Use print function for Python 3 compatibility (iovisor#1748)

and add `from __future__ import print_function` where needed for Python3
print semantics in Python2

examples/tracing/bitehist.py

@@ -13,6 +13,7 @@
 #
 # 15-Aug-2015 Brendan Gregg Created this.
 
+from __future__ import print_function
 from bcc import BPF
 from time import sleep
 
@@ -37,7 +38,7 @@
 try:
  sleep(99999999)
 except KeyboardInterrupt:
- print
+ print()
 
 # output
 b["dist"].print_log2_hist("kbytes")

examples/tracing/trace_fields.py

@@ -6,6 +6,7 @@
 # run in project examples directory with:
 # sudo ./trace_fields.py"
 
+from __future__ import print_function
 from bcc import BPF
 
 prog = """
@@ -16,5 +17,5 @@
 """
 b = BPF(text=prog)
 b.attach_kprobe(event=b.get_syscall_fnname("clone"), fn_name="hello")
-print "PID MESSAGE"
+print("PID MESSAGE")
 b.trace_print(fmt="{1} {5}")

examples/tracing/vfsreadlat.py

@@ -15,6 +15,7 @@
 #
 # 15-Aug-2015 Brendan Gregg Created this.
 
+from __future__ import print_function
 from bcc import BPF
 from ctypes import c_ushort, c_int, c_ulonglong
 from time import sleep
@@ -58,7 +59,7 @@ def usage():
  except KeyboardInterrupt:
  pass; do_exit = 1
 
- print
+ print()
  b["dist"].print_log2_hist("usecs")
  b["dist"].clear()
  if do_exit:

src/cc/frontends/p4/compiler/topoSorting.py

@@ -20,6 +20,7 @@
 
 # -*- coding: utf-8 -*-
 
+from __future__ import print_function
 
 class Node(object):
  def __init__(self, n):
@@ -55,7 +56,7 @@ def visit(node, topo_sorting, sequence=None):
  sequence += [str(node)]
  if node._behavioral_topo_sorting_mark == 1:
  if sequence is not None:
- print "cycle", sequence
+ print("cycle", sequence)
  return False
  if node._behavioral_topo_sorting_mark != 2:
  node._behavioral_topo_sorting_mark = 1

src/cc/frontends/p4/test/testP4toEbpf.py

@@ -6,6 +6,7 @@
 # Runs the compiler on all files in the 'testprograms' folder
 # Writes outputs in the 'testoutputs' folder
 
+from __future__ import print_function
 from bcc import BPF
 import os, sys
 sys.path.append("../compiler") # To get hold of p4toEbpf
@@ -37,9 +38,9 @@ def main():
  errors = 0
 
  if not is_root():
- print "Loading EBPF programs requires root privilege."
- print "Will only test compilation, not loading."
- print "(Run with sudo to test program loading.)"
+ print("Loading EBPF programs requires root privilege.")
+ print("Will only test compilation, not loading.")
+ print("(Run with sudo to test program loading.)")
 
  for f in files:
  path = os.path.join(testpath, f)
@@ -57,7 +58,7 @@ def main():
  result = p4toEbpf.process(args)
  if result.kind != "OK":
  errors += 1
- print path, result.error
+ print(path, result.error)
  set_error(result.kind, path, result.error)
  else:
  # Try to load the compiled function
@@ -72,11 +73,11 @@ def main():
 
  filesDone += 1
 
- print "Compiled", filesDone, "files", errors, "errors"
+ print("Compiled", filesDone, "files", errors, "errors")
  for key in sorted(filesFailed):
- print key, ":", len(filesFailed[key]), "programs"
+ print(key, ":", len(filesFailed[key]), "programs")
  for v in filesFailed[key]:
- print "\t", v
+ print("\t", v)
  exit(len(filesFailed) != 0)