Fix an issue where a (cached) shader program could be used from multiple

[movit] / resource_pool.h

diff --git a/resource_pool.h b/resource_pool.h
index 5cc2e829e8f836635b04980978372973d3618639..8503b29b6e0020d0111e83c459905a57694e9cd3 100644 (file)
--- a/resource_pool.h
+++ b/resource_pool.h
@@ -27,6 +27,7 @@
 #include <stddef.h>
 #include <list>
 #include <map>
+#include <stack>
 #include <string>
 #include <utility>
 #include <vector>
@@ -67,6 +68,18 @@ public:
                                    const std::vector<std::string>& frag_shader_outputs);
        void release_glsl_program(GLuint glsl_program_num);
 
+       // Since uniforms belong to the program and not to the context,
+       // a given GLSL program number can't be used by more than one thread
+       // at a time. Thus, if two threads want to use the same program
+       // (usually because two EffectChains share them via caching),
+       // we will need to make a clone. use_glsl_program() makes such
+       // a clone if needed, calls glUseProgram(), and returns the real
+       // program number that was used; this must be given to
+       // unuse_glsl_program() to release it. unuse_glsl_program() does not
+       // actually change any OpenGL state, though.
+       GLuint use_glsl_program(GLuint glsl_program_num);
+       void unuse_glsl_program(GLuint instance_program_num);
+
        // Allocate a 2D texture of the given internal format and dimensions,
        // or fetch a previous used if possible. Unbinds GL_TEXTURE_2D afterwards.
        // Keeps ownership of the texture; you must call release_2d_texture() instead
@@ -110,6 +123,12 @@ private:
        // is no more than <max_length> elements long.
        void shrink_fbo_freelist(void *context, size_t max_length);
 
+       // Link the given vertex and fragment shaders into a full GLSL program.
+       // See compile_glsl_program() for explanation of <fragment_shader_outputs>.
+       static GLuint link_program(GLuint vs_obj,
+                                  GLuint fs_obj,
+                                  const std::vector<std::string>& fragment_shader_outputs);
+
        // Protects all the other elements in the class.
        pthread_mutex_t lock;
 
@@ -124,7 +143,22 @@ private:
        std::map<GLuint, int> program_refcount;
 
        // A mapping from program number to vertex and fragment shaders.
-       std::map<GLuint, std::pair<GLuint, GLuint> > program_shaders;
+       // Contains everything needed to re-link the program.
+       struct ShaderSpec {
+               GLuint vs_obj, fs_obj;
+               std::vector<std::string> fragment_shader_outputs;
+       };
+       std::map<GLuint, ShaderSpec> program_shaders;
+
+       // For each program, a list of other programs that are exactly like it.
+       // By default, will only contain the program itself, but due to cloning
+       // (see use_glsl_program()), may grow. Programs are taken off this list
+       // while they are in use (by use_glsl_program()).
+       std::map<GLuint, std::stack<GLuint> > program_instances;
+
+       // For each program, the master program that created it
+       // (inverse of program_instances).
+       std::map<GLuint, GLuint> program_masters;
 
        // A list of programs that are no longer in use, most recently freed first.
        // Once this reaches <program_freelist_max_length>, the last element