lttng_ivc/utils/utils.py

   1 import signal
   2 import hashlib
   3 import os
   4 import time
   5 import socket
   6
   7 from lxml import etree
   8 from contextlib import closing
   9
  10
  11 def line_count(file_path):
  12     line_count = 0
  13     with open(file_path) as f:
  14         for line in f:
  15             line_count += 1
  16     return line_count
  17
  18
  19 def sha256_checksum(filename, block_size=65536):
  20     sha256 = hashlib.sha256()
  21     with open(filename, 'rb') as f:
  22         for block in iter(lambda: f.read(block_size), b''):
  23             sha256.update(block)
  24     return sha256.hexdigest()
  25
  26
  27 # TODO: timeout as a parameter or Settings
  28 # TODO: Custom exception
  29 def wait_for_file(path):
  30     i = 0
  31     timeout = 60
  32     while not os.path.exists(path):
  33         time.sleep(1)
  34         i = i + 1
  35         if i > timeout:
  36             raise Exception("File still does not exists. Timeout expired")
  37
  38
  39 # TODO: find better exception
  40 def create_empty_file(path):
  41     if os.path.exists(path):
  42         raise Exception("Path already exist")
  43     open(path, 'w').close()
  44
  45
  46 def __dummy_sigusr1_handler():
  47     pass
  48
  49
  50 def sessiond_spawn(runtime):
  51     agent_port = find_free_port()
  52     previous_handler = signal.signal(signal.SIGUSR1, __dummy_sigusr1_handler)
  53     sessiond = runtime.spawn_subprocess("lttng-sessiond -vvv -S --agent-tcp-port {}".format(agent_port))
  54     signal.sigtimedwait({signal.SIGUSR1}, 60)
  55     previous_handler = signal.signal(signal.SIGUSR1, previous_handler)
  56     return sessiond
  57
  58
  59 def relayd_spawn(runtime, url="localhost"):
  60     """
  61     Return a tuple (relayd_uuid, ctrl_port, data_port, live_port)
  62     """
  63     ports = find_multiple_free_port(3)
  64     data_port = ports.pop()
  65     ctrl_port = ports.pop()
  66     live_port = ports.pop()
  67
  68     base_cmd = "lttng-relayd -vvv"
  69     data_string = "-D tcp://{}:{}".format(url, data_port)
  70     ctrl_string = "-C tcp://{}:{}".format(url, ctrl_port)
  71     live_string = "-L tcp://{}:{}".format(url, live_port)
  72
  73     cmd = " ".join([base_cmd, data_string, ctrl_string, live_string])
  74     relayd = runtime.spawn_subprocess(cmd)
  75
  76     # Synchronization based on verbosity since no -S is available for
  77     # lttng-relayd yet.
  78     log_path = runtime.get_subprocess_stderr_path(relayd)
  79
  80     # TODO: Move to settings.
  81     ready_cue = "Listener accepting live viewers connections"
  82     # TODO: Move to settings.
  83     timeout = 60
  84     ready = False
  85     for i in range(timeout):
  86         if file_contains(log_path, ready_cue):
  87             ready = True
  88             break
  89         time.sleep(1)
  90
  91     if not ready:
  92         # Cleanup is performed by runtime
  93         raise Exception("Relayd readyness timeout expired")
  94
  95     return (relayd, ctrl_port, data_port, live_port)
  96
  97
  98 def find_free_port():
  99     # There is no guarantee that the port will be free at runtime but should be
 100     # good enough
 101     with closing(socket.socket(socket.AF_INET, socket.SOCK_STREAM)) as s:
 102         s.bind(('', 0))
 103         return s.getsockname()[1]
 104
 105
 106 def find_multiple_free_port(number):
 107     """
 108     Return a list of supposedly free port
 109     """
 110     assert(number >= 0)
 111     ports = []
 112     while(len(ports) != number):
 113         port = find_free_port()
 114         if port in ports:
 115             continue
 116         ports.append(port)
 117     return ports
 118
 119
 120 def file_contains(file_path, list_of_string):
 121     with open(file_path, 'r') as f:
 122         for line in f:
 123             for s in list_of_string:
 124                 if s in line:
 125                     return True
 126
 127
 128 def find_dir(root, name):
 129     """
 130     Returns the absolute path or None.
 131     """
 132     abs_path = None
 133     for base, dirs, files in os.walk(root):
 134         for tmp in dirs:
 135             if tmp.endswith(name):
 136                 abs_path = os.path.abspath(os.path.join(base, tmp))
 137     return abs_path
 138
 139
 140 def find_file(root, name):
 141     """
 142     Returns the absolute path or None.
 143     """
 144     abs_path = None
 145     for base, dirs, files in os.walk(root):
 146         for tmp in files:
 147             if tmp.endswith(name):
 148                 abs_path = os.path.abspath(os.path.join(base, tmp))
 149     return abs_path
 150
 151
 152 def validate(xml_path, xsd_path):
 153
 154     xmlschema_doc = etree.parse(xsd_path)
 155     xmlschema = etree.XMLSchema(xmlschema_doc)
 156
 157     xml_doc = etree.parse(xml_path)
 158     result = xmlschema.validate(xml_doc)
 159
 160     return result
 161
 162 def xpath_query(xml_file, xpath):
 163     """
 164     Return a list of xml node corresponding to the xpath. The list can be of lenght
 165     zero.
 166     """
 167     with open(xml_file, 'r') as f:
 168         tree = etree.parse(f)
 169         root = tree.getroot()
 170         # Remove all namespace
 171         # https://stackoverflow.com/questions/18159221/remove-namespace-and-prefix-from-xml-in-python-using-lxml
 172         for elem in root.getiterator():
 173             if not hasattr(elem.tag, 'find'):
 174                 continue
 175             i = elem.tag.find('}')
 176             if i >= 0:
 177                 elem.tag = elem.tag[i+1:]
 178
 179         return root.xpath(xpath)