Reduce per-request CPU overhead: eliminate double stat(), cache content type and policy context, gate logging, configurable stat intervals

app/s3_api.py

@@ -85,6 +85,9 @@ def _bucket_policies() -> BucketPolicyStore:
 
 
 def _build_policy_context() -> Dict[str, Any]:
+    cached = getattr(g, "_policy_context", None)
+    if cached is not None:
+        return cached
     ctx: Dict[str, Any] = {}
     if request.headers.get("Referer"):
         ctx["aws:Referer"] = request.headers.get("Referer")
@@ -98,6 +101,7 @@ def _build_policy_context() -> Dict[str, Any]:
     ctx["aws:SecureTransport"] = str(request.is_secure).lower()
     if request.headers.get("User-Agent"):
         ctx["aws:UserAgent"] = request.headers.get("User-Agent")
+    g._policy_context = ctx
     return ctx
 
 
@@ -1021,11 +1025,15 @@ def _apply_object_headers(
     file_stat,
     metadata: Dict[str, str] | None,
     etag: str,
+    size_override: int | None = None,
+    mtime_override: float | None = None,
 ) -> None:
-    if file_stat is not None:
-        if response.status_code != 206:
-            response.headers["Content-Length"] = str(file_stat.st_size)
-        response.headers["Last-Modified"] = http_date(file_stat.st_mtime)
+    effective_size = size_override if size_override is not None else (file_stat.st_size if file_stat is not None else None)
+    effective_mtime = mtime_override if mtime_override is not None else (file_stat.st_mtime if file_stat is not None else None)
+    if effective_size is not None and response.status_code != 206:
+        response.headers["Content-Length"] = str(effective_size)
+    if effective_mtime is not None:
+        response.headers["Last-Modified"] = http_date(effective_mtime)
     response.headers["ETag"] = f'"{etag}"'
     response.headers["Accept-Ranges"] = "bytes"
     for key, value in (metadata or {}).items():
@@ -2820,6 +2828,8 @@ def object_handler(bucket_name: str, object_key: str):
         if validation_error:
             return _error_response("InvalidArgument", validation_error, 400)
 
+        metadata["__content_type__"] = content_type or mimetypes.guess_type(object_key)[0] or "application/octet-stream"
+
         try:
             meta = storage.put_object(
                 bucket_name,
@@ -2834,10 +2844,11 @@ def object_handler(bucket_name: str, object_key: str):
             if "Bucket" in message:
                 return _error_response("NoSuchBucket", message, 404)
             return _error_response("InvalidArgument", message, 400)
-        current_app.logger.info(
-            "Object uploaded",
-            extra={"bucket": bucket_name, "key": object_key, "size": meta.size},
-        )
+        if current_app.logger.isEnabledFor(logging.INFO):
+            current_app.logger.info(
+                "Object uploaded",
+                extra={"bucket": bucket_name, "key": object_key, "size": meta.size},
+            )
         response = Response(status=200)
         if meta.etag:
             response.headers["ETag"] = f'"{meta.etag}"'
@@ -2871,7 +2882,7 @@ def object_handler(bucket_name: str, object_key: str):
         except StorageError as exc:
             return _error_response("NoSuchKey", str(exc), 404)
         metadata = storage.get_object_metadata(bucket_name, object_key)
-        mimetype = mimetypes.guess_type(object_key)[0] or "application/octet-stream"
+        mimetype = metadata.get("__content_type__") or mimetypes.guess_type(object_key)[0] or "application/octet-stream"
         
         is_encrypted = "x-amz-server-side-encryption" in metadata
         
@@ -2963,10 +2974,7 @@ def object_handler(bucket_name: str, object_key: str):
             response.headers["Content-Type"] = mimetype
             logged_bytes = 0
 
-        try:
-            file_stat = path.stat() if not is_encrypted else None
-        except (PermissionError, OSError):
-            file_stat = None
+        file_stat = stat if not is_encrypted else None
         _apply_object_headers(response, file_stat=file_stat, metadata=metadata, etag=etag)
 
         if request.method == "GET":
@@ -2983,8 +2991,9 @@ def object_handler(bucket_name: str, object_key: str):
                 if value:
                     response.headers[header] = _sanitize_header_value(value)
 
-        action = "Object read" if request.method == "GET" else "Object head"
-        current_app.logger.info(action, extra={"bucket": bucket_name, "key": object_key, "bytes": logged_bytes})
+        if current_app.logger.isEnabledFor(logging.INFO):
+            action = "Object read" if request.method == "GET" else "Object head"
+            current_app.logger.info(action, extra={"bucket": bucket_name, "key": object_key, "bytes": logged_bytes})
         return response
 
     if "uploadId" in request.args:
@@ -3002,7 +3011,8 @@ def object_handler(bucket_name: str, object_key: str):
 
     storage.delete_object(bucket_name, object_key)
     lock_service.delete_object_lock_metadata(bucket_name, object_key)
-    current_app.logger.info("Object deleted", extra={"bucket": bucket_name, "key": object_key})
+    if current_app.logger.isEnabledFor(logging.INFO):
+        current_app.logger.info("Object deleted", extra={"bucket": bucket_name, "key": object_key})
 
     principal, _ = _require_principal()
     _notifications().emit_object_removed(
@@ -3343,12 +3353,20 @@ def head_object(bucket_name: str, object_key: str) -> Response:
         _authorize_action(principal, bucket_name, "read", object_key=object_key)
         path = _storage().get_object_path(bucket_name, object_key)
         metadata = _storage().get_object_metadata(bucket_name, object_key)
-        stat = path.stat()
         etag = metadata.get("__etag__") or _storage()._compute_etag(path)
-        
-        response = Response(status=200)
-        _apply_object_headers(response, file_stat=stat, metadata=metadata, etag=etag)
-        response.headers["Content-Type"] = mimetypes.guess_type(object_key)[0] or "application/octet-stream"
+
+        cached_size = metadata.get("__size__")
+        cached_mtime = metadata.get("__last_modified__")
+        if cached_size is not None and cached_mtime is not None:
+            size_val = int(cached_size)
+            mtime_val = float(cached_mtime)
+            response = Response(status=200)
+            _apply_object_headers(response, file_stat=None, metadata=metadata, etag=etag, size_override=size_val, mtime_override=mtime_val)
+        else:
+            stat = path.stat()
+            response = Response(status=200)
+            _apply_object_headers(response, file_stat=stat, metadata=metadata, etag=etag)
+        response.headers["Content-Type"] = metadata.get("__content_type__") or mimetypes.guess_type(object_key)[0] or "application/octet-stream"
         return response
     except (StorageError, FileNotFoundError):
         return _error_response("NoSuchKey", "Object not found", 404)
@@ -3578,10 +3596,12 @@ def _initiate_multipart_upload(bucket_name: str, object_key: str) -> Response:
         return error
     
     metadata = _extract_request_metadata()
+    content_type = request.headers.get("Content-Type")
+    metadata["__content_type__"] = content_type or mimetypes.guess_type(object_key)[0] or "application/octet-stream"
     try:
         upload_id = _storage().initiate_multipart_upload(
-            bucket_name, 
-            object_key, 
+            bucket_name,
+            object_key,
             metadata=metadata or None
         )
     except StorageError as exc: