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site_scons/site_tools/command_output.py

Index: site_scons/site_tools/command_output.py
===================================================================
--- site_scons/site_tools/command_output.py	(revision 3849)
+++ site_scons/site_tools/command_output.py	(working copy)
@@ -32,11 +32,69 @@
 
 
 import os
+import signal
+import subprocess
+import sys
+import threading
+import time
 import SCons.Script
-import subprocess
 
 
-def RunCommand(cmdargs, cwdir=None, env=None, echo_output=True):
+# TODO(rspangler): Move KillProcessTree() and RunCommand() into their own
+# module.
+
+
+def KillProcessTree(pid):
+  """Kills the process and all of its child processes.
+
+  Args:
+    pid: process to kill.
+
+  Raises:
+    OSError: Unsupported OS.
+  """
+
+  if sys.platform in ('win32', 'cygwin'):
+    # Use Windows' taskkill utility
+    killproc_path = '%s;%s\\system32;%s\\system32\\wbem' % (
+        (os.environ['SYSTEMROOT'],) * 3)
+    killproc_cmd = 'taskkill /F /T /PID %d' % pid
+    killproc_task = subprocess.Popen(killproc_cmd, shell=True,
+                                     stdout=subprocess.PIPE,
+                                     env={'PATH':killproc_path})
+    killproc_task.communicate()
+
+  elif sys.platform in ('linux', 'linux2', 'darwin'):
+    # Use ps to get a list of processes
+    ps_task = subprocess.Popen(['/bin/ps', 'x', '-o', 'pid,ppid'], stdout=subprocess.PIPE)
+    ps_out = ps_task.communicate()[0]
+
+    # Parse out a dict of pid->ppid
+    ppid = {}
+    for ps_line in ps_out.split('\n'):
+      w = ps_line.strip().split()
+      if len(w) < 2:
+          continue      # Not enough words in this line to be a process list
+      try:
+        ppid[int(w[0])] = int(w[1])
+      except ValueError:
+        pass            # Header or footer
+
+    # For each process, kill it if it or any of its parents is our child
+    for p in ppid:
+      p2 = p
+      while p2:
+        if p2 == pid:
+          os.kill(p, signal.SIGKILL)
+          break
+        p2 = ppid.get(p2)
+
+  else:
+    raise OSError('Unsupported OS for KillProcessTree()')
+
+
+def RunCommand(cmdargs, cwdir=None, env=None, echo_output=True, timeout=None,
+               timeout_errorlevel=14):
   """Runs an external command.
 
   Args:
@@ -45,29 +103,63 @@
     cwdir: Working directory for the command, if not None.
     env: Environment variables dict, if not None.
     echo_output: If True, output will be echoed to stdout.
+    timeout: If not None, timeout for command in seconds.  If command times
+        out, it will be killed and timeout_errorlevel will be returned.
+    timeout_errorlevel: The value to return if the command times out.
 
   Returns:
     The integer errorlevel from the command.
     The combined stdout and stderr as a string.
   """
-
   # Force unicode string in the environment to strings.
   if env:
     env = dict([(k, str(v)) for k, v in env.items()])
+  start_time = time.time()
   child = subprocess.Popen(cmdargs, cwd=cwdir, env=env, shell=True,
+                           universal_newlines=True,
                            stdin=subprocess.PIPE,
                            stdout=subprocess.PIPE, stderr=subprocess.STDOUT)
   child_out = []
   child_retcode = None
 
-  # Need to poll the child process, since the stdout pipe can fill.
+  def _ReadThread():
+    """Thread worker function to read output from child process.
+
+    Necessary since there is no cross-platform way of doing non-blocking
+    reads of the output pipe.
+    """
+    read_run = True
+    while read_run:
+      # Need to have a delay of 1 cycle between child completing and
+      # thread exit, to pick up the final output from the child.
+      if child_retcode is not None:
+        read_run = False
+      new_out = child.stdout.read()
+      if new_out:
+        if echo_output:
+          print new_out,
+        child_out.append(new_out)
+
+  read_thread = threading.Thread(target=_ReadThread)
+  read_thread.start()
+
+  # Wait for child to exit or timeout
   while child_retcode is None:
+    time.sleep(1)       # So we don't poll too frequently
     child_retcode = child.poll()
-    new_out = child.stdout.read()
-    if echo_output:
-      print new_out,
-    child_out.append(new_out)
+    if timeout and child_retcode is None:
+      elapsed = time.time() - start_time
+      if elapsed > timeout:
+        print '*** RunCommand() timeout:', cmdargs
+        KillProcessTree(child.pid)
+        child_retcode = timeout_errorlevel
 
+  # Wait for worker thread to pick up final output and die
+  read_thread.join(5)
+  if read_thread.isAlive():
+    print '*** Error: RunCommand() read thread did not exit.'
+    sys.exit(1)
+
   if echo_output:
     print   # end last line of output
   return child_retcode, ''.join(child_out)
@@ -100,8 +192,13 @@
     env.AppendENVPath('LD_LIBRARY_PATH', cwdir)
   else:
     cwdir = None
+  cmdecho = env.get('COMMAND_OUTPUT_ECHO', True)
+  timeout = env.get('COMMAND_OUTPUT_TIMEOUT')
+  timeout_errorlevel = env.get('COMMAND_OUTPUT_TIMEOUT_ERRORLEVEL')
 
-  retcode, output = RunCommand(cmdline, cwdir=cwdir, env=env['ENV'])
+  retcode, output = RunCommand(cmdline, cwdir=cwdir, env=env['ENV'],
+                               echo_output=cmdecho, timeout=timeout,
+                               timeout_errorlevel=timeout_errorlevel)
 
   # Save command line output
   output_file = open(str(target[0]), 'w')
@@ -116,10 +213,17 @@
   """SCons entry point for this tool."""
 
   # Add the builder and tell it which build environment variables we use.
-  action = SCons.Script.Action(CommandOutputBuilder, varlist=[
-      'COMMAND_OUTPUT_CMDLINE',
-      'COMMAND_OUTPUT_RUN_DIR',
-  ])
+  action = SCons.Script.Action(
+      CommandOutputBuilder,
+      'Output "$COMMAND_OUTPUT_CMDLINE" to $TARGET',
+      varlist=[
+          'COMMAND_OUTPUT_CMDLINE',
+          'COMMAND_OUTPUT_RUN_DIR',
+          'COMMAND_OUTPUT_TIMEOUT',
+          'COMMAND_OUTPUT_TIMEOUT_ERRORLEVEL',
+          # We use COMMAND_OUTPUT_ECHO also, but that doesn't change the
+          # command being run or its output.
+      ], )
   builder = SCons.Script.Builder(action = action)
   env.Append(BUILDERS={'CommandOutput': builder})