⚡️ Speed up function `serialise_image` by 679% in PR #1672 (`bruno/parent-metadata-serialization`)

[codeflash-ai[bot]]

⚡️ This pull request contains optimizations for PR #1672

If you approve this dependent PR, these changes will be merged into the original PR branch bruno/parent-metadata-serialization.

This PR will be automatically closed if the original PR is merged.

---

📄 679% (6.79x) speedup for serialise_image in inference/core/workflows/core_steps/common/serializers.py

⏱️ Runtime : 7.36 milliseconds → 944 microseconds (best of 306 runs)

📝 Explanation and details

The optimization eliminates expensive Pydantic model instantiation and serialization by replacing ParentOrigin.from_origin_coordinates_system().model_dump() calls with a simple helper function _parent_origin_as_dict() that directly constructs the required dictionary.

Key changes:

• Bypassed Pydantic overhead: The original code created ParentOrigin BaseModel instances just to immediately serialize them to dictionaries via model_dump(). This involves validation, field processing, and internal Pydantic machinery.
• Direct dictionary construction: The new _parent_origin_as_dict() function directly maps the four required fields (offset_x, offset_y, width, height) from the origin coordinates to a dictionary, eliminating all intermediate object creation.

Why this is faster:

• Reduced object allocation: Eliminates creation of temporary Pydantic model instances that are immediately discarded
• Avoided validation overhead: Skips Pydantic's field validation and processing pipeline
• Simplified data flow: Direct attribute access and dictionary construction is much faster than class instantiation + serialization

Performance characteristics: The optimization shows dramatic speedups (400-700%) specifically for test cases involving crops/slices where parent_metadata.parent_id != root_metadata.parent_id, as these trigger the expensive Pydantic operations. Non-crop cases see minimal impact since they skip this code path entirely. The profiler data confirms this - the original code spent 44.2% of its time in ParentOrigin.from_origin_coordinates_system() and model_dump() calls, which are completely eliminated in the optimized version.

✅ Correctness verification report:

Test	Status
⏪ Replay Tests	🔘 None Found
⚙️ Existing Unit Tests	🔘 None Found
🔎 Concolic Coverage Tests	🔘 None Found
🌀 Generated Regression Tests	✅ 1137 Passed
📊 Tests Coverage	100.0%

🌀 Generated Regression Tests and Runtime

from typing import Any, Dict

# imports
import pytest
from inference.core.workflows.core_steps.common.serializers import \
    serialise_image

# --- Mocked classes and constants for testing ---

# Constants used in the serializer
PARENT_ID_KEY = "parent_id"
PARENT_ORIGIN_KEY = "parent_origin"
ROOT_PARENT_ID_KEY = "root_parent_id"
ROOT_PARENT_ORIGIN_KEY = "root_parent_origin"

# Mock OriginCoordinatesSystem
class OriginCoordinatesSystem:
    def __init__(self, left_top_x, left_top_y, origin_width, origin_height):
        self.left_top_x = left_top_x
        self.left_top_y = left_top_y
        self.origin_width = origin_width
        self.origin_height = origin_height

# Mock VideoMetadata
class VideoMetadata:
    def __init__(self, duration, frame_rate):
        self.duration = duration
        self.frame_rate = frame_rate

    def dict(self):
        return {"duration": self.duration, "frame_rate": self.frame_rate}

# Mock ParentMetadata
class ParentMetadata:
    def __init__(self, parent_id, origin_coordinates):
        self.parent_id = parent_id
        self.origin_coordinates = origin_coordinates

# Mock WorkflowImageData
class WorkflowImageData:
    def __init__(
        self,
        base64_image,
        parent_metadata,
        workflow_root_ancestor_metadata,
        video_metadata=None,
    ):
        self.base64_image = base64_image
        self.parent_metadata = parent_metadata
        self.workflow_root_ancestor_metadata = workflow_root_ancestor_metadata
        self.video_metadata = video_metadata
from inference.core.workflows.core_steps.common.serializers import \
    serialise_image

# --- Unit tests ---

# 1. Basic Test Cases

def test_basic_serialisation_no_video_metadata():
    """Test basic serialisation with no video metadata and parent/root IDs are equal (no crop/slice)."""
    origin = OriginCoordinatesSystem(0, 0, 100, 100)
    parent_metadata = ParentMetadata("parent1", origin)
    root_metadata = ParentMetadata("parent1", origin)
    image = WorkflowImageData("abc123", parent_metadata, root_metadata)
    codeflash_output = serialise_image(image); result = codeflash_output # 1.38μs -> 1.38μs (0.000% faster)

def test_basic_serialisation_with_video_metadata():
    """Test basic serialisation with video metadata present."""
    origin = OriginCoordinatesSystem(10, 20, 200, 300)
    parent_metadata = ParentMetadata("parent1", origin)
    root_metadata = ParentMetadata("parent1", origin)
    video_metadata = VideoMetadata(duration=10.5, frame_rate=30)
    image = WorkflowImageData("xyz789", parent_metadata, root_metadata, video_metadata)
    codeflash_output = serialise_image(image); result = codeflash_output # 1.94μs -> 1.83μs (6.00% faster)

def test_basic_crop_serialisation():
    """Test serialisation for an image that is a crop (parent/root IDs differ)."""
    parent_origin = OriginCoordinatesSystem(5, 10, 50, 60)
    root_origin = OriginCoordinatesSystem(0, 0, 100, 120)
    parent_metadata = ParentMetadata("parent2", parent_origin)
    root_metadata = ParentMetadata("parent1", root_origin)
    image = WorkflowImageData("cropdata", parent_metadata, root_metadata)
    codeflash_output = serialise_image(image); result = codeflash_output # 16.4μs -> 3.02μs (445% faster)

def test_basic_crop_with_video_metadata():
    """Test crop/slice serialisation with video metadata."""
    parent_origin = OriginCoordinatesSystem(1, 2, 3, 4)
    root_origin = OriginCoordinatesSystem(0, 0, 10, 10)
    parent_metadata = ParentMetadata("parentB", parent_origin)
    root_metadata = ParentMetadata("parentA", root_origin)
    video_metadata = VideoMetadata(duration=99.9, frame_rate=60)
    image = WorkflowImageData("vidimg", parent_metadata, root_metadata, video_metadata)
    codeflash_output = serialise_image(image); result = codeflash_output # 15.7μs -> 3.35μs (369% faster)

# 2. Edge Test Cases

def test_empty_base64_image():
    """Test with an empty base64 image string."""
    origin = OriginCoordinatesSystem(0, 0, 1, 1)
    parent_metadata = ParentMetadata("id1", origin)
    root_metadata = ParentMetadata("id1", origin)
    image = WorkflowImageData("", parent_metadata, root_metadata)
    codeflash_output = serialise_image(image); result = codeflash_output # 1.26μs -> 1.25μs (0.718% faster)

def test_zero_offsets_and_minimal_dimensions():
    """Test with zero offsets and minimal dimensions."""
    origin = OriginCoordinatesSystem(0, 0, 1, 1)
    parent_metadata = ParentMetadata("id1", origin)
    root_metadata = ParentMetadata("id2", origin)
    image = WorkflowImageData("minimg", parent_metadata, root_metadata)
    codeflash_output = serialise_image(image); result = codeflash_output # 15.7μs -> 2.98μs (429% faster)

def test_negative_offsets():
    """Test with negative offsets in origin coordinates."""
    parent_origin = OriginCoordinatesSystem(-10, -20, 50, 60)
    root_origin = OriginCoordinatesSystem(-100, -200, 500, 600)
    parent_metadata = ParentMetadata("parentX", parent_origin)
    root_metadata = ParentMetadata("parentY", root_origin)
    image = WorkflowImageData("negimg", parent_metadata, root_metadata)
    codeflash_output = serialise_image(image); result = codeflash_output # 16.2μs -> 3.09μs (424% faster)

def test_none_video_metadata():
    """Test with video_metadata explicitly set to None."""
    origin = OriginCoordinatesSystem(1, 2, 3, 4)
    parent_metadata = ParentMetadata("parent", origin)
    root_metadata = ParentMetadata("parent", origin)
    image = WorkflowImageData("nonevid", parent_metadata, root_metadata, None)
    codeflash_output = serialise_image(image); result = codeflash_output # 1.19μs -> 1.21μs (1.73% slower)

def test_large_offsets_and_dimensions():
    """Test with very large offsets and dimensions."""
    parent_origin = OriginCoordinatesSystem(999999, 888888, 777777, 666666)
    root_origin = OriginCoordinatesSystem(444444, 333333, 222222, 111111)
    parent_metadata = ParentMetadata("pL", parent_origin)
    root_metadata = ParentMetadata("rL", root_origin)
    image = WorkflowImageData("largeimg", parent_metadata, root_metadata)
    codeflash_output = serialise_image(image); result = codeflash_output # 16.2μs -> 3.10μs (420% faster)

def test_parent_id_and_root_id_are_empty_strings():
    """Test with empty strings for parent_id and root_parent_id."""
    origin = OriginCoordinatesSystem(1, 2, 3, 4)
    parent_metadata = ParentMetadata("", origin)
    root_metadata = ParentMetadata("", origin)
    image = WorkflowImageData("emptyidimg", parent_metadata, root_metadata)
    codeflash_output = serialise_image(image); result = codeflash_output # 1.19μs -> 1.24μs (4.03% slower)

def test_parent_and_root_ids_are_none():
    """Test with None for parent_id and root_parent_id."""
    origin = OriginCoordinatesSystem(1, 2, 3, 4)
    parent_metadata = ParentMetadata(None, origin)
    root_metadata = ParentMetadata(None, origin)
    image = WorkflowImageData("noneidimg", parent_metadata, root_metadata)
    codeflash_output = serialise_image(image); result = codeflash_output # 1.38μs -> 1.43μs (3.49% slower)

def test_parent_and_root_ids_are_different_none_and_str():
    """Test with parent_id None and root_parent_id as string."""
    origin = OriginCoordinatesSystem(1, 2, 3, 4)
    parent_metadata = ParentMetadata(None, origin)
    root_metadata = ParentMetadata("root", origin)
    image = WorkflowImageData("diffidimg", parent_metadata, root_metadata)
    codeflash_output = serialise_image(image); result = codeflash_output # 16.7μs -> 3.18μs (426% faster)

def test_parent_and_root_ids_are_different_str_and_none():
    """Test with parent_id as string and root_parent_id None."""
    origin = OriginCoordinatesSystem(1, 2, 3, 4)
    parent_metadata = ParentMetadata("parent", origin)
    root_metadata = ParentMetadata(None, origin)
    image = WorkflowImageData("diffidimg2", parent_metadata, root_metadata)
    codeflash_output = serialise_image(image); result = codeflash_output # 15.6μs -> 3.10μs (404% faster)

# 3. Large Scale Test Cases

def test_large_base64_image_string():
    """Test with a large base64 image string (1000 chars)."""
    large_base64 = "A" * 1000
    origin = OriginCoordinatesSystem(0, 0, 100, 100)
    parent_metadata = ParentMetadata("parent", origin)
    root_metadata = ParentMetadata("parent", origin)
    image = WorkflowImageData(large_base64, parent_metadata, root_metadata)
    codeflash_output = serialise_image(image); result = codeflash_output # 1.17μs -> 1.22μs (4.09% slower)

def test_large_number_of_unique_crop_metadata():
    """Test serialisation for many unique crop slices (1000 distinct parent/root pairs)."""
    for i in range(1, 1001):
        parent_origin = OriginCoordinatesSystem(i, i+1, i+2, i+3)
        root_origin = OriginCoordinatesSystem(i+4, i+5, i+6, i+7)
        parent_metadata = ParentMetadata(f"parent_{i}", parent_origin)
        root_metadata = ParentMetadata(f"root_{i}", root_origin)
        image = WorkflowImageData(f"img_{i}", parent_metadata, root_metadata)
        codeflash_output = serialise_image(image); result = codeflash_output # 6.35ms -> 778μs (715% faster)

def test_large_video_metadata_values():
    """Test with large values in video metadata."""
    origin = OriginCoordinatesSystem(0, 0, 100, 100)
    parent_metadata = ParentMetadata("parent", origin)
    root_metadata = ParentMetadata("parent", origin)
    video_metadata = VideoMetadata(duration=1e6, frame_rate=1e3)
    image = WorkflowImageData("largevid", parent_metadata, root_metadata, video_metadata)
    codeflash_output = serialise_image(image); result = codeflash_output # 1.44μs -> 1.38μs (4.27% faster)

def test_large_dimensions_and_offsets():
    """Test with maximal dimensions and offsets within reasonable bounds."""
    max_val = 999_999_999
    origin = OriginCoordinatesSystem(max_val, max_val, max_val, max_val)
    parent_metadata = ParentMetadata("parent_max", origin)
    root_metadata = ParentMetadata("root_max", origin)
    image = WorkflowImageData("maximg", parent_metadata, root_metadata)
    codeflash_output = serialise_image(image); result = codeflash_output # 17.3μs -> 2.31μs (649% faster)
# codeflash_output is used to check that the output of the original code is the same as that of the optimized code.
#------------------------------------------------
from dataclasses import dataclass
from typing import Any, Dict, Optional

# imports
import pytest
from inference.core.workflows.core_steps.common.serializers import \
    serialise_image

# --- Mocked dependencies and constants for testing ---

# Constants used in serialise_image
PARENT_ID_KEY = "parent_id"
PARENT_ORIGIN_KEY = "parent_origin"
ROOT_PARENT_ID_KEY = "root_parent_id"
ROOT_PARENT_ORIGIN_KEY = "root_parent_origin"

# Mock for video_metadata with a dict() method
@dataclass
class VideoMetadata:
    frame_idx: int
    timestamp: float

    def dict(self):
        return {"frame_idx": self.frame_idx, "timestamp": self.timestamp}

# Mock for OriginCoordinatesSystem
@dataclass
class OriginCoordinatesSystem:
    left_top_x: int
    left_top_y: int
    origin_width: int
    origin_height: int

# Mock for ParentMetadata
@dataclass
class ParentMetadata:
    parent_id: str
    origin_coordinates: OriginCoordinatesSystem

# Mock for WorkflowImageData
@dataclass
class WorkflowImageData:
    base64_image: str
    video_metadata: Optional[VideoMetadata]
    parent_metadata: ParentMetadata
    workflow_root_ancestor_metadata: ParentMetadata
from inference.core.workflows.core_steps.common.serializers import \
    serialise_image

# --- Unit Tests ---

# 1. Basic Test Cases

def test_serialise_image_basic_no_crop():
    """Test with a normal image, no crop (parent_id == root_parent_id), with video metadata."""
    origin = OriginCoordinatesSystem(0, 0, 100, 100)
    parent_meta = ParentMetadata("img_1", origin)
    root_meta = ParentMetadata("img_1", origin)
    video_meta = VideoMetadata(frame_idx=0, timestamp=1.23)
    image = WorkflowImageData("abc123==", video_meta, parent_meta, root_meta)
    codeflash_output = serialise_image(image); result = codeflash_output # 1.95μs -> 1.85μs (5.39% faster)

def test_serialise_image_basic_crop():
    """Test with a cropped image (parent_id != root_parent_id), with video metadata."""
    crop_origin = OriginCoordinatesSystem(10, 20, 50, 60)
    root_origin = OriginCoordinatesSystem(0, 0, 100, 100)
    parent_meta = ParentMetadata("img_2", crop_origin)
    root_meta = ParentMetadata("img_1", root_origin)
    video_meta = VideoMetadata(frame_idx=5, timestamp=9.87)
    image = WorkflowImageData("def456==", video_meta, parent_meta, root_meta)
    codeflash_output = serialise_image(image); result = codeflash_output # 18.6μs -> 3.48μs (436% faster)

def test_serialise_image_basic_no_video_metadata():
    """Test with no video metadata (video_metadata is None)."""
    origin = OriginCoordinatesSystem(0, 0, 100, 100)
    parent_meta = ParentMetadata("img_1", origin)
    root_meta = ParentMetadata("img_1", origin)
    image = WorkflowImageData("xyz789==", None, parent_meta, root_meta)
    codeflash_output = serialise_image(image); result = codeflash_output # 1.21μs -> 1.20μs (0.832% faster)

# 2. Edge Test Cases

def test_serialise_image_edge_empty_base64():
    """Test with empty base64 string."""
    origin = OriginCoordinatesSystem(0, 0, 1, 1)
    parent_meta = ParentMetadata("img_1", origin)
    root_meta = ParentMetadata("img_1", origin)
    image = WorkflowImageData("", None, parent_meta, root_meta)
    codeflash_output = serialise_image(image); result = codeflash_output # 1.01μs -> 1.11μs (8.99% slower)

def test_serialise_image_edge_zero_offsets_and_min_size():
    """Test with zero offsets and minimum positive size."""
    origin = OriginCoordinatesSystem(0, 0, 1, 1)
    crop_origin = OriginCoordinatesSystem(0, 0, 1, 1)
    parent_meta = ParentMetadata("crop_img", crop_origin)
    root_meta = ParentMetadata("root_img", origin)
    image = WorkflowImageData("tiny==", None, parent_meta, root_meta)
    codeflash_output = serialise_image(image); result = codeflash_output # 17.6μs -> 3.09μs (471% faster)

def test_serialise_image_edge_negative_offsets():
    """Test with negative offsets (simulate crop outside parent)."""
    crop_origin = OriginCoordinatesSystem(-10, -20, 30, 40)
    root_origin = OriginCoordinatesSystem(0, 0, 100, 100)
    parent_meta = ParentMetadata("crop_img", crop_origin)
    root_meta = ParentMetadata("root_img", root_origin)
    image = WorkflowImageData("neg==", None, parent_meta, root_meta)
    codeflash_output = serialise_image(image); result = codeflash_output # 16.8μs -> 2.48μs (578% faster)

def test_serialise_image_edge_large_offsets_and_sizes():
    """Test with very large offsets and sizes."""
    crop_origin = OriginCoordinatesSystem(999999, 888888, 777777, 666666)
    root_origin = OriginCoordinatesSystem(0, 0, 1000000, 1000000)
    parent_meta = ParentMetadata("large_crop", crop_origin)
    root_meta = ParentMetadata("large_root", root_origin)
    image = WorkflowImageData("largebase64==", None, parent_meta, root_meta)
    codeflash_output = serialise_image(image); result = codeflash_output # 16.8μs -> 2.65μs (531% faster)

def test_serialise_image_edge_parent_id_empty_string():
    """Test with empty string for parent_id."""
    origin = OriginCoordinatesSystem(0, 0, 100, 100)
    parent_meta = ParentMetadata("", origin)
    root_meta = ParentMetadata("root_img", origin)
    image = WorkflowImageData("emptyid==", None, parent_meta, root_meta)
    codeflash_output = serialise_image(image); result = codeflash_output # 15.6μs -> 2.56μs (510% faster)

def test_serialise_image_edge_parent_id_none():
    """Test with None for parent_id (should not crash, but None != root id triggers crop metadata)."""
    origin = OriginCoordinatesSystem(0, 0, 100, 100)
    parent_meta = ParentMetadata(None, origin)
    root_meta = ParentMetadata("root_img", origin)
    image = WorkflowImageData("noneid==", None, parent_meta, root_meta)
    codeflash_output = serialise_image(image); result = codeflash_output # 15.5μs -> 3.00μs (419% faster)

# 3. Large Scale Test Cases

def test_serialise_image_large_base64_string():
    """Test with a very large base64 string (simulate large image)."""
    origin = OriginCoordinatesSystem(0, 0, 1000, 1000)
    parent_meta = ParentMetadata("img_1", origin)
    root_meta = ParentMetadata("img_1", origin)
    large_base64 = "A" * 1000  # 1000 chars
    image = WorkflowImageData(large_base64, None, parent_meta, root_meta)
    codeflash_output = serialise_image(image); result = codeflash_output # 1.07μs -> 1.12μs (4.54% slower)

def test_serialise_image_large_number_of_crops():
    """Test serialising many cropped images with different parent/root ids and origins."""
    for i in range(10):  # Keep under 1000 for performance
        crop_origin = OriginCoordinatesSystem(i, i*2, 100+i, 200+i)
        root_origin = OriginCoordinatesSystem(0, 0, 1000, 1000)
        parent_meta = ParentMetadata(f"crop_{i}", crop_origin)
        root_meta = ParentMetadata("root_img", root_origin)
        image = WorkflowImageData(f"img{i}==", None, parent_meta, root_meta)
        codeflash_output = serialise_image(image); result = codeflash_output # 82.2μs -> 11.7μs (605% faster)

def test_serialise_image_large_video_metadata():
    """Test with large video metadata values."""
    origin = OriginCoordinatesSystem(0, 0, 100, 100)
    parent_meta = ParentMetadata("img_1", origin)
    root_meta = ParentMetadata("img_1", origin)
    video_meta = VideoMetadata(frame_idx=999999, timestamp=123456.789)
    image = WorkflowImageData("bigvideo==", video_meta, parent_meta, root_meta)
    codeflash_output = serialise_image(image); result = codeflash_output # 1.54μs -> 1.51μs (1.98% faster)

def test_serialise_image_large_scale_stress():
    """Stress test: serialise 100 images with varying metadata."""
    for i in range(100):  # Keep under 1000 for performance
        crop_origin = OriginCoordinatesSystem(i, i+1, i+2, i+3)
        root_origin = OriginCoordinatesSystem(0, 0, 1000, 1000)
        parent_meta = ParentMetadata(f"crop_{i}", crop_origin)
        root_meta = ParentMetadata("root_img", root_origin)
        video_meta = VideoMetadata(frame_idx=i, timestamp=i*0.1)
        image = WorkflowImageData(f"img{i}==", video_meta, parent_meta, root_meta)
        codeflash_output = serialise_image(image); result = codeflash_output # 677μs -> 94.7μs (616% faster)
# codeflash_output is used to check that the output of the original code is the same as that of the optimized code.

To edit these changes git checkout codeflash/optimize-pr1672-2025-11-02T01.50.52 and push.