refactor: simplify design; create metrics on first use

collector.v

@@ -1,16 +1,15 @@
 module metrics
 
-import sync.stdatomic
-
 struct Counter {
 	metric Metric
+mut:
 	data u64
 }
 
 struct FloatSeries {
 	metric Metric
 pub mut:
-	data shared []f64
+	data []f64
 }
 
 [heap]
@@ -29,20 +28,35 @@ pub fn new_default_collector() &DefaultCollector {
 	}
 }
 
-pub fn (mut c DefaultCollector) counter_register(value u64, metric Metric) {
+pub fn (mut c DefaultCollector) counter_increment(metric Metric) {
 	lock c.counters {
-		c.counters[metric.str()] = &Counter{
+		mut entry := c.counters[metric.str()] or {
+			counter := &Counter{
 				metric: metric
-			data: value
+				data: 0
 			}
+			c.counters[metric.str()] = counter
+
+			counter
+		}
+
+		entry.data += 1
 	}
 }
 
-pub fn (c &DefaultCollector) counter_increment(metric Metric) {
+pub fn (mut c DefaultCollector) counter_set(value u64, metric Metric) {
-	rlock c.counters {
+	lock c.counters {
-		entry := c.counters[metric.str()]
+		mut entry := c.counters[metric.str()] or {
+			counter := &Counter{
+				metric: metric
+				data: 0
+			}
+			c.counters[metric.str()] = counter
 
-		stdatomic.add_u64(&entry.data, 1)
+			counter
+		}
+
+		entry.data = value
 	}
 }
 
@@ -50,7 +64,7 @@ pub fn (c &DefaultCollector) counter_get(metric Metric) ?u64 {
 	return rlock c.counters {
 		entry := c.counters[metric.str()] or { return none }
 
-		stdatomic.load_u64(&entry.data)
+		entry.data
 	}
 }
 
@@ -66,82 +80,87 @@ pub fn (c &DefaultCollector) counters() []Metric {
 	return metrics
 }
 
-pub fn (mut c DefaultCollector) histogram_register(metric Metric) {
+pub fn (c &DefaultCollector) histogram_record(value f64, metric Metric) {
 	lock c.histograms {
-		c.histograms[metric.str()] = &FloatSeries{
+		mut entry := c.histograms[metric.str()] or {
+			hist := &FloatSeries{
 				metric: metric
 				data: []f64{}
 			}
-	}
+			c.histograms[metric.str()] = hist
+
+			hist
 		}
 
-pub fn (c &DefaultCollector) histogram_record(value f64, metric Metric) {
-	entry := rlock c.histograms {
-		c.histograms[metric.str()]
-	}
-
-	lock entry.data {
 		entry.data << value
 	}
 }
 
 pub fn (c &DefaultCollector) histogram_get(metric Metric) ?[]f64 {
-	entry := rlock c.histograms {
+	return rlock c.histograms {
-		c.histograms[metric.str()] or { return none }
+		entry := c.histograms[metric.str()] or { return none }
-	}
 
-	return rlock entry.data {
 		// Return a clone of the data to prevent user from altering
 		// internal structure
 		entry.data.clone()
 	}
 }
 
-pub fn (mut c DefaultCollector) gauge_register(value f64, metric Metric) {
+pub fn (mut c DefaultCollector) gauge_add(value f64, metric Metric) {
 	lock c.gauges {
-		c.gauges[metric.str()] = &FloatSeries{
+		mut entry := c.gauges[metric.str()] or {
+			gauge := &FloatSeries{
 				metric: metric
-			data: [value]
+				data: [0.0]
-		}
-	}
 			}
 
-pub fn (c &DefaultCollector) gauge_add(value f64, metric Metric) {
+			c.gauges[metric.str()] = gauge
-	entry := rlock c.gauges {
+
-		c.gauges[metric.str()]
+			gauge
 		}
 
-	lock entry.data {
 		entry.data[0] += value
 	}
 }
 
-pub fn (c &DefaultCollector) gauge_sub(value f64, metric Metric) {
+pub fn (mut c DefaultCollector) gauge_sub(value f64, metric Metric) {
-	entry := rlock c.gauges {
+	lock c.gauges {
-		c.gauges[metric.str()]
+		mut entry := c.gauges[metric.str()] or {
+			gauge := &FloatSeries{
+				metric: metric
+				data: [0.0]
+			}
+
+			c.gauges[metric.str()] = gauge
+
+			gauge
 		}
 
-	lock entry.data {
 		entry.data[0] -= value
 	}
 }
 
-pub fn (c &DefaultCollector) gauge_set(value f64, metric Metric) {
+pub fn (mut c DefaultCollector) gauge_set(value f64, metric Metric) {
-	entry := rlock c.gauges {
+	lock c.gauges {
-		c.gauges[metric.str()]
+		mut entry := c.gauges[metric.str()] or {
+			gauge := &FloatSeries{
+				metric: metric
+				data: [0.0]
+			}
+
+			c.gauges[metric.str()] = gauge
+
+			gauge
 		}
 
-	lock entry.data {
 		entry.data[0] = value
 	}
 }
 
 pub fn (c &DefaultCollector) gauge_get(metric Metric) ?f64 {
-	entry := rlock c.gauges {
+	return rlock c.gauges {
-		c.gauges[metric.str()]
+		entry := c.gauges[metric.str()] or { return none }
-	}
 
-	return rlock entry.data {
 		entry.data[0]
 	}
 }

collector_test.v

@@ -11,7 +11,6 @@ fn test_null_implements_interface() {
 fn test_counter_increment() {
 	mut m := new_default_collector()
 
-	m.counter_register(0, name: 'test')
 	m.counter_increment(name: 'test')
 	assert m.counter_get(name: 'test')? == u64(1)
 
@@ -24,7 +23,7 @@ fn test_counter_increment() {
 		labels: [['hi', 'label']!, ['hi2', 'label2']!]
 	}
 
-	m.counter_register(15, metric)
+	m.counter_set(15, metric)
 	m.counter_increment(metric)
 	assert m.counter_get(metric)? == u64(16)
 }
@@ -32,7 +31,6 @@ fn test_counter_increment() {
 fn test_histogram() {
 	mut m := new_default_collector()
 
-	m.histogram_register(name: 'test')
 	m.histogram_record(5.0, name: 'test')
 	assert m.histogram_get(name: 'test')? == [5.0]
 
@@ -45,7 +43,6 @@ fn test_histogram() {
 		labels: [['hi', 'label']!, ['hi2', 'label2']!]
 	}
 
-	m.histogram_register(metric)
 	m.histogram_record(5.0, metric)
 	assert m.histogram_get(metric)? == [5.0]
 
@@ -56,7 +53,6 @@ fn test_histogram() {
 fn test_gauge_add() {
 	mut m := new_default_collector()
 
-	m.gauge_register(0.0, name: 'test')
 	m.gauge_add(5.0, name: 'test')
 	assert m.gauge_get(name: 'test')? == 5.0
 
@@ -66,7 +62,7 @@ fn test_gauge_add() {
 		labels: [['hi', 'label']!, ['hi2', 'label2']!]
 	}
 
-	m.gauge_register(3.0, metric)
+	m.gauge_set(3.0, metric)
 	m.gauge_add(5.0, metric)
 	assert m.gauge_get(metric)? == 8.0
 }
@@ -74,7 +70,6 @@ fn test_gauge_add() {
 fn test_gauge_sub() {
 	mut m := new_default_collector()
 
-	m.gauge_register(0.0, name: 'test')
 	m.gauge_sub(5.0, name: 'test')
 	assert m.gauge_get(name: 'test')? == -5.0
 
@@ -84,7 +79,7 @@ fn test_gauge_sub() {
 		labels: [['hi', 'label']!, ['hi2', 'label2']!]
 	}
 
-	m.gauge_register(3.0, metric)
+	m.gauge_set(3.0, metric)
 	m.gauge_sub(5.0, metric)
 	assert m.gauge_get(metric)? == -2.0
 }
@@ -92,7 +87,6 @@ fn test_gauge_sub() {
 fn test_gauge_set() {
 	mut m := new_default_collector()
 
-	m.gauge_register(0.0, name: 'test')
 	m.gauge_set(3.0, name: 'test')
 	assert m.gauge_get(name: 'test')? == 3.0
 	m.gauge_set(5.0, name: 'test')
@@ -104,7 +98,6 @@ fn test_gauge_set() {
 		labels: [['hi', 'label']!, ['hi2', 'label2']!]
 	}
 
-	m.gauge_register(0.0, metric)
 	m.gauge_set(3.0, metric)
 	assert m.gauge_get(metric)? == 3.0
 	m.gauge_set(5.0, metric)

metrics.v

@@ -22,21 +22,19 @@ pub fn (m &Metric) str() string {
 }
 
 pub interface MetricsCollector {
-	counter_increment(metric Metric)
 	counter_get(metric Metric) ?u64
 	counters() []Metric
-	histogram_record(value f64, metric Metric)
 	histogram_get(metric Metric) ?[]f64
 	histograms() []Metric
-	gauge_add(value f64, metric Metric)
-	gauge_sub(value f64, metric Metric)
-	gauge_set(value f64, metric Metric)
 	gauge_get(metric Metric) ?f64
 	gauges() []Metric
 mut:
-	counter_register(value u64, metric Metric)
+	counter_set(val u64, metric Metric)
-	histogram_register(metric Metric)
+	counter_increment(metric Metric)
-	gauge_register(value f64, metric Metric)
+	histogram_record(value f64, metric Metric)
+	gauge_set(value f64, metric Metric)
+	gauge_add(value f64, metric Metric)
+	gauge_sub(value f64, metric Metric)
 }
 
 pub interface MetricsExporter {

null.v

@@ -7,10 +7,10 @@ pub fn new_null_collector() &NullCollector {
 	return &NullCollector{}
 }
 
-pub fn (c &NullCollector) counter_register(value u64, metric Metric) {}
-
 pub fn (c &NullCollector) counter_increment(metric Metric) {}
 
+pub fn (c &NullCollector) counter_set(value u64, metric Metric) {}
+
 pub fn (c &NullCollector) counter_get(metric Metric) ?u64 {
 	return none
 }
@@ -19,16 +19,12 @@ pub fn (c &NullCollector) counters() []Metric {
 	return []
 }
 
-pub fn (c &NullCollector) histogram_register(metric Metric) {}
-
 pub fn (c &NullCollector) histogram_record(value f64, metric Metric) {}
 
 pub fn (c &NullCollector) histogram_get(metric Metric) ?[]f64 {
 	return none
 }
 
-pub fn (c &NullCollector) gauge_register(value f64, metric Metric) {}
-
 pub fn (c &NullCollector) gauge_add(value f64, metric Metric) {}
 
 pub fn (c &NullCollector) gauge_sub(value f64, metric Metric) {}

prometheus_test.v

@@ -2,7 +2,6 @@ module metrics
 
 fn test_only_counters() {
 	mut m := new_default_collector()
-	m.counter_register(0, name: 'test')
 	m.counter_increment(name: 'test')
 
 	mut e := new_prometheus_exporter([])
@@ -14,7 +13,6 @@ fn test_only_counters() {
 		name: 'test2'
 		labels: [['hi', 'label']!, ['hi2', 'label2']!]
 	}
-	m.counter_register(0, metric)
 	m.counter_increment(metric)
 	m.counter_increment(metric)
 
@@ -23,7 +21,6 @@ fn test_only_counters() {
 
 fn test_only_gauges() {
 	mut m := new_default_collector()
-	m.gauge_register(0.0, name: 'test')
 	m.gauge_set(3.25, name: 'test')
 
 	mut e := new_prometheus_exporter([])
@@ -35,7 +32,6 @@ fn test_only_gauges() {
 		name: 'test2'
 		labels: [['hi', 'label']!, ['hi2', 'label2']!]
 	}
-	m.gauge_register(0.0, metric)
 	m.gauge_add(2.5, metric)
 
 	assert e.export_to_string()! == 'test 3.25\ntest2{hi="label",hi2="label2"} 2.5\n'
@@ -44,7 +40,6 @@ fn test_only_gauges() {
 fn test_single_histogram() {
 	mut m := new_default_collector()
 
-	m.histogram_register(name: 'test')
 	m.histogram_record(5.0, name: 'test')
 
 	mut e := new_prometheus_exporter([0.5, 5.0])