Initial project import

tools/v/vlib/goroutines/init.v

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+// Copyright (c) 2019-2024 Alexander Medvednikov. All rights reserved.
+// Use of this source code is governed by an MIT license
+// that can be found in the LICENSE file.
+//
+// Goroutine runtime initialization.
+// Translated from Go's schedinit() and procresize() in proc.go.
+module goroutines
+
+import runtime
+
+// init initializes the goroutine scheduler.
+// Creates P's (one per CPU core by default) and the initial M.
+// Translated from Go's schedinit() + procresize().
+fn init() {
+	// Determine number of processors
+	n := runtime.nr_cpus()
+	if n < 1 {
+		gomaxprocs = 1
+	} else if n > 256 {
+		gomaxprocs = 256
+	} else {
+		gomaxprocs = i32(n)
+	}
+
+	// Initialize the scheduler
+	gsched.maxmcount = 10000
+	gsched.mnext = 1
+
+	// Create all P's (translated from procresize in proc.go)
+	gsched.allp = []&Processor{cap: int(gomaxprocs)}
+	for i in 0 .. gomaxprocs {
+		mut pp := &Processor{
+			id:     i
+			status: .idle
+		}
+		// Initialize the local run queue
+		for j in 0 .. local_queue_size {
+			pp.runq[j] = unsafe { nil }
+		}
+		gsched.allp << pp
+	}
+
+	// Create the initial M (M0) for the main thread
+	mut m0 := &Machine{
+		id: 0
+		g0: &Goroutine{
+			id:     0
+			status: .running
+		}
+	}
+
+	// Create a "main goroutine" so chan_send/recv work from the main thread
+	mut main_g := &Goroutine{
+		id:     0
+		status: .running
+	}
+	m0.curg = main_g
+	main_g.m = m0
+
+	// Wire M0 to P0
+	mut p0 := gsched.allp[0]
+	wire_p(mut m0, mut p0)
+
+	// Set the current thread's M
+	set_current_m(m0)
+
+	// Put remaining P's on the idle list
+	for i in 1 .. gomaxprocs {
+		pid_put(gsched.allp[i])
+	}
+}
+
+// set_max_procs changes the number of active processors.
+// Returns the previous value. Translated from Go's GOMAXPROCS().
+pub fn set_max_procs(n int) int {
+	old := int(gomaxprocs)
+	if n < 1 || n == old {
+		return old
+	}
+
+	// TODO: implement full procresize like Go does
+	// For now, just update the count
+	gomaxprocs = i32(n)
+	return old
+}
+
+// num_goroutine returns the number of goroutines that currently exist.
+pub fn num_goroutine() int {
+	allgs_mu.acquire()
+	mut count := 0
+	for g in allgs {
+		if g.status != .dead {
+			count++
+		}
+	}
+	allgs_mu.release()
+	return count
+}
+
+// shutdown gracefully shuts down the goroutine scheduler.
+pub fn shutdown() {
+	gsched.stopped = true
+	// Wake all idle M's so they can exit
+	gsched.mu.acquire()
+	mut mp := gsched.midle
+	for mp != unsafe { nil } {
+		mp.park.post()
+		mp = mp.sched_link
+	}
+	gsched.mu.release()
+}