Automatically hide the SWAPIN/IO columns when they are unavailable

Now that the Linux kernel can enable or disable data collection for them at
runtime, showing the columns when collection is disabled is even less useful,
since the previous data could still be present in the Linux kernel buffers.

Preserve the behaviour of the batch mode though, so that programs parsing
its output aren't broken by the changes to the Linux kernel, but they may
still be broken when the output changes from ?unavailable? to real data.

Since the current sorting keys code makes it hard to dynamically choose which
columns are shown or hidden, when the two columns are hidden, just skip over
displaying them or using them as sorting keys.

Rewrite the data display code to be more flexible wrt column choice though.

Suggested-by: Boian Bonev <bbonev@ipacct.com>

1 files changed, 24 insertions, 7 deletions

diff --git a/iotop/ui.py b/iotop/ui.py
index 7ae8bad..77f82c7 100644
--- a/iotop/ui.py
+++ b/iotop/ui.py
@@ -224,6 +224,12 @@ class IOTopUI(object):
         new_sorting_key += delta
         new_sorting_key = max(0, new_sorting_key)
         new_sorting_key = min(len(IOTopUI.sorting_keys) - 1, new_sorting_key)
+        if not self.has_swapin_io:
+            if new_sorting_key in (5, 6):
+                if delta <= 0:
+                    new_sorting_key = 4
+                elif delta > 0:
+                    new_sorting_key = 7
         return new_sorting_key
 
     # I wonder if switching to urwid for the display would be better here
@@ -421,14 +427,22 @@ class IOTopUI(object):
         def format(p):
             stats = format_stats(self.options, p, self.process_list.duration)
             io_delay, swapin_delay, read_bytes, write_bytes = stats
+            format = '%%%dd' % MAX_PID_WIDTH
+            params = p.pid,
+            format += ' %4s'
+            params += p.get_ioprio(),
+            format += ' %-8s'
+            params += p.get_user()[:8],
+            format += ' %11s %11s'
+            params += read_bytes, write_bytes
             if self.has_swapin_io:
-                delay_stats = '%7s %7s ' % (swapin_delay, io_delay)
-            else:
-                delay_stats = ' ?unavailable?  '
-            pid_format = '%%%dd' % MAX_PID_WIDTH
-            line = (pid_format + ' %4s %-8s %11s %11s %s') % (
-                p.pid, p.get_ioprio(), p.get_user()[:8], read_bytes,
-                write_bytes, delay_stats)
+                format += ' %7s %7s'
+                params += swapin_delay, io_delay
+            elif self.options.batch:
+                format += ' %s '
+                params += '?unavailable?',
+            format += ' '
+            line = format % (params)
             cmdline = p.get_cmdline()
             if not self.options.batch:
                 remaining_length = self.width - len(line)
@@ -481,6 +495,7 @@ class IOTopUI(object):
             # and iotop then uses the sysctl value instead.
             if sysctl_task_delayacct() == False:
                 self.has_swapin_io = False
+        self.adjust_sorting_key(0)
         lines = self.get_data()
         if self.options.time:
             titles = ['    TIME'] + titles
@@ -571,6 +586,8 @@ class IOTopUI(object):
             pos = 0
             remaining_cols = self.width
             for i in range(len(titles)):
+                if not self.has_swapin_io and i in (5, 6):
+                    continue
                 attr = curses.A_REVERSE
                 title = titles[i]
                 if i == self.sorting_key: