Rename asset_stream_manager to cdc_stream (#27)

Fixes #13

cdc_stream/cdc_fuse_manager.h

@@ -0,0 +1,99 @@
+/*
+ * 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_CDC_FUSE_MANAGER_H_
+#define CDC_STREAM_CDC_FUSE_MANAGER_H_
+
+#include "absl/status/status.h"
+#include "common/remote_util.h"
+
+namespace cdc_ft {
+
+class Process;
+class ProcessFactory;
+class RemoteUtil;
+
+// Manages the gamelet-side CDC FUSE filesystem process.
+class CdcFuseManager {
+ public:
+  CdcFuseManager(std::string instance, ProcessFactory* process_factory,
+                 RemoteUtil* remote_util);
+  ~CdcFuseManager();
+
+  CdcFuseManager(CdcFuseManager&) = delete;
+  CdcFuseManager& operator=(CdcFuseManager&) = delete;
+
+  // Starts the CDC FUSE and establishes a reverse SSH tunnel from the gamelet's
+  // |remote_port| to the workstation's |local_port|. Deploys the binary if
+  // necessary.
+  //
+  // |mount_dir| is the remote directory where to mount the FUSE.
+  // |verbosity| is the log verbosity used by the filesystem.
+  // |debug| puts the filesystem into debug mode if set to true. This also
+  // causes the process to run in the foreground, so that logs are piped through
+  // SSH to stdout of the workstation process.
+  // |singlethreaded| puts the filesystem into single-threaded mode if true.
+  // |enable_stats| determines whether FUSE should send debug statistics.
+  // |check| determines whether to execute FUSE consistency check.
+  // |cache_capacity| defines the cache capacity in bytes.
+  // |cleanup_timeout_sec| defines the data provider cleanup timeout in seconds.
+  // |access_idle_timeout_sec| defines the number of seconds after which data
+  // provider is considered to be access-idling.
+  absl::Status Start(const std::string& mount_dir, uint16_t local_port,
+                     uint16_t remote_port, int verbosity, bool debug,
+                     bool singlethreaded, bool enable_stats, bool check,
+                     uint64_t cache_capacity, uint32_t cleanup_timeout_sec,
+                     uint32_t access_idle_timeout_sec);
+
+  // Stops the CDC FUSE.
+  absl::Status Stop();
+
+  // Returns true if the FUSE process is running.
+  bool IsHealthy() const;
+
+ private:
+  // Runs the FUSE process on the gamelet from the given |remote_command| and
+  // establishes a reverse SSH tunnel from the gamelet's |remote_port| to the
+  // workstation's |local_port|.
+  //
+  // If the FUSE is not up-to-date or does not exist, sets |needs_deploy| to
+  // true and returns OK. In that case, Deploy() needs to be called and the FUSE
+  // process should be run again.
+  absl::Status RunFuseProcess(uint16_t local_port, uint16_t remote_port,
+                              const std::string& remote_command,
+                              bool* needs_deploy);
+
+  // Deploys the gamelet components.
+  absl::Status Deploy();
+
+  // Output handler for FUSE's stdout. Sets |needs_deploy| to true if the output
+  // contains a magic marker to indicate that the binary has to be redeployed.
+  // Called in a background thread.
+  absl::Status HandleFuseStdout(const char* data, size_t size,
+                                bool* needs_deploy);
+
+  std::string instance_;
+  ProcessFactory* const process_factory_;
+  RemoteUtil* const remote_util_;
+
+  std::unique_ptr<Process> fuse_process_;
+  std::string fuse_stdout_;
+  std::atomic<bool> fuse_startup_finished_{false};
+};
+
+}  // namespace cdc_ft
+
+#endif  // CDC_STREAM_CDC_FUSE_MANAGER_H_