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.
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72d6a13413
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@ -1342,6 +1342,9 @@ Tools/Demos
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Extension Modules
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-----------------
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- Issue #13159: FileIO and BZ2Compressor/BZ2Decompressor now use a linear-time
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buffer growth strategy instead of a quadratic-time one.
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- Issue #10141: socket: Add SocketCAN (PF_CAN) support. Initial patch by
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Matthias Fuchs, updated by Tiago Gonçalves.
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@ -116,22 +116,14 @@ catch_bz2_error(int bzerror)
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#define SMALLCHUNK BUFSIZ
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#endif
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#if SIZEOF_INT < 4
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#define BIGCHUNK (512 * 32)
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#else
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#define BIGCHUNK (512 * 1024)
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#endif
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static int
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grow_buffer(PyObject **buf)
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{
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/* Expand the buffer by an amount proportional to the current size,
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giving us amortized linear-time behavior. Use a less-than-double
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growth factor to avoid excessive allocation. */
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size_t size = PyBytes_GET_SIZE(*buf);
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if (size <= SMALLCHUNK)
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return _PyBytes_Resize(buf, size + SMALLCHUNK);
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else if (size <= BIGCHUNK)
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return _PyBytes_Resize(buf, size * 2);
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else
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return _PyBytes_Resize(buf, size + BIGCHUNK);
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return _PyBytes_Resize(buf, size + (size >> 3) + 6);
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}
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@ -43,12 +43,6 @@
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#define SMALLCHUNK BUFSIZ
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#endif
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#if SIZEOF_INT < 4
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#define BIGCHUNK (512 * 32)
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#else
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#define BIGCHUNK (512 * 1024)
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#endif
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typedef struct {
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PyObject_HEAD
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int fd;
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@ -572,15 +566,10 @@ new_buffersize(fileio *self, size_t currentsize
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}
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}
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#endif
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if (currentsize > SMALLCHUNK) {
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/* Keep doubling until we reach BIGCHUNK;
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then keep adding BIGCHUNK. */
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if (currentsize <= BIGCHUNK)
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return currentsize + currentsize;
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else
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return currentsize + BIGCHUNK;
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}
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return currentsize + SMALLCHUNK;
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/* Expand the buffer by an amount proportional to the current size,
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giving us amortized linear-time behavior. Use a less-than-double
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growth factor to avoid excessive allocation. */
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return currentsize + (currentsize >> 3) + 6;
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}
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static PyObject *
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