Stop always allocating 8k for each request. We now count the number

of bytes required for the headers for each request, and we just allocate
that number of bytes plus 100 extra.  The extra 100 are a fudge factor,
because it is a bit difficult to compute the exact length for the
basic HTTP headers like date and the status line.

git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/trunk@86781 13f79535-47bb-0310-9956-ffa450edef68

diff --git a/modules/http/http_protocol.c b/modules/http/http_protocol.c
index 9480474d70bb0b4cd9ebcc4691e79ab320012318..507a1b2aedcf26499de9649d2cb02bd41198d637 100644 (file)
--- a/modules/http/http_protocol.c
+++ b/modules/http/http_protocol.c
@@ -1773,6 +1773,14 @@ static int form_header_field(header_struct *h,
     return 1;
 }
 
+static int compute_header_len(apr_size_t *length, const char *fieldname, 
+                              const char *fieldval)
+{
+    /* The extra five are for ": " and CRLF, plus one for a '\0'. */
+    *length = *length + strlen(fieldname) + strlen(fieldval) + 6;
+    return 1;
+}
+
 AP_DECLARE(void) ap_basic_http_header(request_rec *r, char *buf)
 {
     char *protocol;
@@ -2311,7 +2319,7 @@ AP_CORE_DECLARE_NONSTD(apr_status_t) ap_http_header_filter(ap_filter_t *f, ap_bu
     char *buff;
     ap_bucket *e;
     ap_bucket_brigade *b2;
-    apr_size_t len;
+    apr_size_t len = 0;
     header_struct h;
 
     if (r->assbackwards) {
@@ -2345,15 +2353,6 @@ AP_CORE_DECLARE_NONSTD(apr_status_t) ap_http_header_filter(ap_filter_t *f, ap_bu
        fixup_vary(r);
     }
 
-    /* XXX Should count the bytes in the headers and allocate just enough
-     * for the headers we have.
-     */
-    buff = apr_pcalloc(r->pool, HUGE_STRING_LEN);
-    len = HUGE_STRING_LEN;
-    e = ap_bucket_create_pool(buff, len, r->pool);
-    ap_basic_http_header(r, buff);
-    buff += strlen(buff) + 1;
-
     ap_set_keepalive(r);
 
     if (r->chunked) {
@@ -2402,6 +2401,18 @@ AP_CORE_DECLARE_NONSTD(apr_status_t) ap_http_header_filter(ap_filter_t *f, ap_bu
         apr_table_addn(r->headers_out, "Expires", date);
     }
 
+    apr_table_do((int (*) (void *, const char *, const char *)) compute_header_len,
+                 (void *) &len, r->headers_out, NULL);
+    
+    /* Need to add a fudge factor so that the CRLF at the end of the headers
+     * and the basic http headers don't overflow this buffer.
+     */
+    len += strlen(ap_get_server_version()) + 100;
+    buff = apr_pcalloc(r->pool, len);
+    e = ap_bucket_create_pool(buff, len, r->pool);
+    ap_basic_http_header(r, buff);
+    buff += strlen(buff) + 1;
+
     h.r = r;
     h.buf = buff;