GGUI::SnapshotChain class

#include <GGUI/Public/Snapshot.h>

SnapshotChain: the latest snapshot, published by one thread and read by others.

Lock-free, and wait-free for the writer: publishing never waits on a reader. Readers lock the latest snapshot; the writer fills one nobody holds and makes it the latest. There is always one more snapshot than possible holders, so the writer always has one to fill. Up to MaxReaders readers may hold a snapshot at once.

Public static variables

static uint32_t MaxReaders constexpr

the input thread and the render thread

static uint32_t SnapshotCount constexpr

snapshots kept

Public functions

auto BeginWrite() -> GGSnapshot*

Writer: an unheld snapshot to fill and pass to Publish. Null if more than MaxReaders readers hold snapshots (the publish is skipped and counted).

void Publish()

Writer: make the snapshot from BeginWrite the latest.

auto Read() const -> SnapshotRead

Lock the latest snapshot. Any thread.

auto PublishedCount() const -> uint64_t

How many snapshots were published.

auto SkippedCount() const -> uint64_t

How many publishes were skipped because every snapshot was held.

auto Bytes() const -> size_t

Memory held by all snapshots, shared rows counted once. Writer only.