diff options
Diffstat (limited to 'opengl/libs/GLES_trace/DESIGN.txt')
| -rw-r--r-- | opengl/libs/GLES_trace/DESIGN.txt | 34 |
1 files changed, 31 insertions, 3 deletions
diff --git a/opengl/libs/GLES_trace/DESIGN.txt b/opengl/libs/GLES_trace/DESIGN.txt index a189e1d..72a2e15 100644 --- a/opengl/libs/GLES_trace/DESIGN.txt +++ b/opengl/libs/GLES_trace/DESIGN.txt @@ -9,9 +9,6 @@ Code Runtime Behavior: 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. @@ -30,6 +27,37 @@ Code Runtime Behavior: to explore if a more graceful method of stopping the application, or detaching tracing from the application is required. + +Enabling tracing while the application is running: + + In order to allow tracing of an already running application, we allow DdmServer to enable + OpenGL tracing. In such a case, the application already has its GL hooks set up to point to the + real GL implementation, and we need to switch them to point to the trace implementation. + + This is achieved by checking whether tracing should be enabled at every eglSwap call. + (Note: We were already checking for tracing at every eglSwap, the only change now is that + the tracing could actually be ON/OFF at runtime - earlier it was set once and never changed). + + If eglSwap detects that tracing should be enabled now, then it performs the following steps: + - switch the gl hooks to point to the trace implementation. + - call trace eglMakeCurrent to indicate that there is now a new context that is current. + - continue on with tracing the eglSwap call. + This switches the hooks to point to the trace implementation only for the current context. + But the other contexts have their gl hooks updated when they perform eglMakeCurrent. + + The GLTrace version of eglMakeCurrent now has to be updated to allow switching to a context + it may not know of. In such a case, it creates a context matching the version that it is now + switching to. + +Disabling tracing: + + We disable tracing under two conditions: + - stop tracing request from DdmServer + - gltrace transport gets disconnected from the host. + In either case, both actions simply disable the tracing flag. The current context gets its + gl hooks restored in the next eglSwap, and the other traced contexts get their gl hooks + restored when they perform a eglMakeCurrent. + Code Structure: glestrace.h declares all the hooks exposed by libglestrace. These are used by EGL/egl.cpp and |