first shot at debouncer - coming up: tests

Author: shabanzd

pkg/storage/debouncer.go

@@ -0,0 +1,81 @@
+package storage
+
+import (
+	"container/list"
+	"net/http"
+	"sync"
+)
+
+type Debouncer struct {
+	mtx        sync.RWMutex
+	requests   *list.List
+	cache      map[string]*list.Element
+	capacityMB float64
+	sizeMB     float64
+}
+
+type RequestNode struct {
+	value *http.Request
+}
+
+func NewDebouncer(maxSizeMB float64) *Debouncer {
+	if maxSizeMB <= 0 {
+		maxSizeMB = 50.0
+	}
+
+	return &Debouncer{
+		capacityMB: maxSizeMB,
+		sizeMB:     0.0,
+		requests:   list.New(),
+		cache:      make(map[string]*list.Element),
+	}
+}
+
+func (debouncer *Debouncer) Store(key string, value *http.Request) {
+	debouncer.mtx.Lock()
+	defer debouncer.mtx.Unlock()
+
+	bodySizeMB := debouncer.getSize(*value)
+
+	if bodySizeMB < 0 || (bodySizeMB+debouncer.sizeMB > debouncer.capacityMB) {
+		return
+	}
+
+	if _, found := debouncer.cache[key]; !found {
+		element := debouncer.requests.PushFront(&RequestNode{value: value})
+		debouncer.cache[key] = element
+	}
+}
+
+func (debouncer *Debouncer) GetNext() *http.Request {
+	debouncer.mtx.RLock()
+	defer debouncer.mtx.RUnlock()
+
+	return debouncer.requests.Back().Value.(*RequestNode).value
+}
+
+func (debouncer *Debouncer) Erase(key string) bool {
+	debouncer.mtx.RLock()
+	defer debouncer.mtx.RUnlock()
+
+	if val, found := debouncer.cache[key]; found {
+		delete(debouncer.cache, key)
+		debouncer.requests.Remove(val)
+
+		return true
+	}
+
+	return false
+}
+
+func (debouncer *Debouncer) getSize(value http.Request) float64 {
+	sizeBytes := value.ContentLength
+
+	if sizeBytes < 0 {
+		return -1.0
+	}
+
+	sizeMB := float64(sizeBytes) / (1024 * 1024)
+
+	return sizeMB
+}