add StreamReader cancel read steam

examples/async_stream/RequestStreamExampleCtrl.cc

@@ -98,7 +98,7 @@ class RequestStreamExampleCtrl : public HttpController<RequestStreamExampleCtrl>
             [files](const char *data, size_t length) {
                 if (files->back().tmpName.empty())
                 {
-                    return;
+                    return false;
                 }
                 auto &currentFile = files->back().file;
                 if (length == 0)
@@ -109,18 +109,20 @@ class RequestStreamExampleCtrl : public HttpController<RequestStreamExampleCtrl>
                         currentFile.flush();
                         currentFile.close();
                     }
-                    return;
+                    return true;
                 }
                 LOG_INFO << "data[" << length << "]: ";
                 if (currentFile.is_open())
                 {
                     LOG_INFO << "write file";
                     currentFile.write(data, length);
+                    return true;
                 }
                 else
                 {
                     LOG_ERROR << "file not open";
                 }
+                return false;
             },
             [files, callback = std::move(callback)](std::exception_ptr ex) {
                 if (ex)

lib/src/MultipartStreamParser.cc

@@ -252,23 +252,37 @@ void drogon::MultipartStreamParser::parse(
                 }
                 std::string_view v = buffer_.view();
                 auto pos = v.find(crlfDashBoundary_);
+
+                const auto callDataCB = [&dataCb, this](const char * _data, std::size_t _len) {
+                    if(!dataCb(_data, _len)) {
+                        isValid_ = false;
+                        isFinished_ = true;
+                        exception_type_ = ExceptionType::kServerCancel;
+                    }
+                };
+
                 if (pos == std::string::npos)
                 {
                     // boundary not found, leave potential partial boundary
-                    size_t len = v.size() - crlfDashBoundary_.size();
+                    const size_t len = v.size() - crlfDashBoundary_.size();
                     if (len > 0)
                     {
-                        dataCb(v.data(), len);
+                        callDataCB(v.data(), len);
                         buffer_.eraseFront(len);
                     }
                     return;
                 }
                 // found boundary
-                dataCb(v.data(), pos);
-                if (pos > 0)
-                {
-                    dataCb(v.data() + pos, 0);  // notify end of file
+                if(!isFinished() && isValid()) {
+                    callDataCB(v.data(), pos);
+
+                    if (pos > 0)
+                    {
+                        // notify end of file
+                        callDataCB(v.data() + pos, 0);
+                    }
                 }
+
                 buffer_.eraseFront(pos + crlfDashBoundary_.size());
                 status_ = Status::kExpectEndOrNewEntry;
                 continue;

lib/src/MultipartStreamParser.h

@@ -21,6 +21,13 @@ namespace drogon
 {
 class DROGON_EXPORT MultipartStreamParser
 {
+  public:
+    enum class ExceptionType
+    {
+        kNoException = 0,
+        kServerCancel = 1,
+    };
+
   public:
     MultipartStreamParser(const std::string &contentType);
 
@@ -39,6 +46,10 @@ class DROGON_EXPORT MultipartStreamParser
         return isValid_;
     }
 
+    ExceptionType exceptionType() const {
+        return exception_type_;
+    }
+
   private:
     const std::string dash_ = "--";
     const std::string crlf_ = "\r\n";
@@ -70,6 +81,8 @@ class DROGON_EXPORT MultipartStreamParser
         kExpectEndOrNewEntry = 4,
     } status_{Status::kExpectFirstBoundary};
 
+    ExceptionType exception_type_{ExceptionType::kNoException};
+
     MultipartHeader currentHeader_;
     bool isValid_{true};
     bool isFinished_{false};

lib/src/RequestStream.cc

@@ -161,9 +161,17 @@ class MultipartStreamReader : public RequestStreamReader
         parser_.parse(data, length, headerCb_, dataCb_);
         if (!parser_.isValid())
         {
+            std::exception_ptr exception = nullptr;
             // TODO: should we mix stream error and user error?
-            finishCb_(std::make_exception_ptr(
-                std::runtime_error("invalid multipart data")));
+            switch (parser_.exceptionType()) {
+                case MultipartStreamParser::ExceptionType::kServerCancel:
+                    exception = std::make_exception_ptr(std::runtime_error("server cancelled"));
+                    break;
+                default:
+                    exception = std::make_exception_ptr(std::runtime_error("invalid multipart data"));
+                    break;
+            }
+            finishCb_(exception);
         }
         else if (parser_.isFinished())
         {

lib/tests/integration_test/server/RequestStreamTestCtrl.cc

@@ -118,6 +118,7 @@ class RequestStreamTestCtrl : public HttpController<RequestStreamTestCtrl>
                 {
                     ctx->firstFileContent.append(data, length);
                 }
+                return true;
             },
             [ctx, callback = std::move(callback)](std::exception_ptr ex) {
                 auto resp = HttpResponse::newHttpResponse();