# limitations under the License.
"""Python API executor library.
-
-This version supports only simple request / reply VPP API methods.
-
-TODO:
- - Implement:
- - Dump functions
- - vpp-stats
-
"""
import binascii
import json
+from pprint import pformat
from robot.api import logger
from resources.libraries.python.Constants import Constants
-from resources.libraries.python.ssh import SSH, SSHTimeout
from resources.libraries.python.PapiHistory import PapiHistory
+from resources.libraries.python.PythonThree import raise_from
+from resources.libraries.python.ssh import SSH, SSHTimeout
-__all__ = ["PapiExecutor", "PapiResponse"]
-
-
-class PapiResponse(object):
- """Class for metadata specifying the Papi reply, stdout, stderr and return
- code.
- """
-
- def __init__(self, papi_reply=None, stdout="", stderr="", ret_code=None,
- requests=None):
- """Construct the Papi response by setting the values needed.
-
- :param papi_reply: API reply from last executed PAPI command(s).
- :param stdout: stdout from last executed PAPI command(s).
- :param stderr: stderr from last executed PAPI command(s).
- :param ret_code: ret_code from last executed PAPI command(s).
- :param requests: List of used PAPI requests. It is used while verifying
- replies. If None, expected replies must be provided for verify_reply
- and verify_replies methods.
- :type papi_reply: list
- :type stdout: str
- :type stderr: str
- :type ret_code: int
- :type requests: list
- """
-
- # API reply from last executed PAPI command(s).
- self.reply = papi_reply
-
- # stdout from last executed PAPI command(s).
- self.stdout = stdout
-
- # stderr from last executed PAPI command(s).
- self.stderr = stderr
-
- # return code from last executed PAPI command(s).
- self.ret_code = ret_code
-
- # List of used PAPI requests.
- self.requests = requests
-
- # List of expected PAPI replies. It is used while verifying replies.
- if self.requests:
- self.expected_replies = \
- ["{rqst}_reply".format(rqst=rqst) for rqst in self.requests]
-
- def __str__(self):
- """Return string with human readable description of the PapiResponse.
-
- :returns: Readable description.
- :rtype: str
- """
- return ("papi_reply={papi_reply},"
- "stdout={stdout},"
- "stderr={stderr},"
- "ret_code={ret_code},"
- "requests={requests}".
- format(papi_reply=self.reply,
- stdout=self.stdout,
- stderr=self.stderr,
- ret_code=self.ret_code,
- requests=self.requests))
-
- def __repr__(self):
- """Return string executable as Python constructor call.
-
- :returns: Executable constructor call.
- :rtype: str
- """
- return "PapiResponse({str})".format(str=str(self))
-
- def verify_reply(self, cmd_reply=None, idx=0,
- err_msg="Failed to verify PAPI reply."):
- """Verify and return data from the PAPI response.
-
- Note: Use only with a simple request / reply command. In this case the
- PAPI reply includes 'retval' which is checked in this method.
-
- Use if PAPI response includes only one command reply.
+__all__ = ["PapiExecutor"]
- Use it this way (preferred):
- with PapiExecutor(node) as papi_exec:
- data = papi_exec.add('show_version').execute_should_pass().\
- verify_reply()
+class PapiExecutor(object):
+ """Contains methods for executing VPP Python API commands on DUTs.
- or if you must provide the expected reply (not recommended):
+ Note: Use only with "with" statement, e.g.:
with PapiExecutor(node) as papi_exec:
- data = papi_exec.add('show_version').execute_should_pass().\
- verify_reply('show_version_reply')
-
- :param cmd_reply: PAPI reply. If None, list of 'requests' should have
- been provided to the __init__ method as pre-generated list of
- replies is used in this method in this case.
- The .execute* methods are providing the requests automatically.
- :param idx: Index to PapiResponse.reply list.
- :param err_msg: The message used if the verification fails.
- :type cmd_reply: str
- :type idx: int
- :type err_msg: str or None
- :returns: Verified data from PAPI response.
- :rtype: dict
- :raises AssertionError: If the PAPI return value is not 0, so the reply
- is not valid.
- :raises KeyError, IndexError: If the reply does not have expected
- structure.
- """
- cmd_rpl = self.expected_replies[idx] if cmd_reply is None else cmd_reply
+ replies = papi_exec.add('show_version').get_replies(err_msg)
- data = self.reply[idx]['api_reply'][cmd_rpl]
- if data['retval'] != 0:
- raise AssertionError("{msg}\nidx={idx}, cmd_reply={reply}".
- format(msg=err_msg, idx=idx, reply=cmd_rpl))
+ This class processes three classes of VPP PAPI methods:
+ 1. simple request / reply: method='request',
+ 2. dump functions: method='dump',
+ 3. vpp-stats: method='stats'.
- return data
+ The recommended ways of use are (examples):
- def verify_replies(self, cmd_replies=None,
- err_msg="Failed to verify PAPI reply."):
- """Verify and return data from the PAPI response.
+ 1. Simple request / reply
- Note: Use only with request / reply commands. In this case each
- PAPI reply includes 'retval' which is checked.
-
- Use if PAPI response includes more than one command reply.
-
- Use it this way:
+ a. One request with no arguments:
with PapiExecutor(node) as papi_exec:
- papi_exec.add(cmd1, **args1).add(cmd2, **args2).add(cmd2, **args3).\
- execute_should_pass(err_msg).verify_replies()
+ reply = papi_exec.add('show_version').get_reply()
- or if you need the data from the PAPI response:
+ b. Three requests with arguments, the second and the third ones are the same
+ but with different arguments.
with PapiExecutor(node) as papi_exec:
- data = papi_exec.add(cmd1, **args1).add(cmd2, **args2).\
- add(cmd2, **args3).execute_should_pass(err_msg).verify_replies()
+ replies = papi_exec.add(cmd1, **args1).add(cmd2, **args2).\
+ add(cmd2, **args3).get_replies(err_msg)
- or if you must provide the list of expected replies (not recommended):
+ 2. Dump functions
+ cmd = 'sw_interface_rx_placement_dump'
with PapiExecutor(node) as papi_exec:
- data = papi_exec.add(cmd1, **args1).add(cmd2, **args2).\
- add(cmd2, **args3).execute_should_pass(err_msg).\
- verify_replies(cmd_replies=cmd_replies)
-
- :param cmd_replies: List of PAPI command replies. If None, list of
- 'requests' should have been provided to the __init__ method as
- pre-generated list of replies is used in this method in this case.
- The .execute* methods are providing the requests automatically.
- :param err_msg: The message used if the verification fails.
- :type cmd_replies: list of str or None
- :type err_msg: str
- :returns: List of verified data from PAPI response.
- :rtype list
- :raises AssertionError: If the PAPI response does not include at least
- one of specified command replies.
- """
- data = list()
+ details = papi_exec.add(cmd, sw_if_index=ifc['vpp_sw_index']).\
+ get_details(err_msg)
- cmd_rpls = self.expected_replies if cmd_replies is None else cmd_replies
+ 3. vpp-stats
- if len(self.reply) != len(cmd_rpls):
- raise AssertionError(err_msg)
- for idx, cmd_reply in enumerate(cmd_rpls):
- data.append(self.verify_reply(cmd_reply, idx, err_msg))
+ path = ['^/if', '/err/ip4-input', '/sys/node/ip4-input']
- return data
+ with PapiExecutor(node) as papi_exec:
+ stats = papi_exec.add(api_name='vpp-stats', path=path).get_stats()
+ print('RX interface core 0, sw_if_index 0:\n{0}'.\
+ format(stats[0]['/if/rx'][0][0]))
-class PapiExecutor(object):
- """Contains methods for executing Python API commands on DUTs.
+ or
- Use only with "with" statement, e.g.:
+ path_1 = ['^/if', ]
+ path_2 = ['^/if', '/err/ip4-input', '/sys/node/ip4-input']
- with PapiExecutor(node) as papi_exec:
- papi_resp = papi_exec.add('show_version').execute_should_pass(err_msg)
+ with PapiExecutor(node) as papi_exec:
+ stats = papi_exec.add('vpp-stats', path=path_1).\
+ add('vpp-stats', path=path_2).get_stats()
+
+ print('RX interface core 0, sw_if_index 0:\n{0}'.\
+ format(stats[1]['/if/rx'][0][0]))
+
+ Note: In this case, when PapiExecutor method 'add' is used:
+ - its parameter 'csit_papi_command' is used only to keep information
+ that vpp-stats are requested. It is not further processed but it is
+ included in the PAPI history this way:
+ vpp-stats(path=['^/if', '/err/ip4-input', '/sys/node/ip4-input'])
+ Always use csit_papi_command="vpp-stats" if the VPP PAPI method
+ is "stats".
+ - the second parameter must be 'path' as it is used by PapiExecutor
+ method 'add'.
"""
def __init__(self, node):
def __exit__(self, exc_type, exc_val, exc_tb):
self._ssh.disconnect(self._node)
- def clear(self):
- """Empty the internal command list; return self.
-
- Use when not sure whether previous usage has left something in the list.
-
- :returns: self, so that method chaining is possible.
- :rtype: PapiExecutor
- """
- self._api_command_list = list()
- return self
-
- def add(self, csit_papi_command, **kwargs):
+ def add(self, csit_papi_command="vpp-stats", history=True, **kwargs):
"""Add next command to internal command list; return self.
The argument name 'csit_papi_command' must be unique enough as it cannot
be repeated in kwargs.
:param csit_papi_command: VPP API command.
+ :param history: Enable/disable adding command to PAPI command history.
:param kwargs: Optional key-value arguments.
:type csit_papi_command: str
+ :type history: bool
:type kwargs: dict
:returns: self, so that method chaining is possible.
:rtype: PapiExecutor
"""
- PapiHistory.add_to_papi_history(self._node, csit_papi_command, **kwargs)
+ if history:
+ PapiHistory.add_to_papi_history(
+ self._node, csit_papi_command, **kwargs)
self._api_command_list.append(dict(api_name=csit_papi_command,
api_args=kwargs))
return self
- def execute(self, process_reply=True, ignore_errors=False, timeout=120):
- """Turn internal command list into proper data and execute; return
- PAPI response.
+ def get_stats(self, err_msg="Failed to get statistics.", timeout=120):
+ """Get VPP Stats from VPP Python API.
- This method also clears the internal command list.
+ :param err_msg: The message used if the PAPI command(s) execution fails.
+ :param timeout: Timeout in seconds.
+ :type err_msg: str
+ :type timeout: int
+ :returns: Requested VPP statistics.
+ :rtype: list of dict
+ """
- :param process_reply: Process PAPI reply if True.
- :param ignore_errors: If true, the errors in the reply are ignored.
+ paths = [cmd['api_args']['path'] for cmd in self._api_command_list]
+ self._api_command_list = list()
+
+ stdout = self._execute_papi(
+ paths, method='stats', err_msg=err_msg, timeout=timeout)
+
+ return json.loads(stdout)
+
+ def get_replies(self, err_msg="Failed to get replies.", timeout=120):
+ """Get replies from VPP Python API.
+
+ The replies are parsed into dict-like objects,
+ "retval" field is guaranteed to be zero on success.
+
+ :param err_msg: The message used if the PAPI command(s) execution fails.
:param timeout: Timeout in seconds.
- :type process_reply: bool
- :type ignore_errors: bool
+ :type err_msg: str
:type timeout: int
- :returns: Papi response including: papi reply, stdout, stderr and
- return code.
- :rtype: PapiResponse
- :raises KeyError: If the reply is not correct.
+ :returns: Responses, dict objects with fields due to API and "retval".
+ :rtype: list of dict
+ :raises RuntimeError: If retval is nonzero, parsing or ssh error.
"""
+ return self._execute(method='request', err_msg=err_msg, timeout=timeout)
- local_list = self._api_command_list
+ def get_reply(self, err_msg="Failed to get reply.", timeout=120):
+ """Get reply from VPP Python API.
- # Clear first as execution may fail.
- self.clear()
-
- ret_code, stdout, stderr = self._execute_papi(local_list, timeout)
-
- papi_reply = list()
- if process_reply:
- try:
- json_data = json.loads(stdout)
- except ValueError:
- logger.error("An error occured while processing the PAPI "
- "request:\n{rqst}".format(rqst=local_list))
- raise
- for data in json_data:
- try:
- api_reply_processed = dict(
- api_name=data["api_name"],
- api_reply=self._process_reply(data["api_reply"]))
- except KeyError:
- if ignore_errors:
- continue
- else:
- raise
- papi_reply.append(api_reply_processed)
-
- return PapiResponse(papi_reply=papi_reply,
- stdout=stdout,
- stderr=stderr,
- ret_code=ret_code,
- requests=[rqst["api_name"] for rqst in local_list])
-
- def execute_should_pass(self, err_msg="Failed to execute PAPI command.",
- process_reply=True, ignore_errors=False,
- timeout=120):
- """Execute the PAPI commands and check the return code.
- Raise exception if the PAPI command(s) failed.
+ The reply is parsed into dict-like object,
+ "retval" field is guaranteed to be zero on success.
+
+ TODO: Discuss exception types to raise, unify with inner methods.
:param err_msg: The message used if the PAPI command(s) execution fails.
- :param process_reply: Indicate whether or not to process PAPI reply.
- :param ignore_errors: If true, the errors in the reply are ignored.
:param timeout: Timeout in seconds.
:type err_msg: str
- :type process_reply: bool
- :type ignore_errors: bool
:type timeout: int
- :returns: Papi response including: papi reply, stdout, stderr and
- return code.
- :rtype: PapiResponse
- :raises AssertionError: If PAPI command(s) execution failed.
+ :returns: Response, dict object with fields due to API and "retval".
+ :rtype: dict
+ :raises AssertionError: If retval is nonzero, parsing or ssh error.
"""
+ replies = self.get_replies(err_msg=err_msg, timeout=timeout)
+ if len(replies) != 1:
+ raise RuntimeError("Expected single reply, got {replies!r}".format(
+ replies=replies))
+ return replies[0]
- response = self.execute(process_reply=process_reply,
- ignore_errors=ignore_errors,
- timeout=timeout)
+ def get_sw_if_index(self, err_msg="Failed to get reply.", timeout=120):
+ """Get sw_if_index from reply from VPP Python API.
- if response.ret_code != 0:
- raise AssertionError(err_msg)
- return response
+ Frequently, the caller is only interested in sw_if_index field
+ of the reply, this wrapper makes such call sites shorter.
- def execute_should_fail(self,
- err_msg="Execution of PAPI command did not fail.",
- process_reply=False, ignore_errors=False,
- timeout=120):
- """Execute the PAPI commands and check the return code.
- Raise exception if the PAPI command(s) did not fail.
+ TODO: Discuss exception types to raise, unify with inner methods.
- It does not return anything as we expect it fails.
+ :param err_msg: The message used if the PAPI command(s) execution fails.
+ :param timeout: Timeout in seconds.
+ :type err_msg: str
+ :type timeout: int
+ :returns: Response, sw_if_index value of the reply.
+ :rtype: int
+ :raises AssertionError: If retval is nonzero, parsing or ssh error.
+ """
+ return self.get_reply(err_msg=err_msg, timeout=timeout)["sw_if_index"]
+
+ def get_details(self, err_msg="Failed to get dump details.", timeout=120):
+ """Get dump details from VPP Python API.
+
+ The details are parsed into dict-like objects.
+ The number of details per single dump command can vary,
+ and all association between details and dumps is lost,
+ so if you care about the association (as opposed to
+ logging everything at once for debugging purposes),
+ it is recommended to call get_details for each dump (type) separately.
:param err_msg: The message used if the PAPI command(s) execution fails.
- :param process_reply: Indicate whether or not to process PAPI reply.
- :param ignore_errors: If true, the errors in the reply are ignored.
:param timeout: Timeout in seconds.
:type err_msg: str
- :type process_reply: bool
- :type ignore_errors: bool
:type timeout: int
- :raises AssertionError: If PAPI command(s) execution passed.
+ :returns: Details, dict objects with fields due to API without "retval".
+ :rtype: list of dict
"""
+ return self._execute(method='dump', err_msg=err_msg, timeout=timeout)
- response = self.execute(process_reply=process_reply,
- ignore_errors=ignore_errors,
- timeout=timeout)
+ @staticmethod
+ def dump_and_log(node, cmds):
+ """Dump and log requested information, return None.
- if response.ret_code == 0:
- raise AssertionError(err_msg)
+ :param node: DUT node.
+ :param cmds: Dump commands to be executed.
+ :type node: dict
+ :type cmds: list of str
+ """
+ with PapiExecutor(node) as papi_exec:
+ for cmd in cmds:
+ details = papi_exec.add(cmd).get_details()
+ logger.debug("{cmd}:\n{details}".format(
+ cmd=cmd, details=pformat(details)))
+
+ @staticmethod
+ def run_cli_cmd(node, cmd, log=True):
+ """Run a CLI command as cli_inband, return the "reply" field of reply.
+
+ Optionally, log the field value.
+
+ :param node: Node to run command on.
+ :param cmd: The CLI command to be run on the node.
+ :param log: If True, the response is logged.
+ :type node: dict
+ :type cmd: str
+ :type log: bool
+ :returns: CLI output.
+ :rtype: str
+ """
+
+ cli = 'cli_inband'
+ args = dict(cmd=cmd)
+ err_msg = "Failed to run 'cli_inband {cmd}' PAPI command on host " \
+ "{host}".format(host=node['host'], cmd=cmd)
+
+ with PapiExecutor(node) as papi_exec:
+ reply = papi_exec.add(cli, **args).get_reply(err_msg)["reply"]
+
+ if log:
+ logger.info("{cmd}:\n{reply}".format(cmd=cmd, reply=reply))
+
+ return reply
@staticmethod
def _process_api_data(api_d):
:rtype: list
"""
+ def process_value(val):
+ """Process value.
+
+ :param val: Value to be processed.
+ :type val: object
+ :returns: Processed value.
+ :rtype: dict or str or int
+ """
+ if isinstance(val, dict):
+ for val_k, val_v in val.iteritems():
+ val[str(val_k)] = process_value(val_v)
+ return val
+ elif isinstance(val, list):
+ for idx, val_l in enumerate(val):
+ val[idx] = process_value(val_l)
+ return val
+ else:
+ return binascii.hexlify(val) if isinstance(val, str) else val
+
api_data_processed = list()
for api in api_d:
api_args_processed = dict()
for a_k, a_v in api["api_args"].iteritems():
- value = binascii.hexlify(a_v) if isinstance(a_v, str) else a_v
- api_args_processed[str(a_k)] = value
+ api_args_processed[str(a_k)] = process_value(a_v)
api_data_processed.append(dict(api_name=api["api_name"],
api_args=api_args_processed))
return api_data_processed
Apply binascii.unhexlify() method for unicode values.
- TODO: Remove the disabled code when definitely not needed.
+ TODO: Implement complex solution to process of replies.
:param api_r: API reply.
:type api_r: dict
:returns: Processed API reply / a part of API reply.
:rtype: dict
"""
+ def process_value(val):
+ """Process value.
+
+ :param val: Value to be processed.
+ :type val: object
+ :returns: Processed value.
+ :rtype: dict or str or int
+ """
+ if isinstance(val, dict):
+ for val_k, val_v in val.iteritems():
+ val[str(val_k)] = process_value(val_v)
+ return val
+ elif isinstance(val, list):
+ for idx, val_l in enumerate(val):
+ val[idx] = process_value(val_l)
+ return val
+ elif isinstance(val, unicode):
+ return binascii.unhexlify(val)
+ else:
+ return val
reply_dict = dict()
reply_value = dict()
for reply_key, reply_v in api_r.iteritems():
for a_k, a_v in reply_v.iteritems():
- # value = binascii.unhexlify(a_v) if isinstance(a_v, unicode) \
- # else a_v
- # reply_value[a_k] = value
- reply_value[a_k] = a_v
+ reply_value[a_k] = process_value(a_v)
reply_dict[reply_key] = reply_value
return reply_dict
:returns: Processed API reply.
:rtype: list or dict
"""
-
if isinstance(api_reply, list):
reverted_reply = [self._revert_api_reply(a_r) for a_r in api_reply]
else:
reverted_reply = self._revert_api_reply(api_reply)
return reverted_reply
- def _execute_papi(self, api_data, timeout=120):
+ def _execute_papi(self, api_data, method='request', err_msg="",
+ timeout=120):
"""Execute PAPI command(s) on remote node and store the result.
:param api_data: List of APIs with their arguments.
+ :param method: VPP Python API method. Supported methods are: 'request',
+ 'dump' and 'stats'.
+ :param err_msg: The message used if the PAPI command(s) execution fails.
:param timeout: Timeout in seconds.
:type api_data: list
+ :type method: str
+ :type err_msg: str
:type timeout: int
+ :returns: Stdout from remote python utility, to be parsed by caller.
+ :rtype: str
:raises SSHTimeout: If PAPI command(s) execution has timed out.
:raises RuntimeError: If PAPI executor failed due to another reason.
+ :raises AssertionError: If PAPI command(s) execution has failed.
"""
if not api_data:
- RuntimeError("No API data provided.")
+ raise RuntimeError("No API data provided.")
- api_data_processed = self._process_api_data(api_data)
- json_data = json.dumps(api_data_processed)
-
- cmd = "{fw_dir}/{papi_provider} --json_data '{json}'".format(
- fw_dir=Constants.REMOTE_FW_DIR,
- papi_provider=Constants.RESOURCES_PAPI_PROVIDER,
- json=json_data)
+ json_data = json.dumps(api_data) \
+ if method in ("stats", "stats_request") \
+ else json.dumps(self._process_api_data(api_data))
+ cmd = "{fw_dir}/{papi_provider} --method {method} --data '{json}'".\
+ format(
+ fw_dir=Constants.REMOTE_FW_DIR, method=method, json=json_data,
+ papi_provider=Constants.RESOURCES_PAPI_PROVIDER)
try:
- ret_code, stdout, stderr = self._ssh.exec_command_sudo(
- cmd=cmd, timeout=timeout)
+ ret_code, stdout, _ = self._ssh.exec_command_sudo(
+ cmd=cmd, timeout=timeout, log_stdout_err=False)
+ # TODO: Fail on non-empty stderr?
except SSHTimeout:
logger.error("PAPI command(s) execution timeout on host {host}:"
"\n{apis}".format(host=self._node["host"],
apis=api_data))
raise
- except Exception:
- raise RuntimeError("PAPI command(s) execution on host {host} "
- "failed: {apis}".format(host=self._node["host"],
- apis=api_data))
- return ret_code, stdout, stderr
+ except Exception as exc:
+ raise_from(RuntimeError(
+ "PAPI command(s) execution on host {host} "
+ "failed: {apis}".format(
+ host=self._node["host"], apis=api_data)), exc)
+ if ret_code != 0:
+ raise AssertionError(err_msg)
+
+ return stdout
+
+ def _execute(self, method='request', err_msg="", timeout=120):
+ """Turn internal command list into data and execute; return replies.
+
+ This method also clears the internal command list.
+
+ IMPORTANT!
+ Do not use this method in L1 keywords. Use:
+ - get_stats()
+ - get_replies()
+ - get_details()
+
+ :param method: VPP Python API method. Supported methods are: 'request',
+ 'dump' and 'stats'.
+ :param err_msg: The message used if the PAPI command(s) execution fails.
+ :param timeout: Timeout in seconds.
+ :type method: str
+ :type err_msg: str
+ :type timeout: int
+ :returns: Papi responses parsed into a dict-like object,
+ with field due to API or stats hierarchy.
+ :rtype: list of dict
+ :raises KeyError: If the reply is not correct.
+ """
+
+ local_list = self._api_command_list
+
+ # Clear first as execution may fail.
+ self._api_command_list = list()
+
+ stdout = self._execute_papi(
+ local_list, method=method, err_msg=err_msg, timeout=timeout)
+ replies = list()
+ try:
+ json_data = json.loads(stdout)
+ except ValueError as err:
+ raise_from(RuntimeError(err_msg), err)
+ for data in json_data:
+ if method == "request":
+ api_reply = self._process_reply(data["api_reply"])
+ # api_reply contains single key, *_reply.
+ obj = api_reply.values()[0]
+ retval = obj["retval"]
+ if retval != 0:
+ # TODO: What exactly to log and raise here?
+ err = AssertionError("Got retval {rv!r}".format(rv=retval))
+ raise_from(AssertionError(err_msg), err, level="INFO")
+ replies.append(obj)
+ elif method == "dump":
+ api_reply = self._process_reply(data["api_reply"])
+ # api_reply is a list where item contas single key, *_details.
+ for item in api_reply:
+ obj = item.values()[0]
+ replies.append(obj)
+ else:
+ # TODO: Implement support for stats.
+ raise RuntimeError("Unsuported method {method}".format(
+ method=method))
+
+ # TODO: Make logging optional?
+ logger.debug("PAPI replies: {replies}".format(replies=replies))
+
+ return replies
Code Review / csit.git / blobdiff