Add a test-only mechanism for metering most of the relevant resources…

… per-invocation.

This is an opt-in feature that will reset the budget and take a storage snapshot for every 'logical' invocation (such as `call` or a lifecycle operation). Then when the invocation is done we use the snapshot and current budget to produce the estimate for the resources consumed by the invocation (budget-related, IO-related and rent bumps).

This also provides a rough estimation for the respective fee breakdown given a fee config.

soroban-env-host/src/budget/dimension.rs

@@ -131,8 +131,12 @@ impl BudgetDimension {
 
     pub(crate) fn reset(&mut self, limit: u64) {
         self.limit = limit;
-        self.total_count = 0;
         self.shadow_limit = limit;
+        self.reset_count();
+    }
+
+    pub(crate) fn reset_count(&mut self) {
+        self.total_count = 0;
         self.shadow_total_count = 0;
     }
 

soroban-env-host/src/budget/util.rs

@@ -69,6 +69,15 @@ impl Budget {
         Ok(())
     }
 
+    pub fn reset(&self) -> Result<(), HostError> {
+        self.with_mut_budget(|mut b| {
+            b.cpu_insns.reset_count();
+            b.mem_bytes.reset_count();
+            Ok(())
+        })?;
+        self.reset_tracker()
+    }
+
     pub fn reset_cpu_limit(&self, cpu: u64) -> Result<(), HostError> {
         self.with_mut_budget(|mut b| {
             b.cpu_insns.reset(cpu);
@@ -157,7 +166,7 @@ impl Budget {
     }
 }
 
-#[cfg(any(test, feature = "recording_mode"))]
+#[cfg(any(test, feature = "recording_mode", feature = "testutils"))]
 impl Budget {
     /// Variant of `with_shadow_mode`, enabled only in testing and
     /// non-production scenarios, that produces a `Result<>` rather than eating

soroban-env-host/src/events/internal.rs

@@ -267,4 +267,9 @@ impl InternalEventsBuffer {
 
         Ok(Events(vec))
     }
+
+    #[cfg(any(test, feature = "testutils"))]
+    pub(crate) fn clear(&mut self) {
+        self.vec.clear();
+    }
 }

soroban-env-host/src/fees.rs

@@ -10,8 +10,8 @@ pub const TX_BASE_RESULT_SIZE: u32 = 300;
 /// Estimate for any `TtlEntry` ledger entry
 pub const TTL_ENTRY_SIZE: u32 = 48;
 
-const INSTRUCTIONS_INCREMENT: i64 = 10000;
-const DATA_SIZE_1KB_INCREMENT: i64 = 1024;
+pub const INSTRUCTIONS_INCREMENT: i64 = 10000;
+pub const DATA_SIZE_1KB_INCREMENT: i64 = 1024;
 
 // minimum effective write fee per 1KB
 pub const MINIMUM_WRITE_FEE_PER_1KB: i64 = 1000;

soroban-env-host/src/host.rs

@@ -28,6 +28,8 @@ mod data_helper;
 mod declared_size;
 pub(crate) mod error;
 pub(crate) mod frame;
+#[cfg(any(test, feature = "testutils"))]
+mod invocation_metering;
 pub(crate) mod ledger_info_helper;
 pub(crate) mod lifecycle;
 mod mem_helper;
@@ -61,6 +63,9 @@ pub(crate) use frame::Frame;
 #[cfg(any(test, feature = "recording_mode"))]
 use rand_chacha::ChaCha20Rng;
 
+#[cfg(any(test, feature = "testutils"))]
+use invocation_metering::InvocationMeter;
+
 #[cfg(any(test, feature = "testutils"))]
 #[derive(Clone, Copy)]
 pub enum ContractInvocationEvent {
@@ -166,6 +171,9 @@ struct HostImpl {
     #[doc(hidden)]
     #[cfg(any(test, feature = "recording_mode"))]
     need_to_build_module_cache: RefCell<bool>,
+
+    #[cfg(any(test, feature = "testutils"))]
+    pub(crate) invocation_meter: RefCell<InvocationMeter>,
 }
 
 // Host is a newtype on Rc<HostImpl> so we can impl Env for it below.
@@ -382,6 +390,8 @@ impl Host {
             suppress_diagnostic_events: RefCell::new(false),
             #[cfg(any(test, feature = "recording_mode"))]
             need_to_build_module_cache: RefCell::new(false),
+            #[cfg(any(test, feature = "testutils"))]
+            invocation_meter: Default::default(),
         }))
     }
 
@@ -2330,6 +2340,9 @@ impl VmCallerEnv for Host {
         _vmcaller: &mut VmCaller<Host>,
         wasm: BytesObject,
     ) -> Result<BytesObject, HostError> {
+        #[cfg(any(test, feature = "testutils"))]
+        let _invocation_meter_scope = self.maybe_meter_invocation()?;
+
         let wasm_vec =
             self.visit_obj(wasm, |bytes: &ScBytes| bytes.as_vec().metered_clone(self))?;
         self.upload_contract_wasm(wasm_vec)
@@ -2369,6 +2382,9 @@ impl VmCallerEnv for Host {
         func: Symbol,
         args: VecObject,
     ) -> Result<Val, HostError> {
+        #[cfg(any(test, feature = "testutils"))]
+        let _invocation_meter_scope = self.maybe_meter_invocation()?;
+
         let argvec = self.call_args_from_obj(args)?;
         // this is the recommended path of calling a contract, with `reentry`
         // always set `ContractReentryMode::Prohibited`
@@ -2396,6 +2412,9 @@ impl VmCallerEnv for Host {
         func: Symbol,
         args: VecObject,
     ) -> Result<Val, HostError> {
+        #[cfg(any(test, feature = "testutils"))]
+        let _invocation_meter_scope = self.maybe_meter_invocation()?;
+
         let argvec = self.call_args_from_obj(args)?;
         // this is the "loosened" path of calling a contract.
         // TODO: A `reentry` flag will be passed from `try_call` into here.
@@ -3477,6 +3496,31 @@ impl Host {
             )
         })
     }
+
+    /// Returns the resources metered during the last logical contract invocation.
+    ///
+    /// Logical invocations include the direct `invoke_host_function` calls,
+    /// `call`/`try_call` functions, contract lifecycle management operations.
+    ///
+    /// Take the return value with a grain of salt. The returned resources mostly
+    /// correspond only to the operations that have happened during the host
+    /// invocation, i.e. this won't try to simulate the work that happens in
+    /// production scenarios (e.g. certain XDR rountrips). This also doesn't try
+    /// to model resources related to the transaction size.
+    ///
+    /// The returned value is as useful as the preceding setup, e.g. if a test
+    /// contract is used instead of a Wasm contract, all the costs related to
+    /// VM instantiation and execution, as well as Wasm reads/rent bumps will be
+    /// missed.
+    pub fn get_last_invocation_resources(
+        &self,
+    ) -> Option<invocation_metering::InvocationResources> {
+        if let Ok(scope) = self.0.invocation_meter.try_borrow() {
+            scope.get_invocation_resources()
+        } else {
+            None
+        }
+    }
 }
 
 impl Host {

soroban-env-host/src/host/frame.rs

@@ -1069,6 +1069,9 @@ impl Host {
 
     // Notes on metering: covered by the called components.
     pub fn invoke_function(&self, hf: HostFunction) -> Result<ScVal, HostError> {
+        #[cfg(any(test, feature = "testutils"))]
+        let _invocation_meter_scope = self.maybe_meter_invocation()?;
+
         let rv = self.invoke_function_and_return_val(hf)?;
         self.from_host_val(rv)
     }