Revert "Remove cache_time_info and always cache time info"

This reverts commit cfb171c991.

No idea why, but this cache breaks SPL Transient Designer Plus. Perhaps
it overwrites the time info?

src/common/configuration.cpp

@@ -78,7 +78,13 @@ Configuration::Configuration(const fs::path& config_path,
         // their defaults. At this point I'd really wish C++ could do pattern
         // matching.
         for (const auto& [key, value] : table) {
-            if (key == "editor_double_embed") {
+            if (key == "cache_time_info") {
+                if (const auto parsed_value = value.as_boolean()) {
+                    cache_time_info = parsed_value->get();
+                } else {
+                    invalid_options.push_back(key);
+                }
+            } else if (key == "editor_double_embed") {
                 if (const auto parsed_value = value.as_boolean()) {
                     editor_double_embed = parsed_value->get();
                 } else {

src/common/configuration.h

@@ -74,6 +74,20 @@ class Configuration {
     Configuration(const boost::filesystem::path& config_path,
                   const boost::filesystem::path& yabridge_path);
 
+    /**
+     * If set to `true`, then after an `audioMasterGetTime()` call all
+     * subsequent calls to that function during a single processing cycle will
+     * reuse the results from the first call. In theory it would be a bug on the
+     * host's side if this did _not_ return the same value every time, but since
+     * yabridge tries to not have any behaviour of its own and since this
+     * function should only be called at most once every processing cycle this
+     * option is not enabled by default. An example of a situation where this
+     * does become necessary is the SWAM Cello plugin, which calls
+     * `audioMasterGetTime()` for every sample instead of only once. This would
+     * tank performance without this caching behaviour.
+     */
+    bool cache_time_info = false;
+
     /**
      * If this is set to `true`, then the plugin editor should be embedded in
      * yet another window. This would result in an embedding sequence of
@@ -166,6 +180,7 @@ class Configuration {
 
     template <typename S>
     void serialize(S& s) {
+        s.value1b(cache_time_info);
         s.value1b(editor_double_embed);
         s.value1b(editor_force_dnd);
         s.value1b(editor_xembed);

src/plugin/bridges/common.h

@@ -168,6 +168,9 @@ class PluginBridge {
 
         init_msg << "other options: ";
         std::vector<std::string> other_options;
+        if (config.cache_time_info) {
+            other_options.push_back("hack: time info cache");
+        }
         if (config.editor_double_embed) {
             other_options.push_back("editor: double embed");
         }

src/wine-host/bridges/vst2.cpp

@@ -178,7 +178,9 @@ Vst2Bridge::Vst2Bridge(MainContext& main_context,
                 //       value returned by this function during an audio
                 //       processing cycle will be reused for the rest of the
                 //       cycle.
-                cached_time_info.reset();
+                if (config.cache_time_info) {
+                    time_info.reset();
+                }
 
                 // Since the host should only be calling one of `process()`,
                 // processReplacing()` or `processDoubleReplacing()`, we can all
@@ -546,14 +548,15 @@ intptr_t Vst2Bridge::host_callback(AEffect* effect,
                                    void* data,
                                    float option) {
     // HACK: Workaround for a bug in SWAM Cello where it would call
-    //       `audioMasterGetTime()` once for every sample. The `time_info` value
-    //       is assigned inside of `HostCallbackDataConverter::write()`. At the
-    //       beginning of the processing cycle this value will be reset.
-    if (cached_time_info) {
-        return reinterpret_cast<intptr_t>(&*cached_time_info);
+    //       `audioMasterGetTime()` once for every sample. When this option is
+    //       enabled `time_info` should be reset in the process function. The
+    //       `time_info` value is assigned inside of
+    //       `HostCallbackDataConverter::write()`.
+    if (config.cache_time_info && time_info) {
+        return reinterpret_cast<intptr_t>(&*time_info);
     }
 
-    HostCallbackDataConverter converter(effect, cached_time_info);
+    HostCallbackDataConverter converter(effect, time_info);
     return sockets.vst_host_callback.send_event(converter, std::nullopt, opcode,
                                                 index, value, data, option);
 }

src/wine-host/bridges/vst2.h

@@ -77,20 +77,12 @@ class Vst2Bridge : public HostBridge {
     intptr_t host_callback(AEffect*, int, int, intptr_t, void*, float);
 
     /**
-     * The time information returned by the host after the plugin calls
-     * `audioMasterGetTime()`. We'll have to return a pointer to this, so we'll
-     * store it here. If the host returned a null pointer, then we'll just store
-     * a nullopt.
-     *
-     * We'll keep this information around for the entire processing cycle, in
-     * case a plugin somehow calls this function more than once, like the SWAM
-     * Cello plugin does.
-     *
-     * XXX: We don't have any logging for when the plugin calls
-     *      `audioMasterGetTime()` more than once, but printing some message
-     *      44100 times per second also doesn't sound great
+     * With the `audioMasterGetTime` host callback the plugin expects the return
+     * value from the calblack to be a pointer to a VstTimeInfo struct. If the
+     * host did not support a certain time info query, than we'll store the
+     * returned null pointer as a nullopt.
      */
-    std::optional<VstTimeInfo> cached_time_info;
+    std::optional<VstTimeInfo> time_info;
 
    private:
     /**