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DEFAULT_TASK_MAX_DURATION = 36000
module OpenTox
# Class for handling asynchronous tasks
class Task
attr_accessor :pid, :observer_pid
def self.create service_uri, params={}
task = Task.new RestClientWrapper.post(service_uri,params).chomp
pid = fork do
begin
result_uri = yield
task.completed result_uri
rescue
RestClientWrapper.put(File.join(task.uri,'Error'),{:errorReport => $!.report.to_yaml}) if $!.respond_to? :report
task.kill
end
end
Process.detach(pid)
task.pid = pid
# watch if task has been cancelled
observer_pid = fork do
task.wait
begin
Process.kill(9,task.pid) if task.cancelled?
rescue
$logger.warn "Could not kill process of task #{task.uri}, pid: #{task.pid}"
end
end
Process.detach(observer_pid)
task.observer_pid = observer_pid
task
end
def kill
Process.kill(9,@pid)
Process.kill(9,@observer_pid)
rescue # no need to raise an exeption if processes are not running
end
def description
pull
self.[](RDF::DC.description).uniq.first
end
def creator
pull
self.[](RDF::DC.creator).uniq.first
end
def cancel
kill
RestClientWrapper.put(File.join(@uri,'Cancelled'),{})
end
def completed(uri)
#not_found_error "Result URI \"#{uri}\" does not exist." unless URI.accessible? uri
RestClientWrapper.put(File.join(@uri,'Completed'),{:resultURI => uri})
end
# waits for a task, unless time exceeds or state is no longer running
# @param [optional,Numeric] dur seconds pausing before checking again for completion
# TODO: add waiting task
def wait
start_time = Time.new
due_to_time = start_time + DEFAULT_TASK_MAX_DURATION
dur = 0
while running?
sleep dur
dur = [[(Time.new - start_time)/20.0,0.3].max,300.0].min
time_out_error "max wait time exceeded ("+DEFAULT_TASK_MAX_DURATION.to_s+"sec), task: '"+@uri.to_s+"'" if (Time.new > due_to_time)
end
end
end
# get only header for status requests
def running?
RestClientWrapper.head(@uri).code == 202
end
def cancelled?
RestClientWrapper.head(@uri).code == 503
end
def completed?
RestClientWrapper.head(@uri).code == 200
end
def error?
code = RestClientWrapper.head(@uri).code
code >= 400 and code != 503
end
def errorReport
# TODO: fix rdf output at task service
not_implemented_error "RDF output of errorReports has to be fixed at task service"
end
[:hasStatus, :resultURI].each do |method|
define_method method do
response = self.[](RDF::OT[method])
response = self.[](RDF::OT1[method]) unless response # API 1.1 compatibility
response
end
end
#TODO: subtasks (only for progress)
end
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