deprecate the numeric --compression argument, rename null compression to none, update CHANGES

CHANGES.rst

@@ -1,6 +1,38 @@
 Borg Changelog
 ==============
 
+Compression branch
+------------------
+
+Compatibility notes:
+
+- the new compression code is very compatible: as long as you stay with zlib
+  compression, older borg releases will still be able to read data from a
+  repo/archive made with the new code (note: this is not the case for the
+  default "none" compression, use "zlib,0" if you want a "no compression" mode
+  that can be read by older borg). Also the new code is able to read repos and
+  archives made with older borg versions (for all zlib levels  0..9).
+
+Deprecations:
+
+- --compression N (with N being a number, as in 0.24) is deprecated.
+  We keep the --compression 0..9 for now to not break scripts, but it is
+  deprecated and will be removed later, so better fix your scripts now:
+  --compression 0 (as in 0.24) is the same as --compression zlib,0 (now).
+  BUT: if you do not want compression, you rather want --compression none
+  (which is the default).
+  --compression 1 (in 0.24) is the same as --compression zlib,1 (now)
+  --compression 9 (in 0.24) is the same as --compression zlib,9 (now)
+
+New features:
+
+- create --compression none (default, means: do not compress, just pass through
+  data "as is". this is more efficient than zlib level 0 as used in borg 0.24)
+- create --compression lz4 (super-fast, but not very high compression)
+  Please note that borgbackup needs lz4 library as additional requirement.
+- create --compression zlib,N (slower, higher compression, default for N is 6)
+- create --compression lzma,N (slowest, highest compression, default N is 6)
+
 
 Version 0.24.0
 --------------

borg/archiver.py

@@ -668,17 +668,13 @@ Type "Yes I am sure" if you understand this and want to continue.\n""")
                                metavar='CHUNK_MIN_EXP,CHUNK_MAX_EXP,HASH_MASK_BITS,HASH_WINDOW_SIZE',
                                help='specify the chunker parameters. default: %d,%d,%d,%d' % CHUNKER_PARAMS)
         subparser.add_argument('-C', '--compression', dest='compression',
-                               type=CompressionSpec, default=dict(name='null'), metavar='COMPRESSION',
-                               help='select compression algorithm and level, by giving a number: '
-                                    '0 == no compression [default], '
-                                    '1..9 == zlib level 1..9, '
-                                    '10 == lz4, '
-                                    '20-29 == lzma level 0..9.'
-                                    'Alternatively, you can also give a name and optionally additional args: '
-                                    'null == no compression, '
+                               type=CompressionSpec, default=dict(name='none'), metavar='COMPRESSION',
+                               help='select compression algorithm (and level): '
+                                    'none == no compression (default), '
+                                    'lz4 == lz4, '
                                     'zlib == zlib (default level 6), '
                                     'zlib,0 .. zlib,9 == zlib (with level 0..9), '
-                                    'lz4 == lz4, '
+                                    'lzma == lzma (default level 6), '
                                     'lzma,0 .. lzma,9 == lzma (with level 0..9).')
         subparser.add_argument('archive', metavar='ARCHIVE',
                                type=location_validator(archive=True),

borg/compress.pyx

@@ -35,12 +35,12 @@ cdef class CompressorBase:
         return data[2:]
 
 
-class CNULL(CompressorBase):
+class CNONE(CompressorBase):
     """
-    null compression, just pass through data
+    none - no compression, just pass through data
     """
     ID = b'\x00\x00'
-    name = 'null'
+    name = 'none'
 
     def compress(self, data):
         return super().compress(data)
@@ -161,12 +161,12 @@ class ZLIB(CompressorBase):
 
 
 COMPRESSOR_TABLE = {
-    CNULL.name: CNULL,
+    CNONE.name: CNONE,
     LZ4.name: LZ4,
     ZLIB.name: ZLIB,
     LZMA.name: LZMA,
 }
-COMPRESSOR_LIST = [LZ4, CNULL, ZLIB, LZMA, ]  # check fast stuff first
+COMPRESSOR_LIST = [LZ4, CNONE, ZLIB, LZMA, ]  # check fast stuff first
 
 def get_compressor(name, **kwargs):
     cls = COMPRESSOR_TABLE[name]

borg/helpers.py

@@ -295,20 +295,14 @@ def CompressionSpec(s):
         compression = int(compression)
         if count > 1:
             raise ValueError
-        # it is just --compression N
-        if compression == 0:
-            return dict(name='null')
-        if 1 <= compression <= 9:
+        # DEPRECATED: it is just --compression N
+        if 0 <= compression <= 9:
             return dict(name='zlib', level=compression)
-        if compression == 10:
-            return dict(name='lz4')
-        if 20 <= compression <= 29:
-            return dict(name='lzma', level=compression-20)
         raise ValueError
     except ValueError:
         # --compression algo[,...]
         name = compression
-        if name in ('null', 'lz4', ):
+        if name in ('none', 'lz4', ):
             return dict(name=name)
         if name in ('zlib', 'lzma', ):
             if count < 2:

borg/key.py

@@ -68,7 +68,7 @@ class KeyBase:
         self.TYPE_STR = bytes([self.TYPE])
         self.repository = repository
         self.target = None  # key location file path / repo obj
-        self.compressor = Compressor('null', buffer=COMPR_BUFFER)
+        self.compressor = Compressor('none', buffer=COMPR_BUFFER)
 
     def id_hash(self, data):
         """Return HMAC hash using the "id" HMAC key

borg/testsuite/compress.py

@@ -6,7 +6,7 @@ except ImportError:
 
 import pytest
 
-from ..compress import get_compressor, Compressor, CNULL, ZLIB, LZ4
+from ..compress import get_compressor, Compressor, CNONE, ZLIB, LZ4
 
 
 buffer = bytes(2**16)
@@ -15,8 +15,8 @@ params = dict(name='zlib', level=6, buffer=buffer)
 
 
 def test_get_compressor():
-    c = get_compressor(name='null')
-    assert isinstance(c, CNULL)
+    c = get_compressor(name='none')
+    assert isinstance(c, CNONE)
     c = get_compressor(name='lz4', buffer=buffer)
     assert isinstance(c, LZ4)
     c = get_compressor(name='zlib')
@@ -26,7 +26,7 @@ def test_get_compressor():
 
 
 def test_cnull():
-    c = get_compressor(name='null')
+    c = get_compressor(name='none')
     cdata = c.compress(data)
     assert len(cdata) > len(data)
     assert data in cdata  # it's not compressed and just in there 1:1
@@ -83,7 +83,7 @@ def test_zlib_compat():
 
 def test_compressor():
     params_list = [
-        dict(name='null', buffer=buffer),
+        dict(name='none', buffer=buffer),
         dict(name='lz4', buffer=buffer),
         dict(name='zlib', level=0, buffer=buffer),
         dict(name='zlib', level=6, buffer=buffer),

borg/testsuite/helpers.py

@@ -108,17 +108,12 @@ class PatternTestCase(BaseTestCase):
 def test_compression_specs():
     with pytest.raises(ValueError):
         CompressionSpec('')
-    assert CompressionSpec('0') == dict(name='null')
+    assert CompressionSpec('0') == dict(name='zlib', level=0)
     assert CompressionSpec('1') == dict(name='zlib', level=1)
     assert CompressionSpec('9') == dict(name='zlib', level=9)
-    assert CompressionSpec('10') == dict(name='lz4')
     with pytest.raises(ValueError):
-        CompressionSpec('11')
-    assert CompressionSpec('20') == dict(name='lzma', level=0)
-    assert CompressionSpec('29') == dict(name='lzma', level=9)
-    with pytest.raises(ValueError):
-        CompressionSpec('30')
-    assert CompressionSpec('null') == dict(name='null')
+        CompressionSpec('10')
+    assert CompressionSpec('none') == dict(name='none')
     assert CompressionSpec('lz4') == dict(name='lz4')
     assert CompressionSpec('zlib') == dict(name='zlib', level=6)
     assert CompressionSpec('zlib,0') == dict(name='zlib', level=0)