Cache git dependencies as wheels

Currently, poetry install will clone, build and install every git
dependency when it's not present in the environment. This is OK for
developer's machines, but not OK for CI - there environment is always
fresh, and installing git dependencies takes significant time on each CI
run, especially if the dependency has C extensions that need to be
built.

This commit builds a wheel for every git dependency that has precise
reference hash in lock file and is not required to be in editable mode,
stores that wheel in a cache dir and will install from it instead of
cloning the repository again.

src/poetry/installation/chef.py

@@ -251,6 +251,12 @@ def get_cache_directory_for_link(self, link: Link) -> Path:
             self._env.marker_env["interpreter_version"].split(".")[:2]
         )
 
+        return self._get_directory_from_hash(key_parts)
+
+    def get_cache_directory_for_git(self, url: str, ref: str) -> Path:
+        return self._get_directory_from_hash({"url": url, "ref": ref})
+
+    def _get_directory_from_hash(self, key_parts: object) -> Path:
         key = hashlib.sha256(
             json.dumps(
                 key_parts, sort_keys=True, separators=(",", ":"), ensure_ascii=True

src/poetry/installation/executor.py

@@ -5,6 +5,7 @@
 import itertools
 import json
 import os
+import shutil
 import threading
 
 from concurrent.futures import ThreadPoolExecutor
@@ -502,7 +503,6 @@ def _install(self, operation: Install | Update) -> int:
         cleanup_archive: bool = False
         if package.source_type == "git":
             archive = self._prepare_git_archive(operation)
-            cleanup_archive = True
         elif package.source_type == "file":
             archive = self._prepare_archive(operation)
         elif package.source_type == "directory":
@@ -599,14 +599,25 @@ def _prepare_git_archive(self, operation: Install | Update) -> Path:
         from poetry.vcs.git import Git
 
         package = operation.package
+        reference = package.source_resolved_reference or package.source_reference
+        assert package.source_url is not None
+        assert reference is not None
+
+        cache_dir = self._chef.get_cache_directory_for_git(
+            package.source_url, reference
+        )
+        cache_dir.mkdir(parents=True, exist_ok=True)
+        cached_archive = next(cache_dir.glob("*.whl"), None)
+        if cached_archive is not None and not operation.package.develop:
+            return cached_archive
+
         operation_message = self.get_operation_message(operation)
 
         message = (
             f"  <fg=blue;options=bold>•</> {operation_message}: <info>Cloning...</info>"
         )
         self._write(operation, message)
 
-        assert package.source_url is not None
         source = Git.clone(
             url=package.source_url,
             source_root=self._env.path / "src",
@@ -621,7 +632,13 @@ def _prepare_git_archive(self, operation: Install | Update) -> Path:
 
         package._source_url = original_url
 
-        return archive
+        if operation.package.develop:
+            return archive
+        else:
+            cached_archive = cache_dir / archive.name
+            shutil.copy(archive, cached_archive)
+
+            return cached_archive
 
     def _install_directory_without_wheel_installer(
         self, operation: Install | Update