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fix bug with overzealous shrinking; add more comments.

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svn:r597
This commit is contained in:
Nick Mathewson 2003-10-15 19:07:07 +00:00
parent 11a23fc280
commit 75170f052b
1 changed files with 13 additions and 3 deletions
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16
src/or/buffers.c
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@ -38,13 +38,17 @@ static INLINE void buf_resize(buf_t *buf, size_t new_capacity)
static INLINE int buf_ensure_capacity(buf_t *buf, size_t capacity) static INLINE int buf_ensure_capacity(buf_t *buf, size_t capacity)
{ {
size_t new_len; size_t new_len;
if (buf->len >= capacity) if (buf->len >= capacity) /* Don't grow if we're already big enough. */
return 0; return 0;
if (capacity > MAX_BUF_SIZE) if (capacity > MAX_BUF_SIZE) /* Don't grow past the maximum. */
return -1; return -1;
/* Find the smallest new_len equal to (2**X)*len for some X; such that
* new_len is at least capacity.
*/
new_len = buf->len*2; new_len = buf->len*2;
while (new_len < capacity) while (new_len < capacity)
new_len *= 2; new_len *= 2;
/* Resize the buffer. */
log_fn(LOG_DEBUG,"Growing buffer from %d to %d bytes.", log_fn(LOG_DEBUG,"Growing buffer from %d to %d bytes.",
(int)buf->len, (int)new_len); (int)buf->len, (int)new_len);
buf_resize(buf,new_len); buf_resize(buf,new_len);
@ -58,8 +62,14 @@ static INLINE int buf_ensure_capacity(buf_t *buf, size_t capacity)
*/ */
static INLINE void buf_shrink_if_underfull(buf_t *buf) { static INLINE void buf_shrink_if_underfull(buf_t *buf) {
size_t new_len; size_t new_len;
if (buf->datalen >= buf->len/4 || buf->len >= 2*MIN_BUF_SHRINK_SIZE) /* If the buffer is at least .25 full, or if shrinking the buffer would
* put it onder MIN_BUF_SHRINK_SIZE, don't do it. */
if (buf->datalen >= buf->len/4 || buf->len < 2*MIN_BUF_SHRINK_SIZE)
return; return;
/* Shrink new_len by powers of 2 until: datalen is at least 1/4 of
* new_len, OR shrinking new_len more would put it under
* MIN_BUF_SHRINK_SIZE.
*/
new_len = buf->len / 2; new_len = buf->len / 2;
while (buf->datalen < new_len/4 && new_len/2 > MIN_BUF_SHRINK_SIZE) while (buf->datalen < new_len/4 && new_len/2 > MIN_BUF_SHRINK_SIZE)
new_len /= 2; new_len /= 2;