Event pipe: reduced number of file buffers used.
If possible we now just extend already present file buffer in p->out chain
instead of keeping ngx_buf_t for each buffer we've flushed to disk. This
saves about 120 bytes of memory per buffer flushed to disk, and resolves
high CPU usage observed in edge cases (due to coalescing these buffers on
send).
diff --git a/src/event/ngx_event_pipe.c b/src/event/ngx_event_pipe.c
index a770485..c389f2e 100644
--- a/src/event/ngx_event_pipe.c
+++ b/src/event/ngx_event_pipe.c
@@ -680,10 +680,10 @@
static ngx_int_t
ngx_event_pipe_write_chain_to_temp_file(ngx_event_pipe_t *p)
{
- ssize_t size, bsize;
+ ssize_t size, bsize, n;
ngx_buf_t *b;
ngx_uint_t prev_last_shadow;
- ngx_chain_t *cl, *tl, *next, *out, **ll, **last_free, fl;
+ ngx_chain_t *cl, *tl, *next, *out, **ll, **last_out, **last_free, fl;
if (p->buf_to_file) {
fl.buf = p->buf_to_file;
@@ -748,10 +748,63 @@
p->last_in = &p->in;
}
- if (ngx_write_chain_to_temp_file(p->temp_file, out) == NGX_ERROR) {
+ n = ngx_write_chain_to_temp_file(p->temp_file, out);
+
+ if (n == NGX_ERROR) {
return NGX_ABORT;
}
+ if (p->buf_to_file) {
+ p->temp_file->offset = p->buf_to_file->last - p->buf_to_file->pos;
+ n -= p->buf_to_file->last - p->buf_to_file->pos;
+ p->buf_to_file = NULL;
+ out = out->next;
+ }
+
+ if (n > 0) {
+ /* update previous buffer or add new buffer */
+
+ if (p->out) {
+ for (cl = p->out; cl->next; cl = cl->next) { /* void */ }
+
+ b = cl->buf;
+
+ if (b->file_last == p->temp_file->offset) {
+ p->temp_file->offset += n;
+ b->file_last = p->temp_file->offset;
+ goto free;
+ }
+
+ last_out = &cl->next;
+
+ } else {
+ last_out = &p->out;
+ }
+
+ cl = ngx_chain_get_free_buf(p->pool, &p->free);
+ if (cl == NULL) {
+ return NGX_ABORT;
+ }
+
+ b = cl->buf;
+
+ ngx_memzero(b, sizeof(ngx_buf_t));
+
+ b->tag = p->tag;
+
+ b->file = &p->temp_file->file;
+ b->file_pos = p->temp_file->offset;
+ p->temp_file->offset += n;
+ b->file_last = p->temp_file->offset;
+
+ b->in_file = 1;
+ b->temp_file = 1;
+
+ *last_out = cl;
+ }
+
+free:
+
for (last_free = &p->free_raw_bufs;
*last_free != NULL;
last_free = &(*last_free)->next)
@@ -759,31 +812,13 @@
/* void */
}
- if (p->buf_to_file) {
- p->temp_file->offset = p->buf_to_file->last - p->buf_to_file->pos;
- p->buf_to_file = NULL;
- out = out->next;
- }
-
for (cl = out; cl; cl = next) {
next = cl->next;
- cl->next = NULL;
+
+ cl->next = p->free;
+ p->free = cl;
b = cl->buf;
- b->file = &p->temp_file->file;
- b->file_pos = p->temp_file->offset;
- p->temp_file->offset += b->last - b->pos;
- b->file_last = p->temp_file->offset;
-
- b->in_file = 1;
- b->temp_file = 1;
-
- if (p->out) {
- *p->last_out = cl;
- } else {
- p->out = cl;
- }
- p->last_out = &cl->next;
if (b->last_shadow) {
diff --git a/src/event/ngx_event_pipe.h b/src/event/ngx_event_pipe.h
index 2633467..8f55431 100644
--- a/src/event/ngx_event_pipe.h
+++ b/src/event/ngx_event_pipe.h
@@ -30,8 +30,6 @@
ngx_chain_t **last_in;
ngx_chain_t *out;
- ngx_chain_t **last_out;
-
ngx_chain_t *free;
ngx_chain_t *busy;
