glestrace: Framework for GLES tracing library
This patch provides a framework for tracing GLES 1.0 and 2.0
functions. It is missing a lot of features, but here are the
things it accomplishes:
- Stop building the glesv2dbg library, and build the
glestrace library instead.
- Replace the hooks for glesv2dbg with the ones for glestrace.
- Add the basics for the trace library. Currently, this
traces all GL functions, but not all required data is
sent for all the functions. As a result, it will not
be possible to reconstruct the entire GL state on the
host side.
The files gltrace.pb.* and gltrace_api.* are both generated
using the tools/genapi.py script.
Change-Id: Id60a468f7278657f008bc6ea1df01f9bdfecfdd3
diff --git a/opengl/libs/GLES_trace/DESIGN.txt b/opengl/libs/GLES_trace/DESIGN.txt
new file mode 100644
index 0000000..a189e1d
--- /dev/null
+++ b/opengl/libs/GLES_trace/DESIGN.txt
@@ -0,0 +1,51 @@
+Design of the GLES Tracing Library
+
+Code Runtime Behavior:
+
+ Initialization:
+
+ egl_display_t::initialize() calls initEglTraceLevel() to figure out whether tracing should be
+ enabled. Currently, the shell properties "debug.egl.trace" and "debug.egl.debug_proc" together
+ control whether tracing should be enabled for a certain process. If tracing is enabled, this
+ calls GLTrace_start() to start the trace server.
+
+ Note that initEglTraceLevel() is also called from early_egl_init(), but that happens in the
+ context of the zygote, so that invocation has no effect.
+
+ egl_display_t::initialize() then calls setGLHooksThreadSpecific() where we set the thread
+ specific gl_hooks structure to point to the trace implementation. From this point on, every
+ GLES call is redirected to the trace implementation.
+
+ Application runtime:
+
+ While the application is running, all its GLES calls are directly routed to their corresponding
+ trace implementation.
+
+ For EGL calls, the trace library provides a bunch of functions that must be explicitly called
+ from the EGL library. These functions are declared in glestrace.h
+
+ Application shutdown:
+
+ Currently, the application is killed when the user stops tracing from the frontend GUI. We need
+ to explore if a more graceful method of stopping the application, or detaching tracing from the
+ application is required.
+
+Code Structure:
+
+ glestrace.h declares all the hooks exposed by libglestrace. These are used by EGL/egl.cpp and
+ EGL/eglApi.cpp to initialize the trace library, and to inform the library of EGL calls.
+
+ All GL calls are present in GLES_Trace/src/gltrace_api.cpp. This file is generated by the
+ GLES_Trace/src/genapi.py script. The structure of all the functions looks like this:
+
+ void GLTrace_glFunction(args) {
+ // declare a protobuf
+ // copy arguments into the protobuf
+ // call the original GLES function
+ // if there is a return value, save it into the protobuf
+ // fixup the protobuf if necessary
+ // transport the protobuf to the host
+ }
+
+ The fixupGLMessage() call does any custom processing of the protobuf based on the GLES call.
+ This typically amounts to copying the data corresponding to input or output pointers.