Add streaming example.

examples/CMakeLists.txt

@@ -1,10 +1,12 @@
 include(GNUInstallDirs)
 
+find_package(Threads  REQUIRED)
+
 file(GLOB sources_examples *.cpp)
 foreach(src ${sources_examples})
   get_filename_component(bin ${src} NAME_WE)
   add_executable(${bin} ${src})
-  target_link_libraries(${bin} PRIVATE ${PROJECT_NAME})
+  target_link_libraries(${bin} PRIVATE ${PROJECT_NAME} Threads::Threads)
 endforeach()
 
 if(WITH_DOC)

examples/example02_streaming.cpp

@@ -0,0 +1,102 @@
+/*  This file is part of mastodonpp.
+ *  Copyright © 2020 tastytea <tastytea@tastytea.de>
+ *
+ *  Permission to use, copy, modify, and/or distribute this software for any
+ *  purpose with or without fee is hereby granted.
+ *
+ *  THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+ *  WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+ *  MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY
+ *  SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+ *  WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION
+ *  OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN
+ *  CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+ */
+
+// Print information about an instance (/api/v1/instance).
+
+#include "mastodonpp.hpp"
+
+#include <chrono>
+#include <iostream>
+#include <string>
+#include <string_view>
+#include <thread>
+#include <vector>
+
+namespace masto = mastodonpp;
+using namespace std::chrono_literals;
+using std::cout;
+using std::cerr;
+using std::endl;
+using std::to_string;
+using std::string_view;
+using std::thread;
+using std::this_thread::sleep_for;
+using std::vector;
+
+int main(int argc, char *argv[])
+{
+    const vector<string_view> args(argv, argv + argc);
+    if (args.size() <= 1)
+    {
+        cerr << "Usage: " << args[0] << " <instance hostname>\n";
+        return 1;
+    }
+
+    try
+    {
+        // Initialize an Instance.
+        masto::Instance instance{args[1], {}};
+
+        // Initialize a Connection.
+        masto::Connection connection{instance};
+
+        // Find out if the streaming service is fine.
+        auto answer{connection.get(masto::API::v1::streaming_health)};
+        if (answer && answer.body == "OK")
+        {
+            // Make a thread, get all public events.
+            thread stream_thread{[&]
+            {
+                answer = connection.get(masto::API::v1::streaming_public);
+            }};
+
+            // Print new events every 2 seconds, for 10 seconds.
+            for (auto counter{0}; counter < 5; ++counter)
+            {
+                cout << "----------------------------------------" << endl;
+                sleep_for(2s);
+                cout << connection.get_new_stream_contents() << endl;
+            }
+
+            // Cancel the stream, …
+            connection.cancel_stream();
+            // … and get the rest of the data.
+            cout << connection.get_new_stream_contents() << endl;
+            stream_thread.join();
+        }
+        else
+        {
+            if (answer.curl_error_code == 0)
+            {
+                // If it is no libcurl error, it must be an HTTP error.
+                cerr << "HTTP status: " << answer.http_status << endl;
+            }
+            else
+            {
+                // Network errors like “Couldn't resolve host.”.
+                cerr << "libcurl error " << to_string(answer.curl_error_code)
+                     << ": " << answer.error_message << endl;
+            }
+        }
+    }
+    catch (const masto::CURLException &e)
+    {
+        // Only libcurl errors that are not network errors will be thrown.
+        // There went probably something wrong with the initialization.
+        cerr << e.what() << endl;
+    }
+
+    return 0;
+}

src/curl_wrapper.cpp

@@ -137,7 +137,8 @@ answer_type CURLWrapper::make_request(const http_method &method, string uri,
 
     answer_type answer;
     code = curl_easy_perform(_connection);
-    if (code == CURLE_OK)
+    if (code == CURLE_OK
+        || (code == CURLE_ABORTED_BY_CALLBACK && _stream_cancelled))
     {
         long http_status;       // NOLINT(google-runtime-int)
         // NOLINTNEXTLINE(cppcoreguidelines-pro-type-vararg)