[RFC] Add native function create_uuid

aptos-move/aptos-vm/src/move_vm_ext/vm.rs

@@ -112,7 +112,11 @@ impl MoveVmExt {
             _ => vec![],
         };
 
-        extensions.add(NativeTransactionContext::new(script_hash, self.chain_id));
+        extensions.add(NativeTransactionContext::new(
+            txn_hash.to_vec(),
+            script_hash,
+            self.chain_id,
+        ));
         extensions.add(NativeCodeContext::default());
         extensions.add(NativeStateStorageContext::new(remote));
 

aptos-move/aptos-vm/src/natives.rs

@@ -91,7 +91,11 @@ pub fn configure_for_unit_test() {
 #[cfg(feature = "testing")]
 fn unit_test_extensions_hook(exts: &mut NativeContextExtensions) {
     exts.add(NativeCodeContext::default());
-    exts.add(NativeTransactionContext::new(vec![1], ChainId::test().id())); // We use the testing environment chain ID here
+    exts.add(NativeTransactionContext::new(
+        vec![1],
+        vec![1],
+        ChainId::test().id(),
+    )); // We use the testing environment chain ID here
     exts.add(NativeAggregatorContext::new(
         [0; 32],
         &*DUMMY_RESOLVER,

aptos-move/framework/aptos-framework/doc/transaction_context.md

@@ -5,6 +5,7 @@
 
 
 
+-  [Function `create_guid`](#0x1_transaction_context_create_guid)
 -  [Function `get_script_hash`](#0x1_transaction_context_get_script_hash)
 -  [Specification](#@Specification_0)
     -  [Function `get_script_hash`](#@Specification_0_get_script_hash)
@@ -14,6 +15,29 @@
 
 
 
+<a name="0x1_transaction_context_create_guid"></a>
+
+## Function `create_guid`
+
+Return a globally unique identifier
+
+
+<pre><code><b>public</b> <b>fun</b> <a href="transaction_context.md#0x1_transaction_context_create_guid">create_guid</a>(): <b>address</b>
+</code></pre>
+
+
+
+<details>
+<summary>Implementation</summary>
+
+
+<pre><code><b>public</b> <b>native</b> <b>fun</b> <a href="transaction_context.md#0x1_transaction_context_create_guid">create_guid</a>(): <b>address</b>;
+</code></pre>
+
+
+
+</details>
+
 <a name="0x1_transaction_context_get_script_hash"></a>
 
 ## Function `get_script_hash`

aptos-move/framework/aptos-framework/sources/transaction_context.move

@@ -1,4 +1,7 @@
 module aptos_framework::transaction_context {
+    /// Return a globally unique identifier 
+    public native fun create_guid(): address;
+
     /// Return the script hash of the current entry function.
     public native fun get_script_hash(): vector<u8>;
 }

aptos-move/framework/src/natives/mod.rs

@@ -227,6 +227,7 @@ impl GasParameters {
             },
             transaction_context: transaction_context::GasParameters {
                 get_script_hash: transaction_context::GetScriptHashGasParameters { base: 0.into() },
+                create_guid: transaction_context::CreateGUIDGasParameters { base: 0.into() },
             },
             code: code::GasParameters {
                 request_publish: code::RequestPublishGasParameters {

aptos-move/framework/src/natives/transaction_context.rs

@@ -4,9 +4,10 @@
 use crate::natives::helpers::{make_safe_native, SafeNativeContext, SafeNativeResult};
 use aptos_types::on_chain_config::{Features, TimedFeatures};
 use better_any::{Tid, TidAble};
-use move_core_types::gas_algebra::InternalGas;
+use move_core_types::{account_address::AccountAddress, gas_algebra::InternalGas};
 use move_vm_runtime::native_functions::NativeFunction;
 use move_vm_types::{loaded_data::runtime_types::Type, values::Value};
+use sha2::{Digest, Sha256};
 use smallvec::{smallvec, SmallVec};
 use std::{collections::VecDeque, fmt::Debug, sync::Arc};
 
@@ -15,15 +16,20 @@ use std::{collections::VecDeque, fmt::Debug, sync::Arc};
 /// natives of this extension.
 #[derive(Tid)]
 pub struct NativeTransactionContext {
+    txn_hash: Vec<u8>,
+    /// This is the number of GUIDs (Globally unique identifiers) issued during the execution of this transaction
+    guid_counter: u64,
     script_hash: Vec<u8>,
     chain_id: u8,
 }
 
 impl NativeTransactionContext {
     /// Create a new instance of a native transaction context. This must be passed in via an
     /// extension into VM session functions.
-    pub fn new(script_hash: Vec<u8>, chain_id: u8) -> Self {
+    pub fn new(txn_hash: Vec<u8>, script_hash: Vec<u8>, chain_id: u8) -> Self {
         Self {
+            txn_hash,
+            guid_counter: 0,
             script_hash,
             chain_id,
         }
@@ -34,6 +40,40 @@ impl NativeTransactionContext {
     }
 }
 
+/***************************************************************************************************
+ * native fun create_guid
+ *
+ *   gas cost: base_cost
+ *
+ **************************************************************************************************/
+#[derive(Clone, Debug)]
+pub struct CreateGUIDGasParameters {
+    pub base: InternalGas,
+}
+
+fn native_create_guid(
+    gas_params: &CreateGUIDGasParameters,
+    context: &mut SafeNativeContext,
+    mut _ty_args: Vec<Type>,
+    _args: VecDeque<Value>,
+) -> SafeNativeResult<SmallVec<[Value; 1]>> {
+    context.charge(gas_params.base)?;
+
+    let mut transaction_context = context
+        .extensions_mut()
+        .get_mut::<NativeTransactionContext>();
+    transaction_context.guid_counter += 1;
+    let mut hash_arg = Vec::new();
+    hash_arg.extend(transaction_context.txn_hash.clone());
+    hash_arg.extend(transaction_context.guid_counter.to_le_bytes().to_vec());
+    let hash_vec = Sha256::digest(hash_arg.as_slice()).to_vec();
+    Ok(smallvec![Value::address(AccountAddress::new(
+        hash_vec
+            .try_into()
+            .expect("Unable to convert hash vector into [u8]")
+    ))])
+}
+
 /***************************************************************************************************
  * native fun get_script_hash
  *
@@ -67,22 +107,34 @@ fn native_get_script_hash(
 #[derive(Debug, Clone)]
 pub struct GasParameters {
     pub get_script_hash: GetScriptHashGasParameters,
+    pub create_guid: CreateGUIDGasParameters,
 }
 
 pub fn make_all(
     gas_params: GasParameters,
     timed_features: TimedFeatures,
     features: Arc<Features>,
 ) -> impl Iterator<Item = (String, NativeFunction)> {
-    let natives = [(
-        "get_script_hash",
-        make_safe_native(
-            gas_params.get_script_hash,
-            timed_features,
-            features,
-            native_get_script_hash,
+    let natives = [
+        (
+            "get_script_hash",
+            make_safe_native(
+                gas_params.get_script_hash,
+                timed_features.clone(),
+                features.clone(),
+                native_get_script_hash,
+            ),
+        ),
+        (
+            "create_guid",
+            make_safe_native(
+                gas_params.create_guid,
+                timed_features,
+                features,
+                native_create_guid,
+            ),
         ),
-    )];
+    ];
 
     crate::natives::helpers::make_module_natives(natives)
 }