gistfile1.hpp

static Mutex* sharedResourceMutex(curl_lock_data data) {
    DEFINE_STATIC_LOCAL(Mutex, cookieMutex, ());
    DEFINE_STATIC_LOCAL(Mutex, dnsMutex, ());

    switch (data) {
        case CURL_LOCK_DATA_COOKIE:
            return &cookieMutex;
        case CURL_LOCK_DATA_DNS:
            return &dnsMutex;
        default:
            return NULL;
    }
}

// libcurl does not implement its own thread synchronization primitives.
// these two functions provide mutexes for cookies, and for the global DNS
// cache.
static void curl_lock_callback(CURL* handle, curl_lock_data data, curl_lock_access access, void* userPtr)
{
    if (Mutex* mutex = sharedResourceMutex(data))
        mutex->lock();
}

static void curl_unlock_callback(CURL* handle, curl_lock_data data, void* userPtr)
{
    if (Mutex* mutex = sharedResourceMutex(data))
        mutex->unlock();
}