improve cli startup time performance by making more work lazy

Makefile

@@ -35,4 +35,4 @@ clean:
 nixify-zig-deps:
 	cd rose-zig && zon2nix > deps.nix
 
-.PHONY: help check build-zig test-py test-zig test typecheck lintcheck lint clean nixify-zig-deps
+.PHONY: check build-zig test-py test-zig test typecheck lintcheck lint clean nixify-zig-deps

rose-cli/rose_cli/cli.py

@@ -50,8 +50,6 @@
     toggle_release_new,
     update_cache,
 )
-from rose_vfs import mount_virtualfs
-from rose_watch import start_watchdog
 
 from rose_cli.dump import (
     dump_all_artists,
@@ -169,6 +167,7 @@ def update(ctx: Context, force: bool) -> None:
 @click.pass_obj
 def watch(ctx: Context, foreground: bool) -> None:
     """Start a watchdog to auto-update the cache when the source directory changes."""
+    from rose_watch import start_watchdog
 
     if not foreground:
         daemonize(pid_path=ctx.config.watchdog_pid_path)
@@ -203,6 +202,10 @@ def fs() -> None:
 @click.pass_obj
 def mount(ctx: Context, foreground: bool) -> None:
     """Mount the virtual filesystem."""
+    from rose_vfs import mount_virtualfs
+
+    ctx.config.validate_path_templates_expensive()
+
     if not foreground:
         daemonize()
 

rose-py/rose/audiotags.py

@@ -17,14 +17,6 @@
 from pathlib import Path
 from typing import Any, no_type_check
 
-import mutagen
-import mutagen.flac
-import mutagen.id3
-import mutagen.mp3
-import mutagen.mp4
-import mutagen.oggopus
-import mutagen.oggvorbis
-
 from rose.common import Artist, ArtistMapping, RoseError, RoseExpectedError, uniq
 
 if typing.TYPE_CHECKING:
@@ -135,6 +127,14 @@ class AudioTags:
     @classmethod
     def from_file(cls, p: Path) -> AudioTags:
         """Read the tags of an audio file on disk."""
+        import mutagen
+        import mutagen.flac
+        import mutagen.id3
+        import mutagen.mp3
+        import mutagen.mp4
+        import mutagen.oggopus
+        import mutagen.oggvorbis
+
         if not any(p.suffix.lower() == ext for ext in SUPPORTED_AUDIO_EXTENSIONS):
             raise UnsupportedFiletypeError(f"{p.suffix} not a supported filetype")
         try:
@@ -310,6 +310,14 @@ def _get_paired_frame(x: str) -> str | None:
     @no_type_check
     def flush(self, *, validate: bool = True) -> None:
         """Flush the current tags to the file on disk."""
+        import mutagen
+        import mutagen.flac
+        import mutagen.id3
+        import mutagen.mp3
+        import mutagen.mp4
+        import mutagen.oggopus
+        import mutagen.oggvorbis
+
         m = mutagen.File(self.path)
         if not validate and "pytest" not in sys.modules:
             raise Exception("Validate can only be turned off by tests.")
@@ -477,6 +485,8 @@ def _split_tag(t: str | None) -> list[str]:
 
 
 def _get_tag(t: Any, keys: list[str], *, split: bool = False, first: bool = False) -> str | None:
+    import mutagen.id3
+
     if not t:
         return None
     for k in keys:
@@ -503,6 +513,8 @@ def _get_tag(t: Any, keys: list[str], *, split: bool = False, first: bool = Fals
 
 
 def _get_tuple_tag(t: Any, keys: list[str]) -> tuple[str, str] | tuple[None, None]:
+    import mutagen.id3
+
     if not t:
         return None, None
     for k in keys:

rose-py/rose/config.py

@@ -552,13 +552,6 @@ def parse(cls, config_path_override: Path | None = None) -> Config:
             if not data["path_templates"]:
                 del data["path_templates"]
 
-        try:
-            path_templates.parse()
-        except InvalidPathTemplateError as e:
-            raise InvalidConfigValueError(
-                f"Invalid path template in configuration file ({cfgpath}) for template {e.key}: {e}"
-            ) from e
-
         vfs_config = VirtualFSConfig.parse(cfgpath, data.get("vfs", {}))
 
         if data:
@@ -606,3 +599,15 @@ def cache_database_path(self) -> Path:
     @functools.cached_property
     def watchdog_pid_path(self) -> Path:
         return self.cache_dir / "watchdog.pid"
+
+    def validate_path_templates_expensive(self) -> None:
+        """
+        Validate all the path templates. This is expensive, so we don't do it when reading the
+        configuration, only on demand.
+        """
+        try:
+            self.path_templates.parse()
+        except InvalidPathTemplateError as e:
+            raise InvalidConfigValueError(
+                f"Invalid path template in for template {e.key}: {e}"
+            ) from e

rose-py/rose/config_test.py

@@ -468,15 +468,6 @@ def write(x: str) -> None:
 """
         )
 
-        # path_templates
-        write(config + '\npath_templates.source.release = "{% if hi %}{{"')
-        with pytest.raises(InvalidConfigValueError) as excinfo:
-            Config.parse(config_path_override=path)
-        assert (
-            str(excinfo.value)
-            == f"Invalid path template in configuration file ({path}) for template source.release: Failed to compile template: unexpected 'end of template'"
-        )
-
         # rename_source_files
         write(config + '\nrename_source_files = "lalala"')
         with pytest.raises(InvalidConfigValueError) as excinfo:

rose-py/rose/templates.py

@@ -14,12 +14,12 @@
 from functools import cached_property
 from typing import Any
 
-import jinja2
-
 from rose.audiotags import RoseDate
 from rose.common import Artist, ArtistMapping, RoseExpectedError
 
 if typing.TYPE_CHECKING:
+    import jinja2
+
     from rose.cache import Release, Track
     from rose.config import Config
 
@@ -96,13 +96,26 @@ def lastname(x: str) -> str:
         return x
 
 
-ENVIRONMENT = jinja2.Environment()
-ENVIRONMENT.filters["arrayfmt"] = arrayfmt
-ENVIRONMENT.filters["artistsarrayfmt"] = artistsarrayfmt
-ENVIRONMENT.filters["artistsfmt"] = artistsfmt
-ENVIRONMENT.filters["releasetypefmt"] = releasetypefmt
-ENVIRONMENT.filters["sortorder"] = sortorder
-ENVIRONMENT.filters["lastname"] = lastname
+# Global variable cache for a lazy initialization. We lazily initialize the Jinja environment to
+# improve the CLI startup time.
+__environment: jinja2.Environment | None = None
+
+
+def get_environment() -> jinja2.Environment:
+    global __environment
+    if __environment:
+        return __environment
+
+    import jinja2
+
+    __environment = jinja2.Environment()
+    __environment.filters["arrayfmt"] = arrayfmt
+    __environment.filters["artistsarrayfmt"] = artistsarrayfmt
+    __environment.filters["artistsfmt"] = artistsfmt
+    __environment.filters["releasetypefmt"] = releasetypefmt
+    __environment.filters["sortorder"] = sortorder
+    __environment.filters["lastname"] = lastname
+    return __environment
 
 
 class InvalidPathTemplateError(RoseExpectedError):
@@ -122,7 +135,7 @@ class PathTemplate:
 
     @cached_property
     def compiled(self) -> jinja2.Template:
-        return ENVIRONMENT.from_string(self.text)
+        return get_environment().from_string(self.text)
 
     def __hash__(self) -> int:
         return hash(self.text)
@@ -236,6 +249,8 @@ def parse(self) -> None:
         Attempt to parse all the templates into Jinja templates (which will be cached on the
         cached properties). This will raise an InvalidPathTemplateError if a template is invalid.
         """
+        import jinja2
+
         key = ""
         try:
             key = "source.release"

rose-zig/build.zig

@@ -9,18 +9,19 @@ pub fn build(b: *std.Build) void {
         .target = target,
         .optimize = optimize,
     });
-    const ffmpeg = b.dependency("ffmpeg", .{
-        .target = target,
-        .optimize = optimize,
-    });
+    // TODO: This is really expensive, so uncomment it only when we start using it.
+    // const ffmpeg = b.dependency("ffmpeg", .{
+    //     .target = target,
+    //     .optimize = optimize,
+    // });
 
     // Specify the core library module.
     const rose = b.addModule("rose", .{
         .root_source_file = b.path("rose/root.zig"),
         .target = target,
         .optimize = optimize,
         .imports = &[_]std.Build.Module.Import{
-            .{ .name = "av", .module = ffmpeg.module("av") },
+            // .{ .name = "av", .module = ffmpeg.module("av") },
             .{ .name = "sqlite", .module = sqlite.module("sqlite") },
         },
     });