scripts: Adopted crc32c lib when available

Jumping from a simple Python implementation to the fully hardware
accelerated crc32c library basically deletes any crc32c related
bottlenecks:

  crc32c.py disk (1MiB) w/  crc32c lib: 0m0.027s
  crc32c.py disk (1MiB) w/o crc32c lib: 0m0.844s

This uses the same try-import trick we use for inotify_simple, so we get
the speed improvement without losing portability.

---

In dbgbmap.py:

  dbgbmap.py w/  crc32c lib:             0m0.273s
  dbgbmap.py w/o crc32c lib:             0m0.697s
  dbgbmap.py w/  crc32c lib --no-ckdata: 0m0.269s
  dbgbmap.py w/o crc32c lib --no-ckdata: 0m0.490s
  dbgbmap.old.py:                        0m0.231s

The bulk of the runtime is still in Rbyd.fetch, but this is now
dominated by leb128 decoding, which makes sense. We do ~twice as many
fetches in the new dbgbmap.py in order to calculate the gcksum (which
we then ignore...).

scripts/crc32c.py

@@ -9,6 +9,11 @@ import os
 import struct
 import sys
 
+try:
+    import crc32c as crc32c_lib
+except ModuleNotFoundError:
+    crc32c_lib = None
+
 
 def openio(path, mode='r', buffering=-1):
     # allow '-' for stdin/stdout
@@ -22,6 +27,9 @@ def openio(path, mode='r', buffering=-1):
         return open(path, mode, buffering)
 
 def crc32c(data, crc=0):
+    if crc32c_lib is not None:
+        return crc32c_lib.crc32c(data, crc)
+    else:
         crc ^= 0xffffffff
         for b in data:
             crc ^= b

scripts/dbgblock.py

@@ -7,6 +7,11 @@ if __name__ == "__main__":
 import itertools as it
 import os
 
+try:
+    import crc32c as crc32c_lib
+except ModuleNotFoundError:
+    crc32c_lib = None
+
 
 # some ways of block geometry representations
 # 512      -> 512
@@ -79,6 +84,9 @@ def xxd(data, width=16):
                         for b in map(chr, data[i:i+width])))
 
 def crc32c(data, crc=0):
+    if crc32c_lib is not None:
+        return crc32c_lib.crc32c(data, crc)
+    else:
         crc ^= 0xffffffff
         for b in data:
             crc ^= b

scripts/dbgbmap.py

@@ -23,6 +23,11 @@ try:
 except ModuleNotFoundError:
     inotify_simple = None
 
+try:
+    import crc32c as crc32c_lib
+except ModuleNotFoundError:
+    crc32c_lib = None
+
 
 TAG_NULL        = 0x0000    ## 0x0000  v--- ---- ---- ----
 TAG_CONFIG      = 0x0000    ## 0x00tt  v--- ---- -ttt tttt
@@ -161,6 +166,9 @@ def rbydaddr(s):
     return tuple(addr)
 
 def crc32c(data, crc=0):
+    if crc32c_lib is not None:
+        return crc32c_lib.crc32c(data, crc)
+    else:
         crc ^= 0xffffffff
         for b in data:
             crc ^= b

scripts/dbgbmapd3.py

@@ -20,6 +20,11 @@ import re
 import shlex
 import struct
 
+try:
+    import crc32c as crc32c_lib
+except ModuleNotFoundError:
+    crc32c_lib = None
+
 
 TAG_NULL        = 0x0000    ## 0x0000  v--- ---- ---- ----
 TAG_CONFIG      = 0x0000    ## 0x00tt  v--- ---- -ttt tttt
@@ -190,6 +195,9 @@ def rbydaddr(s):
     return tuple(addr)
 
 def crc32c(data, crc=0):
+    if crc32c_lib is not None:
+        return crc32c_lib.crc32c(data, crc)
+    else:
         crc ^= 0xffffffff
         for b in data:
             crc ^= b

scripts/dbgbtree.py

@@ -12,6 +12,11 @@ import math as mt
 import os
 import struct
 
+try:
+    import crc32c as crc32c_lib
+except ModuleNotFoundError:
+    crc32c_lib = None
+
 
 TAG_NULL        = 0x0000    ## 0x0000  v--- ---- ---- ----
 TAG_CONFIG      = 0x0000    ## 0x00tt  v--- ---- -ttt tttt
@@ -117,6 +122,9 @@ def rbydaddr(s):
     return tuple(addr)
 
 def crc32c(data, crc=0):
+    if crc32c_lib is not None:
+        return crc32c_lib.crc32c(data, crc)
+    else:
         crc ^= 0xffffffff
         for b in data:
             crc ^= b

scripts/dbgcat.py

@@ -7,6 +7,11 @@ if __name__ == "__main__":
 import itertools as it
 import os
 
+try:
+    import crc32c as crc32c_lib
+except ModuleNotFoundError:
+    crc32c_lib = None
+
 
 # some ways of block geometry representations
 # 512      -> 512
@@ -79,6 +84,9 @@ def xxd(data, width=16):
                         for b in map(chr, data[i:i+width])))
 
 def crc32c(data, crc=0):
+    if crc32c_lib is not None:
+        return crc32c_lib.crc32c(data, crc)
+    else:
         crc ^= 0xffffffff
         for b in data:
             crc ^= b

scripts/dbglfs.py

@@ -13,6 +13,11 @@ import os
 import struct
 import sys
 
+try:
+    import crc32c as crc32c_lib
+except ModuleNotFoundError:
+    crc32c_lib = None
+
 
 TAG_NULL        = 0x0000    ## 0x0000  v--- ---- ---- ----
 TAG_CONFIG      = 0x0000    ## 0x00tt  v--- ---- -ttt tttt
@@ -118,6 +123,9 @@ def rbydaddr(s):
     return tuple(addr)
 
 def crc32c(data, crc=0):
+    if crc32c_lib is not None:
+        return crc32c_lib.crc32c(data, crc)
+    else:
         crc ^= 0xffffffff
         for b in data:
             crc ^= b

scripts/dbgmtree.py

@@ -12,6 +12,11 @@ import math as mt
 import os
 import struct
 
+try:
+    import crc32c as crc32c_lib
+except ModuleNotFoundError:
+    crc32c_lib = None
+
 
 TAG_NULL        = 0x0000    ## 0x0000  v--- ---- ---- ----
 TAG_CONFIG      = 0x0000    ## 0x00tt  v--- ---- -ttt tttt
@@ -117,6 +122,9 @@ def rbydaddr(s):
     return tuple(addr)
 
 def crc32c(data, crc=0):
+    if crc32c_lib is not None:
+        return crc32c_lib.crc32c(data, crc)
+    else:
         crc ^= 0xffffffff
         for b in data:
             crc ^= b

scripts/dbgrbyd.py

@@ -12,6 +12,11 @@ import math as mt
 import os
 import struct
 
+try:
+    import crc32c as crc32c_lib
+except ModuleNotFoundError:
+    crc32c_lib = None
+
 
 COLORS = [
     '34',   # blue
@@ -127,6 +132,9 @@ def rbydaddr(s):
     return tuple(addr)
 
 def crc32c(data, crc=0):
+    if crc32c_lib is not None:
+        return crc32c_lib.crc32c(data, crc)
+    else:
         crc ^= 0xffffffff
         for b in data:
             crc ^= b