+ statistics: store in separate file

+ GET /control/stats handler

stats/stats.go

@@ -0,0 +1,68 @@
+// Module for managing statistics for DNS filtering server
+
+package stats
+
+import (
+	"net"
+)
+
+type unitIDCallback func() int
+
+// New - create object
+// filename: DB file name
+// limit: time limit (in days)
+// unitID: user function to get the current unit ID.  If nil, the current time hour is used.
+func New(filename string, limit int, unitID unitIDCallback) Stats {
+	return createObject(filename, limit, unitID)
+}
+
+// Stats - main interface
+type Stats interface {
+	// Close object.
+	// This function is not thread safe
+	//  (can't be called in parallel with any other function of this interface).
+	Close()
+
+	// Set new configuration at runtime.
+	// limit: time limit (in days)
+	Configure(limit int)
+
+	// Reset counters and clear database
+	Clear()
+
+	// Update counters
+	Update(e Entry)
+
+	// Get data
+	GetData(timeUnit TimeUnit) map[string]interface{}
+}
+
+// TimeUnit - time unit
+type TimeUnit int
+
+// Supported time units
+const (
+	Hours TimeUnit = iota
+	Days
+)
+
+// Result of DNS request processing
+type Result int
+
+// Supported result values
+const (
+	RNotFiltered Result = iota + 1
+	RFiltered
+	RSafeBrowsing
+	RSafeSearch
+	RParental
+	rLast
+)
+
+// Entry - data to add
+type Entry struct {
+	Domain string
+	Client net.IP
+	Result Result
+	Time   uint // processing time (msec)
+}