HIP-584: Handle read only precompile calls via ViewExecutor/RedirectV…

…iewExecutor (#6557)

This PR allows all type of calls (view/pure/dynamic) to read only precompiles to be handled via ViewExecutor/RedirectViewExecutor, thus removing the need of having a copy of separate precompile class implementations.

That is possible since the executors read the data from the same place (the Store interface) and they share the same gas calculation logic with the precompile class implementations in hedera-services codebase. Consequently, we could just reuse the executor logic to handle eth_call and eth_estimateGas requests.

Signed-off-by: Ivan Ivanov <ivanivanov.ii726@gmail.com>
Signed-off-by: IvanKavaldzhiev <ivankavaldzhiev@gmail.com>
Co-authored-by: Ivan Ivanov <ivanivanov.ii726@gmail.com>

hedera-mirror-web3/src/main/java/com/hedera/services/store/contracts/precompile/HTSPrecompiledContract.java

@@ -63,14 +63,17 @@
 import org.hyperledger.besu.datatypes.Address;
 import org.hyperledger.besu.evm.frame.ExceptionalHaltReason;
 import org.hyperledger.besu.evm.frame.MessageFrame;
-import org.hyperledger.besu.evm.precompile.PrecompiledContract;
 import org.hyperledger.besu.evm.precompile.PrecompiledContract.PrecompileContractResult;
 
 /**
  * This class is a modified copy of HTSPrecompiledContract from hedera-services repo. Additionally, it implements an
  * adapter interface which is used by
  * {@link com.hedera.mirror.web3.evm.store.contract.precompile.MirrorHTSPrecompiledContract}. In this way once we start
  * consuming libraries like smart-contract-service it would be easier to delete the code base inside com.hedera.services package.
+ *
+ * Differences with the original class:
+ * 1. Use abstraction for the state by introducing {@link Store} interface.
+ * 2. Use workaround to execute read only precompiles via calling ViewExecutor and RedirectViewExecutors, thus removing the need of having separate precompile classes
  */
 public class HTSPrecompiledContract implements HTSPrecompiledContractAdapter {
 
@@ -132,21 +135,20 @@ public Pair<Long, Bytes> computeCosted(
 
             return evmHTSPrecompiledContract.computeCosted(input, frame, viewGasCalculator, tokenAccessor);
         }
-        final var result = computePrecompile(input, frame);
-        return Pair.of(gasRequirement, result.getOutput());
-    }
 
-    @NonNull
-    public PrecompileContractResult computePrecompile(final Bytes input, @NonNull final MessageFrame frame) {
-        /* TODO Temporary workaround allowing eth_call to execute precompile methods in a dynamic context (non pure/view).
-        This is done by calling ViewExecutor/RedirectViewExecutor logic instead of Precompile classes.
-        After the Precompile classes are implemented, this workaround won't be needed. */
+        /* Workaround allowing execution of read only precompile methods in a dynamic context (non pure/view).
+        This is done by calling ViewExecutor/RedirectViewExecutor logic instead of Precompile classes.*/
 
-        // redirect operations
         if ((isTokenProxyRedirect(input) || isViewFunction(input)) && !isNestedFunctionSelectorForWrite(input)) {
             return handleReadsFromDynamicContext(input, frame);
         }
 
+        final var result = computePrecompile(input, frame);
+        return Pair.of(gasRequirement, result.getOutput());
+    }
+
+    @NonNull
+    public PrecompileContractResult computePrecompile(final Bytes input, @NonNull final MessageFrame frame) {
         if (unqualifiedDelegateDetected(frame)) {
             frame.setExceptionalHaltReason(Optional.of(ExceptionalHaltReason.PRECOMPILE_ERROR));
             return INVALID_DELEGATE;
@@ -357,8 +359,7 @@ void prepareFields(final MessageFrame frame) {
         this.mirrorNodeEvmProperties = updater.aliases();
     }
 
-    private PrecompiledContract.PrecompileContractResult handleReadsFromDynamicContext(
-            final Bytes input, @NonNull final MessageFrame frame) {
+    private Pair<Long, Bytes> handleReadsFromDynamicContext(final Bytes input, @NonNull final MessageFrame frame) {
         Pair<Long, Bytes> resultFromExecutor = Pair.of(-1L, Bytes.EMPTY);
         if (isTokenProxyRedirect(input)) {
             final var executor =
@@ -368,14 +369,11 @@ private PrecompiledContract.PrecompileContractResult handleReadsFromDynamicConte
             if (resultFromExecutor.getRight() == null) {
                 throw new UnsupportedOperationException(UNSUPPORTED_ERROR);
             }
-
         } else if (isViewFunction(input)) {
             final var executor = infrastructureFactory.newViewExecutor(input, frame, viewGasCalculator, tokenAccessor);
             resultFromExecutor = executor.computeCosted();
         }
-        return resultFromExecutor == null
-                ? PrecompileContractResult.halt(null, Optional.of(ExceptionalHaltReason.NONE))
-                : PrecompileContractResult.success(resultFromExecutor.getRight());
+        return resultFromExecutor;
     }
 
     private boolean isNestedFunctionSelectorForWrite(Bytes input) {