Add Gpu Tracing to Ganesh

src/gpu/GrTracing.h

+/*
+ * Copyright 2014 Google Inc.
+ *
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ */
+
+#ifndef GrTracing_DEFINED
+#define GrTracing_DEFINED
+
+#include "GrDrawTarget.h"
+#include "GrTraceMarker.h"
+#include "SkTraceEvent.h"
+
+/**
+ * Marker generation class used for adding and removing markers around code blocks
+ */
+class GrGpuTraceMarkerGenerator : public ::SkNoncopyable {
+public:
+    GrGpuTraceMarkerGenerator(GrDrawTarget* target) : fTarget(target) {}
+
+    ~GrGpuTraceMarkerGenerator() {
+        if (fTraceMarker.isValid()) {
+            fTarget->removeGpuTraceMarker(fTraceMarker.get());
+        }
+    }
+
+    void initialize(const char* marker_str, int* marker_counter) {
+        GrGpuTraceMarker* traceMarker = fTraceMarker.init();
+        traceMarker->fMarker = marker_str;
+        traceMarker->fID = *marker_counter;
+        fTarget->addGpuTraceMarker(traceMarker);
+    }
+
+private:
+    GrDrawTarget* fTarget;
+    SkTLazy<GrGpuTraceMarker> fTraceMarker;
+};
+
+/**
+ * GR_CREATE_TRACE_MARKER will place begin and end trace markers for both
+ * cpu and gpu (if gpu tracing enabled) for the current scope.

[tomhudson, 2014/03/24 16:31:43]

Just to check: does this default to always-on for CPU tracing? If so,
performance on Android will be unacceptable; always-on TRACE_EVENT()s should be
low-frequency.

[egdaniel, 2014/03/24 16:59:59]

So the cpu Trace events are set using TRACE_EVENT1 call. From my understanding
these trace events are controlled by their category_group_enabled flags, which
by default "skia.gpu" should be disabled as implemented below.

On 2014/03/24 16:31:43, tomhudson wrote:

+ * marker is of type const char* and target is of type GrDrawTarget*
+ */
+#define GR_CREATE_TRACE_MARKER(name, target)                              \
+    static const char* SK_MACRO_APPEND_LINE(static_name) = name;          \
+    static int SK_MACRO_APPEND_LINE(name_counter) = 0;                    \
+    INTERNAL_GR_CREATE_TRACE_MARKER(SK_MACRO_APPEND_LINE(static_name),    \
+                                    SK_MACRO_APPEND_LINE(name_counter),   \
+                                    target)                               \
+
+#define INTERNAL_GR_CREATE_TRACE_MARKER(name, name_counter, target)       \
+    GR_CREATE_GPU_TRACE_MARKER(name, name_counter, target)                \
+    TRACE_EVENT1(TRACE_DISABLED_BY_DEFAULT("skia.gpu"),name,              \
+                 "id", name_counter)                                      \
+    sk_atomic_inc(&name_counter);                                         \
+
+#define GR_CREATE_GPU_TRACE_MARKER(name, name_counter, target)            \
+    GrGpuTraceMarkerGenerator SK_MACRO_APPEND_LINE(TMG)(target);          \
+    if (target->isGpuTracingEnabled()) {                                  \
+        SK_MACRO_APPEND_LINE(TMG).initialize(name, &name_counter);        \
+    }                                                                     \
+
+
+#endif
+