AIC model caching

changelog/3684.changed.md

@@ -0,0 +1,2 @@
+- `AICFilter` now shares read-only AIC models via a singleton `AICModelManager` in `aic_filter.py`.
+  - Multiple filters using the same `model path` or `(model_id, model_download_dir)` share one loaded model, with reference counting and concurrent load deduplication.

src/pipecat/audio/filters/aic_filter.py

@@ -12,10 +12,13 @@
 
 Classes:
     AICFilter: For aic-sdk (uses 'aic_sdk' module)
+    AICModelManager: Singleton manager for read-only AIC Model instances.
 """
 
+import asyncio
 from pathlib import Path
-from typing import List, Optional
+from threading import Lock
+from typing import List, Optional, Tuple
 
 import numpy as np
 from aic_sdk import (
@@ -33,6 +36,174 @@
 from pipecat.frames.frames import FilterControlFrame, FilterEnableFrame
 
 
+class AICModelManager:
+    """Singleton manager for read-only AIC Model instances with reference counting.
+
+    Caches Model instances by path or (model_id + download_dir). Multiple
+    AICFilter instances using the same model share one Model; the manager
+    acquires on first use and releases when the last reference is dropped.
+    """
+
+    _cache: dict[str, Tuple[Model, int]] = {}  # key -> (model, ref_count)
+    _lock = Lock()
+    _loading: dict[
+        str, asyncio.Task[Model]
+    ] = {}  # key -> load task (deduplicates concurrent loads)
+
+    @classmethod
+    def _increment_reference(cls, cache_key: str, entry: Tuple[Model, int]) -> Tuple[Model, str]:
+        """Increment reference count for cached entry. Caller must hold _lock."""
+        cached_model, ref_count = entry
+        cls._cache[cache_key] = (cached_model, ref_count + 1)
+        logger.debug(f"AIC model cache key={cache_key!r} ref_count={ref_count + 1}")
+        return cached_model, cache_key
+
+    @classmethod
+    def _store_new_reference(cls, cache_key: str, model: Model) -> Tuple[Model, str]:
+        """Store new model in cache with ref count 1. Caller must hold _lock."""
+        cls._cache[cache_key] = (model, 1)
+        logger.debug(f"AIC model cached key={cache_key!r} ref_count=1")
+        return model, cache_key
+
+    @classmethod
+    async def _load_model_from_file(
+        cls,
+        cache_key: str,
+        *,
+        model_path: Optional[Path] = None,
+        model_id: Optional[str] = None,
+        model_download_dir: Optional[Path] = None,
+    ) -> Model:
+        """Run the actual load (file or download). Separate to allow create_task and deduplication."""
+        if model_path is not None:
+            logger.debug(f"Loading AIC model from file: {model_path}")
+            return Model.from_file(str(model_path))
+
+        if model_id is not None and model_download_dir is not None:
+            logger.debug(f"Downloading AIC model: {model_id}")
+            model_download_dir.mkdir(parents=True, exist_ok=True)
+            path = await Model.download_async(model_id, str(model_download_dir))
+            logger.debug(f"Model downloaded to: {path}")
+            return Model.from_file(path)
+
+        raise ValueError("Unexpected model_path or (model_id and model_download_dir) state.")
+
+    @staticmethod
+    def _get_cache_key(
+        *,
+        model_path: Optional[Path] = None,
+        model_id: Optional[str] = None,
+        model_download_dir: Optional[Path] = None,
+    ) -> str:
+        """Build a stable cache key for the model.
+
+        Args:
+            model_path: Path to a local .aicmodel file.
+            model_id: Model identifier (See https://artifacts.ai-coustics.io/ for available models).
+            model_download_dir: Directory used for downloading models.
+
+        Returns:
+            A string key unique per (path) or (model_id + download_dir).
+        """
+        if model_path is not None:
+            return f"path:{model_path.resolve()}"
+
+        if model_id is not None and model_download_dir is not None:
+            return f"id:{model_id}:{model_download_dir.resolve()}"
+
+        raise ValueError("Either model_path or (model_id and model_download_dir) must be set.")
+
+    @classmethod
+    async def acquire(
+        cls,
+        *,
+        model_path: Optional[Path] = None,
+        model_id: Optional[str] = None,
+        model_download_dir: Optional[Path] = None,
+    ) -> Tuple[Model, str]:
+        """Get or load a Model and increment its reference count.
+
+        Call this when starting a filter. Store the returned key and pass it
+        to release() when stopping the filter.
+
+        Args:
+            model_path: Path to a local .aicmodel file. If set, model_id is ignored.
+            model_id: Model identifier to download from CDN.
+            model_download_dir: Directory for downloading models. Required if
+                model_id is used.
+
+        Returns:
+            Tuple of (shared Model instance, cache key for release).
+
+        Raises:
+            ValueError: If neither model_path nor (model_id + model_download_dir)
+                is provided, or if model_id is set without model_download_dir.
+        """
+        cache_key = cls._get_cache_key(
+            model_path=model_path,
+            model_id=model_id,
+            model_download_dir=model_download_dir,
+        )
+
+        with cls._lock:
+            entry = cls._cache.get(cache_key)
+            if entry is not None:
+                return cls._increment_reference(cache_key, entry)
+
+            # Deduplicate concurrent loads for the same key
+            load_task = cls._loading.get(cache_key)
+            if load_task is None:
+                load_task = asyncio.create_task(
+                    cls._load_model_from_file(
+                        cache_key,
+                        model_path=model_path,
+                        model_id=model_id,
+                        model_download_dir=model_download_dir,
+                    )
+                )
+                cls._loading[cache_key] = load_task
+
+        try:
+            model = await load_task
+        finally:
+            with cls._lock:
+                cls._loading.pop(cache_key, None)
+
+        with cls._lock:
+            entry = cls._cache.get(cache_key)
+            if entry is not None:
+                return cls._increment_reference(cache_key, entry)
+            return cls._store_new_reference(cache_key, model)
+
+    @classmethod
+    def release(cls, key: str) -> None:
+        """Release a reference to a cached model.
+
+        Call this when stopping a filter, with the key returned from
+        get_model(). When the last reference is released, the model
+        is removed from the cache.
+
+        Args:
+            key: Cache key returned by get_model().
+        """
+        with cls._lock:
+            entry = cls._cache.get(key)
+
+            if entry is None:
+                logger.warning(f"AIC model release unknown key={key!r}")
+                return
+
+            model, ref_count = entry
+            ref_count -= 1
+
+            if ref_count <= 0:
+                del cls._cache[key]
+                logger.debug(f"AIC model evicted key={key!r}")
+            else:
+                cls._cache[key] = (model, ref_count)
+                logger.debug(f"AIC model key={key!r} ref_count={ref_count}")
+
+
 class AICFilter(BaseAudioFilter):
     """Audio filter using ai-coustics' AIC SDK for real-time enhancement.
 
@@ -91,7 +262,8 @@ def __init__(
             32768.0  # 2^15, for normalizing int16 (-32768 to 32767) to float32 (-1.0 to 1.0)
         )
 
-        # AIC SDK objects
+        # AIC SDK objects; model is shared via AICModelManager
+        self._model_cache_key: Optional[str] = None
         self._model = None
         self._processor = None
         self._processor_ctx = None
@@ -162,16 +334,12 @@ async def start(self, sample_rate: int):
         """
         self._sample_rate = sample_rate
 
-        # Load or download model
-        if self._model_path:
-            logger.debug(f"Loading AIC model from: {self._model_path}")
-            self._model = Model.from_file(str(self._model_path))
-        else:
-            logger.debug(f"Downloading AIC model: {self._model_id}")
-            self._model_download_dir.mkdir(parents=True, exist_ok=True)
-            model_path = await Model.download_async(self._model_id, str(self._model_download_dir))
-            logger.debug(f"Model downloaded to: {model_path}")
-            self._model = Model.from_file(model_path)
+        # Acquire shared read-only model from singleton manager
+        self._model, self._model_cache_key = await AICModelManager.acquire(
+            model_path=self._model_path,
+            model_id=self._model_id,
+            model_download_dir=self._model_download_dir,
+        )
 
         # Get optimal frames for this sample rate
         self._frames_per_block = self._model.get_optimal_num_frames(self._sample_rate)
@@ -242,6 +410,10 @@ async def stop(self):
             self._aic_ready = False
             self._audio_buffer.clear()
 
+            if self._model_cache_key is not None:
+                AICModelManager.release(self._model_cache_key)
+                self._model_cache_key = None
+
     async def process_frame(self, frame: FilterControlFrame):
         """Process control frames to enable/disable filtering.