replace /proc scanning code by more versatile one.

Use it where appropriate.
Stop scanning /etc/passwd *for every process*!!! (uid->username)
top: reduce memory usage - we won't save unneeded fields
from /proc info anymore. Downside: ~+250 bytes of code


git-svn-id: svn://busybox.net/trunk/busybox@16509 69ca8d6d-28ef-0310-b511-8ec308f3f277

1 files changed, 93 insertions, 51 deletions

diff --git a/procps/top.c b/procps/top.c
index c76fdc312..8d732d4b2 100644
--- a/procps/top.c
+++ b/procps/top.c
@@ -30,37 +30,76 @@
 
 #include "busybox.h"
 
-typedef int (*cmp_t)(procps_status_t *P, procps_status_t *Q);
 
-static procps_status_t *top;   /* Hehe */
+typedef struct {
+        unsigned long rss;
+#if ENABLE_FEATURE_TOP_CPU_USAGE_PERCENTAGE
+        unsigned long ticks;
+        unsigned pcpu; /* delta of ticks */
+#endif
+        unsigned pid, ppid;
+        unsigned uid;
+        char state[4];
+        char comm[COMM_LEN];
+} top_status_t;
+static top_status_t *top;
 static int ntop;
+/* This structure stores some critical information from one frame to
+   the next. Used for finding deltas. */
+struct save_hist {
+        unsigned long ticks;
+        unsigned pid;
+};
+static struct save_hist *prev_hist;
+static int prev_hist_count;
+/* static int hist_iterations; */
+static unsigned total_pcpu;
+/* static unsigned long total_rss; */
+
+
 #define OPT_BATCH_MODE (option_mask32 & 0x4)
 
 #if ENABLE_FEATURE_USE_TERMIOS
-static int pid_sort(procps_status_t *P, procps_status_t *Q)
+static int pid_sort(top_status_t *P, top_status_t *Q)
 {
+        /* Buggy wrt pids with high bit set */
+        /* (linux pids are in [1..2^15-1]) */
         return (Q->pid - P->pid);
 }
 #endif
 
-static int mem_sort(procps_status_t *P, procps_status_t *Q)
+static int mem_sort(top_status_t *P, top_status_t *Q)
 {
-        return (int)(Q->rss - P->rss);
+        /* We want to avoid unsigned->signed and truncation errors */
+        if (Q->rss < P->rss) return -1;
+        return Q->rss != P->rss; /* 0 if ==, 1 if > */
 }
 
-#if ENABLE_FEATURE_TOP_CPU_USAGE_PERCENTAGE
+
+typedef int (*cmp_funcp)(top_status_t *P, top_status_t *Q);
+
+#if !ENABLE_FEATURE_TOP_CPU_USAGE_PERCENTAGE
+
+static cmp_funcp sort_function;
+
+#else
 
 enum { SORT_DEPTH = 3 };
-static cmp_t sort_function[SORT_DEPTH];
 
-static int pcpu_sort(procps_status_t *P, procps_status_t *Q)
+static cmp_funcp sort_function[SORT_DEPTH];
+
+static int pcpu_sort(top_status_t *P, top_status_t *Q)
 {
-        return (Q->pcpu - P->pcpu);
+        /* Buggy wrt ticks with high bit set */
+        /* Affects only processes for which ticks overflow */
+        return (int)Q->pcpu - (int)P->pcpu;
 }
 
-static int time_sort(procps_status_t *P, procps_status_t *Q)
+static int time_sort(top_status_t *P, top_status_t *Q)
 {
-        return (int)((Q->stime + Q->utime) - (P->stime + P->utime));
+        /* We want to avoid unsigned->signed and truncation errors */
+        if (Q->ticks < P->ticks) return -1;
+        return Q->ticks != P->ticks; /* 0 if ==, 1 if > */
 }
 
 static int mult_lvl_cmp(void* a, void* b) {
@@ -74,24 +113,6 @@ static int mult_lvl_cmp(void* a, void* b) {
         return 0;
 }
 
-/* This structure stores some critical information from one frame to
-   the next. Mostly used for sorting. */
-struct save_hist {
-        int ticks;
-        pid_t pid;
-};
-
-/*
- * Calculates percent cpu usage for each task.
- */
-
-static struct save_hist *prev_hist;
-static int prev_hist_count;
-/* static int hist_iterations; */
-
-
-static unsigned total_pcpu;
-/* static unsigned long total_rss; */
 
 typedef struct {
         unsigned long long usr,nic,sys,idle,iowait,irq,softirq,steal;
@@ -115,11 +136,12 @@ static void get_jiffy_counts(void)
         jif.busy = jif.total - jif.idle - jif.iowait;
 }
 
+
 static void do_stats(void)
 {
-        procps_status_t *cur;
+        top_status_t *cur;
         pid_t pid;
-        int total_time, i, last_i, n;
+        int i, last_i, n;
         struct save_hist *new_hist;
 
         get_jiffy_counts();
@@ -139,8 +161,7 @@ static void do_stats(void)
                  * and system time
                  */
                 pid = cur->pid;
-                total_time = cur->stime + cur->utime;
-                new_hist[n].ticks = total_time;
+                new_hist[n].ticks = cur->ticks;
                 new_hist[n].pid = pid;
 
                 /* find matching entry from previous pass */
@@ -150,13 +171,13 @@ static void do_stats(void)
                 last_i = i;
                 if (prev_hist_count) do {
                         if (prev_hist[i].pid == pid) {
-                                cur->pcpu = total_time - prev_hist[i].ticks;
+                                cur->pcpu = cur->ticks - prev_hist[i].ticks;
+                                total_pcpu += cur->pcpu;
                                 break;
                         }
                         i = (i+1) % prev_hist_count;
                         /* hist_iterations++; */
                 } while (i != last_i);
-                total_pcpu += cur->pcpu;
                 /* total_rss += cur->rss; */
         }
 
@@ -167,10 +188,9 @@ static void do_stats(void)
         prev_hist = new_hist;
         prev_hist_count = ntop;
 }
-#else
-static cmp_t sort_function;
 #endif /* FEATURE_TOP_CPU_USAGE_PERCENTAGE */
 
+
 /* display generic info (meminfo / loadavg) */
 static unsigned long display_generic(int scr_width)
 {
@@ -265,7 +285,7 @@ static void display_status(int count, int scr_width)
                 bits_per_int = sizeof(int)*8
         };
 
-        procps_status_t *s = top;
+        top_status_t *s = top;
         char rss_str_buf[8];
         unsigned long total_memory = display_generic(scr_width); /* or use total_rss? */
         unsigned pmem_shift, pmem_scale;
@@ -333,14 +353,19 @@ static void display_status(int count, int scr_width)
                         sprintf(rss_str_buf, "%6ldM", s->rss/1024);
                 else
                         sprintf(rss_str_buf, "%7ld", s->rss);
-                USE_FEATURE_TOP_CPU_USAGE_PERCENTAGE(pcpu = div((s->pcpu*pcpu_scale) >> pcpu_shift, 10);)
-                col -= printf("\n%5u %-8s %s  %s%6u%3u.%c" \
-                                USE_FEATURE_TOP_CPU_USAGE_PERCENTAGE("%3u.%c") " ",
-                                (unsigned)s->pid, s->user, s->state, rss_str_buf, (unsigned)s->ppid,
+                USE_FEATURE_TOP_CPU_USAGE_PERCENTAGE(
+                pcpu = div((s->pcpu*pcpu_scale) >> pcpu_shift, 10);
+                )
+                col -= printf("\n%5u %-8s %s  "
+                                "%s%6u"
+                                USE_FEATURE_TOP_CPU_USAGE_PERCENTAGE("%3u.%c")
+                                "%3u.%c ",
+                                s->pid, get_cached_username(s->uid), s->state,
+                                rss_str_buf, s->ppid,
                                 USE_FEATURE_TOP_CPU_USAGE_PERCENTAGE(pcpu.quot, '0'+pcpu.rem,)
                                 pmem.quot, '0'+pmem.rem);
                 if (col > 0)
-                        printf("%.*s", col, s->short_cmd);
+                        printf("%.*s", col, s->comm);
                 /* printf(" %d/%d %lld/%lld", s->pcpu, total_pcpu,
                         jif.busy - prev_jif.busy, jif.total - prev_jif.total); */
                 s++;
@@ -350,18 +375,20 @@ static void display_status(int count, int scr_width)
         fflush(stdout);
 }
 
+
 static void clearmems(void)
 {
+        clear_username_cache();
         free(top);
         top = 0;
         ntop = 0;
 }
 
+
 #if ENABLE_FEATURE_USE_TERMIOS
 #include <termios.h>
 #include <signal.h>
 
-
 static struct termios initial_settings;
 
 static void reset_term(void)
@@ -427,7 +454,7 @@ int top_main(int argc, char **argv)
 #endif /* FEATURE_TOP_CPU_USAGE_PERCENTAGE */
 
         while (1) {
-                procps_status_t *p;
+                procps_status_t *p = NULL;
 
                 /* Default to 25 lines - 5 lines for status */
                 lines = 24 - 3;
@@ -442,11 +469,26 @@ int top_main(int argc, char **argv)
 #endif /* FEATURE_USE_TERMIOS */
 
                 /* read process IDs & status for all the processes */
-                while ((p = procps_scan(0)) != 0) {
+                while ((p = procps_scan(p, 0
+                                | PSSCAN_PID
+                                | PSSCAN_PPID
+                                | PSSCAN_RSS
+                                | PSSCAN_STIME
+                                | PSSCAN_UTIME
+                                | PSSCAN_STATE
+                                | PSSCAN_COMM
+                                | PSSCAN_SID
+                                | PSSCAN_UIDGID
+                ))) {
                         int n = ntop;
-
-                        top = xrealloc(top, (++ntop)*sizeof(procps_status_t));
-                        memcpy(top + n, p, sizeof(procps_status_t));
+                        top = xrealloc(top, (++ntop)*sizeof(top_status_t));
+                        top[n].pid = p->pid;
+                        top[n].ppid = p->ppid;
+                        top[n].rss = p->rss;
+                        top[n].ticks = p->stime + p->utime;
+                        top[n].uid = p->uid;
+                        strcpy(top[n].state, p->state);
+                        strcpy(top[n].comm, p->comm);
                 }
                 if (ntop == 0) {
                         bb_error_msg_and_die("can't find process info in /proc");
@@ -459,9 +501,9 @@ int top_main(int argc, char **argv)
                         continue;
                 }
                 do_stats();
-                qsort(top, ntop, sizeof(procps_status_t), (void*)mult_lvl_cmp);
+                qsort(top, ntop, sizeof(top_status_t), (void*)mult_lvl_cmp);
 #else
-                qsort(top, ntop, sizeof(procps_status_t), (void*)sort_function);
+                qsort(top, ntop, sizeof(top_status_t), (void*)sort_function);
 #endif /* FEATURE_TOP_CPU_USAGE_PERCENTAGE */
                 count = lines;
                 if (OPT_BATCH_MODE || count > ntop) {