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| author | Lukas Larsson <[email protected]> | 2016-05-11 11:16:16 +0200 |
|---|---|---|
| committer | Rickard Green <[email protected]> | 2016-05-11 16:48:37 +0200 |
| commit | 3471d44a6a5ed5ab038c4cdc76b350119fe745e2 (patch) | |
| tree | 629de2dea305b83ee00d685cffe6b8e9533eb7d7 /erts/doc | |
| parent | 4aea719054a594a06aceb34afca0ea3df65ead77 (diff) | |
| download | otp-3471d44a6a5ed5ab038c4cdc76b350119fe745e2.tar.gz otp-3471d44a6a5ed5ab038c4cdc76b350119fe745e2.tar.bz2 otp-3471d44a6a5ed5ab038c4cdc76b350119fe745e2.zip | |
erts: Only allow remove from trace_status callback
Make it so that it is only possible to remove a tracer via
returning remove from an erl_tracer. This limition is put in
place in order to avoid a lot of lock checking and taking
in various places, especially in regards to trace events
happening on dirty schedulers.
Diffstat (limited to 'erts/doc')
| -rw-r--r-- | erts/doc/src/erl_tracer.xml | 20 |
1 files changed, 11 insertions, 9 deletions
diff --git a/erts/doc/src/erl_tracer.xml b/erts/doc/src/erl_tracer.xml index 2075b962d8..7fd5512b33 100644 --- a/erts/doc/src/erl_tracer.xml +++ b/erts/doc/src/erl_tracer.xml @@ -90,7 +90,7 @@ <item>If not set to <c>true</c>, the tracer has been requested to include the output of a match specification that was run.</item> <tag><c>scheduler_id</c></tag> - <item>Set to a number of the scheduler id is to be included by the tracer. + <item>Set to a number if the scheduler id is to be included by the tracer. Otherwise it is set to <c>undefined</c>.</item> </taglist> </p> @@ -155,14 +155,13 @@ overhead associated with tracing. If <c>trace</c> is returned the necessary trace data will be created and the trace call-back of the tracer will be called. If <c>discard</c> is returned, this trace call - will be discarded and no call to trace will be done. If - <c>remove</c> is returned, the VM will attempt to remove this tracer - from the tracee, together with any trace flags set on the tracee. + will be discarded and no call to trace will be done. </p> <p><c>trace_status</c> is a special type of <c>TraceTag</c> which is used to check if the tracer should still be active. It is called in multiple scenarios, but most significantly it is used when tracing is started - using this tracer.</p> + using this tracer. If <c>remove</c> is returned when the <c>trace_status</c> + is checked, the tracer will be removed from the tracee.</p> <p>This function may be called multiple times per tracepoint, so it is important that it is both fast and side effect free.</p> </desc> @@ -617,7 +616,7 @@ static int upgrade(ErlNifEnv* env, void** priv_data, void** old_priv_data, } /* - * argv[0]: Trace Tag + * argv[0]: TraceTag * argv[1]: TracerState * argv[2]: Tracee */ @@ -626,8 +625,11 @@ static ERL_NIF_TERM enabled(ErlNifEnv* env, int argc, const ERL_NIF_TERM argv[]) ErlNifPid to_pid; if (enif_get_local_pid(env, argv[1], &to_pid)) if (!enif_is_process_alive(env, &to_pid)) - /* tracer is dead so we should remove this tracepoint */ - return enif_make_atom(env, "remove"); + if (enif_is_identical(enif_make_atom(env, "trace_status"), argv[0])) + /* tracer is dead so we should remove this tracepoint */ + return enif_make_atom(env, "remove"); + else + return enif_make_atom(env, "discard"); /* Only generate trace for when tracer != tracee */ if (enif_is_identical(argv[1], argv[2])) @@ -645,7 +647,7 @@ static ERL_NIF_TERM enabled(ErlNifEnv* env, int argc, const ERL_NIF_TERM argv[]) } /* - * argv[0]: Trace Tag, should only be 'send' + * argv[0]: TraceTag, should only be 'send' * argv[1]: TracerState, process to send {argv[2], argv[4]} to * argv[2]: Tracee * argv[3]: Message, ignored |