Use std::mutex and std::unique_lock instead of pthread mutex/lock.

It simplify a bit the code and ensure that mutex is correctly unlock
even in case of exception.

src/aria2.cpp

@@ -26,8 +26,7 @@ Aria2::Aria2():
   mp_aria(nullptr),
   m_port(42042),
   m_secret("kiwixariarpc"),
-  mp_curl(nullptr),
-  m_lock(PTHREAD_MUTEX_INITIALIZER)
+  mp_curl(nullptr)
 {
   m_downloadDir = getDataDirectory();
   makeDirectory(m_downloadDir);
@@ -115,6 +114,7 @@ Aria2::Aria2():
 
 Aria2::~Aria2()
 {
+  std::unique_lock<std::mutex> lock(m_lock);
   curl_easy_cleanup(mp_curl);
 }
 
@@ -133,19 +133,23 @@ size_t write_callback_to_iss(char* ptr, size_t size, size_t nmemb, void* userdat
 
 std::string Aria2::doRequest(const MethodCall& methodCall)
 {
-  pthread_mutex_lock(&m_lock);
   auto requestContent = methodCall.toString();
   std::stringstream stringstream;
   CURLcode res;
+  long response_code;
+  {
+    std::unique_lock<std::mutex> lock(m_lock);
     curl_easy_setopt(mp_curl, CURLOPT_POSTFIELDSIZE, requestContent.size());
     curl_easy_setopt(mp_curl, CURLOPT_POSTFIELDS, requestContent.c_str());
     curl_easy_setopt(mp_curl, CURLOPT_WRITEFUNCTION, &write_callback_to_iss);
     curl_easy_setopt(mp_curl, CURLOPT_WRITEDATA, &stringstream);
     res = curl_easy_perform(mp_curl);
-  if (res == CURLE_OK) {
-    long response_code;
+    if (res != CURLE_OK) {
+      throw std::runtime_error("Cannot perform request");
+    }
     curl_easy_getinfo(mp_curl, CURLINFO_RESPONSE_CODE, &response_code);
-    pthread_mutex_unlock(&m_lock);
+  }
+
   if (response_code != 200) {
     throw std::runtime_error("Invalid return code from aria");
   }
@@ -156,9 +160,6 @@ std::string Aria2::doRequest(const MethodCall& methodCall)
   }
   return responseContent;
 }
-  pthread_mutex_unlock(&m_lock);
-  throw std::runtime_error("Cannot perform request");
-}
 
 std::string Aria2::addUri(const std::vector<std::string>& uris, const std::vector<std::pair<std::string, std::string>>& options)
 {

src/aria2.h

@@ -12,8 +12,8 @@
 #include "xmlrpc.h"
 
 #include <memory>
+#include <mutex>
 #include <curl/curl.h>
-#include <pthread.h>
 
 namespace kiwix {
 
@@ -25,7 +25,7 @@ class Aria2
     std::string m_secret;
     std::string m_downloadDir;
     CURL* mp_curl;
-    pthread_mutex_t m_lock;
+    std::mutex m_lock;
 
     std::string doRequest(const MethodCall& methodCall);