[$room_id];
 		}
 	}
+
+	file_exists($SOURCES_CACHE) or mkdir($SOURCES_CACHE, 0755, recursive: true);
 ?>