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123456789101112131415161718192021222324252627282930313233343536373839404142434445464748495051525354555657585960616263646566676869707172737475767778798081828384858687888990919293949596979899100101102103104105106107108109110111112113114115116117118119120121122123124125126127128129130131132133134135136137138139140141142143144145146147148149150151152153154155156157158159160161162163164165166167168169170171172173174175176177178179180181182183184185186187188189190191192//! Represents the CFRelease thread. Pools of CFTypeRefs are sent to//! this thread to be released, so that their release callback logic//! doesn't block the execution of a high throughput thread like the//! renderer thread.pub const Thread = @This();
const std = @import("std");const builtin = @import("builtin");const macos = @import("macos");
const internal_os = @import("../os/main.zig");const xev = @import("../global.zig").xev;const BlockingQueue = @import("../datastruct/main.zig").BlockingQueue;
const Allocator = std.mem.Allocator;const log = std.log.scoped(.cf_release_thread);
pub const Message = union(enum) { /// Release a slice of CFTypeRefs. Uses alloc to free the slice after /// releasing all the refs. release: struct { refs: []*anyopaque, alloc: Allocator, },};
/// The type used for sending messages to the thread. For now this is/// hardcoded with a capacity. We can make this a comptime parameter in/// the future if we want it configurable.pub const Mailbox = BlockingQueue(Message, 64);
/// Allocator used for some statealloc: std.mem.Allocator,
/// The main event loop for the thread. The user data of this loop/// is always the allocator used to create the loop. This is a convenience/// so that users of the loop always have an allocator.loop: xev.Loop,
/// This can be used to wake up the thread.wakeup: xev.Async,wakeup_c: xev.Completion = .{},
/// This can be used to stop the thread on the next loop iteration.stop: xev.Async,stop_c: xev.Completion = .{},
/// The mailbox that can be used to send this thread messages. Note/// this is a blocking queue so if it is full you will get errors (or block).mailbox: *Mailbox,
flags: packed struct { /// This is set to true only when an abnormal exit is detected. It /// tells our mailbox system to drain and ignore all messages. drain: bool = false,} = .{},
/// Initialize the thread. This does not START the thread. This only sets/// up all the internal state necessary prior to starting the thread. It/// is up to the caller to start the thread with the threadMain entrypoint.pub fn init( alloc: Allocator,) !Thread { // Create our event loop. var loop = try xev.Loop.init(.{}); errdefer loop.deinit();
// This async handle is used to "wake up" the thread to collect objects. var wakeup_h = try xev.Async.init(); errdefer wakeup_h.deinit();
// This async handle is used to stop the loop and force the thread to end. var stop_h = try xev.Async.init(); errdefer stop_h.deinit();
// The mailbox for messaging this thread var mailbox = try Mailbox.create(alloc); errdefer mailbox.destroy(alloc);
return Thread{ .alloc = alloc, .loop = loop, .wakeup = wakeup_h, .stop = stop_h, .mailbox = mailbox, };}
/// Clean up the thread. This is only safe to call once the thread/// completes executing; the caller must join prior to this.pub fn deinit(self: *Thread) void { self.stop.deinit(); self.wakeup.deinit(); self.loop.deinit();
// Nothing can possibly access the mailbox anymore, destroy it. self.mailbox.destroy(self.alloc);}
/// The main entrypoint for the thread.pub fn threadMain(self: *Thread) void { // Call child function so we can use errors... self.threadMain_() catch |err| { log.warn("error in cf release thread err={}", .{err}); };
// If our loop is not stopped, then we need to keep running so that // messages are drained and we can wait for the surface to send a stop // message. if (!self.loop.stopped()) { log.warn("abrupt cf release thread exit detected, starting xev to drain mailbox", .{}); defer log.debug("cf release thread fully exiting after abnormal failure", .{}); self.flags.drain = true; self.loop.run(.until_done) catch |err| { log.err("failed to start xev loop for draining err={}", .{err}); }; }}
fn threadMain_(self: *Thread) !void { defer log.debug("cf release thread exited", .{});
// Right now, on Darwin, `std.Thread.setName` can only name the current // thread, and we have no way to get the current thread from within it, // so instead we use this code to name the thread instead. if (builtin.os.tag.isDarwin()) { internal_os.macos.pthread_setname_np(&"cf_release".*); }
// Start the async handlers. We start these first so that they're // registered even if anything below fails so we can drain the mailbox. self.wakeup.wait(&self.loop, &self.wakeup_c, Thread, self, wakeupCallback); self.stop.wait(&self.loop, &self.stop_c, Thread, self, stopCallback);
// Run log.debug("starting cf release thread", .{}); defer log.debug("starting cf release thread shutdown", .{}); try self.loop.run(.until_done);}
/// Drain the mailbox, handling all the messages in our terminal implementation.fn drainMailbox(self: *Thread) !void { // If we're draining, we just drain the mailbox and return. if (self.flags.drain) { while (self.mailbox.pop()) |_| {} return; }
while (self.mailbox.pop()) |message| { // log.debug("mailbox message={}", .{message}); switch (message) { .release => |msg| { for (msg.refs) |ref| macos.foundation.CFRelease(ref); // log.debug("Released {} CFTypeRefs.", .{ msg.refs.len }); msg.alloc.free(msg.refs); }, } }}
fn wakeupCallback( self_: ?*Thread, _: *xev.Loop, _: *xev.Completion, r: xev.Async.WaitError!void,) xev.CallbackAction { _ = r catch |err| { log.err("error in wakeup err={}", .{err}); return .rearm; };
const t = self_.?;
// When we wake up, we check the mailbox. Mailbox producers should // wake up our thread after publishing. t.drainMailbox() catch |err| log.err("error draining mailbox err={}", .{err});
return .rearm;}
fn stopCallback( self_: ?*Thread, _: *xev.Loop, _: *xev.Completion, r: xev.Async.WaitError!void,) xev.CallbackAction { _ = r catch unreachable; self_.?.loop.stop(); return .disarm;}