Synnefo » snf-ganeti » ganeti-local

#

#

# Copyright (C) 2007, 2008, 2010 Google Inc.

#

# This program is free software; you can redistribute it and/or modify

# it under the terms of the GNU General Public License as published by

# the Free Software Foundation; either version 2 of the License, or

# (at your option) any later version.

#

# This program is distributed in the hope that it will be useful, but

# WITHOUT ANY WARRANTY; without even the implied warranty of

# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU

# General Public License for more details.

#

# You should have received a copy of the GNU General Public License

# along with this program; if not, write to the Free Software

# Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA

# 02110-1301, USA.

"""HTTP client module.

"""

import logging

import pycurl

import threading

from cStringIO import StringIO

from ganeti import http

from ganeti import compat

from ganeti import netutils

from ganeti import locking

class HttpClientRequest(object):

  def __init__(self, host, port, method, path, headers=None, post_data=None,

               read_timeout=None, curl_config_fn=None, nicename=None):

    """Describes an HTTP request.

    @type host: string

    @param host: Hostname

    @type port: int

    @param port: Port

    @type method: string

    @param method: Method name

    @type path: string

    @param path: Request path

    @type headers: list or None

    @param headers: Additional headers to send, list of strings

    @type post_data: string or None

    @param post_data: Additional data to send

    @type read_timeout: int

    @param read_timeout: if passed, it will be used as the read

        timeout while reading the response from the server

    @type curl_config_fn: callable

    @param curl_config_fn: Function to configure cURL object before request

    @type nicename: string

    @param nicename: Name, presentable to a user, to describe this request (no

                     whitespace)

    """

    assert path.startswith("/"), "Path must start with slash (/)"

    assert curl_config_fn is None or callable(curl_config_fn)

    # Request attributes

    self.host = host

    self.port = port

    self.method = method

    self.path = path

    self.read_timeout = read_timeout

    self.curl_config_fn = curl_config_fn

    self.nicename = nicename

    if post_data is None:

      self.post_data = ""

    else:

      self.post_data = post_data

    if headers is None:

      self.headers = []

    elif isinstance(headers, dict):

      # Support for old interface

      self.headers = ["%s: %s" % (name, value)

                      for name, value in headers.items()]

    else:

      self.headers = headers

    # Response status

    self.success = None

    self.error = None

    # Response attributes

    self.resp_status_code = None

    self.resp_body = None

  def __repr__(self):

    status = ["%s.%s" % (self.__class__.__module__, self.__class__.__name__),

              "%s:%s" % (self.host, self.port),

              self.method,

              self.path]

    return "<%s at %#x>" % (" ".join(status), id(self))

  @property

  def url(self):

    """Returns the full URL for this requests.

    """

    if netutils.IPAddress.IsValid(self.host):

      address = netutils.FormatAddress((self.host, self.port))

    else:

      address = "%s:%s" % (self.host, self.port)

    # TODO: Support for non-SSL requests

    return "https://%s%s" % (address, self.path)

def _StartRequest(curl, req):

  """Starts a request on a cURL object.

  @type curl: pycurl.Curl

  @param curl: cURL object

  @type req: L{HttpClientRequest}

  @param req: HTTP request

  """

  logging.debug("Starting request %r", req)

  url = req.url

  method = req.method

  post_data = req.post_data

  headers = req.headers

  # PycURL requires strings to be non-unicode

  assert isinstance(method, str)

  assert isinstance(url, str)

  assert isinstance(post_data, str)

  assert compat.all(isinstance(i, str) for i in headers)

  # Buffer for response

  resp_buffer = StringIO()

  # Configure client for request

  curl.setopt(pycurl.VERBOSE, False)

  curl.setopt(pycurl.NOSIGNAL, True)

  curl.setopt(pycurl.USERAGENT, http.HTTP_GANETI_VERSION)

  curl.setopt(pycurl.PROXY, "")

  curl.setopt(pycurl.CUSTOMREQUEST, str(method))

  curl.setopt(pycurl.URL, url)

  curl.setopt(pycurl.POSTFIELDS, post_data)

  curl.setopt(pycurl.HTTPHEADER, headers)

  if req.read_timeout is None:

    curl.setopt(pycurl.TIMEOUT, 0)

  else:

    curl.setopt(pycurl.TIMEOUT, int(req.read_timeout))

  # Disable SSL session ID caching (pycurl >= 7.16.0)

  if hasattr(pycurl, "SSL_SESSIONID_CACHE"):

    curl.setopt(pycurl.SSL_SESSIONID_CACHE, False)

  curl.setopt(pycurl.WRITEFUNCTION, resp_buffer.write)

  # Pass cURL object to external config function

  if req.curl_config_fn:

    req.curl_config_fn(curl)

  return _PendingRequest(curl, req, resp_buffer.getvalue)

class _PendingRequest:

  def __init__(self, curl, req, resp_buffer_read):

    """Initializes this class.

    @type curl: pycurl.Curl

    @param curl: cURL object

    @type req: L{HttpClientRequest}

    @param req: HTTP request

    @type resp_buffer_read: callable

    @param resp_buffer_read: Function to read response body

    """

    assert req.success is None

    self._curl = curl

    self._req = req

    self._resp_buffer_read = resp_buffer_read

  def GetCurlHandle(self):

    """Returns the cURL object.

    """

    return self._curl

  def GetCurrentRequest(self):

    """Returns the current request.

    """

    return self._req

  def Done(self, errmsg):

    """Finishes a request.

    @type errmsg: string or None

    @param errmsg: Error message if request failed

    """

    curl = self._curl

    req = self._req

    assert req.success is None, "Request has already been finalized"

    logging.debug("Request %s finished, errmsg=%s", req, errmsg)

    req.success = not bool(errmsg)

    req.error = errmsg

    # Get HTTP response code

    req.resp_status_code = curl.getinfo(pycurl.RESPONSE_CODE)

    req.resp_body = self._resp_buffer_read()

    # Ensure no potentially large variables are referenced

    try:

      # Only available in PycURL 7.19.0 and above

      reset_fn = curl.reset

    except AttributeError:

      curl.setopt(pycurl.POSTFIELDS, "")

      curl.setopt(pycurl.WRITEFUNCTION, lambda _: None)

    else:

      reset_fn()

class _NoOpRequestMonitor: # pylint: disable=W0232

  """No-op request monitor.

  """

  @staticmethod

  def acquire(*args, **kwargs):

    pass

  release = acquire

  Disable = acquire

class _PendingRequestMonitor:

  _LOCK = "_lock"

  def __init__(self, owner, pending_fn):

    """Initializes this class.

    """

    self._owner = owner

    self._pending_fn = pending_fn

    # The lock monitor runs in another thread, hence locking is necessary

    self._lock = locking.SharedLock("PendingHttpRequests")

    self.acquire = self._lock.acquire

    self.release = self._lock.release

  @locking.ssynchronized(_LOCK)

  def Disable(self):

    """Disable monitor.

    """

    self._pending_fn = None

  @locking.ssynchronized(_LOCK, shared=1)

  def GetLockInfo(self, requested): # pylint: disable=W0613

    """Retrieves information about pending requests.

    @type requested: set

    @param requested: Requested information, see C{query.LQ_*}

    """

    # No need to sort here, that's being done by the lock manager and query

    # library. There are no priorities for requests, hence all show up as

    # one item under "pending".

    result = []

    if self._pending_fn:

      owner_name = self._owner.getName()

      for client in self._pending_fn():

        req = client.GetCurrentRequest()

        if req:

          if req.nicename is None:

            name = "%s%s" % (req.host, req.path)

          else:

            name = req.nicename

          result.append(("rpc/%s" % name, None, [owner_name], None))

    return result

def _ProcessCurlRequests(multi, requests):

  """cURL request processor.

  This generator yields a tuple once for every completed request, successful or

  not. The first value in the tuple is the handle, the second an error message

  or C{None} for successful requests.

  @type multi: C{pycurl.CurlMulti}

  @param multi: cURL multi object

  @type requests: sequence

  @param requests: cURL request handles

  """

  for curl in requests:

    multi.add_handle(curl)

  while True:

    (ret, active) = multi.perform()

    assert ret in (pycurl.E_MULTI_OK, pycurl.E_CALL_MULTI_PERFORM)

    if ret == pycurl.E_CALL_MULTI_PERFORM:

      # cURL wants to be called again

      continue

    while True:

      (remaining_messages, successful, failed) = multi.info_read()

      for curl in successful:

        multi.remove_handle(curl)

        yield (curl, None)

      for curl, errnum, errmsg in failed:

        multi.remove_handle(curl)

        yield (curl, "Error %s: %s" % (errnum, errmsg))

      if remaining_messages == 0:

        break

    if active == 0:

      # No active handles anymore

      break

    # Wait for I/O. The I/O timeout shouldn't be too long so that HTTP

    # timeouts, which are only evaluated in multi.perform, aren't

    # unnecessarily delayed.

    multi.select(1.0)

def ProcessRequests(requests, lock_monitor_cb=None, _curl=pycurl.Curl,

                    _curl_multi=pycurl.CurlMulti,

                    _curl_process=_ProcessCurlRequests):

  """Processes any number of HTTP client requests.

  @type requests: list of L{HttpClientRequest}

  @param requests: List of all requests

  @param lock_monitor_cb: Callable for registering with lock monitor

  """

  assert compat.all((req.error is None and

                     req.success is None and

                     req.resp_status_code is None and

                     req.resp_body is None)

                    for req in requests)

  # Prepare all requests

  curl_to_client = \

    dict((client.GetCurlHandle(), client)

         for client in map(lambda req: _StartRequest(_curl(), req), requests))

  assert len(curl_to_client) == len(requests)

  if lock_monitor_cb:

    monitor = _PendingRequestMonitor(threading.currentThread(),

                                     curl_to_client.values)

    lock_monitor_cb(monitor)

  else:

    monitor = _NoOpRequestMonitor

  # Process all requests and act based on the returned values

  for (curl, msg) in _curl_process(_curl_multi(), curl_to_client.keys()):

    monitor.acquire(shared=0)

    try:

      curl_to_client.pop(curl).Done(msg)

    finally:

      monitor.release()

  assert not curl_to_client, "Not all requests were processed"

  # Don't try to read information anymore as all requests have been processed

  monitor.Disable()

  assert compat.all(req.error is not None or

                    (req.success and

                     req.resp_status_code is not None and

                     req.resp_body is not None)

                    for req in requests)