RSync Class Reference

GPU/CPU synchronization fence. More...

#include <RSync.h>

Inheritance diagram for RSync:

Public Member Functions
virtual bool	gpuWait (RDevice *waiter=nullptr) const noexcept=0
	Inserts a GPU-side wait on this fence.
virtual int	cpuWait (int timeoutMs=-1) const noexcept=0
	Blocks the calling thread until the fence is signaled.
virtual CZSpFd	fd () const noexcept=0
	Exports this fence as a sync_file file descriptor.
bool	isExternal () const noexcept
	Whether this sync was imported via FromExternal().
RDevice *	device () const noexcept
	Returns the device this sync is associated with.
Public Member Functions inherited from RObject
	RObject ()=default
	Constructs a default RObject.

Static Public Member Functions
static std::shared_ptr< RSync >	FromExternal (int fd, RDevice *device=nullptr) noexcept
	Imports an external sync_file fence.
static std::shared_ptr< RSync >	Make (RDevice *device=nullptr) noexcept
	Creates a new sync fence.

Detailed Description

GPU/CPU synchronization fence.

RSync represents a point in a device's command stream, backed by a sync_file fence. It lets consumers wait for prior GPU work to complete before reading or overwriting a resource, without stalling unnecessarily.

A sync can be waited on the GPU (gpuWait(), inserting a dependency into a device's next submission) or on the CPU (cpuWait()). Because it is expressed as a sync_file fd, it can be exported and imported (fd(), RSync::FromExternal()) to interoperate with other devices, clients, and DRM sync objects. Images publish their read/write syncs automatically as rendering proceeds.

Member Function Documentation

FromExternal()

static std::shared_ptr< RSync > FromExternal ( int  fd, RDevice *  device = nullptr  )

staticnoexcept

Imports an external sync_file fence.

Parameters

fd	A sync_file file descriptor. Ownership is taken even on failure.
device	Device to associate the sync with. If nullptr, the main device is used.

Returns

A shared pointer to the new RSync, or nullptr on failure.

Make()

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

staticnoexcept

Creates a new sync fence.

Parameters

device

Device to create the sync on. If nullptr, the main device is used.

Returns

A shared pointer to the new RSync, or nullptr on failure.

gpuWait()

virtual bool gpuWait ( RDevice *  waiter = nullptr ) const

pure virtualnoexcept

Inserts a GPU-side wait on this fence.

Non-blocking. Makes the waiter's next submission depend on this fence being signaled.

Parameters

waiter

Device that must wait. If nullptr, the main device is used.

Returns

true on success or if the fence is already signaled, false otherwise.

Implemented in RGLSync, and RVKSync.

cpuWait()

virtual int cpuWait ( int  timeoutMs = -1 ) const

pure virtualnoexcept

Blocks the calling thread until the fence is signaled.

Parameters

timeoutMs

Timeout in milliseconds; -1 waits indefinitely.

Returns

1 if signaled (or already signaled), 0 on timeout, -1 on error.

Implemented in RGLSync, and RVKSync.

fd()

virtual CZSpFd fd ( ) const

pure virtualnoexcept

Exports this fence as a sync_file file descriptor.

Returns

A file descriptor wrapper, invalid (-1) on error.

Implemented in RGLSync, and RVKSync.

isExternal()

bool isExternal ( ) const

inlinenoexcept

Whether this sync was imported via FromExternal().

Returns

true if created with FromExternal(), false otherwise.

device()

RDevice * device ( ) const

inlinenoexcept

Returns the device this sync is associated with.