sar: Take into account a change of CPU number in sar datafile (2)

sadc now accepts a change of CPU count when inserting a restart mark. In
this case, sadc sets the new value in file's header (last_cpu_nr field)
then rewrites it.
The new number of CPU is also written after the restart mark record in
file.

Signed-off-by: Sebastien GODARD <sysstat@users.noreply.github.com>

diff --git a/sa.h b/sa.h
index d24eb8e145c773992ef304ced32c1e51b6eb3d01..f760a827b0bb2a35f0069ae5bf3f752f9385e77c 100644 (file)
--- a/sa.h
+++ b/sa.h
@@ -242,9 +242,12 @@
  */
 #define AO_SELECTED            0x02
 /*
- * Indicate that, when registered again, activity counters will get back
- * the values they had when they were unregistered (eg. CPUs, which can
- * be disabled/enabled on the fly).
+ * When appending data to a file, the number of items (for every activity)
+ * is forced to that of the file (number of network interfaces, serial lines, etc.)
+ * Except for remanent activities like A_CPU: If current
+ * machine has a different number of CPU than that of the file (but is
+ * equal to last_cpu_nr) then data will be appended with a number of items
+ * equal to that of the machine.
  */
 #define AO_REMANENT            0x04
 /*
@@ -464,7 +467,7 @@ struct activity {
  *     |--                         --|
  *
  * (*)Note: If it's a special record, we may find a comment instead of
- * statistics (R_COMMENT record type) or even nothing at all (R_RESTART
+ * statistics (R_COMMENT record type) or the number of CPU items (R_RESTART
  * record type).
  ***************************************************************************
  */

diff --git a/sadc.c b/sadc.c
index 8f42fd83c9fac7383611fa3941833f7518fe3645..15755a3a7da267c24abc40dcc2e185af49daa910 100644 (file)
--- a/sadc.c
+++ b/sadc.c
@@ -499,6 +499,14 @@ void setup_file_hdr(int fd)
        file_hdr.sa_month       = rectime.tm_mon;
        file_hdr.sa_year        = rectime.tm_year;
        file_hdr.sa_sizeof_long = sizeof(long);
+       
+       /*
+        * This is a new file (or stdout): Field last_cpu_nr is set to the number
+        * of CPU items of the machine (1 .. CPU_NR + 1).
+        * A_CPU activity is always collected, hence its number of items is
+        * always counted (in sa_sys_init()).
+        */
+       file_hdr.last_cpu_nr = act[get_activity_position(act, A_CPU)]->nr;
 
        /* Get system name, release number, hostname and machine architecture */
        uname(&header);
@@ -590,7 +598,13 @@ void write_special_record(int ofd, int rtype)
                p_write_error();
        }
 
-       if (rtype == R_COMMENT) {
+       if (rtype == R_RESTART) {
+               /* Also write current number of CPU */
+               if ((n = write_all(ofd, &file_hdr.last_cpu_nr, sizeof(unsigned int))) != sizeof(unsigned int)) {
+                       p_write_error();
+               }
+       }
+       else if (rtype == R_COMMENT) {
                /* Also write the comment */
                if ((n = write_all(ofd, comment, MAX_COMMENT_LEN)) != MAX_COMMENT_LEN) {
                        p_write_error();
@@ -642,6 +656,44 @@ void write_stats(int ofd)
        }
 }
 
+/*
+ ***************************************************************************
+ * Rewrite file's header. Done when number of CPU has changed.
+ *
+ * IN:
+ * @ofd                Output file descriptor.
+ * @fpos       Position in file where header structure has to be written.
+ * @file_magic File magic structure.
+ ***************************************************************************
+ */
+void rewrite_file_hdr(int *ofd, off_t fpos, struct file_magic *file_magic)
+{
+       int n;
+       
+       /* Remove O_APPEND status flag */
+       if (fcntl(*ofd, F_SETFL, 0) < 0) {
+               perror("fcntl");
+               exit(2);
+       }
+       
+       /* Now rewrite file's header with its new CPU number value */
+       if (lseek(*ofd, fpos, SEEK_SET) < fpos) {
+               perror("lseek");
+               exit(2);
+       }
+       
+       n = MINIMUM(file_magic->header_size, FILE_HEADER_SIZE);
+       if (write_all(*ofd, &file_hdr, n) != n) {
+               p_write_error();
+       }
+       
+       /* Restore O_APPEND status flag */
+       if (fcntl(*ofd, F_SETFL, O_APPEND) < 0) {
+               perror("fcntl");
+               exit(2);
+       }
+}
+
 /*
  ***************************************************************************
  * Create a system activity daily data file.
@@ -704,19 +756,23 @@ void open_stdout(int *stdfd)
  * We may enter this function several times (when we rotate a file).
  *
  * IN:
- * @ofile      Name of output file.
+ * @ofile              Name of output file.
+ * @restart_mark       TRUE if sadc called with interval (and count) not
+ *                     set, and no comment given (so we are going to insert
+ *                     a restart mark into the file.
  *
  * OUT:
- * @ofd                Output file descriptor.
+ * @ofd                        Output file descriptor.
  ***************************************************************************
  */
-void open_ofile(int *ofd, char ofile[])
+void open_ofile(int *ofd, char ofile[], int restart_mark)
 {
        struct file_magic file_magic;
        struct file_activity file_act[NR_ACT];
        struct tm rectime;
        void *buffer = NULL;
        ssize_t sz, n;
+       off_t fpos;
        int i, p;
 
        if (ofile[0]) {
@@ -755,6 +811,12 @@ void open_ofile(int *ofd, char ofile[])
 
                        SREALLOC(buffer, char, file_magic.header_size);
        
+                       /* Save current file position */
+                       if ((fpos = lseek(*ofd, 0, SEEK_CUR)) < 0) {
+                               perror("lseek");
+                               exit(2);
+                       }
+                       
                        /* Read file standard header */
                        n = read(*ofd, buffer, file_magic.header_size);
                        memcpy(&file_hdr, buffer, MINIMUM(file_magic.header_size, FILE_HEADER_SIZE));
@@ -805,18 +867,14 @@ void open_ofile(int *ofd, char ofile[])
                                         */
                                        goto append_error;
 
-                               if ((act[p]->nr != file_act[i].nr) || (act[p]->nr2 != file_act[i].nr2)) {
-                                       if (IS_REMANENT(act[p]->options) || !file_act[i].nr || !file_act[i].nr2)
-                                               /*
-                                                * Remanent structures cannot have a different number of items.
-                                                * Also number of items and subitems should never be null.
-                                                */
-                                               goto append_error;
+                               if (!file_act[i].nr || !file_act[i].nr2) {
+                                       /* Number of items and subitems should never be null */
+                                       goto append_error;
                                }
                        }
                        
                        /*
-                        * OK: All tests successfully passed.
+                        * OK: (Almost) all tests successfully passed.
                         * List of activities from the file prevails over that of the user.
                         * So unselect all of them. And reset activity sequence.
                         */
@@ -829,10 +887,12 @@ void open_ofile(int *ofd, char ofile[])
                                
                                p = get_activity_position(act, file_act[i].id);
                                
-                               if ((act[p]->nr != file_act[i].nr) || (act[p]->nr2 != file_act[i].nr2)) {
+                               if (((act[p]->nr != file_act[i].nr) || (act[p]->nr2 != file_act[i].nr2)) &&
+                                   !IS_REMANENT(act[p]->options)) {
                                        /*
                                         * Force number of items (serial lines, network interfaces...)
-                                        * and sub-items to that of the file, and reallocate structures.
+                                        * and sub-items to that of the file (except for remanent activities),
+                                        * and reallocate structures.
                                         */
                                        act[p]->nr  = file_act[i].nr;
                                        act[p]->nr2 = file_act[i].nr2;
@@ -843,6 +903,32 @@ void open_ofile(int *ofd, char ofile[])
                                id_seq[i] = file_act[i].id;
                                act[p]->options |= AO_COLLECTED;
                        }
+                       
+                       p = get_activity_position(act, A_CPU);
+                       if (!IS_COLLECTED(act[p]->options)) {
+                               /* A_CPU activity should always exist in file */
+                               goto append_error;
+                       }
+                       
+                       if (act[p]->nr != file_hdr.last_cpu_nr) {
+                               if (!restart_mark) {
+                                       /*
+                                        * Current number of cpu items (for current system) should match
+                                        * number of cpu items of the last sample saved in file.
+                                        * Yet, this number can be different if we are inserting a restart mark.
+                                       */
+                                       goto append_error;
+                               }
+                               else {
+                                       /*
+                                        * We are inserting a restart mark, and current machine
+                                        * has a different number of CPU than that saved in file,
+                                        * so update last_cpu_nr in file's header and rewrite it.
+                                        */
+                                       file_hdr.last_cpu_nr = act[p]->nr;
+                                       rewrite_file_hdr(ofd, fpos, &file_magic);
+                               }
+                       }
                }
        }
 
@@ -992,7 +1078,7 @@ void rw_sa_stat_loop(long count, struct tm *rectime, int stdfd, int ofd,
                         * This is also used to set activity sequence to that of the file
                         * if the file already exists.
                         */
-                       open_ofile(&ofd, ofile);
+                       open_ofile(&ofd, ofile, FALSE);
 
                        /*
                         * Rewrite header and activity sequence to stdout since
@@ -1045,6 +1131,7 @@ int main(int argc, char **argv)
        char ofile[MAX_FILE_LEN];
        struct tm rectime;
        int stdfd = 0, ofd = -1;
+       int restart_mark;
        long count = 0;
 
        /* Get HZ */
@@ -1171,6 +1258,17 @@ int main(int argc, char **argv)
        /* Init structures according to machine architecture */
        sa_sys_init();
 
+       if (!interval && !comment[0]) {
+               /*
+                * Interval (and count) not set, and no comment given
+                * => We are going to insert a restart mark.
+                */
+               restart_mark = TRUE;
+       }
+       else {
+               restart_mark = FALSE;
+       }
+       
        /*
         * Open output file then STDOUT. Write header for each of them.
         * NB: Output file must be opened first, because we may change
@@ -1178,7 +1276,7 @@ int main(int argc, char **argv)
         * of the file, and the activities collected and activity sequence
         * written on STDOUT must be consistent to those of the file.
         */
-       open_ofile(&ofd, ofile);
+       open_ofile(&ofd, ofile, restart_mark);
        open_stdout(&stdfd);
 
        if (!interval) {