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Shorten pickle for matrix_mod2_dense #39367

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merged 2 commits into from
Jan 27, 2025
Merged

Shorten pickle for matrix_mod2_dense #39367

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392d341
Shorten pickle for matrix_mod2_dense
user202729 Jan 22, 2025
660b757
Avoid long line
user202729 Jan 23, 2025
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64 changes: 52 additions & 12 deletions src/sage/matrix/matrix_mod2_dense.pyx
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Original file line number Diff line number Diff line change
Expand Up @@ -1799,6 +1799,12 @@ cdef class Matrix_mod2_dense(matrix_dense.Matrix_dense): # dense or sparse
sage: A.set_immutable()
sage: loads(dumps(A)).is_immutable()
True

Check that :issue:`39367` is achieved::

sage: l = len(dumps(random_matrix(GF(2), 2000, 2000))); l # random # previously ~ 785000
610207
sage: assert l < 650000
"""
cdef int i,j, r,c, size

Expand All @@ -1817,11 +1823,17 @@ cdef class Matrix_mod2_dense(matrix_dense.Matrix_dense): # dense or sparse
if mzd_read_bit(self._entries, i, j):
gdImageSetPixel(im, j, i, black )

cdef signed char *buf = <signed char*>gdImagePngPtr(im, &size)
cdef char *buf
try:
buf = <char*>gdImagePngPtr(im, &size)
finally:
gdImageDestroy(im)

data = [buf[i] for i in range(size)]
gdFree(buf)
gdImageDestroy(im)
cdef bytes data
try:
data = buf[:size]
finally: # recommended by https://cython.readthedocs.io/en/latest/src/tutorial/strings.html
gdFree(buf)
return unpickle_matrix_mod2_dense_v2, (r,c, data, size, self._is_immutable)

cpdef _export_as_string(self):
Expand Down Expand Up @@ -2195,6 +2207,28 @@ def unpickle_matrix_mod2_dense_v2(r, c, data, size, immutable=False):
sage: loads(s)
[1 0]
[0 1]

Check that old pickles before :issue:`39367` still work::

sage: loads(bytes.fromhex( # hexstring produced with dumps(matrix.zero(GF(2),10,10)).hex()
....: '789c6b604a2e4e4c4fd5cb4d2c29caac8052f1b9f92946f129a979c5a95ca5'
....: '790599c9d939a9f11852f165465c850c1ade5cde5cb1858c1a5e9dfffffff7'
....: '0ef0f6f376f7e6050a4a01310318f27a7b7a7b78bb780741f95c709ad19b19'
....: 'c2f6da0ed4ecf5076442acd73f100551c20634d0c73bc4db15aaec3f481982'
....: '580a226e8288f920e22e4223a77701d0ce48ef62308fcfeb084c0aca64f49a'
....: '0aa2b4bdf9bca5a15af880ce74f17604dac6e135132499ecf50344d57b3580'
....: '75789b7b330195b103fd21e85deeb51064e362908c2f441d03147a025debe7'
....: 'ede2b50e24e8e49de0d50464a47ae775961432051532eb0100093b9ba3'))
[0 0 0 0 0 0 0 0 0 0]
[0 0 0 0 0 0 0 0 0 0]
[0 0 0 0 0 0 0 0 0 0]
[0 0 0 0 0 0 0 0 0 0]
[0 0 0 0 0 0 0 0 0 0]
[0 0 0 0 0 0 0 0 0 0]
[0 0 0 0 0 0 0 0 0 0]
[0 0 0 0 0 0 0 0 0 0]
[0 0 0 0 0 0 0 0 0 0]
[0 0 0 0 0 0 0 0 0 0]
"""
from sage.matrix.constructor import Matrix
from sage.rings.finite_rings.finite_field_constructor import FiniteField as GF
Expand All @@ -2206,15 +2240,21 @@ def unpickle_matrix_mod2_dense_v2(r, c, data, size, immutable=False):
if r == 0 or c == 0:
return A

cdef signed char *buf = <signed char*>check_malloc(size)
for i from 0 <= i < size:
buf[i] = data[i]

sig_on()
cdef gdImagePtr im = gdImageCreateFromPngPtr(size, buf)
sig_off()
cdef signed char *buf
cdef gdImagePtr im
if isinstance(data, bytes):
sig_on()
im = gdImageCreateFromPngPtr(size, <char *><bytes>data)
sig_off()
else:
buf = <signed char*>check_malloc(size)
for i from 0 <= i < size:
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you could use memcpy here.
At least, use for i in range(size)

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The whole issue of the old code is you cannot use memcpy. (since the input is a list of Python int objects.)

changing the style is okay (though it was like that from before cython gets more intelligent)

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Right, I did not pay attention that data is a Python list.

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Actually… the type of size is unknown, range() might lead to worse performance than the existing construct (I don't know what it does exactly, cast to int?)

might be a good idea to be conservative and leave it there? The code path is not encountered anyway except for unpickling old pickles

buf[i] = data[i]

sig_free(buf)
sig_on()
im = gdImageCreateFromPngPtr(size, buf)
sig_off()
sig_free(buf)

if gdImageSX(im) != c or gdImageSY(im) != r:
raise TypeError("Pickled data dimension doesn't match.")
Expand Down
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