Implement Lazy Graph Compute Mode (#652)

# Motivation

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# Content

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# Testing

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# Please check the following before marking your PR as ready for review

- [ ] I have added tests for my changes
- [ ] I have updated the documentation or added new documentation as
needed

Author: EdwardJXLi

src/codegen/configs/models/codebase.py

@@ -16,6 +16,7 @@ def __init__(self, prefix: str = "CODEBASE", *args, **kwargs) -> None:
     ignore_process_errors: bool = True
     disable_graph: bool = False
     disable_file_parse: bool = False
+    exp_lazy_graph: bool = False
     generics: bool = True
     import_resolution_paths: list[str] = Field(default_factory=lambda: [])
     import_resolution_overrides: dict[str, str] = Field(default_factory=lambda: {})

src/codegen/sdk/codebase/codebase_context.py

@@ -144,7 +144,8 @@ def __init__(
         from codegen.sdk.core.parser import Parser
 
         self.progress = progress or StubProgress()
-        self._graph = PyDiGraph()
+        self.__graph = PyDiGraph()
+        self.__graph_ready = False
         self.filepath_idx = {}
         self._ext_module_idx = {}
         self.generation = 0
@@ -189,7 +190,8 @@ def __init__(
             logger.warning("Some features may not work as expected. Advanced static analysis will be disabled but simple file IO will still work.")
 
         # Build the graph
-        self.build_graph(context.repo_operator)
+        if not self.config.exp_lazy_graph:
+            self.build_graph(context.repo_operator)
         try:
             self.synced_commit = context.repo_operator.head_commit
         except ValueError as e:
@@ -203,10 +205,22 @@ def __init__(
     def __repr__(self):
         return self.__class__.__name__
 
+    @property
+    def _graph(self) -> PyDiGraph[Importable, Edge]:
+        if not self.__graph_ready:
+            logger.info("Lazily Computing Graph")
+            self.build_graph(self.projects[0].repo_operator)
+        return self.__graph
+
+    @_graph.setter
+    def _graph(self, value: PyDiGraph[Importable, Edge]) -> None:
+        self.__graph = value
+
     @stopwatch_with_sentry(name="build_graph")
     @commiter
     def build_graph(self, repo_operator: RepoOperator) -> None:
         """Builds a codebase graph based on the current file state of the given repo operator"""
+        self.__graph_ready = True
         self._graph.clear()
 
         # =====[ Add all files to the graph in parallel ]=====