尝试使用sendfile优化http文件服务器 (#1411)

src/Http/HttpBody.cpp

@@ -65,9 +65,23 @@ HttpFileBody::HttpFileBody(const std::shared_ptr<FILE> &fp, size_t offset, size_
     init(fp, offset, max_size, use_mmap);
 }
 
+#if  defined(__linux__) || defined(__linux)
+#include <sys/sendfile.h>
+#endif
+
+int HttpFileBody::sendFile(int fd) {
+#if  defined(__linux__) || defined(__linux)
+    off_t off = _file_offset;
+    return sendfile(fd, fileno(_fp.get()), &off, _max_size);
+#else
+    return -1;
+#endif
+}
+
 void HttpFileBody::init(const std::shared_ptr<FILE> &fp, size_t offset, size_t max_size, bool use_mmap) {
     _fp = fp;
     _max_size = max_size;
+    _file_offset = offset;
 #ifdef ENABLE_MMAP
     if (use_mmap) {
         do {

src/Http/HttpBody.h

@@ -57,6 +57,15 @@ public:
         //(其实并没有读，拷贝文件数据时在内核态完成文件读)
         cb(readData(size));
     }
+
+    /**
+     * 使用sendfile优化文件发送
+     * @param fd socket fd
+     * @return 0成功，其他为错误代码
+     */
+    virtual int sendFile(int fd) {
+        return -1;
+    }
 };
 
 /**
@@ -112,6 +121,7 @@ public:
 
     ssize_t remainSize() override ;
     toolkit::Buffer::Ptr readData(size_t size) override;
+    int sendFile(int fd) override;
 
 private:
     void init(const std::shared_ptr<FILE> &fp,size_t offset,size_t max_size, bool use_mmap);
@@ -119,6 +129,7 @@ private:
 private:
     size_t _max_size;
     size_t _offset = 0;
+    size_t _file_offset = 0;
     std::shared_ptr<FILE> _fp;
     std::shared_ptr<char> _map_addr;
     toolkit::ResourcePool<toolkit::BufferRaw> _pool;

src/Http/HttpSession.cpp

@@ -594,6 +594,11 @@ void HttpSession::sendResponse(int code,
         return;
     }
 
+    if (!body->sendFile(getSock()->rawFD())) {
+        //支持sendfile优化
+        return;
+    }
+
     GET_CONFIG(uint32_t, sendBufSize, Http::kSendBufSize);
     if(body->remainSize() > sendBufSize){
         //文件下载提升发送性能