From f34e7e0dc56abbefb7453948da009289be30b721 Mon Sep 17 00:00:00 2001
From: MasterRoby3 <master.roby3@protonmail.com>
Date: Mon, 28 Aug 2023 01:35:30 +0200
Subject: [PATCH] Added a ControlledQueue class for max size implementation and
 timeout management

---
 ControlledQueue.cxx | 44 ++++++++++++++++++++++++++++++++++++++++++++
 ControlledQueue.h   | 28 ++++++++++++++++++++++++++++
 2 files changed, 72 insertions(+)
 create mode 100644 ControlledQueue.cxx
 create mode 100644 ControlledQueue.h

diff --git a/ControlledQueue.cxx b/ControlledQueue.cxx
new file mode 100644
index 0000000..3340333
--- /dev/null
+++ b/ControlledQueue.cxx
@@ -0,0 +1,44 @@
+#include "ControlledQueue.h"
+#include <chrono>
+#include <mutex>
+
+ControlledQueue::ControlledQueue(uint32_t maxSize, int timeoutMicroseconds) : m_maxSize(maxSize), m_timeoutMicroseconds(timeoutMicroseconds) {;}
+
+void ControlledQueue::put(Fragment fragment) {
+    std::unique_lock<std::mutex> lk(m_mtx);
+
+    /*
+        This while synthax is explicitly used to avoid unwanted spurious awakenings.
+        I'm keeping only the wait with not timeout to transmit backpressure to the upper reading thread, which blocks.
+        Since that thread has locked the mutex corresponding to the fd, basically the whole fd is blocked.
+        That way I can tranmit backpressure with TCP to the sending client.
+    */
+    while (! (m_queue.size() < m_maxSize) ) {
+        m_cv.wait(lk);
+    }
+
+    m_queue.push(fragment);
+
+    lk.unlock();
+    m_cv.notify_all();
+}
+
+/*
+    Basically here a simple string exception is thrown if the wait terminates because of timeout and not because someone has inserted an element.
+    That way it can be catched from the main program that can set the error code accordingly.
+*/
+Fragment ControlledQueue::get() {
+    std::unique_lock<std::mutex> lk(m_mtx);
+
+    if ( !m_cv.wait_for(lk, std::chrono::microseconds(m_timeoutMicroseconds), !(m_queue.empty())) ) {
+        throw "Get Timeout";
+    }
+
+    Fragment fragment = m_queue.front();
+    m_queue.pop();
+
+    lk.unlock();
+    m_cv.notify_all();
+
+    return fragment;
+}
\ No newline at end of file
diff --git a/ControlledQueue.h b/ControlledQueue.h
new file mode 100644
index 0000000..a3d1bc9
--- /dev/null
+++ b/ControlledQueue.h
@@ -0,0 +1,28 @@
+#pragma once
+
+#include <cstdint>
+
+#include <mutex>
+#include <condition_variable>
+#include <queue>
+
+#include "fragment_dataformat.h"
+
+
+
+class ControlledQueue {
+    public:
+        ControlledQueue(uint32_t maxSize, int timeoutMicroseconds);
+
+        void put(Fragment fragment);
+        Fragment get();
+        bool empty() { return m_queue.empty(); }
+
+    private:
+        std::mutex m_mtx;
+        std::condition_variable m_cv;
+        uint32_t m_maxSize;
+        std::queue<Fragment> m_queue;
+        int m_timeoutMicroseconds;
+
+};
\ No newline at end of file