process: Consolidate process related APIs.

As part of retrieving system statistics, process status APIs along with
helper functions were implemented. Some of them are very generic and can
be reused by other subsystems.

Move the APIs in system-stats.c to process.c and util.c and make them
available. This patch doesn't change any functionality.

Signed-off-by: Bhanuprakash Bodireddy <bhanuprakash.bodireddy@intel.com>
Signed-off-by: Ben Pfaff <blp@ovn.org>

lib/util.c

@@ -33,6 +33,7 @@
 #include "ovs-rcu.h"
 #include "ovs-thread.h"
 #include "socket-util.h"
+#include "timeval.h"
 #include "openvswitch/vlog.h"
 #ifdef HAVE_PTHREAD_SET_NAME_NP
 #include <pthread_np.h>
@@ -40,6 +41,13 @@
 
 VLOG_DEFINE_THIS_MODULE(util);
 
+#ifdef __linux__
+#define LINUX 1
+#include <asm/param.h>
+#else
+#define LINUX 0
+#endif
+
 COVERAGE_DEFINE(util_xalloc);
 
 /* argv[0] without directory names. */
@@ -538,6 +546,66 @@ set_subprogram_name(const char *subprogram_name)
 #endif
 }
 
+unsigned int
+get_page_size(void)
+{
+    static unsigned int cached;
+
+    if (!cached) {
+#ifndef _WIN32
+        long int value = sysconf(_SC_PAGESIZE);
+#else
+        long int value;
+        SYSTEM_INFO sysinfo;
+        GetSystemInfo(&sysinfo);
+        value = sysinfo.dwPageSize;
+#endif
+        if (value >= 0) {
+            cached = value;
+        }
+    }
+
+    return cached;
+}
+
+/* Returns the time at which the system booted, as the number of milliseconds
+ * since the epoch, or 0 if the time of boot cannot be determined. */
+long long int
+get_boot_time(void)
+{
+    static long long int cache_expiration = LLONG_MIN;
+    static long long int boot_time;
+
+    ovs_assert(LINUX);
+
+    if (time_msec() >= cache_expiration) {
+        static const char stat_file[] = "/proc/stat";
+        char line[128];
+        FILE *stream;
+
+        cache_expiration = time_msec() + 5 * 1000;
+
+        stream = fopen(stat_file, "r");
+        if (!stream) {
+            VLOG_ERR_ONCE("%s: open failed (%s)",
+                          stat_file, ovs_strerror(errno));
+            return boot_time;
+        }
+
+        while (fgets(line, sizeof line, stream)) {
+            long long int btime;
+            if (ovs_scan(line, "btime %lld", &btime)) {
+                boot_time = btime * 1000;
+                goto done;
+            }
+        }
+        VLOG_ERR_ONCE("%s: btime not found", stat_file);
+    done:
+        fclose(stream);
+    }
+    return boot_time;
+}
+
 /* Returns a pointer to a string describing the program version.  The
  * caller must not modify or free the returned string.
  */