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package balancer |
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import ( |
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"crypto/rand" |
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"fmt" |
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"log" |
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"math/big" |
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"google.golang.org/grpc/balancer" |
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"github.com/Permify/permify/pkg/consistent" |
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) |
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type picker struct { |
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consistent *consistent.Consistent |
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width int |
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} |
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// Generate a cryptographically secure random index function with resilient error handling |
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var randomIndex = func(max int) int { |
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// Ensure max > 0 to avoid issues |
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if max <= 0 { |
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log.Println("randomIndex: max value is less than or equal to 0, returning 0 as fallback") |
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return 0 |
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} |
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// Use crypto/rand to generate a random index |
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n, err := rand.Int(rand.Reader, big.NewInt(int64(max))) |
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if err != nil { |
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// Log the error and return a deterministic fallback value (e.g., 0) |
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log.Printf("randomIndex: failed to generate a secure random number, returning 0 as fallback: %v", err) |
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return 0 |
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} |
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return int(n.Int64()) |
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} |
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func (p *picker) Pick(info balancer.PickInfo) (balancer.PickResult, error) { |
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// Safely extract the key from the context |
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keyValue := info.Ctx.Value(Key) |
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if keyValue == nil { |
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return balancer.PickResult{}, fmt.Errorf("context key missing") |
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} |
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key, ok := keyValue.([]byte) |
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if !ok { |
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return balancer.PickResult{}, fmt.Errorf("context key is not of type []byte") |
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} |
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// Retrieve the closest N members |
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members, err := p.consistent.ClosestN(key, p.width) |
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if err != nil { |
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return balancer.PickResult{}, fmt.Errorf("failed to get closest members: %w", err) |
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} |
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if len(members) == 0 { |
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return balancer.PickResult{}, fmt.Errorf("no available members") |
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} |
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// Randomly pick one member if width > 1 |
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index := 0 |
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if p.width > 1 { |
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index = randomIndex(p.width) |
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} |
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// Assert the member type |
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chosen, ok := members[index].(ConsistentMember) |
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if !ok { |
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return balancer.PickResult{}, fmt.Errorf("invalid member type: expected subConnMember") |
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} |
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// Return the chosen connection |
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return balancer.PickResult{SubConn: chosen.SubConn}, nil |
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} |
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Permify /
permify
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