Method open_background

qa/tasks/cephfs/mount.py:987–1051

Open a file for writing, then block such that the client will hold a capability. Don't return until the remote process has got as far as opening the file, then return the RemoteProcess instance.

(self, basename="background_file", write=True, content="content")

        p.wait()

    def open_background(self, basename="background_file", write=True, content="content"):
        """
        Open a file for writing, then block such that the client
        will hold a capability.

        Don't return until the remote process has got as far as opening
        the file, then return the RemoteProcess instance.
        """
        assert(self.is_mounted())

        path = os.path.join(self.hostfs_mntpt, basename)

        if write:
            pyscript = dedent("""
                import fcntl
                import os
                import sys
                import time

                fcntl.fcntl(sys.stdin, fcntl.F_SETFL, fcntl.fcntl(sys.stdin, fcntl.F_GETFL) | os.O_NONBLOCK)

                with open("{path}", 'w') as f:
                    f.write("{content}")
                    f.flush()
                    while True:
                        print("open_background: keeping file open", file=sys.stderr)
                        try:
                             if os.read(0, 4096) == b"":
                                  break
                        except BlockingIOError:
                            pass
                        time.sleep(2)
                """).format(path=path, content=content)
        else:
            pyscript = dedent("""
                import fcntl
                import os
                import sys
                import time

                fcntl.fcntl(sys.stdin, fcntl.F_SETFL, fcntl.fcntl(sys.stdin, fcntl.F_GETFL) | os.O_NONBLOCK)

                with open("{path}", 'r') as f:
                    while True:
                        print("open_background: keeping file open", file=sys.stderr)
                        try:
                             if os.read(0, 4096) == b"":
                                  break
                        except BlockingIOError:
                            pass
                        time.sleep(2)
                """).format(path=path)

        rproc = self._run_python(pyscript)
        self.background_procs.append(rproc)

        # This wait would not be sufficient if the file had already
        # existed, but it's simple and in practice users of open_background