add accesslog+proxy example

context/counter.go

@@ -0,0 +1,49 @@
+package context
+
+import (
+	"math"
+	"sync/atomic"
+)
+
+// Counter is the shared counter instances between Iris applications of the same process.
+var Counter = NewGlobalCounter() // it's not used anywhere, currently but it's here.
+
+// NewGlobalCounter returns a fresh instance of a global counter.
+// End developers can use it as a helper for their applications.
+func NewGlobalCounter() *GlobalCounter {
+	return &GlobalCounter{Max: math.MaxUint64}
+}
+
+// GlobalCounter is a counter which
+// atomically increments until Max.
+type GlobalCounter struct {
+	value uint64
+	Max   uint64
+}
+
+// Increment increments the Value.
+// The value cannot exceed the Max one.
+// It uses Compare and Swap with the atomic package.
+//
+// Returns the new number value.
+func (c *GlobalCounter) Increment() (newValue uint64) {
+	for {
+		prev := atomic.LoadUint64(&c.value)
+		newValue = prev + 1
+
+		if newValue >= c.Max {
+			newValue = 0
+		}
+
+		if atomic.CompareAndSwapUint64(&c.value, prev, newValue) {
+			break
+		}
+	}
+
+	return
+}
+
+// Get returns the current counter without incrementing.
+func (c *GlobalCounter) Get() uint64 {
+	return atomic.LoadUint64(&c.value)
+}