start implementation on new architecture

sia/background_entry.py

@@ -0,0 +1,175 @@
+from datetime import datetime
+import subprocess
+import xml.etree.ElementTree as ET
+from typing import Optional
+
+from .entry import Entry
+from .util import escape_text_for_xml
+
+class BackgroundEntry(Entry):
+    """
+    Entry type for long-running background processes.
+    
+    Attributes:
+        script: The script/command to execute
+        stdout: Captured standard output since last update
+        stderr: Captured standard error since last update
+        process: The running subprocess.Popen instance
+        _accumulated_stdout: Total stdout collected so far
+        _accumulated_stderr: Total stderr collected so far
+        _exit_code: Exit code when process completes
+    """
+    
+    def __init__(self, script: str, id: str, timestamp: datetime):
+        """
+        Initialize a new background entry.
+        
+        Args:
+            script: The script/command to execute
+            id: Unique identifier for this entry
+            timestamp: Creation timestamp for this entry
+        """
+        super().__init__(id, timestamp)
+        self.script = script
+        self.stdout = ""
+        self.stderr = ""
+        self.process: Optional[subprocess.Popen] = None
+        self._accumulated_stdout = ""
+        self._accumulated_stderr = ""
+        self._exit_code: Optional[int] = None
+
+    def cleanup(self) -> None:
+        """
+        Clean up the background process if it's still running.
+        Ensures process is terminated and file handles are closed.
+        """
+        self._cleanup_process()
+        
+    def _cleanup_process(self):
+        """Clean up process and file handles"""
+        if self.process is not None:
+            try:
+                # Close file handles if they're open
+                if self.process.stdout:
+                    self.process.stdout.close()
+                if self.process.stderr:
+                    self.process.stderr.close()
+                
+                # Terminate process if it's still running
+                if self.process.poll() is None:
+                    self.process.terminate()
+                    try:
+                        self.process.wait(timeout=1.0)
+                    except subprocess.TimeoutExpired:
+                        self.process.kill()
+                        self.process.wait()
+            except:
+                pass  # Ignore cleanup errors
+            finally:
+                self.process = None
+        
+    def update(self) -> None:
+        """
+        Start the process if not running and collect any new output.
+        Updates stdout and stderr with any new output since last update.
+        """
+        try:
+            # Reset current output buffers
+            self.stdout = ""
+            self.stderr = ""
+            
+            # Start process if not running
+            if self.process is None and self._exit_code is None:
+                self.process = subprocess.Popen(
+                    self.script,
+                    shell=True,
+                    stdout=subprocess.PIPE,
+                    stderr=subprocess.PIPE,
+                    text=True,
+                    bufsize=1  # Line buffered
+                )
+                return  # Return after starting to allow process to generate output
+                
+            if self.process is None:
+                return  # Process already completed
+                
+            # Check if process has finished
+            exit_code = self.process.poll()
+            if exit_code is not None:
+                # Process has terminated, collect remaining output
+                try:
+                    remaining_out, remaining_err = self.process.communicate(timeout=0.1)
+                    self.stdout = remaining_out
+                    self.stderr = remaining_err
+                    self._accumulated_stdout += remaining_out
+                    self._accumulated_stderr += remaining_err
+                except subprocess.TimeoutExpired:
+                    pass  # Process didn't finish communicating, try again next update
+                
+                self._exit_code = exit_code
+                self._cleanup_process()
+                return
+            
+            # Read stdout if available
+            if self.process.stdout:
+                while True:
+                    try:
+                        line = self.process.stdout.readline()
+                        if not line:
+                            break
+                        self.stdout += line
+                        self._accumulated_stdout += line
+                    except:
+                        break
+                
+            # Read stderr if available
+            if self.process.stderr:
+                while True:
+                    try:
+                        line = self.process.stderr.readline()
+                        if not line:
+                            break
+                        self.stderr += line
+                        self._accumulated_stderr += line
+                    except:
+                        break
+                
+        except Exception as e:
+            # Handle any errors
+            error_msg = f"Error handling background process: {str(e)}"
+            self.stderr = error_msg
+            self._accumulated_stderr += f"\n{error_msg}"
+            self._exit_code = -1
+            self._cleanup_process()
+
+    def generate_context(self) -> ET.Element:
+        """
+        Generate an XML Element representing this background entry.
+        
+        Returns:
+            ET.Element: XML element containing the entry's data
+        """
+        # Create root element with appropriate status
+        element = ET.Element("background", {"id": self.id})
+        
+        if self.process is not None:
+            element.set("pid", str(self.process.pid))
+        elif self._exit_code is not None:
+            element.set("exit_code", str(self._exit_code))
+        
+        # Add script as CDATA or escaped text
+        element.text = escape_text_for_xml(self.script)
+        
+        # Add stdout element with accumulated output
+        stdout_elem = ET.SubElement(element, "stdout")
+        stdout_elem.text = escape_text_for_xml(self._accumulated_stdout)
+        
+        # Add stderr element with accumulated output
+        stderr_elem = ET.SubElement(element, "stderr")
+        stderr_elem.text = escape_text_for_xml(self._accumulated_stderr)
+        
+        return element
+    
+    def __del__(self):
+        """Ensure process is terminated and file handles are closed when entry is destroyed"""
+        self._cleanup_process()