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Refactor nghttp2_adjust_local_window_size

This commit is contained in:
Tatsuhiro Tsujikawa 2014-12-01 21:49:32 +09:00
parent 6b59609f9b
commit 60cb3f67f2
1 changed files with 46 additions and 41 deletions
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87
lib/nghttp2_helper.c
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@ -172,54 +172,59 @@ int nghttp2_adjust_local_window_size(int32_t *local_window_size_ptr,
int32_t *recv_reduction_ptr,
int32_t *delta_ptr) {
if (*delta_ptr > 0) {
int32_t recv_reduction_delta;
int32_t delta;
int32_t new_recv_window_size =
nghttp2_max(0, *recv_window_size_ptr) - *delta_ptr;
if (new_recv_window_size < 0) {
/* The delta size is strictly more than received bytes. Increase
local_window_size by that difference. */
int32_t recv_reduction_diff;
if (*local_window_size_ptr >
NGHTTP2_MAX_WINDOW_SIZE + new_recv_window_size) {
return NGHTTP2_ERR_FLOW_CONTROL;
}
*local_window_size_ptr -= new_recv_window_size;
/* If there is recv_reduction due to earlier window_size
reduction, we have to adjust it too. */
recv_reduction_diff =
nghttp2_min(*recv_reduction_ptr, -new_recv_window_size);
*recv_reduction_ptr -= recv_reduction_diff;
if (*recv_window_size_ptr < 0) {
*recv_window_size_ptr += recv_reduction_diff;
} else {
/* If *recv_window_size_ptr > 0, then those bytes are going to
be backed to the remote peer (by WINDOW_UPDATE with the
adjusted *delta_ptr), so it is effectively 0 now. We set
to *recv_reduction_diff, because caller does not take into
account it in *delta_ptr. */
*recv_window_size_ptr = recv_reduction_diff;
}
/* recv_reduction_diff must be paied from *delta_ptr, since it
was added in window size reduction (see below). */
*delta_ptr -= recv_reduction_diff;
} else {
if (new_recv_window_size >= 0) {
*recv_window_size_ptr = new_recv_window_size;
return 0;
}
return 0;
} else {
if (*local_window_size_ptr + *delta_ptr < 0 ||
*recv_window_size_ptr < INT32_MIN - *delta_ptr ||
*recv_reduction_ptr > INT32_MAX + *delta_ptr) {
delta = -new_recv_window_size;
/* The delta size is strictly more than received bytes. Increase
local_window_size by that difference |delta|. */
if (*local_window_size_ptr > NGHTTP2_MAX_WINDOW_SIZE - delta) {
return NGHTTP2_ERR_FLOW_CONTROL;
}
/* Decreasing local window size. Note that we achieve this without
noticing to the remote peer. To do this, we cut
recv_window_size by -delta. This means that we don't send
WINDOW_UPDATE for -delta bytes. */
*local_window_size_ptr += *delta_ptr;
*recv_window_size_ptr += *delta_ptr;
*recv_reduction_ptr -= *delta_ptr;
*delta_ptr = 0;
*local_window_size_ptr += delta;
/* If there is recv_reduction due to earlier window_size
reduction, we have to adjust it too. */
recv_reduction_delta = nghttp2_min(*recv_reduction_ptr, delta);
*recv_reduction_ptr -= recv_reduction_delta;
if (*recv_window_size_ptr < 0) {
*recv_window_size_ptr += recv_reduction_delta;
} else {
/* If *recv_window_size_ptr > 0, then those bytes are going to
be returned to the remote peer (by WINDOW_UPDATE with the
adjusted *delta_ptr), so it is effectively 0 now. We set to
*recv_reduction_delta, because caller does not take into
account it in *delta_ptr. */
*recv_window_size_ptr = recv_reduction_delta;
}
/* recv_reduction_delta must be paied from *delta_ptr, since it
was added in window size reduction (see below). */
*delta_ptr -= recv_reduction_delta;
return 0;
}
if (*local_window_size_ptr + *delta_ptr < 0 ||
*recv_window_size_ptr < INT32_MIN - *delta_ptr ||
*recv_reduction_ptr > INT32_MAX + *delta_ptr) {
return NGHTTP2_ERR_FLOW_CONTROL;
}
/* Decreasing local window size. Note that we achieve this without
noticing to the remote peer. To do this, we cut
recv_window_size by -delta. This means that we don't send
WINDOW_UPDATE for -delta bytes. */
*local_window_size_ptr += *delta_ptr;
*recv_window_size_ptr += *delta_ptr;
*recv_reduction_ptr -= *delta_ptr;
*delta_ptr = 0;
return 0;
}