Made it so you can whitelist what events you want to listen to (flutt…

…er#17108)

ci/licenses_golden/licenses_flutter

@@ -107,6 +107,9 @@ FILE: ../../../flutter/flow/view_holder.cc
 FILE: ../../../flutter/flow/view_holder.h
 FILE: ../../../flutter/flutter_frontend_server/bin/starter.dart
 FILE: ../../../flutter/flutter_frontend_server/lib/server.dart
+FILE: ../../../flutter/fml/ascii_trie.cc
+FILE: ../../../flutter/fml/ascii_trie.h
+FILE: ../../../flutter/fml/ascii_trie_unittests.cc
 FILE: ../../../flutter/fml/backtrace.cc
 FILE: ../../../flutter/fml/backtrace.h
 FILE: ../../../flutter/fml/backtrace_stub.cc

common/settings.h

@@ -91,6 +91,7 @@ struct Settings {
   bool enable_checked_mode = false;
   bool start_paused = false;
   bool trace_skia = false;
+  std::string trace_whitelist;
   bool trace_startup = false;
   bool trace_systrace = false;
   bool dump_skp_on_shader_compilation = false;

fml/BUILD.gn

@@ -10,6 +10,8 @@ import("//flutter/testing/testing.gni")
 
 source_set("fml") {
   sources = [
+    "ascii_trie.cc",
+    "ascii_trie.h",
     "backtrace.h",
     "base32.cc",
     "base32.h",
@@ -236,6 +238,7 @@ executable("fml_unittests") {
   testonly = true
 
   sources = [
+    "ascii_trie_unittests.cc",
     "backtrace_unittests.cc",
     "base32_unittest.cc",
     "command_line_unittest.cc",

fml/ascii_trie.cc

@@ -0,0 +1,48 @@
+// Copyright 2013 The Flutter 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 "flutter/fml/ascii_trie.h"
+#include "flutter/fml/logging.h"
+
+namespace fml {
+typedef AsciiTrie::TrieNode TrieNode;
+typedef AsciiTrie::TrieNodePtr TrieNodePtr;
+
+namespace {
+void Add(TrieNodePtr* trie, const char* entry) {
+  int ch = entry[0];
+  FML_DCHECK(ch < AsciiTrie::kMaxAsciiValue);
+  if (ch != 0) {
+    if (!*trie) {
+      *trie = std::make_unique<TrieNode>();
+    }
+    Add(&(*trie)->children[ch], entry + 1);
+  }
+}
+
+TrieNodePtr MakeTrie(const std::vector<std::string>& entries) {
+  TrieNodePtr result;
+  for (const std::string& entry : entries) {
+    Add(&result, entry.c_str());
+  }
+  return result;
+}
+}  // namespace
+
+void AsciiTrie::Fill(const std::vector<std::string>& entries) {
+  node_ = MakeTrie(entries);
+}
+
+bool AsciiTrie::Query(TrieNode* trie, const char* query) {
+  FML_DCHECK(trie);
+  const char* char_position = query;
+  TrieNode* trie_position = trie;
+  TrieNode* child;
+  int ch;
+  while ((ch = *char_position) && (child = trie_position->children[ch].get())) {
+    char_position++;
+    trie_position = child;
+  }
+  return !child && trie_position != trie;
+}
+}  // namespace fml

fml/ascii_trie.h

@@ -0,0 +1,39 @@
+// Copyright 2013 The Flutter Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef FLUTTER_FML_ASCIITRIE_H_
+#define FLUTTER_FML_ASCIITRIE_H_
+
+#include <string>
+#include <vector>
+
+namespace fml {
+
+/// A trie for looking for ASCII prefixes.
+class AsciiTrie {
+ public:
+  struct TrieNode;
+  typedef std::unique_ptr<TrieNode> TrieNodePtr;
+  /// The max Ascii value.
+  static const int kMaxAsciiValue = 128;
+
+  /// Clear and insert all the entries into the trie.
+  void Fill(const std::vector<std::string>& entries);
+
+  /// Returns true if \p argument is prefixed by the contents of the trie.
+  inline bool Query(const char* argument) {
+    return !node_ || Query(node_.get(), argument);
+  }
+
+  struct TrieNode {
+    TrieNodePtr children[kMaxAsciiValue];
+  };
+
+ private:
+  static bool Query(TrieNode* trie, const char* query);
+  TrieNodePtr node_;
+};
+}  // namespace fml
+
+#endif

fml/ascii_trie_unittests.cc

@@ -0,0 +1,36 @@
+// Copyright 2013 The Flutter 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 "flutter/fml/ascii_trie.h"
+#include "gtest/gtest.h"
+
+using fml::AsciiTrie;
+
+TEST(AsciiTableTest, Simple) {
+  AsciiTrie trie;
+  auto entries = std::vector<std::string>{"foo"};
+  trie.Fill(entries);
+  ASSERT_TRUE(trie.Query("foobar"));
+  ASSERT_FALSE(trie.Query("google"));
+}
+
+TEST(AsciiTableTest, ExactMatch) {
+  AsciiTrie trie;
+  auto entries = std::vector<std::string>{"foo"};
+  trie.Fill(entries);
+  ASSERT_TRUE(trie.Query("foo"));
+}
+
+TEST(AsciiTableTest, Empty) {
+  AsciiTrie trie;
+  ASSERT_TRUE(trie.Query("foo"));
+}
+
+TEST(AsciiTableTest, MultipleEntries) {
+  AsciiTrie trie;
+  auto entries = std::vector<std::string>{"foo", "bar"};
+  trie.Fill(entries);
+  ASSERT_TRUE(trie.Query("foozzz"));
+  ASSERT_TRUE(trie.Query("barzzz"));
+}