platypush/platypush/procedure/__init__.py

247 lines
8 KiB
Python

import logging
import re
from ..config import Config
from ..message.request import Request
from ..message.response import Response
logger = logging.getLogger(__name__)
class Procedure(object):
""" Procedure class. A procedure is a pre-configured list of requests """
def __init__(self, name, _async, requests, backend=None):
"""
Params:
name -- Procedure name
_async -- Whether the actions in the procedure are supposed to
be executed sequentially or in parallel (True or False)
requests -- List of platylist.message.request.Request objects
"""
self.name = name
self._async = _async
self.requests = requests
self.backend = backend
for req in requests:
req.backend = self.backend
@classmethod
def build(cls, name, _async, requests, backend=None, id=None, **kwargs):
reqs = []
loop_count = 0
if_count = 0
for request_config in requests:
# Check if this request is a for loop
if len(request_config.keys()) == 1:
key = list(request_config.keys())[0]
m = re.match('\s*(fork?)\s+([\w\d_]+)\s+in\s+(.*)\s*', key)
if m:
loop_count += 1
loop_name = '{}__loop_{}'.format(name, loop_count)
# A 'for' loop is synchronous. Declare a 'fork' loop if you
# want to process the elements in the iterable in parallel
_async = True if m.group(1) == 'fork' else False
iterator_name = m.group(2)
iterable = m.group(3)
loop = LoopProcedure.build(name=loop_name, _async=_async,
requests=request_config[key],
backend=backend, id=id,
iterator_name=iterator_name,
iterable=iterable)
reqs.append(loop)
continue
# Check if this request is an if-else
if len(request_config.keys()) >= 1:
key = list(request_config.keys())[0]
m = re.match('\s*(if)\s+\$\{(.*)\}\s*', key)
if m:
if_count += 1
if_name = '{}__if_{}'.format(name, if_count)
condition = m.group(2)
else_branch = request_config['else'] if 'else' in request_config else []
if_proc = IfProcedure(name=if_name,
requests=request_config[key],
condition=condition,
else_branch=else_branch,
backend=backend, id=id)
reqs.append(if_proc)
continue
request_config['origin'] = Config.get('device_id')
request_config['id'] = id
if 'target' not in request_config:
request_config['target'] = request_config['origin']
request = Request.build(request_config)
reqs.append(request)
return cls(name=name, _async=_async, requests=reqs, backend=backend, **kwargs)
def execute(self, n_tries=1, **context):
"""
Execute the requests in the procedure
Params:
n_tries -- Number of tries in case of failure before raising a RuntimeError
"""
logger.info('Executing request {}'.format(self.name))
response = Response()
token = Config.get('token')
for request in self.requests:
if token:
request.token = token
context['_async'] = self._async; context['n_tries'] = n_tries
response = request.execute(**context)
if not self._async:
if isinstance(response.output, dict):
for (k,v) in response.output.items():
context[k] = v
context['output'] = response.output
context['errors'] = response.errors
return response
class LoopProcedure(Procedure):
"""
Models a loop procedure, which expresses a construct similar to a
for loop in a programming language. The 'for' keyword implies a synchronous
loop, i.e. the nested actions will be executed in sequence. Use 'fork'
instead of 'for' if you want to run the actions in parallel.
Example:
procedure.sync.process_results:
-
action: http.get
args:
url: https://some-service/some/json/endpoint
# Example response: { "results": [ {"id":1, "name":"foo"}, {"id":2,"name":"bar"} ]}
-
for result in ${results}:
-
action: some.custom.action
args:
id: ${result['id']}
name: ${result['name']}
"""
context = {}
def __init__(self, name, iterator_name, iterable, requests, _async=False, backend=None, **kwargs):
super(). __init__(name=name, _async=_async, requests=requests, backend=None, **kwargs)
self.iterator_name = iterator_name
self.iterable = iterable
self.requests = requests
def execute(self, _async=None, **context):
iterable = Request.expand_value_from_context(self.iterable, **context)
response = Response()
for item in iterable:
context[self.iterator_name] = item
response = super().execute(**context)
return response
class IfProcedure(Procedure):
"""
Models an if-else construct.
Example:
procedure.sync.process_results:
-
action: http.get
args:
url: https://some-service/some/json/endpoint
# Example response: { "sensors": [ {"temperature": 18 } ] }
-
if ${sensors['temperature'] < 20}:
-
action: shell.exec
args:
cmd: '/path/turn_on_heating.sh'
else:
-
action: shell.exec
args:
cmd: '/path/turn_off_heating.sh'
"""
context = {}
def __init__(self, name, condition, requests, else_branch=[], backend=None, id=None, **kwargs):
kwargs['_async'] = False
self.condition = condition
self.else_branch = []
reqs = []
for req in requests:
req['origin'] = Config.get('device_id')
req['id'] = id
if 'target' not in req:
req['target'] = req['origin']
reqs.append(Request.build(req))
for req in else_branch:
req['origin'] = Config.get('device_id')
req['id'] = id
if 'target' not in req:
req['target'] = req['origin']
self.else_branch.append(Request.build(req))
super(). __init__(name=name, requests=reqs, backend=None, **kwargs)
def execute(self, **context):
for (k, v) in context.items():
try:
exec('{}={}'.format(k, v))
except:
if isinstance(v, str):
try:
exec('{}="{}"'.format(k, re.sub('(^|[^\\\])"', '\1\\"', v)))
except:
pass
condition_true = eval(self.condition)
response = Response()
if condition_true:
response = super().execute(**context)
elif self.else_branch:
try:
reqs = self.requests
self.requests = self.else_branch
response = super().execute(**context)
finally:
self.requests = reqs
return response
# vim:sw=4:ts=4:et: