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Run system commands with !
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,172 @@ | ||
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| import locale | ||
| import os | ||
| import subprocess | ||
| import signal | ||
| import sys | ||
| import time | ||
| from queue import Queue, Empty | ||
| from threading import Thread | ||
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| from qgis.PyQt.QtCore import QObject, pyqtSignal | ||
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| class ProcessWrapper(QObject): | ||
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| finished = pyqtSignal(int) | ||
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| def __init__(self, command, parent=None): | ||
| super().__init__(parent) | ||
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| self.stdout = "" | ||
| self.stderr = "" | ||
| self.returncode = None | ||
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| options = { | ||
| "stdout": subprocess.PIPE, | ||
| "stdin": subprocess.PIPE, | ||
| "stderr": subprocess.PIPE, | ||
| "shell": True | ||
| } | ||
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| # On Unix, we can use os.setsid | ||
| # This will allow killing the process and its children when pressing Ctrl+C if psutil is not available | ||
| if hasattr(os, "setsid"): | ||
| options["preexec_fn"] = os.setsid | ||
|
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| # Create and start subprocess | ||
| self.p = subprocess.Popen(command, **options) | ||
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| # Read process stdout and push to out queue | ||
| self.q_out = Queue() | ||
| self.t_out = Thread(daemon=True, target=self.enqueue_output, args=[self.p.stdout, self.q_out]) | ||
| self.t_out.start() | ||
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| # Read process stderr and push to err queue | ||
| self.q_err = Queue() | ||
| self.t_err = Thread(daemon=True, target=self.enqueue_output, args=[self.p.stderr, self.q_err]) | ||
| self.t_err.start() | ||
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| # Polls process and output both queues content to sys.stdout and sys.stderr | ||
| self.t_queue = Thread(daemon=True, target=self.dequeue_output) | ||
| self.t_queue.start() | ||
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| def enqueue_output(self, stream, queue): | ||
| while True: | ||
| # We have to read the character one by one to ensure to | ||
| # forward every available character to the queue | ||
| # self.p.stdout.readline would block on a unfinished line | ||
| char = stream.read(1) | ||
| if not char: | ||
| # Process terminated | ||
| break | ||
| queue.put(char) | ||
| stream.close() | ||
|
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| def __repr__(self): | ||
| """ Helpful representation of the maanaged process """ | ||
| status = "Running" if self.returncode is None else f"Completed ({self.returncode})" | ||
| repr = f"ProcessWrapper object at {hex(id(self))}" | ||
| repr += f"\n - Status: {status}" | ||
| repr += f"\n - stdout: {self.stdout}" | ||
| repr += f"\n - stderr: {self.stderr}" | ||
| return repr | ||
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| def decode(self, bytes): | ||
| try: | ||
| # Try to decode the content as utf-8 first | ||
| text = bytes.decode("utf8") | ||
| except UnicodeDecodeError: | ||
| try: | ||
| # If it fails, fallback to the default locale encoding | ||
| text = bytes.decode(locale.getdefaultlocale()[1]) | ||
| except UnicodeDecodeError: | ||
| # If everything fails, use representation | ||
| text = str(bytes)[2:-1] | ||
| return text | ||
|
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| def read_content(self, queue, stream, is_stderr): | ||
| """ Write queue content to the standard stream and append it to the internal buffer """ | ||
| content = b"" | ||
| while True: | ||
| try: | ||
| # While queue contains data, append it to content | ||
| content += queue.get_nowait() | ||
| except Empty: | ||
| text = self.decode(content) | ||
| if text: | ||
| # Append to the internal buffer | ||
| if is_stderr: | ||
| self.stderr += text | ||
| else: | ||
| self.stdout += text | ||
|
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| stream.write(text) | ||
| return | ||
|
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| def dequeue_output(self): | ||
| """ Check process every 0.1s and forward its outputs to stdout and stderr """ | ||
|
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| # Poll process and forward its outputs to stdout and stderr | ||
| while self.p.poll() is None: | ||
| time.sleep(0.1) | ||
| self.read_content(self.q_out, sys.stdout, is_stderr=False) | ||
| self.read_content(self.q_err, sys.stderr, is_stderr=True) | ||
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| # At this point, the process has terminated, so we wait for the threads to finish | ||
| self.t_out.join() | ||
| self.t_err.join() | ||
|
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| # Reaf the remaining content of the queues | ||
| self.read_content(self.q_out, sys.stdout, is_stderr=False) | ||
| self.read_content(self.q_err, sys.stderr, is_stderr=True) | ||
|
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| # Set returncode and emit finished signal | ||
| self.returncode = self.p.returncode | ||
| self.finished.emit(self.returncode) | ||
|
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| def wait(self, timeout=1): | ||
| """ Wait for the managed process to finish. If timeout=-1, waits indefinitely (and freeze the GUI) """ | ||
| self.p.wait(timeout) | ||
|
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| def write(self, data): | ||
| """ Send data to the managed process""" | ||
| try: | ||
| self.p.stdin.write(data.encode("utf8")) | ||
| self.p.stdin.close() | ||
| except BrokenPipeError as exc: | ||
| self.p.stdout.close() | ||
| self.p.stderr.close() | ||
| self.finished.emit(self.p.poll()) | ||
|
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| def kill(self): | ||
| """ Kill the managed process """ | ||
|
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| # Process in run with shell=True, so calling self.p.kill() would only kill the shell | ||
| # (i.e a text editor lauched with !gedit would not close) so we need to iterate | ||
| # over the child processes to kill them all | ||
|
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| try: | ||
| import psutil | ||
| if self.p.returncode is None: | ||
| process = psutil.Process(self.p.pid) | ||
| for child_process in process.children(recursive=True): | ||
| child_process.kill() | ||
| process.kill() | ||
| except ImportError: | ||
| # If psutil is not available, we try to use os.killpg to kill the process group (Unix only) | ||
| try: | ||
| os.killpg(os.getpgid(self.p.pid), signal.SIGTERM) | ||
| except AttributeError: | ||
| # If everything fails, simply kill the process. Children will not be killed | ||
| self.p.kill() | ||
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| def __del__(self): | ||
| """ Ensure streams are closed when the process is destroyed """ | ||
| self.p.stdout.close() | ||
| self.p.stderr.close() | ||
| self.p.stdin.close() | ||
| try: | ||
| self.kill() | ||
| except ProcessLookupError: | ||
| pass |