[PATCH 2/3] Optimize by memmory `empty_gif_size'

["Kirill A. Korinskiy" <catap+nginx@xxxxxxxx>]

From: Kirill A. Korinskiy <catap@xxxxxxxx>

Now for send of very large empty gif did not allocated a lot of
memory, because I allocated buffer and used it multiple times. Size of
buffer is a first optional argument of `empty_gif_size' directive.
---
 src/http/modules/ngx_http_empty_gif_module.c |  109 +++++++++++++++++---------
 1 files changed, 71 insertions(+), 38 deletions(-)

diff --git a/src/http/modules/ngx_http_empty_gif_module.c 
b/src/http/modules/ngx_http_empty_gif_module.c
index 
2abbc19ceb9991be85ebd2236d106c4800ae6508..17b46ac0efb06673232e808ca1d0b44d5994a1a2
 100644
--- a/src/http/modules/ngx_http_empty_gif_module.c
+++ b/src/http/modules/ngx_http_empty_gif_module.c
@@ -9,7 +9,12 @@
 
 
 typedef struct {
-    ngx_str_t fake;
+    size_t     size;
+    ngx_str_t  str;
+} ngx_http_empty_gif_fake_t;
+
+typedef struct {
+    ngx_http_empty_gif_fake_t fake;
 } ngx_http_empty_gif_loc_conf_t;
 
 
@@ -34,7 +39,7 @@ static ngx_command_t  ngx_http_empty_gif_commands[] = {
       NULL },
 
     { ngx_string("empty_gif_size"),
-      NGX_HTTP_LOC_CONF|NGX_CONF_TAKE1,
+      NGX_HTTP_LOC_CONF|NGX_CONF_TAKE1|NGX_CONF_TAKE2,
       ngx_http_empty_gif_size,
       NGX_HTTP_LOC_CONF_OFFSET,
       offsetof(ngx_http_empty_gif_loc_conf_t, fake),
@@ -129,8 +134,9 @@ static ngx_int_t
 ngx_http_empty_gif_handler(ngx_http_request_t *r)
 {
     ngx_int_t                       rc;
-    ngx_buf_t                      *b;
-    ngx_chain_t                     out[2];
+    ngx_buf_t                      *b = NULL;
+    ngx_uint_t                      i, out_count;
+    ngx_chain_t                    *out;
     ngx_http_empty_gif_loc_conf_t  *conf;
 
     conf = ngx_http_get_module_loc_conf(r, ngx_http_empty_gif_module);
@@ -152,8 +158,8 @@ ngx_http_empty_gif_handler(ngx_http_request_t *r)
     if (r->method == NGX_HTTP_HEAD) {
         r->headers_out.status = NGX_HTTP_OK;
         r->headers_out.content_length_n = sizeof(ngx_empty_gif);
-        if (conf->fake.len) {
-            r->headers_out.content_length_n += conf->fake.len;
+        if (conf->fake.size) {
+            r->headers_out.content_length_n += conf->fake.size;
         }
         r->headers_out.last_modified_time = 23349600;
 
@@ -165,39 +171,50 @@ ngx_http_empty_gif_handler(ngx_http_request_t *r)
         return ngx_http_send_header(r);
     }
 
-    b = ngx_pcalloc(r->pool, sizeof(ngx_buf_t));
-    if (b == NULL) {
-        return NGX_HTTP_INTERNAL_SERVER_ERROR;
+    out_count = 1;
+    if (conf->fake.size) {
+        out_count += conf->fake.size / conf->fake.str.len;
+        if (conf->fake.size % conf->fake.str.len) {
+            out_count++;
+        }
     }
 
-    out[0].buf = b;
-    out[0].next = NULL;
-
-    b->pos = ngx_empty_gif;
-    b->last = ngx_empty_gif + sizeof(ngx_empty_gif);
-    b->memory = 1;
-
-    r->headers_out.status = NGX_HTTP_OK;
-    r->headers_out.content_length_n = sizeof(ngx_empty_gif);
-    r->headers_out.last_modified_time = 23349600;
-
-    if (conf->fake.len) {
-        out[0].next = &out[1];
-        r->headers_out.content_length_n += conf->fake.len;
+    out = ngx_palloc(r->pool, sizeof(ngx_chain_t) * out_count);
+    if (out == NULL) {
+        return NGX_HTTP_INTERNAL_SERVER_ERROR;
+    }
 
+    for (i = 0; i < out_count; i++) {
         b = ngx_pcalloc(r->pool, sizeof(ngx_buf_t));
         if (b == NULL) {
             return NGX_HTTP_INTERNAL_SERVER_ERROR;
         }
 
-        out[1].next = NULL;
-        out[1].buf = b;
+        out[i].buf = b;
+
+        if (0 == i) {
+            out[i].next = NULL;
+            b->pos = b->start = ngx_empty_gif;
+            b->last = b->end = ngx_empty_gif + sizeof(ngx_empty_gif);
+        } else if ((conf->fake.size / conf->fake.str.len) + 1 == i) {
+            out[i-1].next = &out[i];
+            out[i].next = NULL;
+            b->pos = b->start = conf->fake.str.data;
+            b->last = b->end = conf->fake.str.data + conf->fake.size % 
conf->fake.str.len;
+        } else {
+            out[i-1].next = &out[i];
+            out[i].next = NULL;
+            b->pos = b->start = conf->fake.str.data;
+            b->last = b->end = conf->fake.str.data + conf->fake.str.len;
+        }
 
-        b->pos = conf->fake.data;
-        b->last = conf->fake.data + conf->fake.len;
         b->memory = 1;
     }
 
+    r->headers_out.status = NGX_HTTP_OK;
+    r->headers_out.content_length_n = sizeof(ngx_empty_gif) + conf->fake.size;
+    r->headers_out.last_modified_time = 23349600;
+
     b->last_buf = 1;
 
     r->headers_out.etag_size = 40;
@@ -210,7 +227,7 @@ ngx_http_empty_gif_handler(ngx_http_request_t *r)
         return rc;
     }
 
-    return ngx_http_output_filter(r, &out[0]);
+    return ngx_http_output_filter(r, out);
 }
 
 
@@ -245,7 +262,7 @@ ngx_http_empty_gif_merge_local_conf(ngx_conf_t *cf, void 
*parent, void *child)
     ngx_http_empty_gif_loc_conf_t  *prev = parent;
     ngx_http_empty_gif_loc_conf_t  *conf = child;
 
-    if (prev->fake.len) {
+    if (prev->fake.size) {
         conf->fake = prev->fake;
     }
 
@@ -257,31 +274,47 @@ ngx_http_empty_gif_size(ngx_conf_t *cf, ngx_command_t 
*cmd, void *conf)
 {
     char  *p = conf;
 
-    ngx_str_t                 *field, *value;
+    ngx_str_t                 *value;
+    ngx_int_t                  i = 1;
     ngx_conf_post_t           *post;
+    ngx_http_empty_gif_fake_t *field;
 
-    field = (ngx_str_t *) (p + cmd->offset);
+    field = (ngx_http_empty_gif_fake_t *) (p + cmd->offset);
 
-    if (field->data) {
+    if (field->str.data) {
         return "is duplicate";
     }
 
     value = cf->args->elts;
 
-    field->len = ngx_parse_size(&value[1]);
+    if (cf->args->nelts == 3) {
+        field->str.len = ngx_parse_size(&value[i]);
+        if (field->str.len == (size_t) NGX_ERROR) {
+            return "invalid value";
+        }
+        i++;
+    } else {
+        field->str.len = 1024;
+    }
+
+    field->size = ngx_parse_size(&value[i]);
 
-    if (field->len == (size_t) NGX_ERROR) {
+    if (field->size == (size_t) NGX_ERROR) {
         return "invalid value";
     }
 
-    if (field->len < sizeof(ngx_empty_gif)) {
+    if (field->size < sizeof(ngx_empty_gif)) {
         return "is shortly";
     }
 
-    field->len -= sizeof(ngx_empty_gif);
+    field->size -= sizeof(ngx_empty_gif);
+
+    if (field->str.len > field->size) {
+        field->str.len = field->size;
+    }
 
-    field->data = ngx_pcalloc(cf->pool, field->len);
-    if (field->data == NULL) {
+    field->str.data = ngx_pcalloc(cf->pool, field->str.len);
+    if (field->str.data == NULL) {
         return NGX_CONF_ERROR;
     }
 
-- 
1.6.2