Lock-Based Protocols(Cont. concurrency-control manager lock-X(B) grant-x(B,T1) read (B) B:=B-50 write(B) unlock(B) lock-S(A grant-S A,T2) read(A) unlock(A lock-S(B) grant-s(B, T2) read(B) unlock(B display(A+B) lock-X(A) grant-X(A, T1) read (A A:=A+50 write(A) unlock(B) Database System Concepts 3rd Edition 16.5 OSilberschatz, Korth and SudarshanDatabase System Concepts 3 16.5 ©Silberschatz, Korth and Sudarshan rd Edition Lock-Based Protocols (Cont.) T1 T2 concurrency-control manager lock-X(B) grant-X(B,T1) read (B) B:=B-50 write(B) unlock(B) lock-S(A) grant-S(A,T2) read (A) unlock(A) lock-S(B) grant-S(B,T2) read (B) unlock(B) display(A+B) lock-X(A) grant-X(A,T1) read(A) A:=A+50 write(A) unlock(B)