no-signal capability

montdidier · mrtazz · commit b0e0c0a91b86 · 2016-12-05T12:35:55.000-05:00
this adds a method to the connection object to be able to turn off libcurl signals for use in multi-threaded context. closes mrtazz#67
diff --git a/README.md b/README.md
@@ -164,6 +164,8 @@ your threads. Do not share connection objects across threads as this would
 mean accessing curl handles from multiple threads at the same time which is
 not allowed.
 
+The connection level method SetNoSignal can be set to skip all signal handling. This is important in multi-threaded applications as DNS resolution timeouts use signals. The signal handlers quite readily get executed on other threads. Note that with this option DNS resolution timeouts do not work. If you have crashes in your multi-threaded executable that appear to be in DNS resolution, this is probably why.
+
 In order to provide an easy to use API, the simple usage via the static
 methods implicitly calls the curl global functions and is therefore also **not
 thread-safe**.
diff --git a/include/restclient-cpp/connection.h b/include/restclient-cpp/connection.h
@@ -95,6 +95,7 @@ class Connection {
       RestClient::HeaderFields headers;
       int timeout;
       bool followRedirects;
+      bool noSignal;
       struct {
         std::string username;
         std::string password;
@@ -119,6 +120,9 @@ class Connection {
     // set connection timeout to seconds
     void SetTimeout(int seconds);
 
+    // set to not use signals
+    void SetNoSignal(bool no);
+
     // set whether to follow redirects
     void FollowRedirects(bool follow);
 
@@ -169,6 +173,7 @@ class Connection {
     RestClient::HeaderFields headerFields;
     int timeout;
     bool followRedirects;
+    bool noSignal;
     struct {
       std::string username;
       std::string password;
diff --git a/source/connection.cc b/source/connection.cc
@@ -34,6 +34,7 @@ RestClient::Connection::Connection(const std::string& baseUrl)
   this->baseUrl = baseUrl;
   this->timeout = 0;
   this->followRedirects = false;
+  this->noSignal = false;
 }
 
 RestClient::Connection::~Connection() {
@@ -55,6 +56,8 @@ RestClient::Connection::GetInfo() {
   ret.baseUrl = this->baseUrl;
   ret.headers = this->GetHeaders();
   ret.timeout = this->timeout;
+  ret.followRedirects = this->followRedirects;
+  ret.noSignal = this->noSignal;
   ret.basicAuth.username = this->basicAuth.username;
   ret.basicAuth.password = this->basicAuth.password;
   ret.customUserAgent = this->customUserAgent;
@@ -165,6 +168,18 @@ RestClient::Connection::SetTimeout(int seconds) {
   this->timeout = seconds;
 }
 
+/**
+ * @brief switch off curl signals for connection (see CURLOPT_NONSIGNAL). By
+ * default signals are used, except when timeout is given.
+ *
+ * @param no - set to true switches signals off
+ *
+ */
+void
+RestClient::Connection::SetNoSignal(bool no) {
+  this->noSignal = no;
+}
+
 /**
  * @brief set username and password for basic auth
  *
@@ -261,6 +276,12 @@ RestClient::Connection::performCurlRequest(const std::string& uri) {
   if (this->followRedirects == true) {
     curl_easy_setopt(this->curlHandle, CURLOPT_FOLLOWLOCATION, 1L);
   }
+
+  if (this->noSignal) {
+    // multi-threaded and prevent entering foreign signal handler (e.g. JNI)
+    curl_easy_setopt(this->curlHandle, CURLOPT_NOSIGNAL, 1);
+  }
+
   // if provided, supply CA path
   if (!this->caInfoFilePath.empty()) {
     curl_easy_setopt(this->curlHandle, CURLOPT_CAINFO,
diff --git a/test/test_connection.cc b/test/test_connection.cc
@@ -207,3 +207,10 @@ TEST_F(ConnectionTest, TestHeadHeaders)
   EXPECT_EQ("bar", headers_returned["Foo"]);
   EXPECT_EQ("lol", headers_returned["Bla"]);
 }
+
+TEST_F(ConnectionTest, TestNoSignal)
+{
+  conn->SetNoSignal(true);
+  RestClient::Response res = conn->get("/get");
+  EXPECT_EQ(200, res.code);
+}
