tracing: split trace event filter classes out of TraceLog

base/trace_event/heap_profiler_event_filter.cc

Index: base/trace_event/heap_profiler_event_filter.cc
diff --git a/base/trace_event/heap_profiler_event_filter.cc b/base/trace_event/heap_profiler_event_filter.cc
new file mode 100644
index 0000000000000000000000000000000000000000..b666f19581275efe2497afb4e9b5d97adaed218d
--- /dev/null
+++ b/base/trace_event/heap_profiler_event_filter.cc
@@ -0,0 +1,60 @@
+// Copyright 2016 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "base/trace_event/heap_profiler_event_filter.h"
+
+#include "base/trace_event/category_registry.h"
+#include "base/trace_event/heap_profiler_allocation_context_tracker.h"
+#include "base/trace_event/trace_category.h"
+#include "base/trace_event/trace_event.h"
+#include "base/trace_event/trace_event_impl.h"
+
+namespace base {
+namespace trace_event {
+
+// static
+const char HeapProfilerEventFilter::kName[] = "heap_profiler_predicate";
+
+HeapProfilerEventFilter::HeapProfilerEventFilter() {}
+HeapProfilerEventFilter::~HeapProfilerEventFilter() {}
+
+bool HeapProfilerEventFilter::FilterTraceEvent(
+    const TraceEvent& trace_event) const {
+  if (AllocationContextTracker::capture_mode() !=
+      AllocationContextTracker::CaptureMode::PSEUDO_STACK) {
+    return true;
+  }
+
+  // TODO(primiano): Add support for events with copied name crbug.com/581079.
+  if (trace_event.flags() & TRACE_EVENT_FLAG_COPY)
+    return true;
+
+  const char* category_name = CategoryRegistry::GetCategoryByStatePtr(
+                                  trace_event.category_group_enabled())

[kraynov, 2016/12/06 18:24:23]

hard readable

[Primiano Tucci (use gerrit), 2016/12/07 11:17:47]

unfortunately this is what our style imposes and what git cl format does.
Feel free to suggest a better way around it.

+                                  ->name();
+  if (trace_event.phase() == TRACE_EVENT_PHASE_BEGIN ||
+      trace_event.phase() == TRACE_EVENT_PHASE_COMPLETE) {
+    AllocationContextTracker::GetInstanceForCurrentThread()
+        ->PushPseudoStackFrame({category_name, trace_event.name()});
+  } else if (trace_event.phase() == TRACE_EVENT_PHASE_END) {
+    // The pop for |TRACE_EVENT_PHASE_COMPLETE| events is in |EndEvent|.
+    AllocationContextTracker::GetInstanceForCurrentThread()
+        ->PopPseudoStackFrame({category_name, trace_event.name()});
+  }
+  // Do not filter-out any events and always return true. TraceLog adds the
+  // event only if it is enabled for recording.
+  return true;
+}
+
+void HeapProfilerEventFilter::EndEvent(const char* category_name,
+                                       const char* event_name) const {
+  if (AllocationContextTracker::capture_mode() ==
+      AllocationContextTracker::CaptureMode::PSEUDO_STACK) {
+    AllocationContextTracker::GetInstanceForCurrentThread()

[kraynov, 2016/12/06 18:24:23]

Should you check that it's TRACE_EVENT_PHASE_COMPLETE? Like you mentioned at
line 41?

[Primiano Tucci (use gerrit), 2016/12/07 11:17:47]

No, in an "EndEvent" there cannot be any BEGIN phases. Also I concretely don't
have any event object on which to test the PHASE_COMPLETE here.

+        ->PopPseudoStackFrame({category_name, event_name});
+  }
+}
+
+}  // namespace trace_event
+}  // namespace base