Today we will cover the analogs of all the block variables from solidity. Not all of them have 1-1 analogs. In solidity, we have the following commonly used block variables:
- block.timestamp
- block.number
- block.hash()
And the lesser known ones:
- block.coinbase
- block.gaslimit
- block.basefee
- block.difficulty
Let's go through one by one, create a new program first.
anchor new day_11
By utilizing the unix_timestamp field within the Clock sysvar, we can access the block timestamp Solana.
use anchor_lang::prelude::*;
declare_id!("2SCX7gj5ByjWvin16BNNDjZxEcsikX15DWMMccc7EVXD");
#[program]
pub mod day_11 {
use super::*;
pub fn get_timestamp(ctx: Context<Initialize>) -> Result<()> {
let clock: Clock = Clock::get()?;
msg!("Current Unix Timestamp: {}", clock.unix_timestamp);
Ok(())
}
}
#[derive(Accounts)]
pub struct Initialize {}test:
let's div further to get the day of the week, we need to use a new carte: chrono, it provides functionality for operations on dates and times in Rust.
# day_11/Cargo.toml
[dependencies]
anchor-lang = "0.30.1"
chrono = "0.4.31"update code, be sure to import use chrono::*
pub fn get_day_of_week(ctx: Context<Initialize>) -> Result<()> {
let clock: Clock = Clock::get()?;
let time_stamp = clock.unix_timestamp;
// let date_time = chrono::NaiveDateTime::from_timestamp(time_stamp, 0); // DEPRECATED!!
let date_time = DateTime::from_timestamp(time_stamp, 0);
msg!(
"Day of the week: {:?}",
date_time.expect("REASON").weekday() // ATTENTION!!
);
Ok(())
}output:
solana has a notion of a slot number which is very related to the block number, we will defer a full discussion of how to get the block number in later tutorials.
In Ethereum, the block.coinbase represents the address of the minter who has successfully minted a block in Proof of Work.
On the other hand, solana uses a leader-based consensus mechanism which is a combination of both Proof of History(POH) and Proof of Stake(POS), removing the concept of mining.
Instead, a block or slot leader is appointed to validate transactions and propose blocks during certain intervals, user a system known as the leader schedule. This schedule determines who will be the block producer at a certain time.
However, presently, there's no specific way to access the address of the block leader in Solana programs.
We include this section for completeness. There is no way to get hash in the future, the current function would be deprecated soon.
Solana has a per-block compute unit limit of 48 million. Each transaction is by default limited to 200,000 compute units, though it can be raised to 1.4 million computes(disscuss later).
In Ethereum, the basefee is dynamice due EIP-1559, it is a function of pervious block utilization.
In Solana, the base price of a transaction is static, so there is no need for a variable like this.
Block difficulty is a concept associated with Proof of Work(PoW) blockchains.
Solana, on the other hand, operates on a Proof of History(PoH) combined with Proof of Stake(Pos) consensus mechanism, which doesn't involve the concept of block difficulty.
Solana doesn't have a chain id because it is not an EVM compatible chain.
Solana runs separate clusters for Devnet, Testnet, and Mainnet, but programs donot have a mechanism to know which one tye are on.
We can programatically adjust your code at deploy time using the Rust cfg feature to have different features depending on which cluster it is deployed to.
- block.timestamp => Clock
- block.number => slot number
- block.coinbase => N/A
- block.hash => N/A
- block.gaslimit => 48million compute units
- block.basefee => N/A
- block.difficulty => N/A
- block.chainid => N/A
- day_11 original article: https://www.rareskills.io/post/solana-clock
- source code: https://github.com/dukedaily/solana-expert-code/tree/day_11