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| author | Nadeem Vawda <nadeem.vawda@gmail.com> | 2011-10-13 11:38:14 (GMT) |
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| committer | Nadeem Vawda <nadeem.vawda@gmail.com> | 2011-10-13 11:38:14 (GMT) |
| commit | 72d6a13413d3dedf9979cfbd7bc41d58f52144b6 (patch) | |
| tree | d7a85107c3913d65df3250c2e82109e8998fbd19 /Modules/_io | |
| parent | 55c991197b8dc971c1358b2b8e71fc9eaf3970c9 (diff) | |
| parent | d41a98bdd9076eeadf4d3ba6d8db287e26b89777 (diff) | |
| download | cpython-72d6a13413d3dedf9979cfbd7bc41d58f52144b6.zip cpython-72d6a13413d3dedf9979cfbd7bc41d58f52144b6.tar.gz cpython-72d6a13413d3dedf9979cfbd7bc41d58f52144b6.tar.bz2 | |
Merge #13159: Replace FileIO's quadratic-time buffer growth algorithm with a linear-time one.
Also fix the bz2 module, which suffered from the same problem.
Diffstat (limited to 'Modules/_io')
| -rw-r--r-- | Modules/_io/fileio.c | 19 |
1 files changed, 4 insertions, 15 deletions
diff --git a/Modules/_io/fileio.c b/Modules/_io/fileio.c index ba5e096..c6b89f3 100644 --- a/Modules/_io/fileio.c +++ b/Modules/_io/fileio.c @@ -43,12 +43,6 @@ #define SMALLCHUNK BUFSIZ #endif -#if SIZEOF_INT < 4 -#define BIGCHUNK (512 * 32) -#else -#define BIGCHUNK (512 * 1024) -#endif - typedef struct { PyObject_HEAD int fd; @@ -572,15 +566,10 @@ new_buffersize(fileio *self, size_t currentsize } } #endif - if (currentsize > SMALLCHUNK) { - /* Keep doubling until we reach BIGCHUNK; - then keep adding BIGCHUNK. */ - if (currentsize <= BIGCHUNK) - return currentsize + currentsize; - else - return currentsize + BIGCHUNK; - } - return currentsize + SMALLCHUNK; + /* Expand the buffer by an amount proportional to the current size, + giving us amortized linear-time behavior. Use a less-than-double + growth factor to avoid excessive allocation. */ + return currentsize + (currentsize >> 3) + 6; } static PyObject * |