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Refactor the code that sets up iovecs for reading into its own function. iocp needs this.

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svn:r1162
This commit is contained in:
Nick Mathewson 2009-04-13 03:05:46 +00:00
parent 0b47b125cf
commit 829b52b6c1
2 changed files with 66 additions and 31 deletions
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89
buffer.c
View File

@ -1410,6 +1410,62 @@ _evbuffer_expand_fast(struct evbuffer *buf, size_t datlen)
#define EVBUFFER_MAX_READ 4096 #define EVBUFFER_MAX_READ 4096
#ifdef USE_IOVEC_IMPL
/** Helper function to figure out which space to use for reading data into
an evbuffer. Internal use only.
@param buf The buffer to read into
@param howmuch How much we want to read.
@param vecs An array of two iovecs or WSABUFs.
@param chainp A pointer to a variable to hold the first chain we're
reading into.
@return The number of buffers we're using.
*/
int
_evbuffer_read_setup_vecs(struct evbuffer *buf, ssize_t howmuch,
IOV_TYPE *vecs, struct evbuffer_chain **chainp)
{
struct evbuffer_chain *chain;
int nvecs;
chain = buf->last;
if (chain->off == 0 && buf->previous_to_last &&
CHAIN_SPACE_LEN(buf->previous_to_last)) {
/* The last chain is empty, so it's safe to
use the space in the next-to-last chain.
*/
struct evbuffer_chain *prev = buf->previous_to_last;
vecs[0].IOV_PTR_FIELD = CHAIN_SPACE_PTR(prev);
vecs[0].IOV_LEN_FIELD = CHAIN_SPACE_LEN(prev);
vecs[1].IOV_PTR_FIELD = CHAIN_SPACE_PTR(chain);
vecs[1].IOV_LEN_FIELD = CHAIN_SPACE_LEN(chain);
if (vecs[0].IOV_LEN_FIELD >= howmuch) {
/* The next-to-last chain has enough
* space on its own. */
nvecs = 1;
} else {
/* We'll need both chains. */
nvecs = 2;
if (vecs[0].IOV_LEN_FIELD + vecs[1].IOV_LEN_FIELD > howmuch) {
vecs[1].IOV_LEN_FIELD = howmuch - vecs[0].IOV_LEN_FIELD;
}
}
} else {
/* There's data in the last chain, so we're
* not allowed to use the next-to-last. */
nvecs = 1;
vecs[0].IOV_PTR_FIELD = CHAIN_SPACE_PTR(chain);
vecs[0].IOV_LEN_FIELD = CHAIN_SPACE_LEN(chain);
if (vecs[0].IOV_LEN_FIELD > howmuch)
vecs[0].IOV_LEN_FIELD = howmuch;
}
*chainp = chain;
return nvecs;
}
#endif
/* TODO(niels): should this function return ssize_t and take ssize_t /* TODO(niels): should this function return ssize_t and take ssize_t
* as howmuch? */ * as howmuch? */
int int
@ -1467,37 +1523,8 @@ evbuffer_read(struct evbuffer *buf, evutil_socket_t fd, int howmuch)
goto done; goto done;
} else { } else {
IOV_TYPE vecs[2]; IOV_TYPE vecs[2];
chain = buf->last; nvecs = _evbuffer_read_setup_vecs(buf, howmuch, vecs,
if (chain->off == 0 && buf->previous_to_last && &chain);
CHAIN_SPACE_LEN(buf->previous_to_last)) {
/* The last chain is empty, so it's safe to
use the space in the next-to-last chain.
*/
struct evbuffer_chain *prev = buf->previous_to_last;
vecs[0].IOV_PTR_FIELD = CHAIN_SPACE_PTR(prev);
vecs[0].IOV_LEN_FIELD = CHAIN_SPACE_LEN(prev);
vecs[1].IOV_PTR_FIELD = CHAIN_SPACE_PTR(chain);
vecs[1].IOV_LEN_FIELD = CHAIN_SPACE_LEN(chain);
if (vecs[0].IOV_LEN_FIELD >= howmuch) {
/* The next-to-last chain has enough
* space on its own. */
nvecs = 1;
} else {
/* We'll need both chains. */
nvecs = 2;
if (vecs[0].IOV_LEN_FIELD + vecs[1].IOV_LEN_FIELD > howmuch) {
vecs[1].IOV_LEN_FIELD = howmuch - vecs[0].IOV_LEN_FIELD;
}
}
} else {
/* There's data in the last chain, so we're
* not allowed to use the next-to-last. */
nvecs = 1;
vecs[0].IOV_PTR_FIELD = CHAIN_SPACE_PTR(chain);
vecs[0].IOV_LEN_FIELD = CHAIN_SPACE_LEN(chain);
if (vecs[0].IOV_LEN_FIELD > howmuch)
vecs[0].IOV_LEN_FIELD = howmuch;
}
#ifdef WIN32 #ifdef WIN32
{ {

8
evbuffer-internal.h
View File

@ -192,6 +192,14 @@ struct evbuffer_chain_reference {
EVTHREAD_WRITE, EVTHREAD_WRITE); \ EVTHREAD_WRITE, EVTHREAD_WRITE); \
} while(0) } while(0)
#ifdef _EVENT_HAVE_SYS_UIO_H
int _evbuffer_read_setup_vecs(struct evbuffer *buf, ssize_t howmuch,
struct iovec *vecs, struct evbuffer_chain **chainp);
#elif defined(WIN32)
int _evbuffer_read_setup_vecs(struct evbuffer *buf, ssize_t howmuch,
WSABUF *vecs, struct evbuffer_chain **chainp);
#endif
#ifdef __cplusplus #ifdef __cplusplus
} }
#endif #endif