[core] add gas arg to ext_gas_price (#461)

* add gas argument

* Add gas parameter to ext_gas_price

* Fix up gas_price offchain api

* Fix up env_access api

* Emulate gas price calculation

* Make clippy happy

* Use Saturating impl for emulating gas price calculation offchain

* Fmt

* Add offchain gas_price test

* Make clippy happy

core/src/env/api.rs

@@ -60,17 +60,17 @@ where
     })
 }
 
-/// Returns the current price for gas.
+/// Returns the price for the specified amount of gas.
 ///
 /// # Errors
 ///
 /// If the returned value cannot be properly decoded.
-pub fn gas_price<T>() -> Result<T::Balance>
+pub fn gas_price<T>(gas: u64) -> Result<T::Balance>
 where
     T: EnvTypes,
 {
     <EnvInstance as OnInstance>::on_instance(|instance| {
-        TypedEnv::gas_price::<T>(instance)
+        TypedEnv::gas_price::<T>(instance, gas)
     })
 }
 

core/src/env/arithmetic.rs

@@ -14,7 +14,12 @@
 
 //! Primitive traits for runtime arithmetic, copied from substrate
 
-use core::ops::{
+use core::{
+    convert::{
+        TryFrom,
+        TryInto,
+    },
+    ops::{
         Add,
         AddAssign,
         Div,
@@ -23,6 +28,7 @@ use core::ops::{
         MulAssign,
         Sub,
         SubAssign,
+    },
 };
 use num_traits::{
     checked_pow,
@@ -40,7 +46,7 @@ use num_traits::{
 /// if needed.
 pub trait BaseArithmetic:
     Sized
-    + From<u32>
+    + From<u8>
     + Bounded
     + Ord
     + PartialOrd<Self>
@@ -57,21 +63,19 @@ pub trait BaseArithmetic:
     + DivAssign<Self>
     + CheckedMul
     + Saturating
+    + TryFrom<u16>
+    + TryFrom<u32>
+    + TryFrom<u64>
+    + TryFrom<u128>
+    + TryFrom<usize>
+    + TryInto<u16>
+    + TryInto<u32>
+    + TryInto<u64>
+    + TryInto<u128>
+    + TryInto<usize>
 // Further trait bounds from the original BaseArithmetic trait
 // that we could use to extend ink!'s BaseArithmetic trait.
 //
-// From<u8> +
-// From<u16> +
-// From<u32> +
-// TryFrom<u64> +
-// TryFrom<u128> +
-// TryFrom<usize> +
-// TryInto<u8> +
-// TryInto<u16> +
-// TryInto<u32> +
-// TryInto<u64> +
-// TryInto<u128> +
-// TryInto<usize> +
 // UniqueSaturatedInto<u8> +
 // UniqueSaturatedInto<u16> +
 // UniqueSaturatedInto<u32> +
@@ -92,7 +96,7 @@ pub trait BaseArithmetic:
 
 impl<T> BaseArithmetic for T where
     T: Sized
-        + From<u32>
+        + From<u8>
         + Bounded
         + Ord
         + PartialOrd<Self>
@@ -108,6 +112,16 @@ impl<T> BaseArithmetic for T where
         + DivAssign<Self>
         + CheckedMul
         + Saturating
+        + TryFrom<u16>
+        + TryFrom<u32>
+        + TryFrom<u64>
+        + TryFrom<u128>
+        + TryFrom<usize>
+        + TryInto<u16>
+        + TryInto<u32>
+        + TryInto<u64>
+        + TryInto<u128>
+        + TryInto<usize>
 {
 }
 

core/src/env/backend.rs

@@ -126,12 +126,12 @@ pub trait TypedEnv: Env {
     /// For more details visit: [`ink_core::env::transferred_balance`]
     fn transferred_balance<T: EnvTypes>(&mut self) -> Result<T::Balance>;
 
-    /// Returns the current price for gas.
+    /// Returns the price for the specified amount of gas.
     ///
     /// # Note
     ///
     /// For more details visit: [`ink_core::env::gas_price`]
-    fn gas_price<T: EnvTypes>(&mut self) -> Result<T::Balance>;
+    fn gas_price<T: EnvTypes>(&mut self, gas: u64) -> Result<T::Balance>;
 
     /// Returns the amount of gas left for the contract execution.
     ///

core/src/env/engine/off_chain/db/chain_spec.rs

@@ -75,6 +75,14 @@ impl ChainSpec {
         self.gas_price.decode().map_err(Into::into)
     }
 
+    /// Set the gas price for the chain.
+    pub fn set_gas_price<T>(&mut self, gas_price: T::Balance)
+    where
+        T: EnvTypes
+    {
+        self.gas_price = OffBalance::new(&gas_price)
+    }
+
     /// Returns the minimum balance for an account on the chain.
     pub fn minimum_balance<T>(&self) -> Result<T::Balance>
     where

core/src/env/engine/off_chain/impls.rs

@@ -31,6 +31,8 @@ use crate::env::{
     TypedEnv,
 };
 use ink_primitives::Key;
+use core::convert::TryInto;
+use num_traits::Bounded;
 
 impl EnvInstance {
     /// Returns the callee account.
@@ -153,11 +155,15 @@ impl TypedEnv for EnvInstance {
             .map_err(Into::into)
     }
 
-    fn gas_price<T: EnvTypes>(&mut self) -> Result<T::Balance> {
-        self.chain_spec
+    /// Emulates gas price calculation
+    fn gas_price<T: EnvTypes>(&mut self, gas: u64) -> Result<T::Balance> {
+        use crate::env::arithmetic::Saturating as _;
+
+        let gas_price = self.chain_spec
             .gas_price::<T>()
-            .map_err(|_| scale::Error::from("could not decode gas price"))
-            .map_err(Into::into)
+            .map_err(|_| scale::Error::from("could not decode gas price"))?;
+
+        Ok(gas_price.saturating_mul(gas.try_into().unwrap_or_else(|_| Bounded::max_value())))
     }
 
     fn gas_left<T: EnvTypes>(&mut self) -> Result<T::Balance> {

core/src/env/engine/off_chain/mod.rs

@@ -254,6 +254,10 @@ impl EnvInstance {
             .last_mut()
             .ok_or_else(|| OffChainError::UninitializedBlocks)
     }
+
+    fn chain_spec_mut(&mut self) -> &mut ChainSpec {
+        &mut self.chain_spec
+    }
 }
 
 impl OnInstance for EnvInstance {

core/src/env/engine/off_chain/test_api.rs

@@ -25,6 +25,7 @@ use super::{
 use crate::env::{
     EnvTypes,
     Result,
+    engine::off_chain::db::ChainSpec,
 };
 use ink_prelude::string::String;
 
@@ -210,6 +211,17 @@ where
     .map_err(Into::into)
 }
 
+/// Update the [ChainSpec](`crate::env::engine::off_chain::db::ChainSpec`) for the test environment
+pub fn update_chain_spec<F>(f: F) -> Result<()>
+where
+    F: FnOnce(&mut ChainSpec)
+{
+    <EnvInstance as OnInstance>::on_instance(|instance| {
+        f(instance.chain_spec_mut())
+    });
+    Ok(())
+}
+
 /// Returns the contents of the past performed environmental `println` in order.
 pub fn recorded_printlns() -> impl Iterator<Item = String> {
     <EnvInstance as OnInstance>::on_instance(|instance| {

core/src/env/engine/off_chain/tests.rs

@@ -68,3 +68,19 @@ fn key_add_sub() -> Result<()> {
         Ok(())
     })
 }
+
+#[test]
+fn gas_price() -> env::Result<()> {
+    env::test::run_test::<env::DefaultEnvTypes, _>(|_| {
+        let gas_price= 2u32;
+        env::test::update_chain_spec(|chain_spec| {
+            chain_spec.set_gas_price::<env::DefaultEnvTypes>(gas_price.into())
+        })?;
+
+        assert_eq!(2u128, env::gas_price::<env::DefaultEnvTypes>(1).unwrap());
+        assert_eq!(20u128, env::gas_price::<env::DefaultEnvTypes>(10).unwrap());
+        assert_eq!(6u128, env::gas_price::<env::DefaultEnvTypes>(3).unwrap());
+
+        Ok(())
+    })
+}

core/src/env/engine/on_chain/ext.rs

@@ -89,7 +89,7 @@ mod sys {
         pub fn ext_block_number();
         pub fn ext_address();
         pub fn ext_balance();
-        pub fn ext_gas_price();
+        pub fn ext_gas_price(gas: u64);
         pub fn ext_gas_left();
         pub fn ext_value_transferred();
         pub fn ext_now();
@@ -285,7 +285,6 @@ impl_ext_wrapper_for! {
     (block_number => ext_block_number),
     (address => ext_address),
     (balance => ext_balance),
-    (gas_price => ext_gas_price),
     (gas_left => ext_gas_left),
     (value_transferred => ext_value_transferred),
     (now => ext_now),
@@ -294,6 +293,10 @@ impl_ext_wrapper_for! {
     (tombstone_deposit => ext_tombstone_deposit),
 }
 
+pub fn gas_price(gas: u64) {
+    unsafe { sys::ext_gas_price(gas) }
+}
+
 pub fn set_rent_allowance(value: &[u8]) {
     unsafe { sys::ext_set_rent_allowance(value.as_ptr() as u32, value.len() as u32) }
 }

core/src/env/engine/on_chain/impls.rs

@@ -208,10 +208,6 @@ impl TypedEnv for EnvInstance {
         self.get_property::<T::Balance>(ext::value_transferred)
     }
 
-    fn gas_price<T: EnvTypes>(&mut self) -> Result<T::Balance> {
-        self.get_property::<T::Balance>(ext::gas_price)
-    }
-
     fn gas_left<T: EnvTypes>(&mut self) -> Result<T::Balance> {
         self.get_property::<T::Balance>(ext::gas_left)
     }
@@ -380,6 +376,11 @@ impl TypedEnv for EnvInstance {
         ext::transfer(destination, value)
     }
 
+    fn gas_price<T: EnvTypes>(&mut self, gas: u64) -> Result<T::Balance> {
+        ext::gas_price(gas);
+        self.decode_scratch_buffer().map_err(Into::into)
+    }
+
     fn random<T>(&mut self, subject: &[u8]) -> Result<T::Hash>
     where
         T: EnvTypes,

lang/src/env_access.rs

@@ -104,13 +104,13 @@ where
         env::transferred_balance::<T>().expect("couldn't decode transferred balance")
     }
 
-    /// Returns the current price for gas.
+    /// Returns the price for the specified amount of gas.
     ///
     /// # Note
     ///
     /// For more details visit: [`ink_core::env::gas_price`]
-    pub fn gas_price(self) -> T::Balance {
-        env::gas_price::<T>().expect("couldn't decode gas price")
+    pub fn gas_price(self, gas: u64) -> T::Balance {
+        env::gas_price::<T>(gas).expect("couldn't decode gas price")
     }
 
     /// Returns the amount of gas left for the contract execution.