[core] Add model cache to speed up code generation (#7250)

Author: sebastien-rosset

modules/openapi-generator/src/main/java/org/openapitools/codegen/DefaultCodegen.java

@@ -247,6 +247,9 @@ apiTemplateFiles are for API outputs only (controllers/handlers).
     // make openapi available to all methods
     protected OpenAPI openAPI;
 
+    // A cache to efficiently lookup a Schema instance based on the return value of `toModelName()`.
+    private Map<String, Schema> modelNameToSchemaCache;
+
     public List<CliOption> cliOptions() {
         return cliOptions;
     }
@@ -450,6 +453,23 @@ public Map<String, Object> postProcessAllModels(Map<String, Object> objs) {
         return objs;
     }
 
+    /**
+     * Return a map from model name to Schema for efficient lookup.
+     * 
+     * @return map from model name to Schema.
+     */
+    protected Map<String, Schema> getModelNameToSchemaCache() {
+        if (modelNameToSchemaCache == null) {
+            // Create a cache to efficiently lookup schema based on model name.
+            Map<String, Schema> m = new HashMap<String, Schema>();
+            ModelUtils.getSchemas(openAPI).forEach((key, schema) -> {
+                m.put(toModelName(key), schema);
+            });
+            modelNameToSchemaCache = Collections.unmodifiableMap(m);
+        }
+        return modelNameToSchemaCache;
+    }
+
     /**
      * Index all CodegenModels by model name.
      *
@@ -1293,14 +1313,13 @@ public String toOperationId(String operationId) {
      * @param name the variable name
      * @return the sanitized variable name
      */
-    public String toVarName(String name) {
+    public String toVarName(final String name) {
         if (reservedWords.contains(name)) {
             return escapeReservedWord(name);
         } else if (((CharSequence) name).chars().anyMatch(character -> specialCharReplacements.keySet().contains("" + ((char) character)))) {
             return escape(name, specialCharReplacements, null, null);
-        } else {
-            return name;
         }
+        return name;
     }
 
     /**
@@ -1318,6 +1337,7 @@ public String toParamName(String name) {
             return escape(name, specialCharReplacements, null, null);
         }
         return name;
+
     }
 
     /**
@@ -2195,7 +2215,8 @@ public String toApiName(String name) {
     }
 
     /**
-     * Output the proper model name (capitalized).
+     * Converts the OpenAPI schema name to a model name suitable for the current code generator.
+     * May be overriden for each programming language.
      * In case the name belongs to the TypeSystem it won't be renamed.
      *
      * @param name the name of the model
@@ -2205,8 +2226,33 @@ public String toModelName(final String name) {
         return camelize(modelNamePrefix + "_" + name + "_" + modelNameSuffix);
     }
 
+    private static class NamedSchema {
+        private NamedSchema(String name, Schema s) {
+            this.name = name;
+            this.schema = s;
+        }
+        private String name;
+        private Schema schema;
+
+        @Override
+        public boolean equals(Object o) {
+            if (this == o) return true;
+            if (o == null || getClass() != o.getClass()) return false;
+            NamedSchema that = (NamedSchema) o;
+            return Objects.equals(name, that.name) &&
+                    Objects.equals(schema, that.schema);
+        }
+
+        @Override
+        public int hashCode() {
+            return Objects.hash(name, schema);
+        }
+    }
+
+    Map<NamedSchema, CodegenProperty> schemaCodegenPropertyCache = new HashMap<NamedSchema, CodegenProperty>();
+
     /**
-     * Convert OAS Model object to Codegen Model object
+     * Convert OAS Model object to Codegen Model object.
      *
      * @param name   the name of the model
      * @param schema OAS Model object
@@ -2565,7 +2611,6 @@ public int compare(CodegenProperty one, CodegenProperty another) {
                 postProcessModelProperty(m, prop);
             }
         }
-
         return m;
     }
 
@@ -2984,7 +3029,13 @@ public String getterAndSetterCapitalize(String name) {
     }
 
     /**
-     * Convert OAS Property object to Codegen Property object
+     * Convert OAS Property object to Codegen Property object.
+     * 
+     * The return value is cached. An internal cache is looked up to determine
+     * if the CodegenProperty return value has already been instantiated for
+     * the (String name, Schema p) arguments.
+     * Any subsequent processing of the CodegenModel return value must be idempotent
+     * for a given (String name, Schema schema).
      *
      * @param name name of the property
      * @param p    OAS property schema
@@ -2996,7 +3047,12 @@ public CodegenProperty fromProperty(String name, Schema p) {
             return null;
         }
         LOGGER.debug("debugging fromProperty for " + name + " : " + p);
-
+        NamedSchema ns = new NamedSchema(name, p);
+        CodegenProperty cpc = schemaCodegenPropertyCache.get(ns);
+        if (cpc != null) {
+            LOGGER.debug("Cached fromProperty for " + name + " : " + p.getName());
+            return cpc;
+        }
         // unalias schema
         p = unaliasSchema(p, importMapping);
 
@@ -3296,6 +3352,7 @@ public CodegenProperty fromProperty(String name, Schema p) {
         }
 
         LOGGER.debug("debugging from property return: " + property);
+        schemaCodegenPropertyCache.put(ns, property);
         return property;
     }
 
@@ -4762,7 +4819,6 @@ private void addVars(CodegenModel m, List<CodegenProperty> vars, Map<String, Sch
 
             final String key = entry.getKey();
             final Schema prop = entry.getValue();
-
             if (prop == null) {
                 LOGGER.warn("Please report the issue. There shouldn't be null property for " + key);
             } else {
@@ -6382,14 +6438,17 @@ protected void modifyFeatureSet(Consumer<FeatureSet.Builder> processor) {
                 .featureSet(builder.build()).build();
     }
 
+    /**
+     * An map entry for cached sanitized names.
+     */
     private static class SanitizeNameOptions {
         public SanitizeNameOptions(String name, String removeCharRegEx, List<String> exceptions) {
             this.name = name;
             this.removeCharRegEx = removeCharRegEx;
             if (exceptions != null) {
                 this.exceptions = Collections.unmodifiableList(exceptions);
             } else {
-                this.exceptions = Collections.unmodifiableList(new ArrayList<>());
+                this.exceptions = Collections.emptyList();
             }
         }
 

modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/PythonClientExperimentalCodegen.java

@@ -493,19 +493,16 @@ public void updateCodegenPropertyEnum(CodegenProperty var) {
         }
 
         String varDataType = var.mostInnerItems != null ? var.mostInnerItems.dataType : var.dataType;
-        Optional<Schema> referencedSchema = ModelUtils.getSchemas(openAPI).entrySet().stream()
-                .filter(entry -> Objects.equals(varDataType, toModelName(entry.getKey())))
-                .map(Map.Entry::getValue)
-                .findFirst();
-        String dataType = (referencedSchema.isPresent()) ? getTypeDeclaration(referencedSchema.get()) : varDataType;
+        Schema referencedSchema = getModelNameToSchemaCache().get(varDataType);
+        String dataType = (referencedSchema != null) ? getTypeDeclaration(referencedSchema) : varDataType;
 
         // put "enumVars" map into `allowableValues", including `name` and `value`
         List<Map<String, Object>> enumVars = buildEnumVars(values, dataType);
 
         // if "x-enum-varnames" or "x-enum-descriptions" defined, update varnames
         Map<String, Object> extensions = var.mostInnerItems != null ? var.mostInnerItems.getVendorExtensions() : var.getVendorExtensions();
-        if (referencedSchema.isPresent()) {
-            extensions = referencedSchema.get().getExtensions();
+        if (referencedSchema != null) {
+            extensions = referencedSchema.getExtensions();
         }
         updateEnumVarsWithExtensions(enumVars, extensions);
         allowableValues.put("enumVars", enumVars);

modules/openapi-generator/src/main/java/org/openapitools/codegen/utils/ModelUtils.java

@@ -1054,7 +1054,7 @@ public static Schema unaliasSchema(OpenAPI openAPI,
     /**
      * Get the actual schema from aliases. If the provided schema is not an alias, the schema itself will be returned.
      *
-     * @param openAPI        specification being checked
+     * @param openAPI        OpenAPI document containing the schemas.
      * @param schema         schema (alias or direct reference)
      * @param importMappings mappings of external types to be omitted by unaliasing
      * @return actual schema