[v3,16/46] tools/lib/traceevent: Man pages for tep_register_print_function() and tep_unregister_print_function()
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Message ID 20181127154153.11315-17-tstoyanov@vmware.com
State New
Headers show
  • Libtraceevent MAN pages
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Commit Message

Tzvetomir Stoyanov Nov. 27, 2018, 3:42 p.m. UTC
Create man pages for tep_register_print_function() and tep_unregister_print_function()
as part of the libtraceevent APIs.

Signed-off-by: Tzvetomir Stoyanov <tstoyanov@vmware.com>
 .../libtraceevent-reg_print_func.txt          | 128 ++++++++++++++++++
 1 file changed, 128 insertions(+)
 create mode 100644 tools/lib/traceevent/Documentation/libtraceevent-reg_print_func.txt

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diff --git a/tools/lib/traceevent/Documentation/libtraceevent-reg_print_func.txt b/tools/lib/traceevent/Documentation/libtraceevent-reg_print_func.txt
new file mode 100644
index 000000000000..fbb2f973f3b0
--- /dev/null
+++ b/tools/lib/traceevent/Documentation/libtraceevent-reg_print_func.txt
@@ -0,0 +1,128 @@ 
+tep_register_print_function,tep_unregister_print_function - Registers / Unregisters
+a helper function.
+*#include <event-parse.h>*
+enum *tep_func_arg_type* {
+typedef unsigned long long (*pass:[*]tep_func_handler*)(struct trace_seq pass:[*]s, unsigned long long pass:[*]args);
+int *tep_register_print_function*(struct tep_handle pass:[*]_tep_, tep_func_handler _func_, enum tep_func_arg_type _ret_type_, char pass:[*]_name_, _..._);
+int *tep_unregister_print_function*(struct tep_handle pass:[*]_tep_, tep_func_handler _func_, char pass:[*]_name_);
+Some events may have helper functions in the print format arguments. This allows
+a plugin to dynamically create a way to process one of these functions.
+The _tep_register_print_function()_ registers such helper function. The _tep_ 
+argument is the trace event parser context. The _func_ argument is the address
+of the helper function. The _ret_type_ argument is  the return type of the 
+helper function, value from the _tep_func_arg_type_ enum. The _name_ is the name
+of the helper function, as seen in the print format arguments. The _..._ is a 
+variable list of _tep_func_arg_type_ enums, the _func_ function arguments. 
+This list must end with _TEP_FUNC_ARG_VOID_.
+The _tep_unregister_print_function()_ unregisters a helper function, previously 
+registered with _tep_register_print_function()_. The _tep_ argument is the 
+trace event parser context. The _func_ and _name_ arguments are the same, used 
+when the helper function was registered.
+The _tep_func_handler_ is the type of the helper function. The _s_ argument is 
+the trace sequence, it can be used to create a custom string.
+The _args_  is a list of arguments, defined when the helper function was 
+The _tep_register_print_function()_ function returns 0 in case of success. 
+In case of an error, TEP_ERRNO_... code is returned.
+The _tep_unregister_print_function()_ returns 0 in case of success, or -1 in
+case of an error.
+#include <event-parse.h>
+#include <trace-seq.h>
+struct tep_handle *tep = tep_alloc();
+static long long
+process_custom_helper(struct trace_seq *s, unsigned long long *args)
+	unsigned long long param = args[0];
+	trace_seq_printf(s, "the helper was called, with argument %lld", param);
+	return 0;
+	if ( tep_register_print_function(tep,
+				    process_custom_helper,
+				    "custom_helper",
+				    TEP_FUNC_ARG_VOID) != 0) {
+		/* Failed to register my process_custom_helper function */
+	}
+	if (tep_unregister_print_function(tep, process_custom_helper,
+				      	  "custom_helper") != 0) {
+		/* Failed to unregister my process_custom_helper function */
+	}				    
+	Header file to include in order to have access to the library APIs.
+	Header file to include in order to have access to trace sequences related APIs.
+	Trace sequences are used to allow a function to call several other functions 
+	to create a string of data to use.
+	Linker switch to add when building a program that uses the library.
+_libtraceevent(3)_, _trace-cmd(1)_
+*Steven Rostedt* <rostedt@goodmis.org>, author of *libtraceevent*.
+*Tzvetomir Stoyanov* <tz.stoyanov@gmail.com>, author of this man page.
+Report bugs to  <linux-trace-devel@vger.kernel.org>
+libtraceevent is Free Software licensed under the GNU LGPL 2.1