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, opt_args=""):
  51     agent_port = find_free_port()
  52     previous_handler = signal.signal(signal.SIGUSR1, __dummy_sigusr1_handler)
  53     cmd = "lttng-sessiond -vvv --verbose-consumer -S --agent-tcp-port {}".format(agent_port)
  54     cmd = " ".join([cmd, opt_args])
  55     sessiond = runtime.spawn_subprocess(cmd)
  56     signal.sigtimedwait({signal.SIGUSR1}, 60)
  57     previous_handler = signal.signal(signal.SIGUSR1, previous_handler)
  58     return sessiond
  59
  60
  61 def relayd_spawn(runtime, url="localhost"):
  62     """
  63     Return a tuple (relayd_uuid, ctrl_port, data_port, live_port)
  64     """
  65     ports = find_multiple_free_port(3)
  66     data_port = ports.pop()
  67     ctrl_port = ports.pop()
  68     live_port = ports.pop()
  69
  70     base_cmd = "lttng-relayd -vvv"
  71     data_string = "-D tcp://{}:{}".format(url, data_port)
  72     ctrl_string = "-C tcp://{}:{}".format(url, ctrl_port)
  73     live_string = "-L tcp://{}:{}".format(url, live_port)
  74
  75     cmd = " ".join([base_cmd, data_string, ctrl_string, live_string])
  76     relayd = runtime.spawn_subprocess(cmd)
  77
  78     # Synchronization based on verbosity since no -S is available for
  79     # lttng-relayd yet.
  80     log_path = runtime.get_subprocess_stderr_path(relayd)
  81
  82     # TODO: Move to settings.
  83     ready_cue = "Listener accepting live viewers connections"
  84     # TODO: Move to settings.
  85     timeout = 60
  86     ready = False
  87     for i in range(timeout):
  88         if file_contains(log_path, ready_cue):
  89             ready = True
  90             break
  91         time.sleep(1)
  92
  93     if not ready:
  94         # Cleanup is performed by runtime
  95         raise Exception("Relayd readyness timeout expired")
  96
  97     return (relayd, ctrl_port, data_port, live_port)
  98
  99
 100 def find_free_port():
 101     # There is no guarantee that the port will be free at runtime but should be
 102     # good enough
 103     with closing(socket.socket(socket.AF_INET, socket.SOCK_STREAM)) as s:
 104         s.bind(('', 0))
 105         return s.getsockname()[1]
 106
 107
 108 def find_multiple_free_port(number):
 109     """
 110     Return a list of supposedly free port
 111     """
 112     assert(number >= 0)
 113     ports = []
 114     while(len(ports) != number):
 115         port = find_free_port()
 116         if port in ports:
 117             continue
 118         ports.append(port)
 119     return ports
 120
 121
 122 def file_contains(file_path, list_of_string):
 123     with open(file_path, 'r') as f:
 124         for line in f:
 125             for s in list_of_string:
 126                 if s in line:
 127                     return True
 128
 129
 130 def find_dir(root, name):
 131     """
 132     Returns the absolute path or None.
 133     """
 134     abs_path = None
 135     for base, dirs, files in os.walk(root):
 136         for tmp in dirs:
 137             if tmp.endswith(name):
 138                 abs_path = os.path.abspath(os.path.join(base, tmp))
 139     return abs_path
 140
 141
 142 def find_file(root, name):
 143     """
 144     Returns the absolute path or None.
 145     """
 146     abs_path = None
 147     for base, dirs, files in os.walk(root):
 148         for tmp in files:
 149             if tmp.endswith(name):
 150                 abs_path = os.path.abspath(os.path.join(base, tmp))
 151     return abs_path
 152
 153
 154 def validate(xml_path, xsd_path):
 155
 156     xmlschema_doc = etree.parse(xsd_path)
 157     xmlschema = etree.XMLSchema(xmlschema_doc)
 158
 159     xml_doc = etree.parse(xml_path)
 160     result = xmlschema.validate(xml_doc)
 161
 162     return result
 163
 164 def xpath_query(xml_file, xpath):
 165     """
 166     Return a list of xml node corresponding to the xpath. The list can be of lenght
 167     zero.
 168     """
 169     with open(xml_file, 'r') as f:
 170         tree = etree.parse(f)
 171         root = tree.getroot()
 172         # Remove all namespace
 173         # https://stackoverflow.com/questions/18159221/remove-namespace-and-prefix-from-xml-in-python-using-lxml
 174         for elem in root.getiterator():
 175             if not hasattr(elem.tag, 'find'):
 176                 continue
 177             i = elem.tag.find('}')
 178             if i >= 0:
 179                 elem.tag = elem.tag[i+1:]
 180
 181         return root.xpath(xpath)