Implemented event queueing (#13)

* Implemented event queueing

* Fixing conformance error

Author: amikhail48

BUILD

@@ -12,7 +12,7 @@ cc_library(
     ]),
     hdrs = glob([
         "include/**",
-        "framework/include/*.h",
+        "framework/include/*.h*",
     ]),
     includes = [
         "include",

framework/include/vx_context.h

@@ -18,6 +18,7 @@
 
 #include <memory>
 
+#include "vx_event_queue.hpp"
 #include "vx_internal.h"
 #include "vx_reference.h"
 
@@ -207,7 +208,7 @@ class Context : public Reference
     /*! \brief The number of available targets in the implementation */
     vx_uint32           num_targets;
     /*! \brief The list of implemented targets */
-    vx_target         targets[VX_INT_MAX_NUM_TARGETS];
+    vx_target           targets[VX_INT_MAX_NUM_TARGETS];
     /*! \brief The list of priority sorted target indexes */
     vx_uint32           priority_targets[VX_INT_MAX_NUM_TARGETS];
     /*! \brief The log callback for errors */
@@ -266,6 +267,10 @@ class Context : public Reference
     cl_context opencl_context;
     cl_command_queue opencl_command_queue;
 #endif
+#ifdef OPENVX_USE_EVENTS
+    /*! \brief The event queue for the context */
+    EventQueue event_queue;
+#endif
 };
 
 #endif /* VX_CONTEXT_H */

framework/include/vx_event_queue.hpp

@@ -0,0 +1,256 @@
+/**
+ * @file vx_event_queue.hpp
+ * @brief
+ * @version 0.1
+ * @date 2025-05-09
+ *
+ * @copyright Copyright (c) 2025
+ *
+ */
+#pragma once
+
+#include <chrono>
+#include <condition_variable>
+#include <deque>
+#include <memory>
+#include <mutex>
+#include <optional>
+#include <vector>
+
+#include <VX/vx_khr_pipelining.h>
+
+/**
+ * @brief Internal Event Queue Object
+ *
+ */
+class EventQueue
+{
+    // Registration structure that stores additional event parameters for a vx_reference.
+    struct RegistrationEntry
+    {
+        vx_reference ref;      // vx_reference being registered
+        vx_event_type_e type;  // Event type associated with this registration
+        vx_uint32 param;       // Optional extra parameter (e.g., graph parameter index)
+        vx_uint32 app_value;   // Application-defined value to associate with events
+    };
+
+public:
+    /**
+     * @brief Construct a new Event Queue object
+     *
+     * @param enabled
+     * @param max_size
+     */
+    explicit EventQueue(bool enabled = false, size_t max_size = 128)
+        : enabled_(enabled), max_size_(max_size) {}
+
+
+    /**
+     * @brief Clear the event queue
+     *
+     */
+    void clear()
+    {
+        std::unique_lock lock(mutex_);
+        queue_.clear();
+    }
+
+    /**
+     * @brief Update the event queue status
+     *
+     * @param status    true to enable, false to disable
+     */
+    vx_status status(bool status)
+    {
+        std::lock_guard lock(mutex_);
+        enabled_ = status;
+        return VX_SUCCESS;
+    }
+
+    /**
+     * @brief Check if the event queue is enabled
+     *
+     * @return true if enabled
+     * @return false if disabled
+     */
+    bool isEnabled() const
+    {
+        return enabled_;
+    }
+
+    /**
+     * @brief Push an event to the queue
+     *
+     * @param type Event type
+     * @param data Optional event value
+     * @param info Optional event info pointer
+     * @param reg  Optional vx_reference used to look up additional registration data
+     * @return true if successful
+     * @return false if failed
+     */
+    vx_status push(vx_event_type_e type, vx_uint32 data = 0, vx_event_info_t* info = nullptr,
+                   vx_reference ref = nullptr)
+    {
+        vx_event_t evt{};
+        evt.type = type;
+        evt.timestamp = getTimestamp();
+        evt.app_value = data;
+        if (info != nullptr)
+        {
+            evt.event_info = *info;
+        }
+
+        // If a reference is provided, look up additional registration info
+        if (ref != nullptr)
+        {
+            const RegistrationEntry* reg = lookupRegistration(ref, type);
+            if (reg && evt.type == reg->type)
+            {
+                // override the app_value with that in the registration.
+                evt.app_value = reg->app_value;
+            }
+        }
+
+        return push(evt);
+    }
+
+    /**
+     * @brief Push an event to the queue
+     *
+     * @param event Event to push
+     * @return true if successful
+     * @return false if failed
+     */
+    vx_status push(vx_event_t event)
+    {
+        vx_status status = VX_SUCCESS;
+        std::unique_lock lock(mutex_);
+
+        if (!enabled_)
+        {
+            status = VX_FAILURE;
+        }
+
+        if (VX_SUCCESS == status)
+        {
+            if (queue_.size() >= max_size_)
+            {
+                queue_.pop_front();  // Drop the oldest event
+            }
+            queue_.emplace_back(std::move(event));
+            cv_.notify_one();
+        }
+
+        return status;
+    }
+
+    vx_status wait(vx_event_t* event, vx_bool do_not_block)
+    {
+        vx_status status = VX_SUCCESS;
+        std::optional<vx_event_t> evt;
+        std::unique_lock lock(mutex_);
+
+        if (!enabled_)
+        {
+            status = VX_FAILURE;
+        }
+
+        if (VX_SUCCESS == status)
+        {
+            if (do_not_block)
+            {
+                evt = wait_and_pop(std::chrono::milliseconds(0));
+            }
+            else
+            {
+                evt = wait_and_pop();
+            }
+
+            if (std::nullopt == evt)
+            {
+                status = VX_FAILURE;
+            }
+        }
+
+        if (VX_SUCCESS == status)
+        {
+            *event = std::move(*evt);
+        }
+
+        return status;
+    }
+
+    vx_status registerEvent(vx_reference ref, vx_event_type_e type, vx_uint32 param,
+                           vx_uint32 app_value)
+    {
+        if (ref == nullptr) return VX_ERROR_INVALID_REFERENCE;
+        std::unique_lock lock(mutex_);
+
+        RegistrationEntry entry;
+        entry.ref = ref;
+        entry.type = type;
+        entry.param = param;
+        entry.app_value = app_value;
+
+        registrations_.push_back(entry);
+        return VX_SUCCESS;
+    }
+
+private : bool enabled_;
+    mutable std::mutex mutex_;
+    std::condition_variable cv_;
+    std::deque<vx_event_t> queue_;
+    size_t max_size_;
+    std::vector<RegistrationEntry> registrations_;
+
+    /**
+     * @brief Lookup a registration entry matching the given vx_reference and event type.
+     *
+     * @param ref The vx_reference to look up.
+     * @param type The event type.
+     * @return const RegistrationEntry* Pointer to the matching entry, or nullptr if not found.
+     */
+    const RegistrationEntry* lookupRegistration(vx_reference ref, vx_event_type_e type) const
+    {
+        for (const auto& entry : registrations_)
+        {
+            if (entry.ref == ref && entry.type == type)
+            {
+                return &entry;
+            }
+        }
+
+        return nullptr;
+    }
+
+    /**
+     * @brief Wait for an event and pop it from the queue
+     *
+     * @param timeout Timeout duration
+     * @return std::optional<vx_event_t> Event if available, otherwise std::nullopt
+     */
+    std::optional<vx_event_t> wait_and_pop(
+        std::chrono::milliseconds timeout = std::chrono::milliseconds::max())
+    {
+        std::unique_lock lock(mutex_);
+        if (!cv_.wait_for(lock, timeout, [this] { return !queue_.empty(); }))
+        {
+            return std::nullopt;  // Timeout
+        }
+
+        vx_event_t evt = std::move(queue_.front());
+        queue_.pop_front();
+        return evt;
+    }
+
+    /**
+     * @brief Get the current timestamp in nanoseconds
+     *
+     * @return vx_uint64 Current timestamp
+     */
+    vx_uint64 getTimestamp() const
+    {
+        auto now = std::chrono::steady_clock::now();
+        return std::chrono::duration_cast<std::chrono::nanoseconds>(now.time_since_epoch()).count();
+    }
+};