Add an option to strip leading zeros from histograms (iovisor#1226)

src/python/bcc/table.py

@@ -54,7 +54,7 @@ def _stars(val, val_max, width):
  return text
 
 
-def _print_log2_hist(vals, val_type):
+def _print_log2_hist(vals, val_type, strip_leading_zero):
  global stars_max
  log2_dist_max = 64
  idx_max = -1
@@ -74,15 +74,23 @@ def _print_log2_hist(vals, val_type):
  stars = int(stars_max / 2)
 
  if idx_max > 0:
- print(header % val_type);
+ print(header % val_type)
+
  for i in range(1, idx_max + 1):
  low = (1 << i) >> 1
  high = (1 << i) - 1
  if (low == high):
  low -= 1
  val = vals[i]
- print(body % (low, high, val, stars,
- _stars(val, val_max, stars)))
+
+ if strip_leading_zero:
+ if val:
+ print(body % (low, high, val, stars,
+ _stars(val, val_max, stars)))
+ strip_leading_zero = False
+ else:
+ print(body % (low, high, val, stars,
+ _stars(val, val_max, stars)))
 
 def _print_linear_hist(vals, val_type):
  global stars_max
@@ -281,7 +289,7 @@ def next(self, key):
  return next_key
 
  def print_log2_hist(self, val_type="value", section_header="Bucket ptr",
- section_print_fn=None, bucket_fn=None):
+ section_print_fn=None, bucket_fn=None, strip_leading_zero=None):
  """print_log2_hist(val_type="value", section_header="Bucket ptr",
  section_print_fn=None, bucket_fn=None)
 
@@ -292,8 +300,10 @@ def print_log2_hist(self, val_type="value", section_header="Bucket ptr",
  If section_print_fn is not None, it will be passed the bucket value
  to format into a string as it sees fit. If bucket_fn is not None,
  it will be used to produce a bucket value for the histogram keys.
- The maximum index allowed is log2_index_max (65), which will
- accomodate any 64-bit integer in the histogram.
+ If the value of strip_leading_zero is not False, prints a histogram
+ that is omitted leading zeros from the beginning. The maximum index
+ allowed is log2_index_max (65), which will accomodate any 64-bit
+ integer in the histogram.
  """
  if isinstance(self.Key(), ct.Structure):
  tmp = {}
@@ -312,12 +322,12 @@ def print_log2_hist(self, val_type="value", section_header="Bucket ptr",
  section_print_fn(bucket)))
  else:
  print("\n%s = %r" % (section_header, bucket))
- _print_log2_hist(vals, val_type)
+ _print_log2_hist(vals, val_type, strip_leading_zero)
  else:
  vals = [0] * log2_index_max
  for k, v in self.items():
  vals[k.value] = v.value
- _print_log2_hist(vals, val_type)
+ _print_log2_hist(vals, val_type, strip_leading_zero)
 
  def print_linear_hist(self, val_type="value", section_header="Bucket ptr",
  section_print_fn=None, bucket_fn=None):
@@ -709,4 +719,3 @@ def __delitem__(self, key):
 
  def clear(self):
  pass
-

tools/funclatency_example.txt

@@ -76,7 +76,7 @@ Tracing 1 function for "pthread:pthread_mutex_lock"... Hit Ctrl-C to end.
  1048576 -> 2097151 : 9 | |
 Detaching...
 
-It seems that most calls to pthread_mutex_lock completed rather quickly (in 
+It seems that most calls to pthread_mutex_lock completed rather quickly (in
 under 4us), but there were some cases of considerable contention, sometimes
 over a full millisecond.