Emulate glReadPixels of GL_ALPHA.

[movit] / resource_pool.h

diff --git a/resource_pool.h b/resource_pool.h
index 6f4d22d0a4001bd23008fa456348afde0c930c5b..d8d8ceca3ca1deb2b50dfd2b45fa256af908beeb 100644 (file)
--- a/resource_pool.h
+++ b/resource_pool.h
@@ -16,12 +16,15 @@
 // safely called from multiple threads at the same time, provided they have
 // separate (but sharing) OpenGL contexts.
 
+#include <epoxy/gl.h>
+#include <pthread.h>
+#include <stddef.h>
 #include <list>
 #include <map>
 #include <string>
 #include <utility>
-#include <GL/glew.h>
-#include <pthread.h>
+
+namespace movit {
 
 class ResourcePool {
 public:
@@ -29,7 +32,15 @@ public:
        // around after they are no longer in use (in case another EffectChain
        // wants that exact program later). Shaders are expensive to compile and do not
        // need a lot of resources to keep around, so this should be a reasonable number.
-       ResourcePool(size_t program_freelist_max_length = 100);
+       //
+       // texture_freelist_max_bytes is how many bytes of unused textures to keep around
+       // after they are no longer in use (in case a new texture of the same dimensions
+       // and format is needed). Note that the size estimate is very coarse; it does not
+       // take into account padding, metadata, and most importantly mipmapping.
+       // This means you should be prepared for actual memory usage of the freelist being
+       // twice this estimate or more.
+       ResourcePool(size_t program_freelist_max_length = 100,
+                    size_t texture_freelist_max_bytes = 100 << 20);  // 100 MB.
        ~ResourcePool();
 
        // All remaining functions are intended for calls from EffectChain only.
@@ -57,7 +68,7 @@ private:
        // Protects all the other elements in the class.
        pthread_mutex_t lock;
 
-       size_t program_freelist_max_length;
+       size_t program_freelist_max_length, texture_freelist_max_bytes;
                
        // A mapping from vertex/fragment shader source strings to compiled program number.
        std::map<std::pair<std::string, std::string>, GLuint> programs;
@@ -74,6 +85,29 @@ private:
        // Once this reaches <program_freelist_max_length>, the last element
        // will be deleted.
        std::list<GLuint> program_freelist;
+
+       struct Texture2D {
+               GLint internal_format;
+               GLsizei width, height;
+       };
+
+       // A mapping from texture number to format details. This is filled if the
+       // texture is given out to a client or on the freelist, but not if it is
+       // deleted from the freelist.
+       std::map<GLuint, Texture2D> texture_formats;
+
+       // A list of all textures that are release but not freed (most recently freed
+       // first), and an estimate of their current memory usage. Once
+       // <texture_freelist_bytes> goes above <texture_freelist_max_bytes>,
+       // elements are deleted off the end of the list until we are under the limit
+       // again.
+       std::list<GLuint> texture_freelist;
+       size_t texture_freelist_bytes;
+
+       // See the caveats at the constructor.
+       static size_t estimate_texture_size(const Texture2D &texture_format);
 };
 
+}  // namespace movit
+
 #endif  // !defined(_MOVIT_RESOURCE_POOL_H)