Choosing a contour for residue integral

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How can I evaluate $$\int_0^{\infty}\frac{x\sin(bx)}{x^2+1}dx \quad(b>0)$$ using residue calculus? I tried computing the residue of $\int_0^{\infty}\frac{z\exp(ibz)}{z^2+1}dz$ at $z=i$ and taking the imaginary part of it, but what contour should I use so that only the integral over the real axis is left?