Rename asset_stream_manager to cdc_stream (#27)

Fixes #13

cdc_stream/asset_stream_config.h

@@ -0,0 +1,111 @@
+/*
+ * Copyright 2022 Google LLC
+ *
+ * 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 CDC_STREAM_ASSET_STREAM_CONFIG_H_
+#define CDC_STREAM_SET_STREAM_CONFIG_H_
+
+#include <map>
+#include <set>
+#include <string>
+
+#include "absl/status/status.h"
+#include "cdc_stream/session_config.h"
+#include "session.h"
+
+namespace lyra {
+class command;
+}
+
+namespace cdc_ft {
+
+class BaseCommand;
+
+// Class containing all configuration settings for asset streaming.
+// Reads flags from the command line and optionally applies overrides from
+// a json file.
+class AssetStreamConfig {
+ public:
+  // Constructs the configuration by applying command line flags.
+  AssetStreamConfig();
+  ~AssetStreamConfig();
+
+  // Registers arguments with Lyra.
+  void RegisterCommandLineFlags(lyra::command& cmd, BaseCommand& base_command);
+
+  // Loads a configuration from the JSON file at |path| and overrides any config
+  // values that are set in this file. Sample json file:
+  // {
+  //   "verbosity":3,
+  //   "debug":0,
+  //   "singlethreaded":0,
+  //   "stats":0,
+  //   "quiet":0,
+  //   "check":0,
+  //   "log_to_stdout":0,
+  //   "cache_capacity":"150G",
+  //   "cleanup_timeout":300,
+  //   "access_idle_timeout":5,
+  //   "manifest_updater_threads":4,
+  //   "file_change_wait_duration_ms":500
+  // }
+  // Returns NotFoundError if the file does not exist.
+  // Returns InvalidArgumentError if the file is not valid JSON.
+  absl::Status LoadFromFile(const std::string& path);
+
+  // Returns a string with all config values, suitable for logging.
+  std::string ToString();
+
+  // Gets a comma-separated list of flags that were read from the JSON file.
+  // These flags override command line flags.
+  std::string GetFlagsReadFromFile();
+
+  // Gets a newline-separated list of errors for each flag that could not be
+  // read from the JSON file.
+  std::string GetFlagReadErrors();
+
+  // Session configuration.
+  const SessionConfig& session_cfg() const { return session_cfg_; }
+
+  // Workstation directory to be streamed. Used for development purposes only
+  // to start a session right away when the service starts up. See dev CLI args.
+  const std::string& dev_src_dir() const { return dev_src_dir_; }
+
+  // Session target. Used for development purposes only to start a session right
+  // away when the service starts up. See dev CLI args.
+  const SessionTarget& dev_target() const { return dev_target_; }
+
+  // Whether to log to a file or to stdout.
+  bool log_to_stdout() const { return log_to_stdout_; }
+
+ private:
+  SessionConfig session_cfg_;
+  bool log_to_stdout_ = false;
+
+  // Configuration used for development. Allows users to specify a session
+  // via the service's command line.
+  std::string dev_src_dir_;
+  SessionTarget dev_target_;
+
+  // Use a set, so the flags are sorted alphabetically.
+  std::set<std::string> flags_read_from_file_;
+
+  // Maps flags to errors occurred while reading this flag.
+  std::map<std::string, std::string> flag_read_errors_;
+};
+
+};  // namespace cdc_ft
+
+#endif  // CDC_STREAM_SET_STREAM_CONFIG_H_