75 lines
2.0 KiB
ReStructuredText
75 lines
2.0 KiB
ReStructuredText
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#############
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DTrace Probes
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#############
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FoundationDB contains many dtrace probes that can be inspected during
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runtime with tools like bcc and SystemTap. All of them are in the
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``foundationdb`` provider namespace.
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``FDB_TRACE_PROBE`` is simply an alias to the varias ``DTRACE_PROBE``
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macros.
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Probes
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======
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Actors
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------
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.. code-block:: c
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FDB_TRACE_PROBE(actor_create, "actorname")
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FDB_TRACE_PROBE(actor_destroy, "actorname")
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Get's called whenever an actor is created or gets destroyed. It provides one argument which is a
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string and it is the name of the actor.
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.. code-block:: c
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FDB_TRACE_PROBE(actor_enter, "name", index)
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FDB_TRACE_PROBE(actor_exit, "name", index)
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Whenever we call into an actor (either directly through a function call or indirectly through a callback)
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we call ``actor_enter``. Whenever we leave an actor (either because it returns or because it calls into
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wait) we call ``actor_exit``. The first argument is a string of the name of the actor and the second is an
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index. ``-1`` means that we entered/exited through in a main function call, otherwise it is a generated index.
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Main-Loop
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---------
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.. code-block:: c
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FDB_TRACE_PROBE(run_loop_begin)
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Is called whenever the main network loop starts over.
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.. code-block:: c
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FDB_TRACE_PROBE(run_loop_ready_timers, numTimers)
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On each iteration of the run-loop, this indicates how many timers (created through ``delay`` or ``yield``) are
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ready. Its argument is of type ``int``.
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.. code-block:: c
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FDB_TRACE_PROBE(run_loop_thread_ready, numReady)
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On each loop-iteration. The second argument is of type ``int`` and it is the number of thread ready processes.
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.. code-block:: c
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FDB_TRACE_PROBE(run_loop_yield)
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Run loop yields.
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.. code-block:: c
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FDB_TRACE_PROBE(run_loop_tasks_start, queueSize)
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.. code-block:: c
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FDB_TRACE_PROBE(run_loop_done, queueSize)
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One iteration of the run-loop is done. The argument is of type ``int`` and is the remaining number of tasks on the
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ready queue.
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