From 0c9c4686f10e9ff9132f5a5bd2f59e2ba3872b76 Mon Sep 17 00:00:00 2001
From: Robbert van der Helm <mail@robbertvanderhelm.nl>
Date: Thu, 23 Sep 2021 14:29:12 +0200
Subject: [PATCH] Use the small buffer optimization for VST3 SysEx

We apparently didn't do that yet. SysEx should be super rare (outside of
octave switching on Arturia keyboards), but there's still no reason not
to do it.
---
 CHANGELOG.md                                 |  6 ++++++
 src/common/serialization/vst3/event-list.cpp |  9 ++++++---
 src/common/serialization/vst3/event-list.h   | 12 +++++++++---
 3 files changed, 21 insertions(+), 6 deletions(-)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index a4b55521..79b4df57 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -33,6 +33,12 @@ Versioning](https://semver.org/spec/v2.0.0.html).
 - The `editor_double_embed` option added in yabridge 1.4.0 has been removed as
   the `editor_coordinate_hack` option supersedes it.
 
+### Changed
+
+- VST3 Data (SysEx) events now use the same small buffer optimization we use for
+  VST2 SysEx events. This avoids allocations when a VST3 plugin sends or
+  receives a SysEx event.
+
 ### Fixed
 
 - Fixed _New Sonic Arts' Vice_ plugin freezing when loading the plugin. This
diff --git a/src/common/serialization/vst3/event-list.cpp b/src/common/serialization/vst3/event-list.cpp
index 756cc002..cc9e0b42 100644
--- a/src/common/serialization/vst3/event-list.cpp
+++ b/src/common/serialization/vst3/event-list.cpp
@@ -24,9 +24,12 @@ YaDataEvent::YaDataEvent(const Steinberg::Vst::DataEvent& event) noexcept
     : type(event.type), buffer(event.bytes, event.bytes + event.size) {}
 
 Steinberg::Vst::DataEvent YaDataEvent::get() const noexcept {
-    return Steinberg::Vst::DataEvent{.size = static_cast<uint32>(buffer.size()),
-                                     .type = type,
-                                     .bytes = buffer.data()};
+    static_assert(sizeof(decltype(buffer)::value_type) == sizeof(uint8));
+
+    return Steinberg::Vst::DataEvent{
+        .size = static_cast<uint32>(buffer.size()),
+        .type = type,
+        .bytes = reinterpret_cast<const uint8*>(buffer.data())};
 }
 
 YaNoteExpressionTextEvent::YaNoteExpressionTextEvent() noexcept {}
diff --git a/src/common/serialization/vst3/event-list.h b/src/common/serialization/vst3/event-list.h
index 1fc84020..ec31e493 100644
--- a/src/common/serialization/vst3/event-list.h
+++ b/src/common/serialization/vst3/event-list.h
@@ -31,7 +31,7 @@
 
 /**
  * A wrapper around `DataEvent` for serialization purposes, as this event
- * contains a heap array.
+ * contains a heap array. This would presumably be used for SysEx.
  */
 struct YaDataEvent {
     YaDataEvent() noexcept;
@@ -50,12 +50,18 @@ struct YaDataEvent {
     Steinberg::Vst::DataEvent get() const noexcept;
 
     uint32 type;
-    std::vector<uint8> buffer;
+
+    /**
+     * We'll just abuse the standard library's Small String Optimization to
+     * avoid allocations for small messages, just like we do for VST2 SysEx
+     * events.
+     */
+    std::string buffer;
 
     template <typename S>
     void serialize(S& s) {
         s.value4b(type);
-        s.container1b(buffer, 1 << 16);
+        s.text1b(buffer, 1 << 16);
     }
 };