This is the "Boole map", described by George Boole (yes, that George Boole) in his 1857 "On the Comparison of Transcendents, with Certain Applications to the Theory of Definite Integrals". A standard modern reference is the 1973 paper by R. Adler and B. Weiss, "The ergodic measure preserving transformation of Boole". It shows up in the answer to this MSE question.