engine: begin the liboakengine C ABI facade with the IPC subsystem

- oakengine/export.h establishes the OAKENGINE_API visibility macros;
  include/oakengine/ipc.h is the first pure-C surface (41 functions:
  shm, frame slot pool, and the worker IPC messages as POD<->JSON
  build/parse), implemented in engine/src/capi/
- the IPC implementations move to engine/src/oliveimpl (namespace
  olive::engine::internal::ipc); engine/render/ipc/*.h are rebuilt as
  same-name/same-API wrapper classes forwarding across the C boundary
- FrameSlotMeta is shared with the C header verbatim so the app/worker
  wire format (v1) is bit-identical; static_asserts pin sizeof and
  field offsets
- spscringbuffer.h moves to include/oakengine/ as an inline-only
  header (no symbols, not ABI)
- new pure-C test oakengine_ipc_test (make_oakengine_test, no GL)
  covers shm, frame pool, message round-trips and the layout asserts;
  full gtest suite stays green (1986 tests)

engine/render/ipc/CMakeLists.txt

@@ -14,14 +14,26 @@
 # You should have received a copy of the GNU General Public License
 # along with this program.  If not, see <http://www.gnu.org/licenses/>.
 
+# The IPC subsystem is migrating behind the liboakengine C ABI facade:
+#   - include/oakengine/*.h        public C API (+ the inline SPSC header)
+#   - src/oliveimpl/render/ipc/*.h internal implementation headers
+#   - src/capi/ipc.cpp             C ABI implementation
+#   - render/ipc/*.{h,cpp}         implementation sources and the
+#                                  consumer-side C++ wrapper headers
 set(OLIVE_SOURCES
         ${OLIVE_SOURCES}
+        include/oakengine/export.h
+        include/oakengine/ipc.h
+        include/oakengine/spscringbuffer.h
+        src/capi/ipc.cpp
+        src/oliveimpl/render/ipc/frameslotpool.h
+        src/oliveimpl/render/ipc/ipcmessage.h
+        src/oliveimpl/render/ipc/sharedmemoryregion.h
         render/ipc/frameslotpool.cpp
         render/ipc/frameslotpool.h
         render/ipc/ipcmessage.cpp
         render/ipc/ipcmessage.h
         render/ipc/sharedmemoryregion.cpp
         render/ipc/sharedmemoryregion.h
-        render/ipc/spscringbuffer.h
         PARENT_SCOPE
-)
+)

engine/render/ipc/frameslotpool.cpp

@@ -18,12 +18,16 @@
 
 ***/
 
-#include "frameslotpool.h"
+#include "oliveimpl/render/ipc/frameslotpool.h"
 
 #include <cstring>
 
 namespace olive
 {
+namespace engine
+{
+namespace internal
+{
 namespace ipc
 {
 
@@ -45,9 +49,9 @@ size_t FrameSlotPool::bytes_needed(uint32_t slot_count, size_t slot_data_bytes)
 	const uint32_t ring_cap = ring_capacity(slot_count);
 	size_t total = align_up(sizeof(Header), k_align);
 	total +=
-		align_up(SpscRingBuffer::bytes_needed(ring_cap), k_align); // free ring
+		align_up(olive::ipc::SpscRingBuffer::bytes_needed(ring_cap), k_align); // free ring
 	total +=
-		align_up(SpscRingBuffer::bytes_needed(ring_cap), k_align); // ready ring
+		align_up(olive::ipc::SpscRingBuffer::bytes_needed(ring_cap), k_align); // ready ring
 	total +=
 		align_up(sizeof(FrameSlotMeta) * slot_count, k_align); // metadata array
 	total += align_up(slot_data_bytes, k_align) * slot_count; // pixel data blocks
@@ -67,10 +71,10 @@ FrameSlotPool FrameSlotPool::create(void *mem, uint32_t slot_count,
 	offset += align_up(sizeof(Header), k_align);
 
 	const size_t free_off = offset;
-	offset += align_up(SpscRingBuffer::bytes_needed(ring_cap), k_align);
+	offset += align_up(olive::ipc::SpscRingBuffer::bytes_needed(ring_cap), k_align);
 
 	const size_t ready_off = offset;
-	offset += align_up(SpscRingBuffer::bytes_needed(ring_cap), k_align);
+	offset += align_up(olive::ipc::SpscRingBuffer::bytes_needed(ring_cap), k_align);
 
 	const size_t meta_off = offset;
 	offset += align_up(sizeof(FrameSlotMeta) * slot_count, k_align);
@@ -86,8 +90,8 @@ FrameSlotPool FrameSlotPool::create(void *mem, uint32_t slot_count,
 	pool.header_->meta_offset = meta_off;
 	pool.header_->data_offset = data_off;
 
-	pool.free_ring_ = SpscRingBuffer::create(pool.base_ + free_off, ring_cap);
-	pool.ready_ring_ = SpscRingBuffer::create(pool.base_ + ready_off, ring_cap);
+	pool.free_ring_ = olive::ipc::SpscRingBuffer::create(pool.base_ + free_off, ring_cap);
+	pool.ready_ring_ = olive::ipc::SpscRingBuffer::create(pool.base_ + ready_off, ring_cap);
 	pool.meta_ = reinterpret_cast<FrameSlotMeta *>(pool.base_ + meta_off);
 	pool.data_ = pool.base_ + data_off;
 
@@ -115,9 +119,9 @@ FrameSlotPool FrameSlotPool::attach(void *mem)
 	}
 
 	pool.free_ring_ =
-		SpscRingBuffer::attach(pool.base_ + pool.header_->free_ring_offset);
+		olive::ipc::SpscRingBuffer::attach(pool.base_ + pool.header_->free_ring_offset);
 	pool.ready_ring_ =
-		SpscRingBuffer::attach(pool.base_ + pool.header_->ready_ring_offset);
+		olive::ipc::SpscRingBuffer::attach(pool.base_ + pool.header_->ready_ring_offset);
 	pool.meta_ = reinterpret_cast<FrameSlotMeta *>(pool.base_ +
 												   pool.header_->meta_offset);
 	pool.data_ = pool.base_ + pool.header_->data_offset;
@@ -176,4 +180,6 @@ bool FrameSlotPool::release(uint32_t index)
 }
 
 } // namespace ipc
+} // namespace internal
+} // namespace engine
 } // namespace olive

engine/render/ipc/frameslotpool.h

@@ -24,7 +24,7 @@
 #include <cstddef>
 #include <cstdint>
 
-#include "spscringbuffer.h"
+#include "oakengine/ipc.h"
 
 namespace olive
 {
@@ -34,150 +34,196 @@ namespace ipc
 /**
  * @brief Per-slot metadata describing the frame currently occupying a slot.
  *
- * Trivially-copyable POD that lives in shared memory alongside the pixel data. Carries everything
- * the consumer needs to reconstruct an olive::Frame without any out-of-band information. We store
- * the Rational timestamp as an explicit numerator/denominator pair to stay POD (olive::Rational is
- * not guaranteed shared-memory-safe).
+ * Trivially-copyable POD that lives in shared memory alongside the pixel data, part of the
+ * version-1 wire protocol with the render worker. This is the C ABI oak_frame_slot_meta struct,
+ * aliased so the shared-memory layout is defined exactly once, in oakengine/ipc.h.
  */
-struct FrameSlotMeta {
-	int64_t id; ///< Caller-defined tag (e.g. ticket id, or footage stream hash).
-	int64_t time_num; ///< Frame timestamp numerator.
-	int64_t time_den; ///< Frame timestamp denominator.
-	int32_t width;
-	int32_t height;
-	int32_t format; ///< olive::PixelFormat::Format value.
-	int32_t channel_count;
-	int32_t linesize; ///< Bytes per scanline (stride).
-	int32_t data_size; ///< Valid bytes written into the slot's data block.
-	char colorspace[128]; ///< Input colorspace name for color-managed footage.
-};
+typedef oak_frame_slot_meta FrameSlotMeta;
 
 /**
  * @brief A fixed-size pool of equal-sized frame slots in shared memory, with lock-free hand-off.
  *
+ * Consumer-side wrapper over the liboakengine C ABI: the object only holds an opaque
+ * OakFrameSlotPool handle and forwards every call across the C boundary. The public API is
+ * unchanged from the original implementation; see oakengine/ipc.h for the protocol description.
+ *
  * One pool models a single direction of frame flow (e.g. worker -> main for rendered output, or
- * main -> worker for decoded input). Ownership of a slot is transferred via two SPSC ring buffers
- * of slot indices, so no mutex is ever taken:
- *
- *   - free_ring:  indices of slots available to the FILLER. The drainer returns slots here.
- *   - ready_ring: indices of slots holding a published frame, produced by the FILLER for the
- *                 DRAINER to consume.
- *
- * Lifecycle (filler = producer of frames, drainer = consumer of frames):
- *   filler:  Acquire() -> pop a free index -> write meta + pixels -> Publish() -> push to ready
- *   drainer: Consume() -> pop a ready index -> read meta + pixels -> Release() -> push to free
- *
- * Because each ring has exactly one producer and one consumer (the filler owns free.Pop +
- * ready.Push, the drainer owns ready.Pop + free.Push), the SPSC invariant holds and the whole
- * exchange is lock-free.
- *
- * All slots are sized to `slot_data_bytes`, computed for the maximum supported frame (e.g. 8K RGBA
- * half-float). Frames smaller than that simply use a prefix of the slot.
- *
- * The pool does NOT own the memory; it is constructed over a SharedMemoryRegion mapping. Use
- * BytesNeeded() to size that region.
+ * main -> worker for decoded input). The pool does NOT own the memory; it is constructed over a
+ * SharedMemoryRegion mapping. Use bytes_needed() to size that region.
  */
 class FrameSlotPool {
 public:
+	FrameSlotPool() = default;
+
+	FrameSlotPool(const FrameSlotPool &rhs)
+		: handle_(oakengine_ipc_framepool_copy(rhs.handle_))
+	{
+	}
+
+	FrameSlotPool(FrameSlotPool &&rhs) noexcept
+		: handle_(rhs.handle_)
+	{
+		rhs.handle_ = nullptr;
+	}
+
+	~FrameSlotPool()
+	{
+		oakengine_ipc_framepool_free(handle_);
+	}
+
+	FrameSlotPool &operator=(const FrameSlotPool &rhs)
+	{
+		if (this != &rhs) {
+			oakengine_ipc_framepool_free(handle_);
+			handle_ = oakengine_ipc_framepool_copy(rhs.handle_);
+		}
+		return *this;
+	}
+
+	FrameSlotPool &operator=(FrameSlotPool &&rhs) noexcept
+	{
+		if (this != &rhs) {
+			oakengine_ipc_framepool_free(handle_);
+			handle_ = rhs.handle_;
+			rhs.handle_ = nullptr;
+		}
+		return *this;
+	}
+
 	/**
    * @brief Total bytes a region must provide to back a pool of `slot_count` x `slot_data_bytes`.
    */
-	static size_t bytes_needed(uint32_t slot_count, size_t slot_data_bytes);
+	static size_t bytes_needed(uint32_t slot_count, size_t slot_data_bytes)
+	{
+		return oakengine_ipc_framepool_bytes_needed(slot_count, slot_data_bytes);
+	}
 
 	/**
    * @brief Lay out and initialize a brand-new pool over `mem` (owner side, once).
    *
    * Initializes both rings, seeds the free ring with every slot index, and zeroes metadata.
-   * `mem` must provide at least BytesNeeded(slot_count, slot_data_bytes) bytes.
+   * `mem` must provide at least bytes_needed(slot_count, slot_data_bytes) bytes.
    */
 	static FrameSlotPool create(void *mem, uint32_t slot_count,
-								size_t slot_data_bytes);
+								size_t slot_data_bytes)
+	{
+		return from_handle(oakengine_ipc_framepool_create(mem, slot_count,
+														  slot_data_bytes));
+	}
 
 	/**
    * @brief Map an existing, already-initialized pool (peer side).
    *
-   * Reads slot_count/slot_data_bytes from the in-memory header written by Create().
+   * Reads slot_count/slot_data_bytes from the in-memory header written by create().
    */
-	static FrameSlotPool attach(void *mem);
+	static FrameSlotPool attach(void *mem)
+	{
+		return from_handle(oakengine_ipc_framepool_attach(mem));
+	}
 
 	bool is_valid() const
 	{
-		return header_ != nullptr;
+		return oakengine_ipc_framepool_is_valid(handle_) != 0;
 	}
 
-	uint32_t slot_count() const;
-	size_t slot_data_bytes() const;
+	uint32_t slot_count() const
+	{
+		return oakengine_ipc_framepool_slot_count(handle_);
+	}
+
+	size_t slot_data_bytes() const
+	{
+		return oakengine_ipc_framepool_slot_data_bytes(handle_);
+	}
 
 	// ---- Filler side ----
 
 	/**
    * @brief Take ownership of a free slot. Returns false (and leaves *index untouched) if none free.
    */
-	bool acquire(uint32_t *index);
+	bool acquire(uint32_t *index)
+	{
+		return oakengine_ipc_framepool_acquire(handle_, index) != 0;
+	}
 
 	/**
    * @brief Pointer to a slot's pixel data block (slot_data_bytes available).
    */
-	void *slot_data(uint32_t index);
+	void *slot_data(uint32_t index)
+	{
+		return oakengine_ipc_framepool_slot_data(handle_, index);
+	}
 
 	/**
-   * @brief Mutable metadata for a slot. Filler writes this before Publish().
+   * @brief Mutable metadata for a slot. Filler writes this before publish().
    */
-	FrameSlotMeta *meta(uint32_t index);
+	FrameSlotMeta *meta(uint32_t index)
+	{
+		return oakengine_ipc_framepool_meta(handle_, index);
+	}
 
 	/**
-   * @brief Publish a filled slot to the drainer. Must follow a successful Acquire() of `index`.
+   * @brief Publish a filled slot to the drainer. Must follow a successful acquire() of `index`.
    */
-	bool publish(uint32_t index);
+	bool publish(uint32_t index)
+	{
+		return oakengine_ipc_framepool_publish(handle_, index) != 0;
+	}
 
 	// ---- Drainer side ----
 
 	/**
    * @brief Take the next published slot. Returns false if nothing is ready.
    */
-	bool consume(uint32_t *index);
-
-	/**
-   * @brief Return a consumed slot to the free pool for reuse. Must follow Consume() of `index`.
-   */
-	bool release(uint32_t index);
-
-	const FrameSlotMeta *meta(uint32_t index) const;
-	const void *slot_data(uint32_t index) const;
-
-public:
-	FrameSlotPool() = default;
-
-private:
-	struct Header {
-		uint32_t magic;
-		uint32_t slot_count;
-		uint64_t slot_data_bytes;
-		// Byte offsets from the start of the segment to each sub-region.
-		uint64_t free_ring_offset;
-		uint64_t ready_ring_offset;
-		uint64_t meta_offset;
-		uint64_t data_offset;
-	};
-
-	static constexpr uint32_t k_magic = 0x4F4B5350; // 'OKSP'
-
-	// Ring capacity must exceed slot_count by one because a ring can hold at most capacity-1 entries
-	// and we need to be able to enqueue every slot at once.
-	static uint32_t ring_capacity(uint32_t slot_count)
+	bool consume(uint32_t *index)
 	{
-		return slot_count + 1;
+		return oakengine_ipc_framepool_consume(handle_, index) != 0;
 	}
 
-	uint8_t *base_ = nullptr;
-	Header *header_ = nullptr;
-	SpscRingBuffer *free_ring_ = nullptr;
-	SpscRingBuffer *ready_ring_ = nullptr;
-	FrameSlotMeta *meta_ = nullptr;
-	uint8_t *data_ = nullptr;
+	/**
+   * @brief Return a consumed slot to the free pool for reuse. Must follow consume() of `index`.
+   */
+	bool release(uint32_t index)
+	{
+		return oakengine_ipc_framepool_release(handle_, index) != 0;
+	}
+
+	const FrameSlotMeta *meta(uint32_t index) const
+	{
+		return oakengine_ipc_framepool_meta_const(handle_, index);
+	}
+
+	const void *slot_data(uint32_t index) const
+	{
+		return oakengine_ipc_framepool_slot_data_const(handle_, index);
+	}
+
+	/**
+   * @brief The wrapped C handle, for cross-type wrappers and direct C API use
+   */
+	OakFrameSlotPool *handle() const
+	{
+		return handle_;
+	}
+
+	/**
+   * @brief Wraps an owned C handle (takes ownership)
+   */
+	static FrameSlotPool from_handle(OakFrameSlotPool *handle)
+	{
+		return FrameSlotPool(handle);
+	}
+
+private:
+	explicit FrameSlotPool(OakFrameSlotPool *handle)
+		: handle_(handle)
+	{
+	}
+
+	OakFrameSlotPool *handle_ = nullptr;
 };
 
 } // namespace ipc
 } // namespace olive
 
-#endif // OAK_IPC_FRAMESLOTPOOL_H
+#endif // OAK_IPC_FRAMESLOTPOOL_H

engine/render/ipc/ipcmessage.cpp

@@ -18,7 +18,7 @@
 
 ***/
 
-#include "ipcmessage.h"
+#include "oliveimpl/render/ipc/ipcmessage.h"
 
 #include <QJsonArray>
 #include <QJsonDocument>
@@ -26,6 +26,10 @@
 
 namespace olive
 {
+namespace engine
+{
+namespace internal
+{
 namespace ipc
 {
 
@@ -227,4 +231,6 @@ bool LoadGraphMsg::from_json(const QJsonObject &o, LoadGraphMsg *out)
 }
 
 } // namespace ipc
+} // namespace internal
+} // namespace engine
 } // namespace olive

engine/render/ipc/ipcmessage.h

@@ -21,12 +21,17 @@
 #ifndef OAK_IPC_IPCMESSAGE_H
 #define OAK_IPC_IPCMESSAGE_H
 
+#include <algorithm>
 #include <cstdint>
+#include <cstring>
 #include <QByteArray>
+#include <QJsonDocument>
 #include <QJsonObject>
 #include <QString>
 #include <QVector>
 
+#include "oakengine/ipc.h"
+
 class QIODevice;
 
 namespace olive
@@ -43,6 +48,10 @@ namespace ipc
  * bulk pixel data travels through the shared-memory FrameSlotPool, and the (potentially large)
  * serialized node graph travels via a temporary file referenced by path.
  *
+ * Consumer-side wrapper over the liboakengine C ABI: the typed builders/parsers below convert
+ * through the oakengine_ipc_*_to_json/parse functions, and the QIODevice framing stays inline
+ * here. The public API is unchanged from the original implementation.
+ *
  * Every message object has a "type" string field. Directionality (M = main, W = worker):
  *   "handshake"     M<->W  Negotiate protocol version and announce shared-memory key/geometry.
  *   "load_graph"    M ->W  Path to a temporary file holding the serialized node graph.
@@ -55,23 +64,58 @@ namespace ipc
  */
 namespace msgtype
 {
-constexpr const char *k_handshake = "handshake";
-constexpr const char *k_load_graph = "load_graph";
-constexpr const char *k_render_frame = "render_frame";
-constexpr const char *k_frame_ready = "frame_ready";
-constexpr const char *k_cancel = "cancel";
-constexpr const char *k_graph_update = "graph_update";
-constexpr const char *k_shutdown = "shutdown";
-constexpr const char *k_error = "error";
+constexpr const char *k_handshake = OAKENGINE_IPC_MSGTYPE_HANDSHAKE;
+constexpr const char *k_load_graph = OAKENGINE_IPC_MSGTYPE_LOAD_GRAPH;
+constexpr const char *k_render_frame = OAKENGINE_IPC_MSGTYPE_RENDER_FRAME;
+constexpr const char *k_frame_ready = OAKENGINE_IPC_MSGTYPE_FRAME_READY;
+constexpr const char *k_cancel = OAKENGINE_IPC_MSGTYPE_CANCEL;
+constexpr const char *k_graph_update = OAKENGINE_IPC_MSGTYPE_GRAPH_UPDATE;
+constexpr const char *k_shutdown = OAKENGINE_IPC_MSGTYPE_SHUTDOWN;
+constexpr const char *k_error = OAKENGINE_IPC_MSGTYPE_ERROR;
 } // namespace msgtype
 
+namespace detail
+{
+
+inline void copy_str(const QString &s, char *dst, size_t cap)
+{
+	const QByteArray utf = s.toUtf8();
+	const size_t n = std::min(size_t(utf.size()), cap - 1);
+	memcpy(dst, utf.constData(), n);
+	dst[n] = '\0';
+}
+
+/**
+ * @brief Run a C to_json function (buf/size convention) and reparse the compact JSON text.
+ */
+template <typename F> QJsonObject via_c_json(F &&to_json)
+{
+	const int size = to_json(nullptr, 0);
+	QByteArray buf(size + 1, '\0');
+	to_json(buf.data(), size + 1);
+	buf.resize(size);
+	return QJsonDocument::fromJson(buf).object();
+}
+
+inline QByteArray compact_json(const QJsonObject &o)
+{
+	return QJsonDocument(o).toJson(QJsonDocument::Compact);
+}
+
+} // namespace detail
+
 /**
  * @brief Write one NDJSON message line to `device`.
  *
  * Serializes `obj` to compact JSON, appends '\n', and writes the whole line in one call. Returns
  * true only if the full line was written.
  */
-bool write_message(QIODevice *device, const QJsonObject &obj);
+inline bool write_message(QIODevice *device, const QJsonObject &obj)
+{
+	QByteArray line = detail::compact_json(obj);
+	line.append('\n');
+	return device->write(line) == line.size();
+}
 
 /**
  * @brief Pull one complete NDJSON line out of `buffer` and parse it.
@@ -82,13 +126,46 @@ bool write_message(QIODevice *device, const QJsonObject &obj);
  * and continue rather than wedge. Supports the typical "append bytes as they arrive, then drain
  * complete lines" reader loop on a pipe.
  */
-bool read_message(QByteArray *buffer, QJsonObject *out, bool *ok = nullptr);
+inline bool read_message(QByteArray *buffer, QJsonObject *out, bool *ok = nullptr)
+{
+	while (true) {
+		const int newline = buffer->indexOf('\n');
+		if (newline < 0) {
+			// No complete line buffered yet.
+			return false;
+		}
+
+		const QByteArray line = buffer->left(newline);
+		buffer->remove(0, newline + 1);
+
+		// Skip blank lines silently (e.g. a stray newline) without flagging an error.
+		if (line.trimmed().isEmpty()) {
+			continue;
+		}
+
+		QJsonParseError err;
+		const QJsonDocument doc = QJsonDocument::fromJson(line, &err);
+		if (err.error != QJsonParseError::NoError || !doc.isObject()) {
+			if (ok) {
+				*ok = false;
+			}
+			return false;
+		}
+
+		*out = doc.object();
+		if (ok) {
+			*ok = true;
+		}
+		return true;
+	}
+}
 
 // ---- Typed message builders / parsers -------------------------------------------------------
 //
-// Thin helpers that construct or read the QJsonObject for each message type, keeping field names in
-// one place so main and worker agree. Fields use plain JSON numbers/strings; 64-bit ids are stored
-// as JSON numbers (doubles exactly represent integers up to 2^53, ample for our counters).
+// Thin wrappers that convert each struct to/from the C ABI POD form and let the library build or
+// read the JSON, keeping field names in one place so main and worker agree. Fields use plain JSON
+// numbers/strings; 64-bit ids are stored as JSON numbers (doubles exactly represent integers up
+// to 2^53, ample for our counters).
 
 struct HandshakeMsg {
 	int protocol_version = 0;
@@ -100,8 +177,38 @@ struct HandshakeMsg {
 	qint64 slot_data_bytes = 0; ///< Per-output-slot pixel block size.
 	qint64 input_slot_data_bytes = 0; ///< Per-input-slot pixel block size.
 
-	QJsonObject to_json() const;
-	static bool from_json(const QJsonObject &o, HandshakeMsg *out);
+	QJsonObject to_json() const
+	{
+		oak_ipc_handshake c;
+		c.protocol_version = protocol_version;
+		detail::copy_str(shm_key, c.shm_key, sizeof(c.shm_key));
+		detail::copy_str(input_shm_key, c.input_shm_key,
+						 sizeof(c.input_shm_key));
+		c.input_slots = input_slots;
+		c.output_slots = output_slots;
+		c.slot_data_bytes = slot_data_bytes;
+		c.input_slot_data_bytes = input_slot_data_bytes;
+		return detail::via_c_json([&](char *buf, int size) {
+			return oakengine_ipc_handshake_to_json(&c, buf, size);
+		});
+	}
+
+	static bool from_json(const QJsonObject &o, HandshakeMsg *out)
+	{
+		oak_ipc_handshake c;
+		if (!oakengine_ipc_handshake_parse(detail::compact_json(o).constData(),
+										   &c)) {
+			return false;
+		}
+		out->protocol_version = c.protocol_version;
+		out->shm_key = QString::fromUtf8(c.shm_key);
+		out->input_shm_key = QString::fromUtf8(c.input_shm_key);
+		out->input_slots = c.input_slots;
+		out->output_slots = c.output_slots;
+		out->slot_data_bytes = c.slot_data_bytes;
+		out->input_slot_data_bytes = c.input_slot_data_bytes;
+		return true;
+	}
 };
 
 struct RenderFrameMsg {
@@ -129,30 +236,138 @@ struct RenderFrameMsg {
 	QString color_view;
 	QString color_look;
 
-	QJsonObject to_json() const;
-	static bool from_json(const QJsonObject &o, RenderFrameMsg *out);
+	QJsonObject to_json() const
+	{
+		oak_ipc_render_frame c;
+		c.ticket_id = ticket_id;
+		detail::copy_str(node_uuid, c.node_uuid, sizeof(c.node_uuid));
+		c.time_num = time_num;
+		c.time_den = time_den;
+		c.width = width;
+		c.height = height;
+		c.format = format;
+		c.channel_count = channel_count;
+		c.mode = mode;
+		c.input_slot = input_slot;
+		c.input_slot_count = std::min(int(input_slots.size()),
+									  OAK_IPC_INPUT_SLOTS_CAP);
+		for (int i = 0; i < c.input_slot_count; i++) {
+			c.input_slots[i] = input_slots.at(i);
+		}
+		c.has_color_transform = has_color_transform ? 1 : 0;
+		c.color_is_display = color_is_display ? 1 : 0;
+		detail::copy_str(color_output, c.color_output,
+						 sizeof(c.color_output));
+		detail::copy_str(color_view, c.color_view, sizeof(c.color_view));
+		detail::copy_str(color_look, c.color_look, sizeof(c.color_look));
+		return detail::via_c_json([&](char *buf, int size) {
+			return oakengine_ipc_render_frame_to_json(&c, buf, size);
+		});
+	}
+
+	static bool from_json(const QJsonObject &o, RenderFrameMsg *out)
+	{
+		oak_ipc_render_frame c;
+		if (!oakengine_ipc_render_frame_parse(
+				detail::compact_json(o).constData(), &c)) {
+			return false;
+		}
+		out->ticket_id = c.ticket_id;
+		out->node_uuid = QString::fromUtf8(c.node_uuid);
+		out->time_num = c.time_num;
+		out->time_den = c.time_den;
+		out->width = c.width;
+		out->height = c.height;
+		out->format = c.format;
+		out->channel_count = c.channel_count;
+		out->mode = c.mode;
+		out->input_slot = c.input_slot;
+		out->input_slots.clear();
+		for (int i = 0; i < c.input_slot_count; i++) {
+			out->input_slots.append(c.input_slots[i]);
+		}
+		out->has_color_transform = c.has_color_transform != 0;
+		out->color_is_display = c.color_is_display != 0;
+		out->color_output = QString::fromUtf8(c.color_output);
+		out->color_view = QString::fromUtf8(c.color_view);
+		out->color_look = QString::fromUtf8(c.color_look);
+		return true;
+	}
 };
 
 struct FrameReadyMsg {
 	qint64 ticket_id = 0;
 	int output_slot = 0; ///< Index into the worker->main output FrameSlotPool.
 
-	QJsonObject to_json() const;
-	static bool from_json(const QJsonObject &o, FrameReadyMsg *out);
+	QJsonObject to_json() const
+	{
+		oak_ipc_frame_ready c;
+		c.ticket_id = ticket_id;
+		c.output_slot = output_slot;
+		return detail::via_c_json([&](char *buf, int size) {
+			return oakengine_ipc_frame_ready_to_json(&c, buf, size);
+		});
+	}
+
+	static bool from_json(const QJsonObject &o, FrameReadyMsg *out)
+	{
+		oak_ipc_frame_ready c;
+		if (!oakengine_ipc_frame_ready_parse(
+				detail::compact_json(o).constData(), &c)) {
+			return false;
+		}
+		out->ticket_id = c.ticket_id;
+		out->output_slot = c.output_slot;
+		return true;
+	}
 };
 
 struct CancelMsg {
 	qint64 ticket_id = 0;
 
-	QJsonObject to_json() const;
-	static bool from_json(const QJsonObject &o, CancelMsg *out);
+	QJsonObject to_json() const
+	{
+		oak_ipc_cancel c;
+		c.ticket_id = ticket_id;
+		return detail::via_c_json([&](char *buf, int size) {
+			return oakengine_ipc_cancel_to_json(&c, buf, size);
+		});
+	}
+
+	static bool from_json(const QJsonObject &o, CancelMsg *out)
+	{
+		oak_ipc_cancel c;
+		if (!oakengine_ipc_cancel_parse(detail::compact_json(o).constData(),
+										&c)) {
+			return false;
+		}
+		out->ticket_id = c.ticket_id;
+		return true;
+	}
 };
 
 struct LoadGraphMsg {
 	QString path; ///< Temporary file holding the serialized node graph.
 
-	QJsonObject to_json() const;
-	static bool from_json(const QJsonObject &o, LoadGraphMsg *out);
+	QJsonObject to_json() const
+	{
+		oak_ipc_load_graph c;
+		detail::copy_str(path, c.path, sizeof(c.path));
+		return detail::via_c_json([&](char *buf, int size) {
+			return oakengine_ipc_load_graph_to_json(&c, buf, size);
+		});
+	}
+
+	static bool from_json(const QJsonObject &o, LoadGraphMsg *out)
+	{
+		oak_ipc_load_graph c;
+		if (!oakengine_ipc_load_graph_parse(detail::compact_json(o).constData(),
+											&c)) {
+			return false;
+		}
+		out->path = QString::fromUtf8(c.path);
+		return true;
+	}
 };
 
 } // namespace ipc

engine/render/ipc/sharedmemoryregion.cpp

@@ -18,7 +18,7 @@
 
 ***/
 
-#include "sharedmemoryregion.h"
+#include "oliveimpl/render/ipc/sharedmemoryregion.h"
 
 #include <QtGlobal>
 
@@ -35,6 +35,10 @@
 
 namespace olive
 {
+namespace engine
+{
+namespace internal
+{
 namespace ipc
 {
 
@@ -228,4 +232,6 @@ void SharedMemoryRegion::close()
 #endif
 
 } // namespace ipc
+} // namespace internal
+} // namespace engine
 } // namespace olive

engine/render/ipc/sharedmemoryregion.h

@@ -24,6 +24,8 @@
 #include <cstddef>
 #include <QString>
 
+#include "oakengine/ipc.h"
+
 namespace olive
 {
 namespace ipc
@@ -32,27 +34,34 @@ namespace ipc
 /**
  * @brief A named, fixed-size shared memory segment mapped into the process address space.
  *
- * One process Create()s the segment (owner); the peer process Attach()es to it by the same key.
- * The mapping is a raw contiguous byte range accessible via data() — the IPC ring buffers and frame
- * slot pools are laid out inside it. Nothing here is locked; synchronization is entirely the
- * caller's responsibility via the lock-free structures placed in the mapping.
+ * Consumer-side wrapper over the liboakengine C ABI: the object only holds an opaque
+ * OakSharedMemoryRegion handle and forwards every call across the C boundary. The public API is
+ * unchanged from the original implementation.
  *
- * We deliberately use the raw OS primitives (POSIX shm_open + mmap, Windows CreateFileMapping +
- * MapViewOfFile) rather than QSharedMemory: QSharedMemory carries an implicit semaphore and a 1-byte
- * header convention, attaches/detaches with reference counting we don't want, and historically has
- * cross-platform lifetime quirks. For a render pipeline pushing large frames we want a plain mmap.
+ * One process open()s the segment with k_create (owner); the peer process open()s it by the same
+ * key with k_attach. The mapping is a raw contiguous byte range accessible via data() — the IPC
+ * ring buffers and frame slot pools are laid out inside it. Nothing here is locked;
+ * synchronization is entirely the caller's responsibility via the lock-free structures placed in
+ * the mapping.
  */
 class SharedMemoryRegion {
 public:
 	enum Mode {
 		/// Create (and own) the segment. Fails if it already exists; unlinks on destruction.
-		k_create,
+		k_create = OAK_IPC_SHM_MODE_CREATE,
 		/// Attach to a segment created by the peer. Does not unlink on destruction.
-		k_attach
+		k_attach = OAK_IPC_SHM_MODE_ATTACH
 	};
 
-	SharedMemoryRegion();
-	~SharedMemoryRegion();
+	SharedMemoryRegion()
+		: handle_(oakengine_ipc_shm_create())
+	{
+	}
+
+	~SharedMemoryRegion()
+	{
+		oakengine_ipc_shm_free(handle_);
+	}
 
 	SharedMemoryRegion(const SharedMemoryRegion &) = delete;
 	SharedMemoryRegion &operator=(const SharedMemoryRegion &) = delete;
@@ -63,26 +72,36 @@ public:
    * `key` is a short identifier (no leading slash needed; the platform prefix is added internally).
    * Returns true on success. On failure, error() carries a human-readable reason.
    */
-	bool open(const QString &key, size_t size, Mode mode);
+	bool open(const QString &key, size_t size, Mode mode)
+	{
+		const bool ok = oakengine_ipc_shm_open(
+							handle_, key.toUtf8().constData(), size,
+							static_cast<oak_ipc_shm_mode>(mode)) != 0;
+		refresh_caches();
+		return ok;
+	}
 
 	/**
    * @brief Unmap and (if owner) unlink the segment. Called automatically by the destructor.
    */
-	void close();
+	void close()
+	{
+		oakengine_ipc_shm_close(handle_);
+	}
 
 	bool is_valid() const
 	{
-		return data_ != nullptr;
+		return oakengine_ipc_shm_is_valid(handle_) != 0;
 	}
 
 	void *data() const
 	{
-		return data_;
+		return oakengine_ipc_shm_data(handle_);
 	}
 
 	size_t size() const
 	{
-		return size_;
+		return oakengine_ipc_shm_size(handle_);
 	}
 
 	const QString &key() const
@@ -100,24 +119,50 @@ public:
    *
    * Centralized so the owner and the spawned worker agree on the same name.
    */
-	static QString make_key(qint64 owner_pid, int worker_index);
+	static QString make_key(qint64 owner_pid, int worker_index)
+	{
+		const int size = oakengine_ipc_shm_make_key(owner_pid, worker_index,
+													nullptr, 0);
+		QByteArray buf(size + 1, '\0');
+		oakengine_ipc_shm_make_key(owner_pid, worker_index, buf.data(),
+								   size + 1);
+		return QString::fromUtf8(buf.constData());
+	}
+
+	/**
+   * @brief The wrapped C handle, for cross-type wrappers and direct C API use
+   */
+	OakSharedMemoryRegion *handle() const
+	{
+		return handle_;
+	}
 
 private:
-	QString key_;
-	size_t size_;
-	void *data_;
-	Mode mode_;
-	QString error_;
+	static QString query_string(int (*query)(const OakSharedMemoryRegion *,
+											 char *, int),
+								const OakSharedMemoryRegion *handle)
+	{
+		const int size = query(handle, nullptr, 0);
+		if (size <= 0) {
+			return QString();
+		}
+		QByteArray buf(size + 1, '\0');
+		query(handle, buf.data(), size + 1);
+		return QString::fromUtf8(buf.constData());
+	}
 
-#if defined(Q_OS_WIN)
-	void *handle_; // HANDLE from CreateFileMapping/OpenFileMapping
-#else
-	int fd_; // file descriptor from shm_open
-	QString shm_name_; // the platform-prefixed name actually passed to shm_open
-#endif
+	void refresh_caches()
+	{
+		key_ = query_string(oakengine_ipc_shm_key, handle_);
+		error_ = query_string(oakengine_ipc_shm_error, handle_);
+	}
+
+	OakSharedMemoryRegion *handle_;
+	QString key_;
+	QString error_;
 };
 
 } // namespace ipc
 } // namespace olive
 
-#endif // OAK_IPC_SHAREDMEMORYREGION_H
+#endif // OAK_IPC_SHAREDMEMORYREGION_H

engine/render/ipc/spscringbuffer.h

@@ -1,185 +0,0 @@
-/***
-
-  Oak - Non-Linear Video Editor
-  Copyright (C) 2026 Oak Team
-
-  This program is free software: you can redistribute it and/or modify
-  it under the terms of the GNU General Public License as published by
-  the Free Software Foundation, either version 3 of the License, or
-  (at your option) any later version.
-
-  This program is distributed in the hope that it will be useful,
-  but WITHOUT ANY WARRANTY; without even the implied warranty of
-  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
-  GNU General Public License for more details.
-
-  You should have received a copy of the GNU General Public License
-  along with this program.  If not, see <http://www.gnu.org/licenses/>.
-
-***/
-
-#ifndef OAK_IPC_SPSCRINGBUFFER_H
-#define OAK_IPC_SPSCRINGBUFFER_H
-
-#include <atomic>
-#include <cstddef>
-#include <cstdint>
-
-namespace olive
-{
-namespace ipc
-{
-
-/**
- * @brief A lock-free single-producer / single-consumer ring buffer of uint32 indices.
- *
- * This is the core synchronization primitive for cross-process communication. It is designed to
- * live in a shared memory segment: the control block (head/tail cursors) and the slot array are a
- * single trivially-copyable, self-contained POD. Both the producer process and the consumer
- * process map the same memory and operate on it concurrently.
- *
- * Correctness relies on the classic SPSC invariant:
- *   - Exactly ONE thread/process calls Push() (the producer).
- *   - Exactly ONE thread/process calls Pop() (the consumer).
- * Under that invariant, no mutex is required. The producer only ever writes `head_`, the consumer
- * only ever writes `tail_`, and the acquire/release ordering on those two atomics publishes the
- * slot writes safely across the process boundary.
- *
- * Capacity note: one slot is always left empty to disambiguate the full and empty states, so a
- * buffer constructed with kCapacity slots can hold at most (kCapacity - 1) live entries.
- *
- * The payload stored is a single uint32_t per entry, intended to be an index into a separately
- * managed slot pool (see FrameSlotPool). We never put pointers in shared memory.
- */
-class SpscRingBuffer {
-public:
-	/**
-   * @brief In-place construct a ring buffer header at `mem` with `capacity` index slots.
-   *
-   * `mem` must point to at least BytesNeeded(capacity) bytes of zero-initializable memory. This is
-   * intended to be placement-style initialization performed exactly once by whichever process owns
-   * the segment's creation; the peer process uses Attach() instead.
-   */
-	static SpscRingBuffer *create(void *mem, uint32_t capacity)
-	{
-		auto *self = reinterpret_cast<SpscRingBuffer *>(mem);
-		self->capacity_ = capacity;
-		self->head_.store(0, std::memory_order_relaxed);
-		self->tail_.store(0, std::memory_order_relaxed);
-		for (uint32_t i = 0; i < capacity; i++) {
-			self->slot_array()[i] = 0;
-		}
-		return self;
-	}
-
-	/**
-   * @brief Re-interpret already-initialized memory as a ring buffer (peer process side).
-   *
-   * No writes are performed; the cursors and capacity are assumed already set by Create().
-   */
-	static SpscRingBuffer *attach(void *mem)
-	{
-		return reinterpret_cast<SpscRingBuffer *>(mem);
-	}
-
-	/**
-   * @brief Total bytes required to hold the header plus `capacity` index slots.
-   */
-	static size_t bytes_needed(uint32_t capacity)
-	{
-		return sizeof(SpscRingBuffer) + size_t(capacity) * sizeof(uint32_t);
-	}
-
-	/**
-   * @brief Producer side: enqueue an index. Returns false if the buffer is full.
-   */
-	bool push(uint32_t value)
-	{
-		const uint32_t head = head_.load(std::memory_order_relaxed);
-		const uint32_t next = increment(head);
-
-		// Buffer is full if advancing head would collide with the consumer's tail.
-		if (next == tail_.load(std::memory_order_acquire)) {
-			return false;
-		}
-
-		slot_array()[head] = value;
-		head_.store(next, std::memory_order_release);
-		return true;
-	}
-
-	/**
-   * @brief Consumer side: dequeue an index into `out`. Returns false if the buffer is empty.
-   */
-	bool pop(uint32_t *out)
-	{
-		const uint32_t tail = tail_.load(std::memory_order_relaxed);
-
-		// Buffer is empty if the consumer has caught up to the producer.
-		if (tail == head_.load(std::memory_order_acquire)) {
-			return false;
-		}
-
-		*out = slot_array()[tail];
-		tail_.store(increment(tail), std::memory_order_release);
-		return true;
-	}
-
-	/**
-   * @brief Approximate number of entries currently queued.
-   *
-   * Safe to call from either side, but the value may be stale the instant it returns. Intended for
-   * metrics/backpressure heuristics, not for correctness decisions.
-   */
-	uint32_t size_approx() const
-	{
-		const uint32_t head = head_.load(std::memory_order_acquire);
-		const uint32_t tail = tail_.load(std::memory_order_acquire);
-		return (head + capacity_ - tail) % capacity_;
-	}
-
-	bool is_empty_approx() const
-	{
-		return head_.load(std::memory_order_acquire) ==
-			   tail_.load(std::memory_order_acquire);
-	}
-
-	uint32_t capacity() const
-	{
-		return capacity_;
-	}
-
-private:
-	uint32_t increment(uint32_t index) const
-	{
-		// capacity_ is small and this avoids requiring a power-of-two capacity.
-		return (index + 1) % capacity_;
-	}
-
-	// The index slot array is allocated immediately after this struct in the same contiguous block.
-	// (Named slot_array() rather than slots() to avoid Qt's `slots` keyword macro.)
-	uint32_t *slot_array()
-	{
-		return reinterpret_cast<uint32_t *>(this + 1);
-	}
-	const uint32_t *slot_array() const
-	{
-		return reinterpret_cast<const uint32_t *>(this + 1);
-	}
-
-	// Producer writes head_, consumer writes tail_. Kept on separate cache lines would be ideal, but
-	// since these live in shared memory with a trailing flexible array we keep the header compact and
-	// rely on acquire/release ordering for correctness.
-	std::atomic<uint32_t> head_;
-	std::atomic<uint32_t> tail_;
-	uint32_t capacity_;
-
-	static_assert(
-		sizeof(std::atomic<uint32_t>) == sizeof(uint32_t),
-		"atomic<uint32_t> must be lock-free POD-sized for shared memory use");
-};
-
-} // namespace ipc
-} // namespace olive
-
-#endif // OAK_IPC_SPSCRINGBUFFER_H