It works, thank you for helping out!!! At 2022-08-16 04:29:51, "Philippe Proulx" <eeppelitel...@gmail.com> wrote: >On Sun, Aug 14, 2022 at 4:48 AM zenan <dantefu9...@163.com> wrote: >> >> In command line, I use “babeltrace2 net://somehost/some-session” to read >> live lttng session trace, and I want to use python bindings to do the same, >> is it possible? >> >> here is my code: > >Almost there. > >Some `src.ctf.lttng-live` component and message iterator methods may >return a "try again" status code (I don't remember exactly under which >circumstances). This propagates to bt_graph_run() [1] (in C) eventually >which itself returns `BT_GRAPH_RUN_STATUS_AGAIN`. The Python >bt2.Graph.run() method translates this status code to throwing >`bt2.TryAgain`. > >Just catch those `bt2.TryAgain`, wait a bit, and call `graph.run()` >again: > > # Run the trace processing graph. > while True: > try: > graph.run() > except bt2.TryAgain: > time.sleep(.1) > >Works for me. > >If you ever need to access the messages themselves instead of forwarding >them to a `sink.text.pretty` component, then use a >`bt2.TraceCollectionMessageIterator` instance [2]. > >Hope it helps, > >Phil > >[1]: >https://babeltrace.org/docs/v2.0/libbabeltrace2/group__api-graph.html#gad2e1c1ab20d1400af1b552e70b3d567c >[2]: >https://babeltrace.org/docs/v2.0/python/bt2/examples.html#iterate-trace-events > >> >> import bt2 >> import sys >> >> # Create an empty graph. >> graph = bt2.Graph() >> >> # Add a `source.text.dmesg` component. >> # >> # graph.add_component() returns the created and added component. >> # >> # Such a component reads Linux kernel ring buffer messages (see >> # `dmesg(1)`) from the standard input and creates corresponding event >> # messages. See `babeltrace2-source.text.dmesg(7)`. >> # >> # `my source` is the unique name of this component within `graph`. >> >> # the original source code here in the example is: >> # comp_cls = bt2.find_plugin('text').source_component_classes['dmesg'] >> # src_comp = graph.add_component(comp_cls,'my source') >> comp_cls = bt2.find_plugin('ctf').source_component_classes['lttng-live'] >> src_comp = graph.add_component(comp_cls, 'my source', params = { >> 'inputs': [sys.argv[1]], >> }) >> >> # Add a `sink.text.pretty` component. >> # >> # Such a component pretty-prints event messages on the standard output >> # (one message per line). See `babeltrace2-sink.text.pretty(7)`. >> # >> # The `babeltrace2 convert` CLI command uses a `sink.text.pretty` >> # sink component by default. >> comp_cls = bt2.find_plugin('text').sink_component_classes['pretty'] >> sink_comp = graph.add_component(comp_cls, 'my sink') >> >> # Connect the `out` output port of the `source.text.dmesg` component >> # to the `in` input port of the `sink.text.pretty` component. >> graph.connect_ports(src_comp.output_ports['out'], >> sink_comp.input_ports['in']) >> >> # Run the trace processing graph. >> graph.run() >> >> >> >> >> >> 发件人: Philippe Proulx >> 发送时间: 2022年8月10日 22:08 >> 收件人: zenan >> 抄送: lttng-dev@lists.lttng.org >> 主题: Re: [lttng-dev] babeltrace2 python api related question >> >> >> >> On Wed, Aug 10, 2022 at 9:54 AM zenan via lttng-dev >> >> <lttng-dev@lists.lttng.org> wrote: >> >> > >> >> > >> >> > >> >> > Hi there, >> >> > >> >> > I’m trying to use babeltrace2 python bindings to track live lttng trace, >> > as shown in some examples in the documents, I tried to use ctf.lttng-live( >> > ctf.fs in the documents) plugin as source, and use text.pretty as sink, >> > but it didn’t work out as I expected. So does the api support tracking >> > live lttng trace and print them out yet? >> >> > >> >> > >> >> >> >> What did you try exactly? >> >> >> >> I need command lines and/or some code (keep it minimal) to help you. >> >> >> >> Philippe >> >> >> >> > >> >> > >> >> > >> >> > Yours sincerely >> >> > >> >> > _______________________________________________ >> >> > lttng-dev mailing list >> >> > lttng-dev@lists.lttng.org >> >> > https://lists.lttng.org/cgi-bin/mailman/listinfo/lttng-dev >> >>
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