tracing: split trace event filter classes out of TraceLog

base/trace_event/heap_profiler_event_filter.cc

+// 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 {
+
+namespace {
+
+inline bool IsPseudoStackEnabled() {
+  return AllocationContextTracker::capture_mode() ==
+         AllocationContextTracker::CaptureMode::PSEUDO_STACK;
+}
+
+inline AllocationContextTracker* GetThreadLocalTracker() {
+  return AllocationContextTracker::GetInstanceForCurrentThread();
+}
+
+}  // namespace
+
+// static
+const char HeapProfilerEventFilter::kName[] = "heap_profiler_predicate";
+
+HeapProfilerEventFilter::HeapProfilerEventFilter() {}
+HeapProfilerEventFilter::~HeapProfilerEventFilter() {}
+
+bool HeapProfilerEventFilter::FilterTraceEvent(
+    const TraceEvent& trace_event) const {
+  if (!IsPseudoStackEnabled())
+    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 auto* category = CategoryRegistry::GetCategoryByStatePtr(
+      trace_event.category_group_enabled());
+  AllocationContextTracker::PseudoStackFrame frame = {category->name(),
+                                                      trace_event.name()};
+  if (trace_event.phase() == TRACE_EVENT_PHASE_BEGIN ||
+      trace_event.phase() == TRACE_EVENT_PHASE_COMPLETE) {
+    GetThreadLocalTracker()->PushPseudoStackFrame(frame);
+  } else if (trace_event.phase() == TRACE_EVENT_PHASE_END) {
+    // The pop for |TRACE_EVENT_PHASE_COMPLETE| events is in |EndEvent|.
+    GetThreadLocalTracker()->PopPseudoStackFrame(frame);
+  }
+  // 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 (IsPseudoStackEnabled())
+    GetThreadLocalTracker()->PopPseudoStackFrame({category_name, event_name});
+}
+
+}  // namespace trace_event
+}  // namespace base