diff options
Diffstat (limited to 'erts/doc/src/match_spec.xml')
| -rw-r--r-- | erts/doc/src/match_spec.xml | 52 |
1 files changed, 47 insertions, 5 deletions
diff --git a/erts/doc/src/match_spec.xml b/erts/doc/src/match_spec.xml index 975f01cf2c..3944f24f84 100644 --- a/erts/doc/src/match_spec.xml +++ b/erts/doc/src/match_spec.xml @@ -287,7 +287,7 @@ can <em>not</em> be one of the atoms <c><![CDATA[all]]></c>, <c><![CDATA[new]]></c> or <c><![CDATA[existing]]></c> (unless, of course, they are registered names). <c><![CDATA[P2]]></c> can <em>not</em> be <c><![CDATA[cpu_timestamp]]></c> nor - <c><![CDATA[{tracer,_}]]></c>. + <c><![CDATA[tracer]]></c>. Returns <c><![CDATA[true]]></c> and may only be used in the <c><![CDATA[MatchBody]]></c> part when tracing. </p> @@ -298,7 +298,7 @@ be either a process identifier or a registered name and is given as the first argument to the match_spec function. <c><![CDATA[P2]]></c> can <em>not</em> be <c><![CDATA[cpu_timestamp]]></c> nor - <c><![CDATA[{tracer,_}]]></c>. Returns + <c><![CDATA[tracer]]></c>. Returns <c><![CDATA[true]]></c> and may only be used in the <c><![CDATA[MatchBody]]></c> part when tracing. </p> @@ -308,11 +308,14 @@ disable list is applied first, but effectively all changes are applied atomically. The trace flags are the same as for <c><![CDATA[erlang:trace/3]]></c> not including - <c><![CDATA[cpu_timestamp]]></c> but including <c><![CDATA[{tracer,_}]]></c>. If a + <c><![CDATA[cpu_timestamp]]></c> but including <c><![CDATA[tracer]]></c>. If a tracer is specified in both lists, the tracer in the enable list takes precedence. If no tracer is specified the same tracer as the process executing the match spec is - used. With three parameters to this function the first is + used. When using a <seealso marker="erl_tracer">tracer module</seealso> + the module has to be loaded before the match specification is executed. + If it is not loaded the match will fail. + With three parameters to this function the first is either a process identifier or the registered name of a process to set trace flags on, the second is the disable list, and the third is the enable list. Returns @@ -525,7 +528,7 @@ </section> <section> - <title>Examples</title> + <title>ETS Examples</title> <p>Match an argument list of three where the first and third arguments are equal:</p> <code type="none"><![CDATA[ @@ -616,5 +619,44 @@ <p>The function <c><![CDATA[ets:test_ms/2]]></c> can be useful for testing complicated ets matches.</p> </section> + <section> + <title>Tracing Examples</title> + <p>Only generate trace message if trace control word is set to 1:</p> + <code type="none"><![CDATA[ +[{'_', + [{'==',{get_tcw},{const, 1}}], + []}] + ]]></code> + <p>Only generate trace message if there is a seq trace token:</p> + <code type="none"><![CDATA[ +[{'_', + [{'==',{is_seq_trace},{const, 1}}], + []}] + ]]></code> + <p>Remove 'silent' trace flag when first argument is 'verbose' + and add it when it is 'silent':</p> + <code type="none"><![CDATA[ +[{'$1', + [{'==',{hd, '$1'},verbose}], + [{trace, [silent],[]}]}, + {'$1', + [{'==',{hd, '$1'},silent}], + [{trace, [],[silent]}]}] + ]]></code> + <p>Add return_trace message if function is of arity 3:</p> + <code type="none"><![CDATA[ +[{'$1', + [{'==',{length, '$1'},3}], + [{return_trace}]}, + {'_',[],[]}] + ]]></code> + <p>Only generate trace message if function is of arity 3 and first argument is 'trace':</p> + <code type="none"><![CDATA[ +[{['trace','$2','$3'], + [], + []}, + {'_',[],[]}] + ]]></code> + </section> </chapter> |