API change: ngx_chain_update_chains() now requires pool.

The ngx_chain_update_chains() needs pool to free chain links used for buffers
with non-matching tags.  Providing one helps to reduce memory consumption
for long-lived requests.

src/core/ngx_buf.c

diff --git a/src/core/ngx_buf.c b/src/core/ngx_buf.c
index 2f2c437..53cd50c 100644
--- a/src/core/ngx_buf.c
+++ b/src/core/ngx_buf.c
@@ -180,7 +180,7 @@
 
 
 void
-ngx_chain_update_chains(ngx_chain_t **free, ngx_chain_t **busy,
+ngx_chain_update_chains(ngx_pool_t *p, ngx_chain_t **free, ngx_chain_t **busy,
     ngx_chain_t **out, ngx_buf_tag_t tag)
 {
     ngx_chain_t  *cl;
@@ -197,19 +197,21 @@
     *out = NULL;
 
     while (*busy) {
-        if (ngx_buf_size((*busy)->buf) != 0) {
+        cl = *busy;
+
+        if (ngx_buf_size(cl->buf) != 0) {
             break;
         }
 
-        if ((*busy)->buf->tag != tag) {
-            *busy = (*busy)->next;
+        if (cl->buf->tag != tag) {
+            *busy = cl->next;
+            ngx_free_chain(p, cl);
             continue;
         }
 
-        (*busy)->buf->pos = (*busy)->buf->start;
-        (*busy)->buf->last = (*busy)->buf->start;
+        cl->buf->pos = cl->buf->start;
+        cl->buf->last = cl->buf->start;
 
-        cl = *busy;
         *busy = cl->next;
         cl->next = *free;
         *free = cl;

src/core/ngx_buf.h

diff --git a/src/core/ngx_buf.h b/src/core/ngx_buf.h
index 847eaad..a6bf39f 100644
--- a/src/core/ngx_buf.h
+++ b/src/core/ngx_buf.h
@@ -154,8 +154,8 @@
 ngx_int_t ngx_chain_add_copy(ngx_pool_t *pool, ngx_chain_t **chain,
     ngx_chain_t *in);
 ngx_chain_t *ngx_chain_get_free_buf(ngx_pool_t *p, ngx_chain_t **free);
-void ngx_chain_update_chains(ngx_chain_t **free, ngx_chain_t **busy,
-    ngx_chain_t **out, ngx_buf_tag_t tag);
+void ngx_chain_update_chains(ngx_pool_t *p, ngx_chain_t **free,
+    ngx_chain_t **busy, ngx_chain_t **out, ngx_buf_tag_t tag);
 
 
 #endif /* _NGX_BUF_H_INCLUDED_ */

src/core/ngx_output_chain.c

diff --git a/src/core/ngx_output_chain.c b/src/core/ngx_output_chain.c
index 4f100a8..e45f034 100644
--- a/src/core/ngx_output_chain.c
+++ b/src/core/ngx_output_chain.c
@@ -208,7 +208,8 @@
             return last;
         }
 
-        ngx_chain_update_chains(&ctx->free, &ctx->busy, &out, ctx->tag);
+        ngx_chain_update_chains(ctx->pool, &ctx->free, &ctx->busy, &out,
+                                ctx->tag);
         last_out = &out;
     }
 }

src/event/ngx_event_pipe.c

diff --git a/src/event/ngx_event_pipe.c b/src/event/ngx_event_pipe.c
index 53d738f..6f068fe 100644
--- a/src/event/ngx_event_pipe.c
+++ b/src/event/ngx_event_pipe.c
@@ -638,7 +638,7 @@
             return ngx_event_pipe_drain_chains(p);
         }
 
-        ngx_chain_update_chains(&p->free, &p->busy, &out, p->tag);
+        ngx_chain_update_chains(p->pool, &p->free, &p->busy, &out, p->tag);
 
         for (cl = p->free; cl; cl = cl->next) {
 

src/http/modules/ngx_http_chunked_filter_module.c

diff --git a/src/http/modules/ngx_http_chunked_filter_module.c b/src/http/modules/ngx_http_chunked_filter_module.c
index ee15228..e42f3b5 100644
--- a/src/http/modules/ngx_http_chunked_filter_module.c
+++ b/src/http/modules/ngx_http_chunked_filter_module.c
@@ -221,7 +221,7 @@
 
     rc = ngx_http_next_body_filter(r, out);
 
-    ngx_chain_update_chains(&ctx->free, &ctx->busy, &out,
+    ngx_chain_update_chains(r->pool, &ctx->free, &ctx->busy, &out,
                             (ngx_buf_tag_t) &ngx_http_chunked_filter_module);
 
     return rc;

src/http/modules/ngx_http_gzip_filter_module.c

diff --git a/src/http/modules/ngx_http_gzip_filter_module.c b/src/http/modules/ngx_http_gzip_filter_module.c
index d624e36..1882405 100644
--- a/src/http/modules/ngx_http_gzip_filter_module.c
+++ b/src/http/modules/ngx_http_gzip_filter_module.c
@@ -378,7 +378,7 @@
 
         cl = NULL;
 
-        ngx_chain_update_chains(&ctx->free, &ctx->busy, &cl,
+        ngx_chain_update_chains(r->pool, &ctx->free, &ctx->busy, &cl,
                                 (ngx_buf_tag_t) &ngx_http_gzip_filter_module);
         ctx->nomem = 0;
     }
@@ -448,7 +448,7 @@
 
         ngx_http_gzip_filter_free_copy_buf(r, ctx);
 
-        ngx_chain_update_chains(&ctx->free, &ctx->busy, &ctx->out,
+        ngx_chain_update_chains(r->pool, &ctx->free, &ctx->busy, &ctx->out,
                                 (ngx_buf_tag_t) &ngx_http_gzip_filter_module);
         ctx->last_out = &ctx->out;
 

src/http/ngx_http_upstream.c

diff --git a/src/http/ngx_http_upstream.c b/src/http/ngx_http_upstream.c
index 29432dc..f698833 100644
--- a/src/http/ngx_http_upstream.c
+++ b/src/http/ngx_http_upstream.c
@@ -2382,7 +2382,7 @@
                     return;
                 }
 
-                ngx_chain_update_chains(&u->free_bufs, &u->busy_bufs,
+                ngx_chain_update_chains(r->pool, &u->free_bufs, &u->busy_bufs,
                                         &u->out_bufs, u->output.tag);
             }