daemon: Make --monitor process change its process title.

When --monitor is used, administrators sometimes become confused about the
presence of two copies of each process.  This commit attempts to clarify
the situation by making the monitoring process change its process name, as
seen in /proc/$pid/cmdline and in "ps", to clearly indicate what is going
on.

CC: Dan Wendlandt <dan@nicira.com>

diff --git a/extras/ezio/ezio-term.c b/extras/ezio/ezio-term.c
index 8f12a7bc47780cf0f8759e4ac18b38d3d26b6a16..cedc5c96741ae57be03ce98a21d2207f99e8dd1c 100644 (file)
--- a/extras/ezio/ezio-term.c
+++ b/extras/ezio/ezio-term.c
@@ -96,6 +96,7 @@ main(int argc, char *argv[])
     int retval;
     int i;
 
+    proctitle_init(argc, argv);
     set_program_name(argv[0]);
     time_init();
     vlog_init();

diff --git a/extras/ezio/ovs-switchui.c b/extras/ezio/ovs-switchui.c
index 864e34c1e744895a1ade9030d2253bc45ddeed09..31e37f6869e9041ea687e8c539d303566dfb223c 100644 (file)
--- a/extras/ezio/ovs-switchui.c
+++ b/extras/ezio/ovs-switchui.c
@@ -144,6 +144,7 @@ main(int argc, char *argv[])
     long long int last_key_time = 0;
     int repeat_count = 0;
 
+    proctitle_init(argc, argv);
     set_program_name(argv[0]);
     time_init();
     vlog_init();

diff --git a/lib/command-line.c b/lib/command-line.c
index a2a43a1c3ce0426793cdbf21a59d35b96ae9c04f..2f99798489113b0c070bfea0b2db198555b1e34d 100644 (file)
--- a/lib/command-line.c
+++ b/lib/command-line.c
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2008, 2009 Nicira Networks.
+ * Copyright (c) 2008, 2009, 2010 Nicira Networks.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -20,7 +20,6 @@
 #include <limits.h>
 #include <stdlib.h>
 #include "util.h"
-#include "vlog.h"
 
 /* Given the GNU-style long options in 'options', returns a string that may be
  * passed to getopt() with the corresponding short options.  The caller is
@@ -87,3 +86,111 @@ run_command(int argc, char *argv[], const struct command commands[])
 
     ovs_fatal(0, "unknown command '%s'; use --help for help", argv[0]);
 }
+\f
+/* Process title. */
+
+#ifdef __linux__
+static char *argv_start;       /* Start of command-line arguments in memory. */
+static size_t argv_size;       /* Number of bytes of command-line arguments. */
+static char *saved_proctitle;  /* Saved command-line arguments. */
+
+/* Prepares the process so that proctitle_set() can later succeed.
+ *
+ * This modifies the argv[] array so that it no longer points into the memory
+ * that it originally does.  Later, proctitle_set() might overwrite that
+ * memory.  That means that this function should be called before anything else
+ * that accesses the process's argv[] array.  Ideally, it should be called
+ * before anything else, period, at the very beginning of program
+ * execution.  */
+void
+proctitle_init(int argc, char **argv)
+{
+    int i;
+
+    if (!argc || !argv[0]) {
+        /* This situation should never occur, but... */
+        return;
+    }
+
+    /* Specialized version of first loop iteration below. */
+    argv_start = argv[0];
+    argv_size = strlen(argv[0]) + 1;
+    argv[0] = xstrdup(argv[0]);
+
+    for (i = 1; i < argc; i++) {
+        size_t size = strlen(argv[i]) + 1;
+
+        /* Add (argv[i], strlen(argv[i])+1) to (argv_start, argv_size). */
+        if (argv[i] + size == argv_start) {
+            /* Arguments grow downward in memory. */
+            argv_start -= size;
+            argv_size += size;
+        } else if (argv[i] == argv_start + argv_size) {
+            /* Arguments grow upward in memory. */
+            argv_size += size;
+        } else {
+            /* Arguments not contiguous.  (Is this really Linux?) */
+        }
+
+        /* Copy out the old argument so we can reuse the space. */
+        argv[i] = xstrdup(argv[i]);
+    }
+}
+
+/* Changes the name of the process, as shown by "ps", to 'format', which is
+ * formatted as if by printf(). */
+void
+proctitle_set(const char *format, ...)
+{
+    va_list args;
+    int n;
+
+    if (!argv_start || argv_size < 8) {
+        return;
+    }
+
+    if (!saved_proctitle) {
+        saved_proctitle = xmemdup(argv_start, argv_size);
+    }
+
+    va_start(args, format);
+    n = vsnprintf(argv_start, argv_size, format, args);
+    if (n >= argv_size) {
+        /* The name is too long, so add an ellipsis at the end. */
+        strcpy(&argv_start[argv_size - 4], "...");
+    } else {
+        /* Fill the extra space with null bytes, so that trailing bytes don't
+         * show up in the command line. */
+        memset(&argv_start[n], '\0', argv_size - n);
+    }
+    va_end(args);
+}
+
+/* Restores the process's original command line, as seen by "ps". */
+void
+proctitle_restore(void)
+{
+    if (saved_proctitle) {
+        memcpy(argv_start, saved_proctitle, argv_size);
+        free(saved_proctitle);
+        saved_proctitle = NULL;
+    }
+}
+#else  /* !__linux__ */
+/* Stubs that don't do anything on non-Linux systems. */
+
+void
+proctitle_init(int argc UNUSED, char **argv UNUSED)
+{
+}
+
+void
+proctitle_set(const char *format UNUSED, ...)
+{
+}
+
+void
+proctitle_restore(void)
+{
+}
+#endif  /* !__linux__ */

diff --git a/lib/command-line.h b/lib/command-line.h
index bc2071eff1a96a2bff18bb3b7e6dabee08851859..1c8800335c7ada332204d7b7049295511fef6c9d 100644 (file)
--- a/lib/command-line.h
+++ b/lib/command-line.h
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2008, 2009 Nicira Networks.
+ * Copyright (c) 2008, 2009, 2010 Nicira Networks.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -33,4 +33,9 @@ struct command {
 char *long_options_to_short_options(const struct option *options);
 void run_command(int argc, char *argv[], const struct command[]);
 
+void proctitle_init(int argc, char **argv);
+void proctitle_set(const char *, ...)
+    PRINTF_FORMAT(1, 2);
+void proctitle_restore(void);
+
 #endif /* command-line.h */

diff --git a/lib/daemon.c b/lib/daemon.c
index 8629114637f0df62cb2631d82145ca6b8615fbf3..140e0f725f9bf84a32b472a178ae65eccc1ad9c2 100644 (file)
--- a/lib/daemon.c
+++ b/lib/daemon.c
@@ -22,6 +22,7 @@
 #include <string.h>
 #include <sys/wait.h>
 #include <unistd.h>
+#include "command-line.h"
 #include "fatal-signal.h"
 #include "dirs.h"
 #include "lockfile.h"
@@ -325,13 +326,19 @@ monitor_daemon(pid_t daemon_pid)
     /* XXX Should limit the rate at which we restart the daemon. */
     /* XXX Should log daemon's stderr output at startup time. */
     const char *saved_program_name;
+    char *status_msg;
 
     saved_program_name = program_name;
     program_name = xasprintf("monitor(%s)", program_name);
+    status_msg = xstrdup("healthy");
     for (;;) {
         int retval;
         int status;
 
+        proctitle_set("%s: monitoring pid %lu (%s)",
+                      saved_program_name, (unsigned long int) daemon_pid,
+                      status_msg);
+
         do {
             retval = waitpid(daemon_pid, &status, 0);
         } while (retval == -1 && errno == EINTR);
@@ -339,25 +346,27 @@ monitor_daemon(pid_t daemon_pid)
         if (retval == -1) {
             ovs_fatal(errno, "waitpid failed");
         } else if (retval == daemon_pid) {
-            char *status_msg = process_status_msg(status);
-            if (should_restart(status)) {
-                VLOG_ERR("%s daemon died unexpectedly (%s), restarting",
-                         saved_program_name, status_msg);
-                free(status_msg);
+            char *s = process_status_msg(status);
+            free(status_msg);
+            status_msg = xasprintf("pid %lu died, %s",
+                                   (unsigned long int) daemon_pid, s);
+            free(s);
 
+            if (should_restart(status)) {
+                VLOG_ERR("%s, restarting", status_msg);
                 daemon_pid = fork_and_wait_for_startup(&daemonize_fd);
                 if (!daemon_pid) {
                     break;
                 }
             } else {
-                VLOG_INFO("%s daemon exited normally (%s), exiting",
-                          saved_program_name, status_msg);
+                VLOG_INFO("%s, exiting", status_msg);
                 exit(0);
             }
         }
     }
 
     /* Running in new daemon process. */
+    proctitle_restore();
     free((char *) program_name);
     program_name = saved_program_name;
 }

diff --git a/ovsdb/ovsdb-client.c b/ovsdb/ovsdb-client.c
index baf525d4e83e1690e531744ee8d49aef1f88db38..02946df6d02a58104813c046b52da2fd88e598dc 100644 (file)
--- a/ovsdb/ovsdb-client.c
+++ b/ovsdb/ovsdb-client.c
@@ -67,6 +67,7 @@ static void parse_options(int argc, char *argv[]);
 int
 main(int argc, char *argv[])
 {
+    proctitle_init(argc, argv);
     set_program_name(argv[0]);
     time_init();
     vlog_init();

diff --git a/ovsdb/ovsdb-server.c b/ovsdb/ovsdb-server.c
index e3740a36c5ae3b4f709936de8da7dc26e1f6f41d..900f4eccb1e63e58650cc2ec214b1d9b41a7513c 100644 (file)
--- a/ovsdb/ovsdb-server.c
+++ b/ovsdb/ovsdb-server.c
@@ -71,6 +71,7 @@ main(int argc, char *argv[])
     bool exiting;
     int retval;
 
+    proctitle_init(argc, argv);
     set_program_name(argv[0]);
     time_init();
     vlog_init();

diff --git a/tests/test-jsonrpc.c b/tests/test-jsonrpc.c
index da92cec90196a10d296a194e7c0c8c83a5887bd8..570ae11a839fa451996c98d64bd580001a525b70 100644 (file)
--- a/tests/test-jsonrpc.c
+++ b/tests/test-jsonrpc.c
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2009 Nicira Networks.
+ * Copyright (c) 2009, 2010 Nicira Networks.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -42,6 +42,7 @@ static void parse_options(int argc, char *argv[]);
 int
 main(int argc, char *argv[])
 {
+    proctitle_init(argc, argv);
     set_program_name(argv[0]);
     time_init();
     vlog_init();

diff --git a/tests/test-timeval.c b/tests/test-timeval.c
index 7aa6867a8797ca48b33e928e92eccb00b12b5496..3b39b4117963452bc8d370b25e374bcab43a6b66 100644 (file)
--- a/tests/test-timeval.c
+++ b/tests/test-timeval.c
@@ -24,6 +24,7 @@
 #include <sys/types.h>
 #include <unistd.h>
 
+#include "command-line.h"
 #include "daemon.h"
 #include "util.h"
 
@@ -83,6 +84,7 @@ usage(void)
 int
 main(int argc, char *argv[])
 {
+    proctitle_init(argc, argv);
     set_program_name(argv[0]);
     time_init();
 

diff --git a/utilities/ovs-controller.c b/utilities/ovs-controller.c
index 34198b5a3eb9e2b7040a5601193bba8861fd5b66..0497d9a48154ea1cd1c34500b84cabf9db91210b 100644 (file)
--- a/utilities/ovs-controller.c
+++ b/utilities/ovs-controller.c
@@ -82,6 +82,7 @@ main(int argc, char *argv[])
     int retval;
     int i;
 
+    proctitle_init(argc, argv);
     set_program_name(argv[0]);
     time_init();
     vlog_init();

diff --git a/utilities/ovs-discover.c b/utilities/ovs-discover.c
index 8f46b992e35504922634b910d81c0a44327ed5c1..dbdd741a6650bfc5c380b74538965c170ccbef69 100644 (file)
--- a/utilities/ovs-discover.c
+++ b/utilities/ovs-discover.c
@@ -75,6 +75,7 @@ main(int argc, char *argv[])
     int retval;
     int i;
 
+    proctitle_init(argc, argv);
     set_program_name(argv[0]);
     time_init();
     vlog_init();

diff --git a/utilities/ovs-openflowd.c b/utilities/ovs-openflowd.c
index 43cbd6e0146c6bd0b2f367541b0c70610e40bd99..e0cfdc957bca741cf1ceaed93e90cc16347085b0 100644 (file)
--- a/utilities/ovs-openflowd.c
+++ b/utilities/ovs-openflowd.c
@@ -112,6 +112,7 @@ main(int argc, char *argv[])
     int error;
     struct netflow_options nf_options;
 
+    proctitle_init(argc, argv);
     set_program_name(argv[0]);
     time_init();
     vlog_init();

diff --git a/vswitchd/ovs-brcompatd.c b/vswitchd/ovs-brcompatd.c
index 04ee2c061b55fa3489cfc37996309e5547b4bc1a..585ab2c70576f3f080ddf84f890e0ebde5fc3fb9 100644 (file)
--- a/vswitchd/ovs-brcompatd.c
+++ b/vswitchd/ovs-brcompatd.c
@@ -1144,6 +1144,7 @@ main(int argc, char *argv[])
     struct ovsdb_idl *idl;
     int retval;
 
+    proctitle_init(argc, argv);
     set_program_name(argv[0]);
     time_init();
     vlog_init();

diff --git a/vswitchd/ovs-vswitchd.c b/vswitchd/ovs-vswitchd.c
index d9086dc93b7ffc967347178a7b3331fd166a24f8..ea997b0e424685cbaa09cd8d8bc2c96d42f2df71 100644 (file)
--- a/vswitchd/ovs-vswitchd.c
+++ b/vswitchd/ovs-vswitchd.c
@@ -62,6 +62,7 @@ main(int argc, char *argv[])
     unsigned int idl_seqno;
     int retval;
 
+    proctitle_init(argc, argv);
     set_program_name(argv[0]);
     time_init();
     vlog_init();