update readme / iovec optimizations

README.md

@@ -0,0 +1,49 @@
+| ![LOGO](http://i.imgur.com/uBd4iIz.png) | <h1>Libevhtp</h1> |
+| :------------- | -------------: |
+
+[![Build Status](https://travis-ci.org/criticalstack/libevhtp.svg?branch=develop)](https://travis-ci.org/criticalstack/libevhtp)
+[![Gitter](https://badges.gitter.im/criticalstack/libevhtp.svg)](https://gitter.im/criticalstack/libevhtp?utm_source=badge&utm_medium=badge&utm_campaign=pr-badge)
+[![Packaging status](https://repology.org/badge/tiny-repos/libevhtp.svg)](https://repology.org/metapackage/libevhtp/versions)
+
+<a href="https://scan.coverity.com/projects/libevhtp">
+  <img alt="Coverity Scan Build Status"
+       src="https://scan.coverity.com/projects/15294/badge.svg"/>
+</a>
+
+## Required Dependencies
+* [gcc](http://gcc.gnu.org/) or [clang](https://clang.llvm.org/)
+* [Libevent2](http://libevent.org)
+* [CMake](http://cmake.org)
+
+## Optional Dependencies
+* [OpenSSL](http://openssl.org)
+* pthreads
+* [onig (regex)](https://github.com/kkos/oniguruma)
+
+## Building
+* cd build
+* cmake ..
+* make
+* make examples
+
+## For Windows MinGW
+* cmake -G "MSYS Makefiles" -DCMAKE_INCLUDE_PATH=/mingw/include -DCMAKE_LIBRARY_PATH=/mingw/lib -DCMAKE_INSTALL_PREFIX=/mingw  .
+* make
+
+## Performance stuff
+
+While we never documented any benchmark publically,
+the popular open source project [ZIMG](http://zimg.buaa.us) did a bit of that
+for us.The ZIMG team decided to move away from NGINX to libevhtp for their
+software, and the results were pretty outstanding. Here is a graph showing their
+application under very high load
+
+![ZIMG GRAPH](/zimg_vs_nginx.png)
+
+The X-axis is the number of connections, while the Y-axis is requests per
+second.
+
+You can read the whole article here: [Architecture Design of an Image Server](http://zimg.buaa.us/documents/Architecture_Design_of_Image_Server/)
+
+Slightly outdated (Now faster!)
+![HI NGINX](http://i.imgur.com/kiSkSLH.png)

evhtp.c

@@ -4,6 +4,7 @@
  * @brief implementation file for libevhtp.
  */
 
+#define _GNU_SOURCE
 #include <stdlib.h>
 #include <string.h>
 #include <stdint.h>
@@ -12,6 +13,7 @@
 #include <strings.h>
 #include <inttypes.h>
 #include <stdbool.h>
+#include <sys/param.h> /* MIN/MAX macro */
 #ifndef WIN32
 #include <sys/socket.h>
 #include <netinet/in.h>
@@ -2013,32 +2015,38 @@ htp__request_parse_fini_(htparser * p)
     return 0;
 } /* htp__request_parse_fini_ */
 
-static size_t
+static int
 htp__evbuffer_add_iovec_(struct evbuffer * buf, struct evbuffer_iovec * vec, int n_vec)
 {
-#if LIBEVENT_VERSION_NUMBER < 0x02010000
     int    n;
-    size_t res;
     size_t to_alloc;
+    char * bufptr;
+    size_t to_copy;
 
-    res = to_alloc = 0;
+    to_alloc = 0;
 
     for (n = 0; n < n_vec; n++) {
         to_alloc += vec[n].iov_len;
     }
 
-    evbuffer_expand(buf, to_alloc);
+    char buffer[to_alloc];
 
-    for (n = 0; n < n_vec; n++) {
-        evbuffer_add(buf, vec[n].iov_base, vec[n].iov_len);
+    bufptr  = buffer;
+    to_copy = to_alloc;
+
+    for (n = 0; n < n_vec; n++)
+    {
+        size_t copy = MIN(vec[n].iov_len, to_copy);
+
+        bufptr   = mempcpy(bufptr, vec[n].iov_base, copy);
+        to_copy -= copy;
 
-        res += vec[n].iov_len;
+        if (evhtp_unlikely(to_copy == 0)) {
+            break;
+        }
     }
 
-    return res;
-#else
-    return evbuffer_add_iovec(buf, vec, n_vec);
-#endif
+    return evbuffer_add(buf, buffer, to_alloc);
 }
 
 static int

examples/CMakeLists.txt

@@ -13,8 +13,15 @@ add_executable(example_request_fini EXCLUDE_FROM_ALL example_request_fini.c)
 add_executable(example_basic EXCLUDE_FROM_ALL example_basic.c)
 
 if(NOT EVHTP_DISABLE_EVTHR)
-    #add_executable(example_locality EXCLUDE_FROM_ALL example_locality.c)
-    #target_link_libraries(example_locality evhtp ${LIBEVHTP_EXTERNAL_LIBS} ${SYS_LIBS})
+    if ("${CMAKE_SYSTEM}" MATCHES "Linux")
+        add_executable(example_locality EXCLUDE_FROM_ALL example_locality.c)
+        target_link_libraries(example_locality evhtp ${LIBEVHTP_EXTERNAL_LIBS} ${SYS_LIBS})
+
+        add_executable(reuse_thread_svr EXCLUDE_FROM_ALL reuse_thread_svr.c)
+        target_link_libraries(reuse_thread_svr evhtp ${LIBEVHTP_EXTERNAL_LIBS} ${SYS_LIBS})
+
+        add_dependencies(examples example_locality reuse_thread_svr)
+    endif()
 
 	add_executable(test_proxy EXCLUDE_FROM_ALL test_proxy.c)
 	target_link_libraries(test_proxy evhtp ${LIBEVHTP_EXTERNAL_LIBS} ${SYS_LIBS})