PR6930: stap: supports on-file flight recorder options

Add on-file flight recorder options (the combination of -F and -o,
and -S option) to stap command, and change manpages and NEWS.
 - Both of -F and -o is specified, stap passes -D option to staprun.
 - stap just passes -S option to staprun.

6 files changed, 57 insertions, 7 deletions

diff --git a/NEWS b/NEWS
index fff8afc9..d85ec2c0 100644
--- a/NEWS
+++ b/NEWS
@@ -1,5 +1,22 @@
 * What's new
 
+- On-file flight recorder is supported. It allows stap to record huge
+  trace log on the disk and to run in background.
+  Passing -F option with -o option runs stap in background mode. In this
+  mode, staprun is detached from console, and stap itself shows staprun's
+  pid and exits.
+  Specifying the max size and the max number of log files are also available
+  by passing -S option. This option has one or two arguments seperated by
+  a comma. The first argument is the max size of a log file in MB. If the
+  size of a log file exceeds it, stap switches to the next log file
+  automatically. The second is how many files are kept on the disk. If the
+  number of log files exceeds it, the oldest log file is removed
+  automatically. The second argument can be omitted.
+
+  For example, this will record output on log files each of them is smaller
+  than 1024MB and keep last 3 logs, in background.
+    % stap -F -o /tmp/staplog -S 1024,3 script.stp
+
 - In guru mode (-g), the kernel probing blacklist is disabled, leaving 
   only a subset - the kernel's own internal kprobe blacklist - to attempt
   to filter out areas unsafe to probe.  The differences may be enough to
diff --git a/buildrun.cxx b/buildrun.cxx
index 0e9e0e17..e3634545 100644
--- a/buildrun.cxx
+++ b/buildrun.cxx
@@ -329,7 +329,10 @@ run_pass (systemtap_session& s)
     staprun_cmd += "-u ";
 
   if (s.load_only)
-    staprun_cmd += "-L ";
+    staprun_cmd += (s.output_file.empty() ? "-L " : "-D ");
+
+  if (!s.size_option.empty())
+    staprun_cmd += "-S " + s.size_option + " ";
 
   staprun_cmd += s.tmpdir + "/" + s.module_name + ".ko";
 
diff --git a/main.cxx b/main.cxx
index 890f65bc..6f4064a5 100644
--- a/main.cxx
+++ b/main.cxx
@@ -111,7 +111,9 @@ usage (systemtap_session& s, int exitcode)
     << "   -o FILE    send script output to file, instead of stdout" << endl
     << "   -c CMD     start the probes, run CMD, and exit when it finishes" << endl
     << "   -x PID     sets target() to PID" << endl
-    << "   -F         load module and start probes, then detach" << endl
+    << "   -F         run as on-file flight recorder with -o." << endl
+    << "              run as on-memory flight recorder without -o." << endl
+    << "   -S size[,n] set maximum of the size and the number of files." << endl
     << "   -d OBJECT  add unwind/symbol data for OBJECT file";
   if (s.unwindsym_modules.size() == 0)
     clog << endl;
@@ -444,7 +446,7 @@ main (int argc, char * const argv [])
         { "vp", 1, &long_opt, LONG_OPT_VERBOSE_PASS },
         { NULL, 0, NULL, 0 }
       };
-      int grc = getopt_long (argc, argv, "hVMvtp:I:e:o:R:r:m:kgPc:x:D:bs:uqwl:d:L:F",
+      int grc = getopt_long (argc, argv, "hVMvtp:I:e:o:R:r:m:kgPc:x:D:bs:uqwl:d:L:FS:",
                                                           long_options, NULL);
       if (grc < 0)
         break;
@@ -628,6 +630,10 @@ main (int argc, char * const argv [])
 	  s.macros.push_back (string (optarg));
 	  break;
 
+	case 'S':
+	  s.size_option = string (optarg);
+	  break;
+
 	case 'q':
 	  s.tapset_compile_coverage = true;
 	  break;
diff --git a/session.h b/session.h
index ec6c2e3e..820b819e 100644
--- a/session.h
+++ b/session.h
@@ -90,6 +90,7 @@ struct systemtap_session
   std::string module_name;
   std::string stapconf_name;
   std::string output_file;
+  std::string size_option;
   std::string cmd;
   int target_pid;
   int last_pass;
diff --git a/stap.1.in b/stap.1.in
index 5a2e35f9..f997b788 100644
--- a/stap.1.in
+++ b/stap.1.in
@@ -175,7 +175,7 @@ even if they do not have an explicit probe placed into them.
 .TP
 .BI \-o " FILE"
 Send standard output to named file. In bulk mode, percpu files will
-start with FILE_ followed by the cpu number.
+start with FILE_ (FILE_cpu with -F) followed by the cpu number.
 .TP
 .BI \-c " CMD"
 Start the probes, run CMD, and exit when CMD finishes.
@@ -193,8 +193,18 @@ and aliases.
 Similar to "-l", but list probe points and script-level local variables.
 .TP
 .BI \-F
-Load module and start probes, then detach from the module leaving the
-probes running.
+Without -o option, load module and start probes, then detach from the module
+leaving the probes running.
+With -o option, run staprun in background as a daemon and show it's pid.
+.TP
+.BI \-S " size[,N]"
+Sets the maximum size of output file and the maximum number of output files.
+If the size of output file will exceed
+.B size
+, systemtap switches output file to the next file. And if the number of
+output files exceed
+.B N
+, systemtap removes the oldest output file. You can omit the second argument.
 .TP
 .B \-\-kelf
 For names and addresses of functions to probe,
diff --git a/staprun.8.in b/staprun.8.in
index c7e77dc4..68b5c947 100644
--- a/staprun.8.in
+++ b/staprun.8.in
@@ -52,7 +52,8 @@ The '_stp_target' variable will be set to PID.
 .TP
 .B \-o FILE
 Send output to FILE. If the module uses bulk mode, the output will
-be in percpu files FILE_x where 'x' is the cpu number.
+be in percpu files FILE_x(FILE_cpux in backgroud and bulk mode)
+where 'x' is the cpu number.
 .TP
 .B \-b BUFFER_SIZE
 The systemtap module will specify a buffer size.
@@ -73,6 +74,18 @@ Attach to loaded systemtap module.
 Delete a module.  Only detached or unused modules
 the user has permission to access will be deleted. Use "*"
 (quoted) to delete all unused modules.
+.TP
+.BI \-D
+Run staprun in background as a daemon and show it's pid.
+.TP
+.BI \-S " size[,N]"
+Sets the maximum size of output file and the maximum number of output files.
+If the size of output file will exceed
+.B size
+, systemtap switches output file to the next file. And if the number of
+output files exceed
+.B N
+, systemtap removes the oldest output file. You can omit the second argument.
 
 .SH ARGUMENTS
 .B MODULE