allow custom callback and response, fix CI

Enables streaming get, and out-of-band termination of connection.
Had to fix CI as well. Added necessary tests, and enabled a
previously disabled test.

Author: ejacques

Makefile.am

@@ -16,27 +16,35 @@ librestclient_cpp_la_LDFLAGS=-version-info 2:1:1
 
 dist_doc_DATA = README.md
 
-.PHONY: test check clean-coverage-files coverage-html include/restclient-cpp/version.h lint ci docker-services
+.PHONY: test check clean-coverage-files coverage-html include/restclient-cpp/version.h lint ci docker-services clean-docker-services
 
 include/restclient-cpp/version.h:
 	m4 -I ${top_srcdir}/m4 -DM4_RESTCLIENT_VERSION=$(PACKAGE_VERSION) version.h.m4 > ${top_srcdir}/$@ 
 
 
 
-test: check
+test: check docker-services
 	./test-program
 
 valgrind: check
 	valgrind --leak-check=full --error-exitcode=1 ./test-program
 
 lint:
-	cpplint --filter=-legal/copyright include/restclient-cpp/*.h source/*.cc
+	cpplint --filter=-legal/copyright --root=$(CURDIR) include/restclient-cpp/*.h source/*.cc
 
 docker-services:
-	docker inspect --format="{{ .State.Running }}" restclient-proxy &> /dev/null || docker run -d --name restclient-proxy -p 3128:3128 chrisdaish/squid
-	docker ps -a
-
-ci: lint docker-services test valgrind
+	[ -n "$$(docker ps --quiet --filter name=restclient-cpp-httpbin)" ] || \
+		docker run --detach -p 8998:80 --name restclient-cpp-httpbin kennethreitz/httpbin
+	[ -n "$$(docker ps --quiet --filter name=restclient-cpp-squid)" ] || \
+		docker run --detach -p 3128:3128 --name restclient-cpp-squid \
+		--volume "$(CURDIR)/test/squid.conf:/etc/squid/squid.conf:ro" sameersbn/squid:3.5.27-2
+	docker ps --all --filter 'name=^restclient-cpp-'
+
+clean-docker-services:
+	docker rm --force restclient-cpp-httpbin 2>/dev/null || true
+	docker rm --force restclient-cpp-squid 2>/dev/null || true
+
+ci: lint test valgrind
 
 clean-local:
 	find . -name "*.gcda" -print0 | xargs -0 rm

README.md

@@ -175,6 +175,47 @@ conn->SetFileProgressCallback(progressFunc);
 conn->SetFileProgressCallbackData(data);
 ```
 
+### Write callback
+
+A write callback function can be provided for processing data as it's received from a GET call (for instance the [Kubernetes Watch API](https://kubernetes.io/docs/reference/using-api/api-concepts/#efficient-detection-of-changes)).
+
+Calling `conn->SetWriteFunction(callback)` with a function parameter matching the prototype `size_t write_function(void *data, size_t size, size_t nmemb, void *userdata)int progress_callback(void *clientp, double dltotal, double dlnow, double ultotal, double ulnow)` will setup the write function.
+
+Here is an example of a write callback function, processing result data line by line.
+
+```cpp
+auto writeCallback = [](void *data, size_t size, size_t nmemb, void *userdata) -> size_t
+{
+  size_t bytes = size * nmemb;
+  try
+  {
+      // Add to the buffer
+      auto res = reinterpret_cast<RestClient::Response *>(userdata);
+      res->body.append(static_cast<char*>(data), bytes);
+      // If the last character is not a new line, wait for the rest.
+      if ('\n' != *(res->body.end() - 1))
+      {
+          return bytes;
+      }
+      // Process data one line at a time.
+      std::stringstream stream(res->body);
+      std::string line;
+      while (std::getline(stream, line))
+      {
+        // Do something with the line here...
+      }
+      // Done processing the line
+      res->body.clear();
+  }
+  catch(std::exception e)
+  {
+      // Log caught exception here
+      return 0;
+  }
+  return bytes;
+};
+```
+
 ## Error handling
 When restclient-cpp encounters an error, generally the error (or "status") code is returned in the `Response` (see
 [Response struct in restclient.h](https://github.com/mrtazz/restclient-cpp/blob/master/include/restclient-cpp/restclient.h)). This error code can be either

include/restclient-cpp/connection.h

@@ -22,6 +22,12 @@
  */
 namespace RestClient {
 
+/**
+ * @brief define type used for RestClient write callback
+ */
+typedef size_t (*WriteCallback)(void *data, size_t size,
+                  size_t nmemb, void *userdata);
+
 /**
   * @brief Connection object for advanced usage
   */
@@ -146,6 +152,9 @@ class Connection {
     explicit Connection(const std::string& baseUrl);
     ~Connection();
 
+    // Terminate open connection
+    void Terminate();
+
     // Instance configuration methods
     // configure basic auth
     void SetBasicAuth(const std::string& username,
@@ -193,6 +202,9 @@ class Connection {
     // set CURLOPT_UNIX_SOCKET_PATH
     void SetUnixSocketPath(const std::string& unixSocketPath);
 
+    // set CURLOPT_WRITEFUNCTION
+    void SetWriteFunction(WriteCallback write_callback);
+
     std::string GetUserAgent();
 
     RestClient::Connection::Info GetInfo();
@@ -220,7 +232,12 @@ class Connection {
     RestClient::Response head(const std::string& uri);
     RestClient::Response options(const std::string& uri);
 
+    // GET with custom response structure
+    RestClient::Response*
+    get(const std::string& uri, RestClient::Response* response);
+
  private:
+    CURL* getCurlHandle();
     CURL* curlHandle;
     std::string baseUrl;
     RestClient::HeaderFields headerFields;
@@ -244,6 +261,9 @@ class Connection {
     std::string uriProxy;
     std::string unixSocketPath;
     char curlErrorBuf[CURL_ERROR_SIZE];
+    RestClient::WriteCallback writeCallback;
+    RestClient::Response*
+    performCurlRequest(const std::string& uri, RestClient::Response* resp);
     RestClient::Response performCurlRequest(const std::string& uri);
 };
 };  // namespace RestClient