lttng_ivc/utils/utils.py

   1 # Copyright (c) 2017 Jonathan Rajotte-Julien <jonathan.rajotte-julien@efficios.com>
   2 #
   3 # Permission is hereby granted, free of charge, to any person obtaining a copy
   4 # of this software and associated documentation files (the "Software"), to deal
   5 # in the Software without restriction, including without limitation the rights
   6 # to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
   7 # copies of the Software, and to permit persons to whom the Software is
   8 # furnished to do so, subject to the following conditions:
   9 #
  10 # The above copyright notice and this permission notice shall be included in all
  11 # copies or substantial portions of the Software.
  12 #
  13 # THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  14 # IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  15 # FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
  16 # AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
  17 # LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
  18 # OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
  19 # SOFTWARE.
  20
  21 import signal
  22 import hashlib
  23 import os
  24 import time
  25 import socket
  26
  27 from lxml import etree
  28 from contextlib import closing
  29
  30
  31 def line_count(file_path):
  32     line_count = 0
  33     with open(file_path) as f:
  34         for line in f:
  35             line_count += 1
  36     return line_count
  37
  38
  39 def sha256_checksum(filename, block_size=65536):
  40     sha256 = hashlib.sha256()
  41     with open(filename, 'rb') as f:
  42         for block in iter(lambda: f.read(block_size), b''):
  43             sha256.update(block)
  44     return sha256.hexdigest()
  45
  46
  47 # TODO: timeout as a parameter or Settings
  48 # TODO: Custom exception
  49 def wait_for_file(path):
  50     i = 0
  51     timeout = 60
  52     while not os.path.exists(path):
  53         time.sleep(1)
  54         i = i + 1
  55         if i > timeout:
  56             raise Exception("File still does not exists. Timeout expired")
  57
  58
  59 # TODO: find better exception
  60 def create_empty_file(path):
  61     if os.path.exists(path):
  62         raise Exception("Path already exist")
  63     open(path, 'w').close()
  64
  65
  66 def __dummy_sigusr1_handler():
  67     pass
  68
  69
  70 def sessiond_spawn(runtime, opt_args=""):
  71     agent_port = find_free_port()
  72     previous_handler = signal.signal(signal.SIGUSR1, __dummy_sigusr1_handler)
  73     cmd = "lttng-sessiond -vvv --verbose-consumer -S --agent-tcp-port {}".format(agent_port)
  74     cmd = " ".join([cmd, opt_args])
  75     sessiond = runtime.spawn_subprocess(cmd)
  76     signal.sigtimedwait({signal.SIGUSR1}, 60)
  77     previous_handler = signal.signal(signal.SIGUSR1, previous_handler)
  78     return sessiond
  79
  80
  81 def relayd_spawn(runtime, url="localhost"):
  82     """
  83     Return a tuple (relayd_uuid, ctrl_port, data_port, live_port)
  84     """
  85     ports = find_multiple_free_port(3)
  86     data_port = ports.pop()
  87     ctrl_port = ports.pop()
  88     live_port = ports.pop()
  89
  90     base_cmd = "lttng-relayd -vvv"
  91     data_string = "-D tcp://{}:{}".format(url, data_port)
  92     ctrl_string = "-C tcp://{}:{}".format(url, ctrl_port)
  93     live_string = "-L tcp://{}:{}".format(url, live_port)
  94
  95     cmd = " ".join([base_cmd, data_string, ctrl_string, live_string])
  96     relayd = runtime.spawn_subprocess(cmd)
  97
  98     # Synchronization based on verbosity since no -S is available for
  99     # lttng-relayd yet.
 100     log_path = runtime.get_subprocess_stderr_path(relayd)
 101
 102     # TODO: Move to settings.
 103     ready_cue = "Listener accepting live viewers connections"
 104     # TODO: Move to settings.
 105     timeout = 60
 106     ready = False
 107     for i in range(timeout):
 108         if file_contains(log_path, ready_cue):
 109             ready = True
 110             break
 111         time.sleep(1)
 112
 113     if not ready:
 114         # Cleanup is performed by runtime
 115         raise Exception("Relayd readyness timeout expired")
 116
 117     return (relayd, ctrl_port, data_port, live_port)
 118
 119
 120 def find_free_port():
 121     # There is no guarantee that the port will be free at runtime but should be
 122     # good enough
 123     with closing(socket.socket(socket.AF_INET, socket.SOCK_STREAM)) as s:
 124         s.bind(('', 0))
 125         return s.getsockname()[1]
 126
 127
 128 def find_multiple_free_port(number):
 129     """
 130     Return a list of supposedly free port
 131     """
 132     assert(number >= 0)
 133     ports = []
 134     while(len(ports) != number):
 135         port = find_free_port()
 136         if port in ports:
 137             continue
 138         ports.append(port)
 139     return ports
 140
 141
 142 def file_contains(file_path, list_of_string):
 143     with open(file_path, 'r') as f:
 144         for line in f:
 145             for s in list_of_string:
 146                 if s in line:
 147                     return True
 148
 149
 150 def find_dir(root, name):
 151     """
 152     Returns the absolute path or None.
 153     """
 154     abs_path = None
 155     for base, dirs, files in os.walk(root):
 156         for tmp in dirs:
 157             if tmp.endswith(name):
 158                 abs_path = os.path.abspath(os.path.join(base, tmp))
 159     return abs_path
 160
 161
 162 def find_file(root, name):
 163     """
 164     Returns the absolute path or None.
 165     """
 166     abs_path = None
 167     for base, dirs, files in os.walk(root):
 168         for tmp in files:
 169             if tmp.endswith(name):
 170                 abs_path = os.path.abspath(os.path.join(base, tmp))
 171     return abs_path
 172
 173
 174 def validate(xml_path, xsd_path):
 175
 176     xmlschema_doc = etree.parse(xsd_path)
 177     xmlschema = etree.XMLSchema(xmlschema_doc)
 178
 179     xml_doc = etree.parse(xml_path)
 180     result = xmlschema.validate(xml_doc)
 181
 182     return result
 183
 184 def xpath_query(xml_file, xpath):
 185     """
 186     Return a list of xml node corresponding to the xpath. The list can be of lenght
 187     zero.
 188     """
 189     with open(xml_file, 'r') as f:
 190         tree = etree.parse(f)
 191         root = tree.getroot()
 192         # Remove all namespace
 193         # https://stackoverflow.com/questions/18159221/remove-namespace-and-prefix-from-xml-in-python-using-lxml
 194         for elem in root.getiterator():
 195             if not hasattr(elem.tag, 'find'):
 196                 continue
 197             i = elem.tag.find('}')
 198             if i >= 0:
 199                 elem.tag = elem.tag[i+1:]
 200
 201         return root.xpath(xpath)