From 349249f42358f83569ad782ceb1760d97a3f6b49 Mon Sep 17 00:00:00 2001
From: Richard Fuchs <rfuchs@sipwise.com>
Date: Fri, 3 Jan 2025 14:40:11 -0400
Subject: [PATCH] MT#61822 add on-demand caching of memory files

Change-Id: I39deff0fd89d45df5739900dac3aa236f528161c
---
 daemon/media_player.c | 34 ++++++++++++++++++++++++++++++++--
 docs/rtpengine.md     |  5 +++++
 etc/rtpengine.conf    |  2 +-
 3 files changed, 38 insertions(+), 3 deletions(-)

diff --git a/daemon/media_player.c b/daemon/media_player.c
index 3fafc51a6..dc46a1ccc 100644
--- a/daemon/media_player.c
+++ b/daemon/media_player.c
@@ -1218,7 +1218,7 @@ static struct media_player_media_file *media_player_media_file_read_str(const st
 	return media_player_media_file_read_c(file_s);
 }
 
-static struct media_player_media_file *media_player_media_files_get(const str *fn) {
+static struct media_player_media_file *media_player_media_files_get_only(const str *fn) {
 	struct media_player_media_file *fo;
 
 	{
@@ -1261,6 +1261,31 @@ static mp_cached_code media_player_set_media_file(struct media_player *mp,
 	return __media_player_add_blob_id(mp, opts, dst_pt);
 }
 
+static struct media_player_media_file *media_player_media_files_get_create(const str *fn) {
+	__auto_type fo = media_player_media_files_get_only(fn);
+	if (fo)
+		return fo;
+
+	fo = media_player_media_file_read_str(fn);
+	if (!fo)
+		return NULL;
+
+	RWLOCK_W(&media_player_media_files_names_lock);
+	LOCK(&media_player_media_files_lock);
+	// someone else may have beaten us to it
+	if (t_hash_table_is_set(media_player_media_files) && t_hash_table_lookup(media_player_media_files, fn))
+		return fo; // return the only reference, will disappear once player finishes
+
+	// insert new reference
+	media_player_media_files_insert(fn, obj_get(fo));
+
+	return fo;
+}
+
+static struct media_player_media_file *(*media_player_media_files_get)(const str *fn)
+	= media_player_media_files_get_only;
+
+
 static void __media_player_set_opts(struct media_player *mp, media_player_opts_t opts) {
 	mp->opts = opts;
 
@@ -1914,6 +1939,11 @@ bool media_player_preload_files(char **files) {
 		while (*file == ' ')
 			file++;
 
+		if (!strcmp(file, "ondemand") || !strcmp(file, "on demand") || !strcmp(file, "on-demand")) {
+			media_player_media_files_get = media_player_media_files_get_create;
+			continue;
+		}
+
 		ilog(LOG_DEBUG, "Reading media file '%s' for caching", file);
 
 		str f = STR(file);
@@ -1936,7 +1966,7 @@ bool media_player_reload_file(str *name) {
 	bool ret = false;
 
 #ifdef WITH_TRANSCODING
-	__auto_type fo = media_player_media_files_get(name);
+	__auto_type fo = media_player_media_files_get_only(name);
 	assert(fo != NULL);
 
 	// get file mtime
diff --git a/docs/rtpengine.md b/docs/rtpengine.md
index a15b028dd..e8fd1c2d4 100644
--- a/docs/rtpengine.md
+++ b/docs/rtpengine.md
@@ -1159,6 +1159,11 @@ call to inject-DTMF won't be sent to __\-\-dtmf-log-dest=__ or __\-\-listen-tcp-
     file name differs (or an entirely different file is requested for playback)
     then playback will happen from file as usual.
 
+    The special string `on-demand` can be used instead of a file name to enable
+    on-demand loading and caching of media files. Any file requested for
+    playback that wasn't already present in the memory cache will then be read
+    only once and then retained in the cache for the lifetime of the daemon.
+
 - __\-\-media-files-reload=__*SECONDS*
 
     Spawn a background thread to periodically check and, if needed, update
diff --git a/etc/rtpengine.conf b/etc/rtpengine.conf
index 338eb6a73..4bddd8806 100644
--- a/etc/rtpengine.conf
+++ b/etc/rtpengine.conf
@@ -165,7 +165,7 @@ recording-method = proc
 # whenever MoH is triggered. If not defined, then not in use.
 # moh-attr-name = rtpengine-hold
 
-# preload-media-files = /var/media/file1.wav ; /var/media/file2.wav ; /var/media/file3.wav
+# preload-media-files = /var/media/file1.wav ; /var/media/file2.wav ; /var/media/file3.wav ; on-demand
 # media-files-reload = 60
 
 # signalling templates (see key `templates` above)