46
46
unsigned long agg_offset
47
47
struct delta_index:
49
delta_index * create_delta_index(source_info *src, delta_index *old) nogil
50
delta_index * create_delta_index_from_delta(source_info *delta,
51
delta_index *old) nogil
49
ctypedef enum delta_result:
57
delta_result create_delta_index(source_info *src,
60
int max_entries) nogil
61
delta_result create_delta_index_from_delta(source_info *delta,
63
delta_index **fresh) nogil
52
64
void free_delta_index(delta_index *index) nogil
53
void *create_delta(delta_index *indexes,
54
void *buf, unsigned long bufsize,
55
unsigned long *delta_size, unsigned long max_delta_size) nogil
65
delta_result create_delta(delta_index *indexes,
66
void *buf, unsigned long bufsize,
67
unsigned long *delta_size,
68
unsigned long max_delta_size,
69
void **delta_data) nogil
56
70
unsigned long get_delta_hdr_size(unsigned char **datap,
57
71
unsigned char *top) nogil
58
72
unsigned long sizeof_delta_index(delta_index *index)
59
73
Py_ssize_t DELTA_SIZE_MIN
74
int get_hash_offset(delta_index *index, int pos, unsigned int *hash_offset)
75
int get_entry_summary(delta_index *index, int pos,
76
unsigned int *global_offset, unsigned int *hash_val)
77
unsigned int rabin_hash (unsigned char *data)
62
80
cdef void *safe_malloc(size_t count) except NULL:
86
104
return DeltaIndex(source)
107
cdef object _translate_delta_failure(delta_result result):
108
if result == DELTA_OUT_OF_MEMORY:
109
return MemoryError("Delta function failed to allocate memory")
110
elif result == DELTA_INDEX_NEEDED:
111
return ValueError("Delta function requires delta_index param")
112
elif result == DELTA_SOURCE_EMPTY:
113
return ValueError("Delta function given empty source_info param")
114
elif result == DELTA_SOURCE_BAD:
115
return RuntimeError("Delta function given invalid source_info param")
116
elif result == DELTA_BUFFER_EMPTY:
117
return ValueError("Delta function given empty buffer params")
118
return AssertionError("Unrecognised delta result code: %d" % result)
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def _rabin_hash(content):
122
if not PyString_CheckExact(content):
123
raise ValueError('content must be a string')
124
if len(content) < 16:
125
raise ValueError('content must be at least 16 bytes long')
126
# Try to cast it to an int, if it can fit
127
return int(rabin_hash(<unsigned char*>(PyString_AS_STRING(content))))
89
130
cdef class DeltaIndex:
91
132
# We need Pyrex 0.9.8+ to understand a 'list' definition, and this object
96
137
cdef delta_index *_index
97
138
cdef public unsigned long _source_offset
98
139
cdef readonly unsigned int _max_num_sources
140
cdef public int _max_bytes_to_index
100
def __init__(self, source=None):
142
def __init__(self, source=None, max_bytes_to_index=None):
101
143
self._sources = []
102
144
self._index = NULL
103
145
self._max_num_sources = 65000
104
146
self._source_infos = <source_info *>safe_malloc(sizeof(source_info)
105
147
* self._max_num_sources)
106
148
self._source_offset = 0
149
self._max_bytes_to_index = 0
150
if max_bytes_to_index is not None:
151
self._max_bytes_to_index = max_bytes_to_index
108
153
if source is not None:
109
154
self.add_source(source, 0)
137
182
def _has_index(self):
138
183
return (self._index != NULL)
185
def _dump_index(self):
186
"""Dump the pointers in the index.
188
This is an arbitrary layout, used for testing. It is not meant to be
189
used in production code.
191
:return: (hash_list, entry_list)
192
hash_list A list of offsets, so hash[i] points to the 'hash
193
bucket' starting at the given offset and going until
195
entry_list A list of (text_offset, hash_val). text_offset is the
196
offset in the "source" texts, and hash_val is the RABIN
197
hash for that offset.
198
Note that the entry should be in the hash bucket
200
hash[(hash_val & mask)] && hash[(hash_val & mask) + 1]
203
cdef unsigned int text_offset
204
cdef unsigned int hash_val
205
cdef unsigned int hash_offset
206
if self._index == NULL:
210
while get_hash_offset(self._index, pos, &hash_offset):
211
hash_list.append(int(hash_offset))
215
while get_entry_summary(self._index, pos, &text_offset, &hash_val):
216
# Map back using 'int' so that we don't get Long everywhere, when
217
# almost everything is <2**31.
218
val = tuple(map(int, [text_offset, hash_val]))
219
entry_list.append(val)
221
return hash_list, entry_list
140
223
def add_delta_source(self, delta, unadded_bytes):
141
224
"""Add a new delta to the source texts.
165
249
src.size = c_delta_size
166
250
src.agg_offset = self._source_offset + unadded_bytes
168
index = create_delta_index_from_delta(src, self._index)
252
res = create_delta_index_from_delta(src, self._index, &index)
254
raise _translate_delta_failure(res)
169
255
self._source_offset = src.agg_offset + src.size
256
if index != self._index:
171
257
free_delta_index(self._index)
172
258
self._index = index
177
263
:param source: The text in question, this must be a byte string
178
264
:param unadded_bytes: Assume there are this many bytes that didn't get
179
265
added between this source and the end of the previous source.
266
:param max_pointers: Add no more than this many entries to the index.
267
By default, we sample every 16 bytes, if that would require more
268
than max_entries, we will reduce the sampling rate.
269
A value of 0 means unlimited, None means use the default limit.
181
271
cdef char *c_source
182
272
cdef Py_ssize_t c_source_size
183
273
cdef delta_index *index
274
cdef delta_result res
184
275
cdef unsigned int source_location
185
276
cdef source_info *src
186
277
cdef unsigned int num_indexes
278
cdef int max_num_entries
188
280
if not PyString_CheckExact(source):
189
281
raise TypeError('source is not a str')
206
298
# We delay creating the index on the first insert
207
299
if source_location != 0:
209
index = create_delta_index(src, self._index)
301
res = create_delta_index(src, self._index, &index,
302
self._max_bytes_to_index)
304
raise _translate_delta_failure(res)
305
if index != self._index:
211
306
free_delta_index(self._index)
212
307
self._index = index
214
309
cdef _populate_first_index(self):
215
310
cdef delta_index *index
311
cdef delta_result res
216
312
if len(self._sources) != 1 or self._index != NULL:
217
313
raise AssertionError('_populate_first_index should only be'
218
314
' called when we have a single source and no index yet')
220
# We know that self._index is already NULL, so whatever
221
# create_delta_index returns is fine
316
# We know that self._index is already NULL, so create_delta_index
317
# will always create a new index unless there's a malloc failure
223
self._index = create_delta_index(&self._source_infos[0], NULL)
224
assert self._index != NULL
319
res = create_delta_index(&self._source_infos[0], NULL, &index,
320
self._max_bytes_to_index)
322
raise _translate_delta_failure(res)
226
325
cdef _expand_sources(self):
227
326
raise RuntimeError('if we move self._source_infos, then we need to'
256
356
# allocate the bytes into the final string
257
357
c_max_delta_size = max_delta_size
259
delta = create_delta(self._index,
261
&delta_size, c_max_delta_size)
359
res = create_delta(self._index, target, target_size,
360
&delta_size, c_max_delta_size, &delta)
264
363
result = PyString_FromStringAndSize(<char *>delta, delta_size)
365
elif res != DELTA_SIZE_TOO_BIG:
366
raise _translate_delta_failure(res)
369
470
# Copy instruction
370
471
data = _decode_copy_instruction(data, cmd, &cp_off, &cp_size)
371
472
if (cp_off + cp_size < cp_size or
372
cp_off + cp_size > source_size or
473
cp_off + cp_size > <unsigned int>source_size or
474
cp_size > <unsigned int>size):
376
477
memcpy(out, source + cp_off, cp_size)