fix: refine codes

core/src/ten_manager/src/cmd/cmd_install.rs

@@ -861,7 +861,7 @@ do you want to continue?",
 
         Ok(())
     } else {
-        // The last model always represents the latest version.
+        // The last model always represents the optimal version.
         //
         // The first error messages (i.e., non_usable_models.first()) might be
         // changed when we run `tman install` in an app folder, if the app
@@ -904,19 +904,15 @@ do you want to continue?",
         // depends_on_declared("app", "ten_agent", "0.4.0", "extension", "agora_rtm", "0.1.0").
         // depends_on_declared("app", "ten_agent", "0.4.0", "extension", "agora_rtm", "0.1.1").
         // ```
-        //
-        // When clingo analyzes the input.lp, it generates the answer models
-        // based on the order of the `depends_on_declared` facts. If there is no
-        // answer for the version declared in the first `depends_on_declared`
-        // fact, it will ignore the versions smaller than it. Ex: in case 1,
-        // there will be answer models for both 0.1.0, 0.1.1 and 0.1.2, and the
-        // first model is for 0.1.0, and the last is for 0.1.2. While in case 2,
-        // there only be answer models for 0.1.2. If we take the first error
-        // message (i.e., non_usable_models.first()) from the answer models, the
-        // error messages for those two cases are as above.
-        //
-        // That's also why we need to take the last model as the final error
-        // message.
+        // Due to the different order of input data, clingo may start searching
+        // from different points. However, clingo will only output increasingly
+        // better models. Therefore, if we select the first `non_usable_models`,
+        // it is often inconsistent. But if we select the last model, it is
+        // usually consistent, representing the optimal error model that clingo
+        // can find. This phenomenon is similar to the gradient descent process
+        // in neural networks that seeks local optima. Thus, we should select
+        // the last model to obtain the optimal error model and achieve stable
+        // results.
         if let Some(non_usable_model) = non_usable_models.last() {
             // Extract introducer relations, and parse the error message.
             if let Ok(conflict_info) = parse_error_statement(non_usable_model) {

core/src/ten_manager/src/solver/introducer.rs

@@ -88,9 +88,9 @@ pub fn extract_introducer_relations_from_raw_solver_results(
 
 pub fn get_dependency_chain(
     introducer: &PkgInfo,
-    conflict_pkg: &PkgInfo,
+    conflict_pkg_identity: &PkgIdentity,
     introducer_relations: &HashMap<PkgInfo, (String, Option<PkgInfo>)>,
-) -> Vec<(String, PkgInfo)> {
+) -> Vec<(String, PkgIdentity)> {
     let mut chain = Vec::new();
     let mut current_pkg = introducer.clone();
     let mut visited = HashSet::new();
@@ -99,8 +99,8 @@ pub fn get_dependency_chain(
     // dependency chain first.
     let requested_dep_in_introducer = introducer
         .get_dependency_by_type_and_name(
-            &conflict_pkg.pkg_identity.pkg_type.to_string(),
-            &conflict_pkg.pkg_identity.name,
+            &conflict_pkg_identity.pkg_type.to_string(),
+            &conflict_pkg_identity.name,
         )
         .unwrap();
     chain.push((
@@ -109,7 +109,7 @@ pub fn get_dependency_chain(
             .as_ref()
             .unwrap()
             .clone(),
-        conflict_pkg.clone(),
+        conflict_pkg_identity.clone(),
     ));
 
     loop {
@@ -124,12 +124,18 @@ pub fn get_dependency_chain(
                 // `current_pkg`@`requested_version`, i.e., the
                 // `requested_version` is used to declared the `current_pkg` in
                 // the manifest.json of `introducer_pkg`.
-                chain.push((requested_version.clone(), current_pkg.clone()));
+                chain.push((
+                    requested_version.clone(),
+                    current_pkg.pkg_identity.clone(),
+                ));
                 current_pkg = introducer_pkg.clone();
             }
             Some((requested_version, None)) => {
                 // Reached the root.
-                chain.push((requested_version.clone(), current_pkg.clone()));
+                chain.push((
+                    requested_version.clone(),
+                    current_pkg.pkg_identity.clone(),
+                ));
                 break;
             }
             None => {

core/src/ten_manager/src/solver/solver_error.rs

@@ -120,7 +120,7 @@ pub fn parse_error_statement(clingo_output: &[String]) -> Result<ConflictInfo> {
 }
 
 fn print_dependency_chain(
-    chain: &[(String, PkgInfo)],
+    chain: &[(String, PkgIdentity)],
     pkg_type: &str,
     pkg_name: &str,
     version: &str,
@@ -133,8 +133,8 @@ fn print_dependency_chain(
         println!(
             "{:indent$}└─ [{}]{}@{}",
             "",
-            pkg.1.pkg_identity.pkg_type,
-            pkg.1.pkg_identity.name,
+            pkg.1.pkg_type,
+            pkg.1.name,
             pkg.0,
             indent = i * 3
         );
@@ -169,27 +169,21 @@ pub fn print_conflict_info(
     )?;
 
     // The introducer_pkg_info_1/introducer_pkg_info_2 (i.e., the introducer)
-    // depends on the pkg identified by `conflict_pkg_type` &
-    // `conflict_pkg_name` (i.e., the leaf node). The conflict_pkg_version_x
-    // used to get the pkg_info does not matter, as it will be replaced by
-    // the `version_req_str` of the introducer, refer
-    // to `get_dependency_chain()`.
-    let leaf_node_pkg = get_pkg_info_from_candidates(
-        &conflict_info.conflict_pkg_type,
-        &conflict_info.conflict_pkg_name,
-        &conflict_info.conflict_pkg_version_1.pkg_version,
-        all_candidates,
-    )?;
+    // depends on the pkg identified by `conflict_pkg_identity`.
+    let conflict_pkg_identity = PkgIdentity {
+        pkg_type: conflict_info.conflict_pkg_type.parse()?,
+        name: conflict_info.conflict_pkg_name.clone(),
+    };
 
-    // Get dependency chains
+    // Get dependency chains.
     let chain1 = get_dependency_chain(
         &introducer_pkg_info_1,
-        &leaf_node_pkg,
+        &conflict_pkg_identity,
         introducer_relations,
     );
     let chain2 = get_dependency_chain(
         &introducer_pkg_info_2,
-        &leaf_node_pkg,
+        &conflict_pkg_identity,
         introducer_relations,
     );