zmq_init 源码学习

Posted 2021-03-11 mysky007

 197 void *zmq_init (int io_threads_)
 198 { 
 199     if (io_threads_ >= 0) {
 200         void *ctx = zmq_ctx_new ();  
 201         zmq_ctx_set (ctx, ZMQ_IO_THREADS, io_threads_);
 202         return ctx;      
 203     }
 204     errno = EINVAL;      
 205     return NULL;
 206 } 

 128 //  New context API
 129 
 130 void *zmq_ctx_new (void)
 131 {
 132     //  We do this before the ctx constructor since its embedded mailbox_t
 133     //  object needs the network to be up and running (at least on Windows).
 134     if (!zmq::initialize_network ()) {
 135         return NULL;
 136     }
 137 
 138     //  Create 0MQ context.
 139     zmq::ctx_t *ctx = new (std::nothrow) zmq::ctx_t; /* 这里使用的是不抛出异常的new，因为zmq作为库来说，要与不支持异常的调用者兼容，如C。*/
 140     if (ctx) {
 141         if (!ctx->valid ()) {
 142             delete ctx;
 143             return NULL;
 144         }
 145     }
 146     return ctx;
 147 }
 148 

 68 zmq::ctx_t::ctx_t () :
 69     _tag (ZMQ_CTX_TAG_VALUE_GOOD),
 70     _starting (true),
 71     _terminating (false),
 72     _reaper (NULL),
 73     _max_sockets (clipped_maxsocket (ZMQ_MAX_SOCKETS_DFLT)),
 74     _max_msgsz (INT_MAX),
 75     _io_thread_count (ZMQ_IO_THREADS_DFLT),
 76     _blocky (true), 
 77     _ipv6 (false),
 78     _zero_copy (true)
 79 {    
 80 #ifdef HAVE_FORK
 81     _pid = getpid ();
 82 #endif
 83 #ifdef ZMQ_HAVE_VMCI
 84     _vmci_fd = -1;
 85     _vmci_family = -1;
 86 #endif
 87 
 88     //  Initialise crypto library, if needed.
 89     zmq::random_open ();
 90 }

 36 zmq::reaper_t::reaper_t (class ctx_t *ctx_, uint32_t tid_) :
 37     object_t (ctx_, tid_),
 38     _mailbox_handle (static_cast<poller_t::handle_t> (NULL)),
 39     _poller (NULL),
 40     _sockets (0),
 41     _terminating (false)
 42 {
 43     if (!_mailbox.valid ())
 44         return;
 45      /* Linux下，poller_t实际上即为epoll_t*/
 46     _poller = new (std::nothrow) poller_t (*ctx_);
 47     alloc_assert (_poller);
 48     //这里的mailbox.get_fd()得到该reaper_t拥有的mailbox的读描述符
 49     if (_mailbox.get_fd () != retired_fd) {
 50         _mailbox_handle = _poller->add_fd (_mailbox.get_fd (), this);
 51         _poller->set_pollin (_mailbox_handle);
 52     }
 53 
 54 #ifdef HAVE_FORK
 55     _pid = getpid ();
 56 #endif
 57 }