use a single file for storing persistent properties
We have seen that storing persistent properties in separate files
causes increased boot latency compared to if they were stored in a
single contiguous file.
This change creates a simple format for a contiguously stored property
file, and adds the support for arbitrary characters in the names of
persistent properties, which previously had been restricted. It has a
mechanism for converting older devices to the new format as well.
Bug: 64392887
Test: boot bullhead with new properties
Test: boot bullhead and verify old properties are converted to the new
property file
Test: corrupt property file and ensure that it gets recovered from memory
Test: new unit tests
Change-Id: I60d8201d655ce5c97b33faae81d5ca8dbbb21a14
diff --git a/init/persistent_properties.h b/init/persistent_properties.h
new file mode 100644
index 0000000..d84d9db
--- /dev/null
+++ b/init/persistent_properties.h
@@ -0,0 +1,42 @@
+/*
+ * Copyright (C) 2017 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.
+ */
+
+#ifndef _INIT_PERSISTENT_PROPERTIES_H
+#define _INIT_PERSISTENT_PROPERTIES_H
+
+#include <string>
+#include <vector>
+
+#include "result.h"
+
+namespace android {
+namespace init {
+
+std::vector<std::pair<std::string, std::string>> LoadPersistentProperties();
+void WritePersistentProperty(const std::string& name, const std::string& value);
+
+// Exposed only for testing
+Result<std::vector<std::pair<std::string, std::string>>> LoadPersistentPropertyFile();
+std::string GenerateFileContents(
+ const std::vector<std::pair<std::string, std::string>>& persistent_properties);
+Result<Success> WritePersistentPropertyFile(
+ const std::vector<std::pair<std::string, std::string>>& persistent_properties);
+extern std::string persistent_property_filename;
+
+} // namespace init
+} // namespace android
+
+#endif