Add compat framework logging to ART

Log first call for every change id in ART to logcat.

Test: manual
Bug: 153061480

Change-Id: I37ff5b88572478ae6c24b0b7dec2020da03b2172
diff --git a/runtime/compat_framework.cc b/runtime/compat_framework.cc
new file mode 100644
index 0000000..40c4540
--- /dev/null
+++ b/runtime/compat_framework.cc
@@ -0,0 +1,65 @@
+/*
+ * Copyright (C) 2020 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include "compat_framework.h"
+
+#include "android-base/logging.h"
+#include <sys/types.h>
+#include <unistd.h>
+
+namespace art {
+
+// Compat change states as strings.
+static constexpr char kUnknownChangeState[] = "UNKNOWN";
+static constexpr char kEnabledChangeState[] = "ENABLED";
+static constexpr char kDisabledChangeState[] = "DISABLED";
+static constexpr char kLoggedState[] = "LOGGED";
+
+bool CompatFramework::IsChangeEnabled(uint64_t change_id) {
+  const auto enabled = disabled_compat_changes_.count(change_id) == 0;
+  ReportChange(change_id, enabled ? ChangeState::kEnabled : ChangeState::kDisabled);
+  return enabled;
+}
+
+void CompatFramework::LogChange(uint64_t change_id) {
+  ReportChange(change_id, ChangeState::kLogged);
+}
+
+void CompatFramework::ReportChange(uint64_t change_id, ChangeState state) {
+  bool already_reported = reported_compat_changes_.count(change_id) != 0;
+  if (already_reported) {
+    return;
+  }
+  LOG(DEBUG) << "Compat change id reported: " << change_id << "; UID " << getuid()
+            << "; state: " << ChangeStateToString(state);
+  // TODO(145743810): add an up call to java to log to statsd
+  reported_compat_changes_.emplace(change_id);
+}
+
+std::string_view CompatFramework::ChangeStateToString(ChangeState state) {
+  switch (state) {
+    case ChangeState::kUnknown:
+      return kUnknownChangeState;
+    case ChangeState::kEnabled:
+      return kEnabledChangeState;
+    case ChangeState::kDisabled:
+      return kDisabledChangeState;
+    case ChangeState::kLogged:
+      return kLoggedState;
+  }
+}
+
+}  // namespace art