[DO NOT MERGE] PaddleOCR crash diagnostics on top of sockets-server-posix

Common/Cpp/Sockets/AbstractServerSocket.h

@@ -78,7 +78,10 @@ class AbstractServerSocket{
     //  State::LISTENING on success or State::NOT_RUNNING on failure.
     virtual void start(const std::string& address, uint16_t port) = 0;
 
-    //  Closes the active connection, if any, and keeps listening.
+    //  Closes the active connection, if any, and keeps listening. Unlike
+    //  "close()", this does not wait for the worker threads, so it is safe
+    //  to call from within a listener callback. "Listener::on_disconnect"
+    //  is not called for the connection closed this way.
     virtual void close_connection() = 0;
 
     //  Stops the server: it stops accepting new connections, closes the

Common/Cpp/Sockets/ClientSocket_POSIX.cpp

@@ -133,10 +133,11 @@ size_t ClientSocket_POSIX::send(const void* data, size_t bytes){
         size_t current = std::min<size_t>(bytes, BLOCK_SIZE);
         ssize_t current_sent = ::send(socket, ptr, (int)current, MSG_DONTWAIT | MSG_NOSIGNAL);
         if (current_sent != -1){
+            //  send() may return after writing only part of the
+            //  buffer (macOS does this when the kernel's send
+            //  buffer is full); loop until everything has been
+            //  written, the same way the Qt backend does.
             sent += current_sent;
-            if ((size_t)current_sent < current){
-                return sent;
-            }
             ptr += current_sent;
             bytes -= current_sent;
             continue;

Common/Cpp/Sockets/ClientSocket_Qt.h

@@ -9,7 +9,6 @@
 
 #include <string>
 #include <atomic>
-#include <condition_variable>
 #include <QObject>
 #include "Common/Cpp/Concurrency/Mutex.h"
 #include "Common/Cpp/Concurrency/ConditionVariable.h"
@@ -32,7 +31,7 @@ class ClientSocket_Qt final : public QObject, public AbstractClientSocket{
         bool done = false;
 
         Mutex lock;
-        std::condition_variable cv;
+        ConditionVariable cv;
     };