Get Current TimeStamp

Question

I am working on the Solana contract with rust language and faced one critical problem.

In order to get current Unix timestamp, I used SystemTime like below.

let current_timestamp: i64 = SystemTime::now()
        .duration_since(UNIX_EPOCH)
        .unwrap()
        .as_secs() as i64;

Btw, the client asking to not to use SystemTime because it waste too many compute unit.
For this problem, I used BpfClock but it doesn't pass the unit test.

let clock = BpfClock::get()?;
let current_timestamp: i64 = clock.unix_timestamp;

The unit test result below error message:

thread 'processor::tests::test_withdraw' panicked at 'called `Result::unwrap()` on an `Err` value: UnsupportedSysvar'

Answer 1

This is expected behavior. On-chain, you do not have access to the system time, only utilities that are exposed by the runtime, so SystemTime::now() will completely fail on-chain. You can read more about these restrictions at https://docs.solana.com/developing/on-chain-programs/developing-rust#restrictions

To access the clock, you are doing the right thing, but you must be runing in some sort of runtime-like environment for this to work. This could be fully on-chain or through solana_program_test, which gives access to utilities such as Clock. You can see a working example of using the Clock on-chain at https://github.com/solana-labs/solana-program-library/tree/master/examples/rust/sysvar

Be sure to run the tests using cargo test-bpf from the Solana CLI -- you can find the installation instructions at https://docs.solana.com/cli/install-solana-cli-tools