1recorder_trace_set(3) Recorder Library recorder_trace_set(3)
4
8 recorder_trace_set - Configure tracing for event recorders
9 RECORDER_TRACE - Retrieve configured value
10
14 #include <recorder/recorder.h>
15 int recorder_trace_set(const char * trace_set);
17 #define RECORDER_TRACE(trace_name) ...
18
20 The recorder_trace_set() function configures tracing for event
21 recorder, based on a trace description given in trace_set. The func‐
22 tion accepts a NULL input. A typical usage is to call it twice at the
23 beginning of the program, the first time to set some default configura‐
24 tion for important recorders such as warnings or errors, the second
25 time to pass some environment variable letting users configure tracing
26 easily.
27 /* Activate tracing for all _warning and _error event recorders */
30 recorder_trace_set(".*_(warning|error)");
31 /* User trace configuration, possible overriding the above */
33 recorder_trace_set(getenv("MY_PROGRAM_TRACES"));
34 The trace description is a space-delimited list of trace actions.
37 Alternatively, a colon (:) can also be used as a separator.
38 Each trace action starts with a regular expression used to select event
41 recorders by name. That regular expression can optionally be followed
42 by an equal sign = itself followed by either a numerical value or a
43 comma-separated list of names.
44 Tracing
47 If a numerical value is given, this value is associated to the selected
48 recorder(s), and can be read in the program by using
49 RECORDER_TRACE(trace_name).
50 The configured value is primarily used to activate tracing for the
53 record(3) and record_fast(3) functions. When the value is non-zero,
54 these functions will immediately show the events (tracing mode). Other‐
55 wise, they will simply record the events.
56 If no equal sign is given, the numerical value 1 is used.
59 Sharing for real-time graphing
62 If a comma-separated list of names is given, the corresponding event
63 recorder is shared for use by external programs such as
64 recorder_scope(1). All events must have the same number and type of
65 arguments. The comma-separated list sets the names of the data channels
66 that can then be graphed in real-time.
67 Special trace selectors
70 A number of trace selectors have a special meaning, and are normally
71 intended for the user of the program.
72 help displays the list of all available recorders, along with the
75 associated self-documentation string.
76 share sets the name of the shared-memory file used to communicate with
79 external programs, see recorder_share(3).
80 dump causes a recorder dump. See recorder_dump(3).
83 traces lists the current values for all trace configurations.
86 all activates all traces.
89
93 The function can return one of:
94 RECORDER_TRACE_OK
97 Thec trace description was successfully applied
98 RECORDER_TRACE_INVALID_NAME
101 One of the trace selection regular expressions is invalid.
102 RECORDER_TRACE_INVALID_VALUE
105 One of the trace configuration values is neither a numerical
106 value nor a comma-separated list of names.
107
111 The program below records its input arguments, and crashes if passed
112 crash as the first command-line argument.
113 #include <recorder/recorder.h>
115 #include <string.h>
116 RECORDER(program_args, 32, "Program command-line arguments");
118 int main(int argc, char **argv)
119 {
120 int a;
121 recorder_dump_on_common_signals(0, 0);
122 for (a = 0; a < argc; a++)
123 record(program_args, "Argument %d is %+s", a, argv[a]);
124 if (argc >= 2 && strcmp(argv[1], "crash") == 0)
126 {
127 char *ptr = NULL;
128 strcpy(ptr, argv[1]);
129 }
130 }
131 When a crash occurs, previously recorded events are printed out on the
133 console.
134 The program below is an instrumented version of the classical recursive
137 Fibonacci computation. It uses several recorders corresponding to dif‐
138 ferent types of events, and activates warnings and errors in a way that
139 can be configured by setting an environment variable.
140 #include <recorder/recorder.h>
142 #include <string.h>
143 #include <stdio.h>
144 #include <stdlib.h>
145 RECORDER(fib_main, 32, "Loops in fib function");
147 RECORDER(fib_loops, 32, "Loops in fib function");
148 RECORDER(fib_warning, 32, "Warnings in fib function");
149 RECORDER(fib_error, 32, "Errors in fib function");
150 int fib(int n)
152 {
153 if (n <= 1) {
154 if (n < 0)
155 record(fib_error, "fib is undefined for negative value %d", n);
156 return n;
157 }
158 record(fib_loops, "Computing fib(%d)", n);
159 int result = fib(n-1) + fib(n-2);
160 record(fib_loops, "Computed fib(%d) = %d", n, result);
161 return result;
162 }
163 int main(int argc, char **argv)
165 {
166 int a;
167 recorder_dump_on_common_signals(0, 0);
168 recorder_trace_set(".*_warning=35 .*_error");
169 recorder_trace_set(getenv("FIB_TRACES"));
170 for (a = 1; a < argc; a++) {
171 int n = atoi(argv[a]);
172 if (n >= RECORDER_TRACE(fib_warning))
173 record(fib_warning, "Computing for %d may take a while", n);
174 printf("fib(%d) = %d0, n, fib(n));
175 if (n >= RECORDER_TRACE(fib_warning))
176 record(fib_warning, "Computation for %d finally completed", n);
177 }
178 }
179 This program will produce an output similar to the following:
181 % fib 1 2 3 4 10 20 30 35 10 40 -1
183 fib(1) = 1
184 fib(2) = 1
185 fib(3) = 2
186 fib(4) = 3
187 fib(10) = 55
188 fib(20) = 6765
189 fib(30) = 832040
190 [2714667 0.177725] fib_warning: Computing for 35 may take a while
191 fib(35) = 9227465
192 [32575370 1.859156] fib_warning: Computation for 35 finally completed
193 fib(10) = 55
194 [32575547 1.859171] fib_warning: Computing for 40 may take a while
195 fib(40) = 102334155
196 [363735828 20.527882] fib_warning: Computation for 40 finally completed
197 [363735829 20.527887] fib_error: fib is undefined for negative value -1
198 fib(-1) = -1
199 The first column in trace outputs is the number of events that were
200 recorded. THe second column is the time in seconds since the program
201 started.
202 The same program can also be run with additional tracing or warnings,
205 for example:
206 % FIB_TRACES="recorder_location fib_loops fib_warning=3" /tmp/fib 3 4
208 /tmp/fib.c:33:[82 0.000496] fib_warning: Computing for 3 may take a while
209 /tmp/fib.c:18:[83 0.000561] fib_loops: Computing fib(3)
210 /tmp/fib.c:18:[84 0.000570] fib_loops: Computing fib(2)
211 /tmp/fib.c:20:[85 0.000575] fib_loops: Computed fib(2) = 1
212 /tmp/fib.c:20:[86 0.000581] fib_loops: Computed fib(3) = 2
213 fib(3) = 2
214 /tmp/fib.c:36:[87 0.000590] fib_warning: Computation for 3 finally completed
215 /tmp/fib.c:33:[88 0.000596] fib_warning: Computing for 4 may take a while
216 /tmp/fib.c:18:[89 0.000601] fib_loops: Computing fib(4)
217 /tmp/fib.c:18:[90 0.000607] fib_loops: Computing fib(3)
218 /tmp/fib.c:18:[91 0.000612] fib_loops: Computing fib(2)
219 /tmp/fib.c:20:[92 0.000619] fib_loops: Computed fib(2) = 1
220 /tmp/fib.c:20:[93 0.000625] fib_loops: Computed fib(3) = 2
221 /tmp/fib.c:18:[94 0.000664] fib_loops: Computing fib(2)
222 /tmp/fib.c:20:[95 0.000707] fib_loops: Computed fib(2) = 1
223 /tmp/fib.c:20:[96 0.000724] fib_loops: Computed fib(4) = 3
224 fib(4) = 3
225 /tmp/fib.c:36:[97 0.000741] fib_warning: Computation for 4 finally completed
226
229 When a recorder is shared, incorrect data can be fetched by the client
230 graphing program if the types and number of arguments is not consistent
231 for all entries in the recorder.
232 Bugs should be reported using https://github.com/c3d/recorder/issues.
235
239 RECORDER_DEFINE(3), RECORDER_DECLARE(3)
240 recorder_dump(3), recorder_dump_for(3),
241 recorder_configure_output(3), recorder_configure_show(3)
242 recorder_configure_format(3), recorder_configure_type(3)
243 Additional documentation and tutorials can be found at
246 https://github.com/c3d/recorder.
247
251 Written by Christophe de Dinechin
2521.0 2019-03-09 recorder_trace_set(3)