[http/spotify] Add support for http sessions across multiple requests

This change allows to reuse curl handles for multiple requests.
Reusing a curl handle improves performance if more than one request is
made against a service (connection, session cache, dns cache are kept
between requests).

src/artwork.c

@@ -439,7 +439,7 @@ artwork_read_byurl(struct evbuffer *evbuf, const char *url)
   client.input_headers = kv;
   client.input_body = evbuf;
 
-  ret = http_client_request(&client);
+  ret = http_client_request(&client, NULL);
   if (ret < 0)
     {
       DPRINTF(E_LOG, L_ART, "Request to '%s' failed with return value %d\n", url, ret);
@@ -1288,7 +1288,7 @@ online_source_search(struct online_source *src, struct artwork_ctx *ctx)
   client.url = url;
   client.output_headers = &output_headers;
 
-  ret = http_client_request(&client);
+  ret = http_client_request(&client, NULL);
   keyval_clear(&output_headers);
   if (ret < 0 || client.response_code != HTTP_OK)
     {

src/http.c

@@ -55,6 +55,19 @@
 // Number of seconds the client will wait for a response before aborting
 #define HTTP_CLIENT_TIMEOUT 8
 
+
+void
+http_client_session_init(struct http_client_session *session)
+{
+  session->curl = curl_easy_init();
+}
+
+void
+http_client_session_deinit(struct http_client_session *session)
+{
+  curl_easy_cleanup(session->curl);
+}
+
 static void
 curl_headers_save(struct keyval *kv, CURL *curl)
 {
@@ -95,7 +108,7 @@ curl_request_cb(char *ptr, size_t size, size_t nmemb, void *userdata)
 }
 
 int
-http_client_request(struct http_client_ctx *ctx)
+http_client_request(struct http_client_ctx *ctx, struct http_client_session *session)
 {
   CURL *curl;
   CURLcode res;
@@ -106,7 +119,15 @@ http_client_request(struct http_client_ctx *ctx)
   char header[1024];
   long response_code;
 
-  curl = curl_easy_init();
+  if (session)
+    {
+      curl = session->curl;
+      curl_easy_reset(curl);
+    }
+  else
+    {
+      curl = curl_easy_init();
+    }
   if (!curl)
     {
       DPRINTF(E_LOG, L_HTTP, "Error: Could not get curl handle\n");
@@ -153,7 +174,10 @@ http_client_request(struct http_client_ctx *ctx)
     {
       DPRINTF(E_LOG, L_HTTP, "Request to %s failed: %s\n", ctx->url, curl_easy_strerror(res));
       curl_slist_free_all(headers);
-      curl_easy_cleanup(curl);
+      if (!session)
+	{
+	  curl_easy_cleanup(curl);
+	}
       return -1;
     }
 
@@ -162,7 +186,10 @@ http_client_request(struct http_client_ctx *ctx)
   curl_headers_save(ctx->input_headers, curl);
 
   curl_slist_free_all(headers);
-  curl_easy_cleanup(curl);
+  if (!session)
+    {
+      curl_easy_cleanup(curl);
+    }
 
   return 0;
 }
@@ -262,7 +289,7 @@ http_stream_setup(char **stream, const char *url)
   ctx.url = url;
   ctx.input_body = evbuf;
 
-  ret = http_client_request(&ctx);
+  ret = http_client_request(&ctx, NULL);
   if (ret < 0)
     {
       DPRINTF(E_LOG, L_HTTP, "Couldn't fetch internet playlist: %s\n", url);

src/http.h

@@ -4,10 +4,16 @@
 
 #include <event2/buffer.h>
 #include <event2/http.h>
+#include <curl/curl.h>
 #include "misc.h"
 
 #include <libavformat/avformat.h>
 
+struct http_client_session
+{
+  CURL *curl;
+};
+
 struct http_client_ctx
 {
   /* Destination URL, header and body of outgoing request body. If output_body
@@ -54,6 +60,11 @@ struct http_icy_metadata
   uint32_t hash;
 };
 
+void
+http_client_session_init(struct http_client_session *session);
+
+void
+http_client_session_deinit(struct http_client_session *session);
 
 /* Make a http(s) request. We use libcurl to make https requests. We could use
  * libevent and avoid the dependency, but for SSL, libevent needs to be v2.1
@@ -63,7 +74,7 @@ struct http_icy_metadata
  * @return 0 if successful, -1 if an error occurred (e.g. no libcurl)
  */
 int
-http_client_request(struct http_client_ctx *ctx);
+http_client_request(struct http_client_ctx *ctx, struct http_client_session *session);
 
 
 /* Converts the keyval dictionary to a application/x-www-form-urlencoded string.

src/inputs/http.c

@@ -194,7 +194,7 @@ streamurl_process(struct input_metadata *metadata, const char *url)
   client.input_headers = &kv;
   client.input_body = evbuf;
 
-  ret = http_client_request(&client);
+  ret = http_client_request(&client, NULL);
   if (ret < 0 || client.response_code != HTTP_OK)
     {
       DPRINTF(E_WARN, L_PLAYER, "Request for StreamUrl resource '%s' failed, response code %d\n", url, client.response_code);

src/inputs/spotify_librespotc.c

@@ -228,7 +228,7 @@ https_get_cb(char **out, const char *url)
   ctx.url = url;
   ctx.input_body = evbuffer_new();
 
-  ret = http_client_request(&ctx);
+  ret = http_client_request(&ctx, NULL);
   if (ret < 0 || ctx.response_code != HTTP_OK)
     {
       DPRINTF(E_LOG, L_SPOTIFY, "Failed to AP list from '%s' (return %d, error code %d)\n", ctx.url, ret, ctx.response_code);

src/lastfm.c

@@ -239,7 +239,7 @@ request_post(const char *url, struct keyval *kv, char **errmsg)
   ctx.url = url;
   ctx.input_body = evbuffer_new();
 
-  ret = http_client_request(&ctx);
+  ret = http_client_request(&ctx, NULL);
   if (ret < 0)
     goto out_free_ctx;
 

src/library/rssscanner.c

@@ -144,7 +144,7 @@ apple_rss_feedurl_get(const char *rss_url)
   ctx.url = url;
   ctx.input_body = evbuf;
 
-  ret = http_client_request(&ctx);
+  ret = http_client_request(&ctx, NULL);
   if (ret < 0 || ctx.response_code != HTTP_OK)
     {
       evbuffer_free(evbuf);
@@ -256,7 +256,7 @@ rss_xml_get(const char *url)
   CHECK_NULL(L_LIB, ctx.input_body = evbuffer_new());
   ctx.url = feedurl;
 
-  ret = http_client_request(&ctx);
+  ret = http_client_request(&ctx, NULL);
   if (ret < 0 || ctx.response_code != HTTP_OK)
     {
       DPRINTF(E_LOG, L_LIB, "Failed to fetch RSS from '%s' (return %d, error code %d)\n", ctx.url, ret, ctx.response_code);

src/library/spotify_webapi.c

@@ -166,6 +166,7 @@ static const char *spotify_shows_uri           = "https://api.spotify.com/v1/me/
 static const char *spotify_shows_episodes_uri  = "https://api.spotify.com/v1/shows/%s/episodes";
 static const char *spotify_episode_uri         = "https://api.spotify.com/v1/episodes/%s";
 
+static struct http_client_session session = { 0 };
 
 static enum spotify_item_type
 parse_type_from_uri(const char *uri)
@@ -256,7 +257,7 @@ request_access_tokens(struct keyval *kv, const char **err)
   ctx.output_body = param;
   ctx.input_body = evbuffer_new();
 
-  ret = http_client_request(&ctx);
+  ret = http_client_request(&ctx, NULL);
   if (ret < 0)
     {
       *err = "Did not get a reply from Spotify";
@@ -366,7 +367,7 @@ request_endpoint(const char *uri)
 
   DPRINTF(E_DBG, L_SPOTIFY, "Request Spotify API endpoint: '%s')\n", uri);
 
-  ret = http_client_request(ctx);
+  ret = http_client_request(ctx, &session);
   if (ret < 0)
     {
       DPRINTF(E_LOG, L_SPOTIFY, "Request for '%s' failed\n", uri);
@@ -2321,10 +2322,15 @@ spotifywebapi_access_token_get(struct spotifywebapi_access_token *info)
 static int
 spotifywebapi_init()
 {
-  CHECK_ERR(L_SPOTIFY, mutex_init(&token_lck));
+  int ret;
 
-  // Required for libspotify backend
-  return spotify_init();
+  CHECK_ERR(L_SPOTIFY, mutex_init(&token_lck));
+  ret = spotify_init();
+  if (ret < 0)
+    return -1;
+
+  http_client_session_init(&session);
+  return 0;
 }
 
 static void
@@ -2333,6 +2339,7 @@ spotifywebapi_deinit()
   CHECK_ERR(L_SPOTIFY, pthread_mutex_destroy(&token_lck));
 
   spotify_deinit();
+  http_client_session_deinit(&session);
 
   free_credentials();
 }