def __exit__(self, x_type, x_value, x_traceback):
     now_us = monotonic_time_nanos() / 1000
     self._add_trace_event(
         'buck-launcher',
         self.name,
         _TraceEventPhases.END,
         self.pid,
         1,
         now_us,
         self.args)

 def __enter__(self):
     now_us = monotonic_time_nanos() / 1000
     self._add_trace_event(
         'buck-launcher',
         self.name,
         _TraceEventPhases.BEGIN,
         self.pid,
         1,
         now_us,
         self.args)

    def launch_buckd(self, buck_version_uid=None):
        with Tracing('BuckRepo.launch_buckd'):
            self._setup_watchman_watch()
            if buck_version_uid is None:
                buck_version_uid = self._get_buck_version_uid()
            # Override self._tmp_dir to a long lived directory.
            buckd_tmp_dir = self._buck_project.create_buckd_tmp_dir()
            ngserver_output_path = os.path.join(buckd_tmp_dir, 'ngserver-out')

            '''
            Use SoftRefLRUPolicyMSPerMB for immediate GC of javac output.
            Set timeout to 60s (longer than the biggest GC pause seen for a 2GB
            heap) and GC target to 15s. This means that the GC has to miss its
            target by 100% or many 500ms heartbeats must be missed before a client
            disconnection occurs. Specify port 0 to allow Nailgun to find an
            available port, then parse the port number out of the first log entry.
            '''
            command = ["buckd"]
            command.extend(self._get_java_args(buck_version_uid))
            command.append("-Dbuck.buckd_launch_time_nanos={0}".format(monotonic_time_nanos()))
            command.append("-XX:MaxGCPauseMillis={0}".format(GC_MAX_PAUSE_TARGET))
            command.append("-XX:SoftRefLRUPolicyMSPerMB=0")
            command.append("-Djava.io.tmpdir={0}".format(buckd_tmp_dir))
            command.append("-Dcom.martiansoftware.nailgun.NGServer.outputPath={0}".format(
                ngserver_output_path))
            command.append("com.facebook.buck.cli.bootstrapper.ClassLoaderBootstrapper")
            command.append("com.martiansoftware.nailgun.NGServer")
            command.append("localhost:0")
            command.append("{0}".format(BUCKD_CLIENT_TIMEOUT_MILLIS))

            '''
            Change the process group of the child buckd process so that when this
            script is interrupted, it does not kill buckd.
            '''
            def preexec_func():
                # Close any open file descriptors to further separate buckd from its
                # invoking context (e.g. otherwise we'd hang when running things like
                # `ssh localhost buck clean`).

                # N.B. preexec_func is POSIX-only, and any reasonable
                # POSIX system has a /dev/null
                os.setpgrp()
                dev_null_fd = os.open("/dev/null", os.O_RDWR)
                os.dup2(dev_null_fd, 0)
                os.dup2(dev_null_fd, 1)
                os.dup2(dev_null_fd, 2)
                os.close(dev_null_fd)

            process = subprocess.Popen(
                command,
                executable=which("java"),
                cwd=self._buck_project.root,
                close_fds=True,
                preexec_fn=preexec_func,
                env=self._environ_for_buck())

            buckd_port = None
            for i in range(100):
                if buckd_port:
                    break
                try:
                    with open(ngserver_output_path) as f:
                        for line in f:
                            match = BUCKD_LOG_FILE_PATTERN.match(line)
                            if match:
                                buckd_port = match.group(1)
                                break
                except IOError as e:
                    pass
                finally:
                    time.sleep(0.1)
            else:
                print(
                    "nailgun server did not respond after 10s. Aborting buckd.",
                    file=sys.stderr)
                return 1

            self._buck_project.save_buckd_port(buckd_port)
            self._buck_project.save_buckd_version(buck_version_uid)
            self._buck_project.update_buckd_run_count(0)

            returncode = process.poll()
            # If the process hasn't exited yet, everything is working as expected
            if returncode is None:
                return 0

            return returncode

    def launch_buckd(self, buck_version_uid=None):
        with Tracing("BuckRepo.launch_buckd"):
            self._setup_watchman_watch()
            if buck_version_uid is None:
                buck_version_uid = self._get_buck_version_uid()
            # Override self._tmp_dir to a long lived directory.
            buckd_tmp_dir = self._buck_project.create_buckd_tmp_dir()
            ngserver_output_path = os.path.join(buckd_tmp_dir, "ngserver-out")

            """
            Use SoftRefLRUPolicyMSPerMB for immediate GC of javac output.
            Set timeout to 60s (longer than the biggest GC pause seen for a 2GB
            heap) and GC target to 15s. This means that the GC has to miss its
            target by 100% or many 500ms heartbeats must be missed before a client
            disconnection occurs. Specify port 0 to allow Nailgun to find an
            available port, then parse the port number out of the first log entry.
            """
            command = ["buckd"]
            extra_default_options = [
                "-Dbuck.buckd_launch_time_nanos={0}".format(monotonic_time_nanos()),
                "-XX:MaxGCPauseMillis={0}".format(GC_MAX_PAUSE_TARGET),
                "-XX:SoftRefLRUPolicyMSPerMB=0",
                # Stop Java waking up every 50ms to collect thread
                # statistics; doing it once every five seconds is much
                # saner for a long-lived daemon.
                "-XX:PerfDataSamplingInterval=5000",
                # Likewise, waking up once per second just in case
                # there's some rebalancing to be done is silly.
                "-XX:+UnlockDiagnosticVMOptions",
                "-XX:GuaranteedSafepointInterval=5000",
                "-Djava.io.tmpdir={0}".format(buckd_tmp_dir),
                "-Dcom.martiansoftware.nailgun.NGServer.outputPath={0}".format(ngserver_output_path),
            ]

            if is_java8():
                extra_default_options.extend(["-XX:+UseG1GC", "-XX:MaxHeapFreeRatio=40"])

            command.extend(self._get_java_args(buck_version_uid, extra_default_options))
            command.append("com.facebook.buck.cli.bootstrapper.ClassLoaderBootstrapper")
            command.append("com.martiansoftware.nailgun.NGServer")
            command.append("local:.buckd/sock")
            command.append("{0}".format(BUCKD_CLIENT_TIMEOUT_MILLIS))

            """
            Change the process group of the child buckd process so that when this
            script is interrupted, it does not kill buckd.
            """

            def preexec_func():
                # Close any open file descriptors to further separate buckd from its
                # invoking context (e.g. otherwise we'd hang when running things like
                # `ssh localhost buck clean`).

                # N.B. preexec_func is POSIX-only, and any reasonable
                # POSIX system has a /dev/null
                os.setpgrp()
                dev_null_fd = os.open("/dev/null", os.O_RDWR)
                os.dup2(dev_null_fd, 0)
                os.dup2(dev_null_fd, 1)
                os.dup2(dev_null_fd, 2)
                os.close(dev_null_fd)

            buck_socket_path = self._buck_project.get_buckd_socket_path()

            # Make sure the Unix domain socket doesn't exist before this call.
            try:
                os.unlink(buck_socket_path)
            except OSError as e:
                if e.errno == errno.ENOENT:
                    # Socket didn't previously exist.
                    pass
                else:
                    raise e

            process = subprocess.Popen(
                command,
                executable=which("java"),
                cwd=self._buck_project.root,
                close_fds=True,
                preexec_fn=preexec_func,
                env=self._environ_for_buck(),
            )

            self._buck_project.save_buckd_version(buck_version_uid)
            self._buck_project.update_buckd_run_count(0)

            # Give Java some time to create the listening socket.
            for i in range(0, 100):
                if not os.path.exists(buck_socket_path):
                    time.sleep(0.01)

            returncode = process.poll()

            # If the process hasn't exited yet, everything is working as expected
            if returncode is None:
                return 0

            return returncode

    def launch_buckd(self):
        with Tracing('BuckRepo.launch_buckd'):
            self._setup_watchman_watch()
            self._buck_project.create_buckd_tmp_dir()
            # Override self._tmp_dir to a long lived directory.
            buckd_tmp_dir = self._buck_project.buckd_tmp_dir

            '''
            Use SoftRefLRUPolicyMSPerMB for immediate GC of javac output.
            Set timeout to 60s (longer than the biggest GC pause seen for a 2GB
            heap) and GC target to 15s. This means that the GC has to miss its
            target by 100% or many 500ms heartbeats must be missed before a client
            disconnection occurs. Specify port 0 to allow Nailgun to find an
            available port, then parse the port number out of the first log entry.
            '''
            command = ["java"]
            command.extend(self._get_java_args(self._buck_version_uid))
            command.append("-Dbuck.buckd_launch_time_nanos={0}".format(monotonic_time_nanos()))
            command.append("-Dbuck.buckd_watcher=Watchman")
            command.append("-XX:MaxGCPauseMillis={0}".format(GC_MAX_PAUSE_TARGET))
            command.append("-XX:SoftRefLRUPolicyMSPerMB=0")
            command.append("-Djava.io.tmpdir={0}".format(buckd_tmp_dir))
            command.append("-classpath")
            command.append(self._get_java_classpath())
            command.append("com.martiansoftware.nailgun.NGServer")
            command.append("localhost:0")
            command.append("{0}".format(BUCKD_CLIENT_TIMEOUT_MILLIS))

            '''
            We want to launch the buckd process in such a way that it finds the
            terminal as a tty while being able to read its output. We also want to
            shut up any nailgun output. If we simply redirect stdout/stderr to a
            file, the super console no longer works on subsequent invocations of
            buck. So use a pseudo-terminal to interact with it.
            '''
            master, slave = pty.openpty()

            '''
            Change the process group of the child buckd process so that when this
            script is interrupted, it does not kill buckd.
            '''
            def preexec_func():
                os.setpgrp()

            process = subprocess.Popen(
                command,
                cwd=self._buck_project.root,
                stdout=slave,
                stderr=slave,
                preexec_fn=preexec_func)
            stdout = os.fdopen(master)

            for i in range(100):
                line = stdout.readline().strip()
                match = BUCKD_LOG_FILE_PATTERN.match(line)
                if match:
                    buckd_port = match.group(1)
                    break
                time.sleep(0.1)
            else:
                print(
                    "nailgun server did not respond after 10s. Aborting buckd.",
                    file=sys.stderr)
                return

            self._buck_project.save_buckd_port(buckd_port)
            self._buck_project.save_buckd_version(self._buck_version_uid)
            self._buck_project.update_buckd_run_count(0)

    def launch_buckd(self, buck_version_uid=None):
        with Tracing('BuckTool.launch_buckd'):
            setup_watchman_watch()
            if buck_version_uid is None:
                buck_version_uid = self._get_buck_version_uid()
            # Override self._tmp_dir to a long lived directory.
            buckd_tmp_dir = self._buck_project.create_buckd_tmp_dir()
            ngserver_output_path = os.path.join(buckd_tmp_dir, 'ngserver-out')

            """
            Use SoftRefLRUPolicyMSPerMB for immediate GC of javac output.
            Set timeout to 60s (longer than the biggest GC pause seen for a 2GB
            heap) and GC target to 15s. This means that the GC has to miss its
            target by 100% or many 500ms heartbeats must be missed before a client
            disconnection occurs. Specify port 0 to allow Nailgun to find an
            available port, then parse the port number out of the first log entry.
            """
            command = ["buckd"]
            extra_default_options = [
                "-Dbuck.buckd_launch_time_nanos={0}".format(monotonic_time_nanos()),
                "-Dfile.encoding=UTF-8",
                "-XX:MaxGCPauseMillis={0}".format(GC_MAX_PAUSE_TARGET),
                "-XX:SoftRefLRUPolicyMSPerMB=0",
                # Stop Java waking up every 50ms to collect thread
                # statistics; doing it once every five seconds is much
                # saner for a long-lived daemon.
                "-XX:PerfDataSamplingInterval=5000",
                # Do not touch most signals
                "-Xrs",
                # Likewise, waking up once per second just in case
                # there's some rebalancing to be done is silly.
                "-XX:+UnlockDiagnosticVMOptions",
                "-XX:GuaranteedSafepointInterval=5000",
                "-Djava.io.tmpdir={0}".format(buckd_tmp_dir),
                "-Dcom.martiansoftware.nailgun.NGServer.outputPath={0}".format(
                    ngserver_output_path),
                "-XX:+UseG1GC",
                "-XX:MaxHeapFreeRatio=40",
            ]

            command.extend(self._get_java_args(buck_version_uid, extra_default_options))
            command.append("com.facebook.buck.cli.bootstrapper.ClassLoaderBootstrapper")
            command.append("com.facebook.buck.cli.Main$DaemonBootstrap")
            command.append(self._buck_project.get_buckd_transport_address())
            command.append("{0}".format(BUCKD_CLIENT_TIMEOUT_MILLIS))

            buckd_transport_file_path = self._buck_project.get_buckd_transport_file_path()
            if os.name == 'nt':
                preexec_fn = None
                # https://msdn.microsoft.com/en-us/library/windows/desktop/ms684863.aspx#DETACHED_PROCESS
                DETACHED_PROCESS = 0x00000008
                creationflags = DETACHED_PROCESS
            else:
                """
                Change the process group of the child buckd process so that when this
                script is interrupted, it does not kill buckd.
                """

                def preexec_fn():
                    # Close any open file descriptors to further separate buckd from its
                    # invoking context (e.g. otherwise we'd hang when running things like
                    # `ssh localhost buck clean`).
                    dev_null_fd = os.open("/dev/null", os.O_RDWR)
                    os.dup2(dev_null_fd, 0)
                    os.dup2(dev_null_fd, 1)
                    os.dup2(dev_null_fd, 2)
                    os.close(dev_null_fd)

                creationflags = 0
            process = subprocess.Popen(
                command,
                executable=which("java"),
                cwd=self._buck_project.root,
                close_fds=True,
                preexec_fn=preexec_fn,
                env=self._environ_for_buck(),
                creationflags=creationflags)

            self._buck_project.save_buckd_version(buck_version_uid)

            # Give Java some time to create the listening socket.

            wait_seconds = 0.01
            repetitions = int(BUCKD_STARTUP_TIMEOUT_MILLIS / 1000.0 / wait_seconds)
            for i in range(repetitions):
                if transport_exists(buckd_transport_file_path):
                    break
                time.sleep(wait_seconds)

            if not transport_exists(buckd_transport_file_path):
                return False

            returncode = process.poll()

            # If the process hasn't exited yet, everything is working as expected
            if returncode is None:
                return True

            return False

    def launch_buckd(self, java_path, jvm_args, buck_version_uid=None):
        with Tracing("BuckTool.launch_buckd"):
            setup_watchman_watch()
            if buck_version_uid is None:
                buck_version_uid = self._get_buck_version_uid()
            # Override self._tmp_dir to a long lived directory.
            buckd_tmp_dir = self._buck_project.create_buckd_tmp_dir()
            ngserver_output_path = os.path.join(buckd_tmp_dir, "ngserver-out")

            """
            Use SoftRefLRUPolicyMSPerMB for immediate GC of javac output.
            Set timeout to 60s (longer than the biggest GC pause seen for a 2GB
            heap) and GC target to 15s. This means that the GC has to miss its
            target by 100% or many 500ms heartbeats must be missed before a client
            disconnection occurs. Specify port 0 to allow Nailgun to find an
            available port, then parse the port number out of the first log entry.
            """
            command = ["buckd"]
            extra_default_options = [
                "-Dbuck.buckd_launch_time_nanos={0}".format(monotonic_time_nanos()),
                "-Dfile.encoding=UTF-8",
                "-XX:MaxGCPauseMillis={0}".format(GC_MAX_PAUSE_TARGET),
                "-XX:SoftRefLRUPolicyMSPerMB=0",
                # Stop Java waking up every 50ms to collect thread
                # statistics; doing it once every five seconds is much
                # saner for a long-lived daemon.
                "-XX:PerfDataSamplingInterval=5000",
                # Do not touch most signals
                "-Xrs",
                # Likewise, waking up once per second just in case
                # there's some rebalancing to be done is silly.
                "-XX:+UnlockDiagnosticVMOptions",
                "-XX:GuaranteedSafepointInterval=5000",
                "-Djava.io.tmpdir={0}".format(buckd_tmp_dir),
                "-Dcom.facebook.nailgun.NGServer.outputPath={0}".format(
                    ngserver_output_path
                ),
                "-XX:+UseG1GC",
                "-XX:MaxHeapFreeRatio=40",
            ]

            command.extend(extra_default_options)
            command.extend(jvm_args)
            command.append("com.facebook.buck.cli.bootstrapper.ClassLoaderBootstrapper")
            command.append("com.facebook.buck.cli.BuckDaemon")
            command.append(self._buck_project.get_buckd_transport_address())
            command.append("{0}".format(BUCKD_CLIENT_TIMEOUT_MILLIS))

            buckd_transport_file_path = (
                self._buck_project.get_buckd_transport_file_path()
            )
            if os.name == "nt":
                # https://msdn.microsoft.com/en-us/library/windows/desktop/ms684863.aspx#DETACHED_PROCESS
                DETACHED_PROCESS = 0x00000008
                creationflags = DETACHED_PROCESS
                # do not redirect output for Windows as it deadlocks
                stdin = None
                stdout = None
                stderr = None
                close_fds = True
            else:
                """
                Change the process group of the child buckd process so that when this
                script is interrupted, it does not kill buckd.
                """
                creationflags = 0
                stdin = open(os.devnull, mode="r")
                stdout = open(
                    self._buck_project.get_buckd_stdout(), mode="w+b", buffering=0
                )
                stderr = open(
                    self._buck_project.get_buckd_stderr(), mode="w+b", buffering=0
                )
                close_fds = False

            process = subprocess.Popen(
                command,
                executable=java_path,
                cwd=self._buck_project.root,
                env=self._environ_for_buck(),
                creationflags=creationflags,
                close_fds=close_fds,
                stdin=stdin,
                stdout=stdout,
                stderr=stderr,
            )

            self._buck_project.save_buckd_version(buck_version_uid)
            self._buck_project.save_buckd_jvm_args(
                self._get_java_args(buck_version_uid)
            )

            # Give Java some time to create the listening socket.

            wait_seconds = 0.01
            repetitions = int(BUCKD_STARTUP_TIMEOUT_MILLIS / 1000.0 / wait_seconds)
            for i in range(repetitions):
                if transport_exists(buckd_transport_file_path):
                    break
                time.sleep(wait_seconds)
#.........这里部分代码省略.........

    def launch_buckd(self, buck_version_uid=None):
        with Tracing('BuckRepo.launch_buckd'):
            self._setup_watchman_watch()
            if buck_version_uid is None:
                buck_version_uid = self._get_buck_version_uid()
            # Override self._tmp_dir to a long lived directory.
            buckd_tmp_dir = self._buck_project.create_buckd_tmp_dir()
            ngserver_output_path = os.path.join(buckd_tmp_dir, 'ngserver-out')

            '''
            Use SoftRefLRUPolicyMSPerMB for immediate GC of javac output.
            Set timeout to 60s (longer than the biggest GC pause seen for a 2GB
            heap) and GC target to 15s. This means that the GC has to miss its
            target by 100% or many 500ms heartbeats must be missed before a client
            disconnection occurs. Specify port 0 to allow Nailgun to find an
            available port, then parse the port number out of the first log entry.
            '''
            command = [which("java")]
            command.extend(self._get_java_args(buck_version_uid))
            command.append("-Dbuck.buckd_launch_time_nanos={0}".format(monotonic_time_nanos()))
            command.append("-Dbuck.buckd_watcher=Watchman")
            command.append("-XX:MaxGCPauseMillis={0}".format(GC_MAX_PAUSE_TARGET))
            command.append("-XX:SoftRefLRUPolicyMSPerMB=0")
            command.append("-Djava.io.tmpdir={0}".format(buckd_tmp_dir))
            command.append("-Dcom.martiansoftware.nailgun.NGServer.outputPath={0}".format(
                ngserver_output_path))
            command.append("-classpath")
            command.append(self._get_bootstrap_classpath())
            command.append("com.facebook.buck.cli.bootstrapper.ClassLoaderBootstrapper")
            command.append(self._get_java_classpath())
            command.append("com.martiansoftware.nailgun.NGServer")
            command.append("localhost:0")
            command.append("{0}".format(BUCKD_CLIENT_TIMEOUT_MILLIS))

            '''
            Change the process group of the child buckd process so that when this
            script is interrupted, it does not kill buckd.
            '''
            def preexec_func():
                os.setpgrp()

            process = subprocess.Popen(
                command,
                cwd=self._buck_project.root,
                preexec_fn=preexec_func)

            buckd_port = None
            for i in range(100):
                if buckd_port:
                    break
                try:
                    with open(ngserver_output_path) as f:
                        for line in f:
                            match = BUCKD_LOG_FILE_PATTERN.match(line)
                            if match:
                                buckd_port = match.group(1)
                                break
                except IOError as e:
                    pass
                finally:
                    time.sleep(0.1)
            else:
                print(
                    "nailgun server did not respond after 10s. Aborting buckd.",
                    file=sys.stderr)
                return

            self._buck_project.save_buckd_port(buckd_port)
            self._buck_project.save_buckd_version(buck_version_uid)
            self._buck_project.update_buckd_run_count(0)