1 files changed, 134 insertions, 0 deletions
diff --git a/src/aiet/backend/controller.py b/src/aiet/backend/controller.py
new file mode 100644
index 0000000..2650902
--- /dev/null
+++ b/src/aiet/backend/controller.py
@@ -0,0 +1,134 @@
+# SPDX-FileCopyrightText: Copyright 2022, Arm Limited and/or its affiliates.
+# SPDX-License-Identifier: Apache-2.0
+"""Controller backend module."""
+import time
+from pathlib import Path
+from typing import List
+from typing import Optional
+from typing import Tuple
+
+import psutil
+import sh
+
+from aiet.backend.common import ConfigurationException
+from aiet.utils.fs import read_file_as_string
+from aiet.utils.proc import execute_command
+from aiet.utils.proc import get_stdout_stderr_paths
+from aiet.utils.proc import read_process_info
+from aiet.utils.proc import save_process_info
+from aiet.utils.proc import terminate_command
+from aiet.utils.proc import terminate_external_process
+
+
+class SystemController:
+    """System controller class."""
+
+    def __init__(self) -> None:
+        """Create new instance of service controller."""
+        self.cmd: Optional[sh.RunningCommand] = None
+        self.out_path: Optional[Path] = None
+        self.err_path: Optional[Path] = None
+
+    def before_start(self) -> None:
+        """Run actions before system start."""
+
+    def after_start(self) -> None:
+        """Run actions after system start."""
+
+    def start(self, commands: List[str], cwd: Path) -> None:
+        """Start system."""
+        if not isinstance(cwd, Path) or not cwd.is_dir():
+            raise ConfigurationException("Wrong working directory {}".format(cwd))
+
+        if len(commands) != 1:
+            raise ConfigurationException("System should have only one command to run")
+
+        startup_command = commands[0]
+        if not startup_command:
+            raise ConfigurationException("No startup command provided")
+
+        self.before_start()
+
+        self.out_path, self.err_path = get_stdout_stderr_paths(startup_command)
+
+        self.cmd = execute_command(
+            startup_command,
+            cwd,
+            bg=True,
+            out=str(self.out_path),
+            err=str(self.err_path),
+        )
+
+        self.after_start()
+
+    def stop(
+        self, wait: bool = False, wait_period: float = 0.5, number_of_attempts: int = 20
+    ) -> None:
+        """Stop system."""
+        if self.cmd is not None and self.is_running():
+            terminate_command(self.cmd, wait, wait_period, number_of_attempts)
+
+    def is_running(self) -> bool:
+        """Check if underlying process is running."""
+        return self.cmd is not None and self.cmd.is_alive()
+
+    def get_output(self) -> Tuple[str, str]:
+        """Return application output."""
+        if self.cmd is None or self.out_path is None or self.err_path is None:
+            return ("", "")
+
+        return (read_file_as_string(self.out_path), read_file_as_string(self.err_path))
+
+
+class SystemControllerSingleInstance(SystemController):
+    """System controller with support of system's single instance."""
+
+    def __init__(self, pid_file_path: Optional[Path] = None) -> None:
+        """Create new instance of the service controller."""
+        super().__init__()
+        self.pid_file_path = pid_file_path
+
+    def before_start(self) -> None:
+        """Run actions before system start."""
+        self._check_if_previous_instance_is_running()
+
+    def after_start(self) -> None:
+        """Run actions after system start."""
+        self._save_process_info()
+
+    def _check_if_previous_instance_is_running(self) -> None:
+        """Check if another instance of the system is running."""
+        process_info = read_process_info(self._pid_file())
+
+        for item in process_info:
+            try:
+                process = psutil.Process(item.pid)
+                same_process = (
+                    process.name() == item.name
+                    and process.exe() == item.executable
+                    and process.cwd() == item.cwd
+                )
+                if same_process:
+                    print(
+                        "Stopping previous instance of the system [{}]".format(item.pid)
+                    )
+                    terminate_external_process(process)
+            except psutil.NoSuchProcess:
+                pass
+
+    def _save_process_info(self, wait_period: float = 2) -> None:
+        """Save information about system's processes."""
+        if self.cmd is None or not self.is_running():
+            return
+
+        # give some time for the system to start
+        time.sleep(wait_period)
+
+        save_process_info(self.cmd.process.pid, self._pid_file())
+
+    def _pid_file(self) -> Path:
+        """Return path to file which is used for saving process info."""
+        if not self.pid_file_path:
+            raise Exception("No pid file path presented")
+
+        return self.pid_file_path