A DRM synchronization object (syncobj) timeline for explicit synchronization. More...

#include <RDRMTimeline.h>

Inheritance diagram for RDRMTimeline:

Public Types
using	Callback = std::function< void(RDRMTimeline *timeline)>
	Callback type invoked by waitAsync() when a point condition is met.

Public Member Functions
CZSpFd	exportTimeline () const noexcept
	Exports the whole timeline syncobj as a file descriptor.

CZSpFd	exportSyncFile (UInt64 point) const noexcept
	Exports the fence at a given timeline point as a `sync_file` file descriptor.

bool	importSyncFile (int fd, UInt64 point, CZOwn own) noexcept
	Imports a `sync_file` fence into a given timeline point.

bool	transferPoint (UInt64 srcPoint, std::shared_ptr< RDRMTimeline > dst, UInt64 dstPoint) noexcept
	Copies the fence at a source point of this timeline to a point of another timeline.

int	waitSync (UInt64 point, UInt32 flags, Int64 timeoutNs=0) noexcept
	Synchronously waits for a timeline point.

std::shared_ptr< CZEventSource >	waitAsync (UInt64 point, UInt32 flags, Callback callback) noexcept
	Asynchronously waits for a timeline point via an eventfd-backed event source.

bool	signalPoint (UInt64 point) noexcept
	Immediately signals a timeline point.

std::shared_ptr< RCore >	core () const noexcept
	Returns the internal shared reference to the core instance.

RDevice *	device () const noexcept
	Returns the DRM device this timeline belongs to.

UInt32	handle () const noexcept
	Returns the DRM syncobj handle backing this timeline.

	~RDRMTimeline () noexcept
	Destroys the underlying DRM syncobj.

Public Member Functions inherited from RObject
	RObject ()=default
	Constructs a default RObject.

Static Public Member Functions
static std::shared_ptr< RDRMTimeline >	Make (RDevice *device=nullptr) noexcept
	Creates a new empty timeline syncobj.

static std::shared_ptr< RDRMTimeline >	Import (int timelineFd, CZOwn own, RDevice *device=nullptr) noexcept
	Imports a timeline from an exported syncobj file descriptor.

Detailed Description

A DRM synchronization object (syncobj) timeline for explicit synchronization.

Wraps a DRM timeline syncobj, which associates fences with monotonically increasing 64-bit timeline points. Timelines are used for explicit GPU/display synchronization: a producer signals a point once its work completes, and consumers wait on that point before accessing the shared buffer.

A timeline is bound to a specific DRM device, which must advertise the Timeline capability. Timelines can be exported/imported as file descriptors for sharing across processes, and individual points can be exported to or imported from sync_file file descriptors to interoperate with implicit-sync APIs.

Use Make() to create a new timeline, or Import() to adopt an exported one.

Member Typedef Documentation

◆ Callback

using Callback = std::function<void(RDRMTimeline *timeline)>

Callback type invoked by waitAsync() when a point condition is met.

Parameters

timeline The timeline that triggered the callback.

Constructor & Destructor Documentation

◆ ~RDRMTimeline()

~RDRMTimeline ( )

noexcept

Destroys the underlying DRM syncobj.

Member Function Documentation

◆ Make()

static std::shared_ptr< RDRMTimeline > Make ( RDevice * device = nullptr )

staticnoexcept

Creates a new empty timeline syncobj.

Parameters

device The DRM device to create the timeline on. If nullptr, RCore::mainDevice() is used. The device must support the Timeline capability.

Returns: A shared pointer to the created timeline, or nullptr on failure.

◆ Import()

static std::shared_ptr< RDRMTimeline > Import	(	int	timelineFd,
		CZOwn	own,
		RDevice *	device = `nullptr`
	)

staticnoexcept

Imports a timeline from an exported syncobj file descriptor.

Parameters

timelineFd	A file descriptor previously produced by exportTimeline().
own	CZOwn::Own to close `timelineFd` before returning (in all cases), or CZOwn::Borrow to leave it open for the caller to manage.
device	The DRM device to import onto. If nullptr, RCore::mainDevice() is used. The device must support the Timeline capability.

Returns: A shared pointer to the imported timeline, or nullptr on failure.

◆ exportTimeline()

CZSpFd exportTimeline ( ) const

noexcept

Exports the whole timeline syncobj as a file descriptor.

The returned descriptor can be shared and re-imported via Import().

Returns: A valid CZSpFd on success, or an empty/invalid CZSpFd on failure.

◆ exportSyncFile()

CZSpFd exportSyncFile ( UInt64 point ) const

noexcept

Exports the fence at a given timeline point as a sync_file file descriptor.

Parameters

point The timeline point whose fence should be exported.

Returns: A valid CZSpFd wrapping the sync_file on success, or an empty/invalid CZSpFd on failure.

◆ importSyncFile()

bool importSyncFile	(	int	fd,
		UInt64	point,
		CZOwn	own
	)

noexcept

Imports a sync_file fence into a given timeline point.

Parameters

fd	A `sync_file` file descriptor.
point	The timeline point to associate the imported fence with.
own	CZOwn::Own to close `fd` before returning (in all cases), or CZOwn::Borrow to leave it open for the caller to manage.

Returns: true on success, false on failure.

◆ transferPoint()

bool transferPoint	(	UInt64	srcPoint,
		std::shared_ptr< RDRMTimeline >	dst,
		UInt64	dstPoint
	)

noexcept

Copies the fence at a source point of this timeline to a point of another timeline.

Parameters

srcPoint	The source point on this timeline.
dst	The destination timeline, which must belong to the same device as this one.
dstPoint	The destination point on `dst`.

Returns: true on success, false if dst is null, belongs to a different device, or the transfer fails.

◆ waitSync()

int waitSync	(	UInt64	point,
		UInt32	flags,
		Int64	timeoutNs = `0`
	)

noexcept

Synchronously waits for a timeline point.

Parameters

point	The timeline point to wait on.
flags	DRM syncobj wait flags (e.g. DRM_SYNCOBJ_WAIT_FLAGS_WAIT_AVAILABLE to wait for a fence to become available rather than signalled).
timeoutNs	Absolute/relative timeout in nanoseconds as accepted by the DRM syncobj timeline wait (0 for an immediate poll).

Returns: 1 if the point was satisfied, 0 on timeout, or -1 on error.

◆ waitAsync()

std::shared_ptr< CZEventSource > waitAsync	(	UInt64	point,
		UInt32	flags,
		Callback	callback
	)

noexcept

Asynchronously waits for a timeline point via an eventfd-backed event source.

Registers an eventfd with the DRM syncobj and returns a CZEventSource that invokes callback once the point condition is met. Keep the returned event source alive for as long as the wait should remain active.

Parameters

point	The timeline point to wait on.
flags	Zero to wait for the point to be signalled, or DRM_SYNCOBJ_WAIT_FLAGS_WAIT_AVAILABLE to wait for a fence to be available for the point.
callback	The callback to invoke; must not be null.

Returns: A shared pointer to the event source, or nullptr on failure (including a null callback).

◆ signalPoint()

bool signalPoint ( UInt64 point )

noexcept

Immediately signals a timeline point.

Parameters

point The timeline point to signal.

Returns: true on success, false on failure.

◆ core()

std::shared_ptr< RCore > core ( ) const

inlinenoexcept

Returns the internal shared reference to the core instance.

This ensures the current RCore instance stays alive while the timeline exists.

◆ device()

RDevice * device ( ) const

inlinenoexcept

Returns the DRM device this timeline belongs to.

◆ handle()

UInt32 handle ( ) const

inlinenoexcept

Returns the DRM syncobj handle backing this timeline.

Public Types

Public Member Functions

Static Public Member Functions

Detailed Description

Member Typedef Documentation

◆ Callback

Constructor & Destructor Documentation

◆ ~RDRMTimeline()

Member Function Documentation

◆ Make()

◆ Import()

◆ exportTimeline()

◆ exportSyncFile()

◆ importSyncFile()

◆ transferPoint()

◆ waitSync()

◆ waitAsync()

◆ signalPoint()

◆ core()

◆ device()

◆ handle()