first commit

core/keyselectors/weightedrandom.go

@@ -0,0 +1,35 @@
+package keyselectors
+
+import (
+	"math/rand"
+
+	"github.com/maximhq/bifrost/core/schemas"
+)
+
+func WeightedRandom(ctx *schemas.BifrostContext, keys []schemas.Key, providerKey schemas.ModelProvider, model string) (schemas.Key, error) {
+	// Use a weighted random selection based on key weights
+	totalWeight := 0
+	for _, key := range keys {
+		totalWeight += int(key.Weight * 100) // Convert float to int for better performance
+	}
+
+	// If all keys have zero weight, fall back to uniform random selection
+	if totalWeight == 0 {
+		return keys[rand.Intn(len(keys))], nil
+	}
+
+	// Use global thread-safe random (Go 1.20+) - no allocation, no syscall
+	randomValue := rand.Intn(totalWeight)
+
+	// Select key based on weight
+	currentWeight := 0
+	for _, key := range keys {
+		currentWeight += int(key.Weight * 100)
+		if randomValue < currentWeight {
+			return key, nil
+		}
+	}
+
+	// Fallback to first key if something goes wrong
+	return keys[0], nil
+}