1 files changed, 132 insertions, 0 deletions
diff --git a/vendor/codeberg.org/gruf/go-nowish/clock.go b/vendor/codeberg.org/gruf/go-nowish/clock.go
new file mode 100644
index 000000000..781e59f18
--- /dev/null
+++ b/vendor/codeberg.org/gruf/go-nowish/clock.go
@@ -0,0 +1,132 @@
+package nowish
+
+import (
+	"sync"
+	"sync/atomic"
+	"time"
+	"unsafe"
+)
+
+// Start returns a new Clock instance initialized and
+// started with the provided precision, along with the
+// stop function for it's underlying timer
+func Start(precision time.Duration) (*Clock, func()) {
+	c := Clock{}
+	return &c, c.Start(precision)
+}
+
+type Clock struct {
+	// format stores the time formatting style string
+	format string
+
+	// valid indicates whether the current value stored in .Format is valid
+	valid uint32
+
+	// mutex protects writes to .Format, not because it would be unsafe, but
+	// because we want to minimize unnnecessary allocations
+	mutex sync.Mutex
+
+	// nowfmt is an unsafe pointer to the last-updated time format string
+	nowfmt unsafe.Pointer
+
+	// now is an unsafe pointer to the last-updated time.Time object
+	now unsafe.Pointer
+}
+
+// Start starts the clock with the provided precision, the returned
+// function is the stop function for the underlying timer. For >= 2ms,
+// actual precision is usually within AT LEAST 10% of requested precision,
+// less than this and the actual precision very quickly deteriorates.
+func (c *Clock) Start(precision time.Duration) func() {
+	// Create ticker from duration
+	tick := time.NewTicker(precision / 10)
+
+	// Set initial time
+	t := time.Now()
+	atomic.StorePointer(&c.now, unsafe.Pointer(&t))
+
+	// Set initial format
+	s := ""
+	atomic.StorePointer(&c.nowfmt, unsafe.Pointer(&s))
+
+	// If formatting string unset, set default
+	c.mutex.Lock()
+	if c.format == "" {
+		c.format = time.RFC822
+	}
+	c.mutex.Unlock()
+
+	// Start main routine
+	go c.run(tick)
+
+	// Return stop fn
+	return tick.Stop
+}
+
+// run is the internal clock ticking loop.
+func (c *Clock) run(tick *time.Ticker) {
+	for {
+		// Wait on tick
+		_, ok := <-tick.C
+
+		// Channel closed
+		if !ok {
+			break
+		}
+
+		// Update time
+		t := time.Now()
+		atomic.StorePointer(&c.now, unsafe.Pointer(&t))
+
+		// Invalidate format string
+		atomic.StoreUint32(&c.valid, 0)
+	}
+}
+
+// Now returns a good (ish) estimate of the current 'now' time.
+func (c *Clock) Now() time.Time {
+	return *(*time.Time)(atomic.LoadPointer(&c.now))
+}
+
+// NowFormat returns the formatted "now" time, cached until next tick and "now" updates.
+func (c *Clock) NowFormat() string {
+	// If format still valid, return this
+	if atomic.LoadUint32(&c.valid) == 1 {
+		return *(*string)(atomic.LoadPointer(&c.nowfmt))
+	}
+
+	// Get mutex lock
+	c.mutex.Lock()
+
+	// Double check still invalid
+	if atomic.LoadUint32(&c.valid) == 1 {
+		c.mutex.Unlock()
+		return *(*string)(atomic.LoadPointer(&c.nowfmt))
+	}
+
+	// Calculate time format
+	nowfmt := c.Now().Format(c.format)
+
+	// Update the stored value and set valid!
+	atomic.StorePointer(&c.nowfmt, unsafe.Pointer(&nowfmt))
+	atomic.StoreUint32(&c.valid, 1)
+
+	// Unlock and return
+	c.mutex.Unlock()
+	return nowfmt
+}
+
+// SetFormat sets the time format string used by .NowFormat().
+func (c *Clock) SetFormat(format string) {
+	// Get mutex lock
+	c.mutex.Lock()
+
+	// Update time format
+	c.format = format
+
+	// Invalidate current format string
+	atomic.StoreUint32(&c.valid, 0)
+
+	// Unlock
+	c.mutex.Unlock()
+}