[gl] Added mbgl::gl::BufferHolder

2 files changed, 33 insertions, 10 deletions

diff --git a/src/mbgl/gl/gl_object_store.cpp b/src/mbgl/gl/gl_object_store.cpp
index 7a6037d505..68d743cd95 100644
--- a/src/mbgl/gl/gl_object_store.cpp
+++ b/src/mbgl/gl/gl_object_store.cpp
@@ -35,15 +35,28 @@ void ShaderHolder::reset() {
     id = 0;
 }
 
+void BufferHolder::create() {
+    if (id) return;
+    assert(util::ThreadContext::currentlyOn(util::ThreadType::Map));
+    MBGL_CHECK_ERROR(glGenBuffers(1, &id));
+}
+
+void BufferHolder::reset() {
+    if (!id) return;
+    assert(util::ThreadContext::currentlyOn(util::ThreadType::Map));
+    MBGL_CHECK_ERROR(glDeleteBuffers(1, &id));
+    id = 0;
+}
+
 
 void GLObjectStore::abandonVAO(GLuint vao) {
     assert(util::ThreadContext::currentlyOn(util::ThreadType::Map));
     abandonedVAOs.emplace_back(vao);
 }
 
-void GLObjectStore::abandonBuffer(GLuint buffer) {
+void GLObjectStore::abandon(BufferHolder&& buffer) {
     assert(util::ThreadContext::currentlyOn(util::ThreadType::Map));
-    abandonedBuffers.emplace_back(buffer);
+    abandonedBuffers.push_back(std::move(buffer));
 }
 
 void GLObjectStore::abandonTexture(GLuint texture) {
@@ -60,17 +73,13 @@ void GLObjectStore::performCleanup() {
         abandonedVAOs.clear();
     }
 
+    abandonedBuffers.clear();
+
     if (!abandonedTextures.empty()) {
         MBGL_CHECK_ERROR(glDeleteTextures(static_cast<GLsizei>(abandonedTextures.size()),
                                           abandonedTextures.data()));
         abandonedTextures.clear();
     }
-
-    if (!abandonedBuffers.empty()) {
-        MBGL_CHECK_ERROR(glDeleteBuffers(static_cast<GLsizei>(abandonedBuffers.size()),
-                                         abandonedBuffers.data()));
-        abandonedBuffers.clear();
-    }
 }
 
 } // namespace gl
diff --git a/src/mbgl/gl/gl_object_store.hpp b/src/mbgl/gl/gl_object_store.hpp
index 6c7f3c92f2..7b9409f329 100644
--- a/src/mbgl/gl/gl_object_store.hpp
+++ b/src/mbgl/gl/gl_object_store.hpp
@@ -51,11 +51,23 @@ private:
     GLenum type = 0;
 };
 
+class BufferHolder : public GLHolder {
+public:
+    BufferHolder() = default;
+    ~BufferHolder() { reset(); }
+
+    BufferHolder(BufferHolder&& o) noexcept : GLHolder(std::move(o)) {}
+    BufferHolder& operator=(BufferHolder&& o) noexcept { GLHolder::operator=(std::move(o)); return *this; }
+
+    void create();
+    void reset();
+};
+
 class GLObjectStore : private util::noncopyable {
 public:
     // Mark OpenGL objects for deletion
     void abandonVAO(GLuint vao);
-    void abandonBuffer(GLuint buffer);
+    void abandon(BufferHolder&&);
     void abandonTexture(GLuint texture);
 
     // Actually remove the objects we marked as abandoned with the above methods.
@@ -63,8 +75,10 @@ public:
     void performCleanup();
 
 private:
+    // We split the holder objects in separate containers because each
+    // GLHolder-derived object can vary in size.
     std::vector<GLuint> abandonedVAOs;
-    std::vector<GLuint> abandonedBuffers;
+    std::vector<BufferHolder> abandonedBuffers;
     std::vector<GLuint> abandonedTextures;
 };