Add vds generation

pyproject.toml

@@ -13,10 +13,11 @@ description = "Eiger control system integration with FastCS"
 dependencies = [
     "aiohttp",
     "fastcs[epicsca]",
-    "fastcs-odin @ git+https://github.com/DiamondLightSource/fastcs-odin.git@0.8.0a1",
+    "fastcs-odin @ git+https://github.com/DiamondLightSource/fastcs-odin.git@eb1d85bfcd42deb6907a6e41e29f55aafc33f6b5",
     "numpy",
     "pillow",
     "typer",
+    "h5py",
 ] # Add project dependencies here, e.g. ["click", "numpy"]
 dynamic = ["version"]
 license.file = "LICENSE"
@@ -25,7 +26,7 @@ requires-python = ">=3.11"
 
 [project.optional-dependencies]
 dev = [
-    "tickit-devices @ git+https://github.com/dls-controls/tickit-devices.git@eiger-stream2",
+    "tickit-devices @ git+https://github.com/dls-controls/tickit-devices.git@main",
     "black",
     "copier",
     "myst-parser",

src/fastcs_eiger/controllers/odin/eiger_odin_controller.py

@@ -1,15 +1,21 @@
 import asyncio
+from pathlib import Path
 
+from fastcs.attributes import AttrRW
 from fastcs.connections import IPConnectionSettings
+from fastcs.datatypes import Bool
 from fastcs.methods import command
 
 from fastcs_eiger.controllers.eiger_controller import EigerController
+from fastcs_eiger.controllers.odin.generate_vds import create_interleave_vds
 from fastcs_eiger.controllers.odin.odin_controller import OdinController
 
 
 class EigerOdinController(EigerController):
     """Eiger controller with Odin sub controller"""
 
+    enable_vds_creation = AttrRW(Bool())
+
     def __init__(
         self,
         detector_connection_settings: IPConnectionSettings,
@@ -58,3 +64,18 @@ async def start_writing(self):
             await self.OD.writing.wait_for_value(True, timeout=1)
         except TimeoutError as e:
             raise TimeoutError("File writers failed to start") from e
+
+        if self.enable_vds_creation.get():
+            create_interleave_vds(
+                path=Path(self.OD.file_path.get()),
+                prefix=self.OD.file_prefix.get(),
+                datasets=["data1", "data2", "data3"],
+                frame_count=self.OD.FP.frames.get(),
+                frames_per_block=self.OD.block_size.get(),
+                blocks_per_file=self.OD.FP.process_blocks_per_file.get(),
+                frame_shape=(
+                    self.OD.FP.data_dims_1.get(),
+                    self.OD.FP.data_dims_0.get(),
+                ),
+                dtype=self.OD.FP.data_datatype.get(),
+            )

src/fastcs_eiger/controllers/odin/generate_vds.py

@@ -0,0 +1,118 @@
+import math
+from dataclasses import dataclass
+from pathlib import Path
+
+import h5py
+
+
+@dataclass
+class FileFrames:
+    frames: int
+    start: int
+    frames_per_block: int
+
+    @property
+    def blocks(self):
+        return self.frames // self.frames_per_block
+
+    @property
+    def remainder_frames(self):
+        return self.frames % self.frames_per_block
+
+
+def _get_frames_per_file_writer(
+    frame_count: int, frames_per_block: int, n_file_writers: int
+) -> list[int]:
+    n_blocks = math.ceil(frame_count / frames_per_block)
+    min_blocks_per_file = n_blocks // n_file_writers
+    remainder = n_blocks - min_blocks_per_file * n_file_writers
+
+    frames_per_file_writer = []
+    for i in range(n_file_writers):
+        blocks = min_blocks_per_file + (i < remainder)
+        frames_per_file_writer.append(blocks * frames_per_block)
+
+    overflow = sum(frames_per_file_writer) - frame_count
+    frames_per_file_writer[remainder - 1] -= overflow
+    return frames_per_file_writer
+
+
+def _calculate_frame_distribution(
+    frame_count, frames_per_block, blocks_per_file, n_file_writers
+) -> dict[int, FileFrames]:
+
+    frame_distribution: dict[int, FileFrames] = {}
+
+    max_frames_per_file = (
+        frames_per_block * blocks_per_file if blocks_per_file else frame_count
+    )
+    # total frames written before one of the file writers has to start a new file
+    frames_before_new_file = n_file_writers * max_frames_per_file
+    frames_per_file_writer = _get_frames_per_file_writer(
+        frame_count, frames_per_block, n_file_writers
+    )
+    for file_writer_idx, n_frames in enumerate(frames_per_file_writer):
+        n_files = math.ceil(n_frames / max_frames_per_file)
+        for i in range(n_files):
+            file_idx = file_writer_idx + i * n_file_writers
+
+            frame_distribution[file_idx + 1] = FileFrames(
+                frames=min(n_frames - i * max_frames_per_file, max_frames_per_file),
+                frames_per_block=frames_per_block,
+                start=frames_per_block * file_writer_idx
+                + file_idx // n_file_writers * frames_before_new_file,
+            )
+
+    return frame_distribution
+
+
+def create_interleave_vds(
+    path: Path,
+    prefix: str,
+    datasets: list[str],
+    frame_count: int,
+    frames_per_block: int,
+    blocks_per_file: int,
+    frame_shape: tuple[int, int],
+    dtype: str = "float",
+    n_file_writers: int = 4,
+) -> None:
+    frame_distribution = _calculate_frame_distribution(
+        frame_count, frames_per_block, blocks_per_file, n_file_writers
+    )
+    stride = n_file_writers * frames_per_block
+
+    with h5py.File(f"{path / prefix}_vds.h5", "w", libver="latest") as f:
+        for dataset_name in datasets:
+            v_layout = h5py.VirtualLayout(
+                shape=(frame_count, frame_shape[0], frame_shape[1]),
+                dtype=dtype,
+            )
+            for file_number, file_frames in frame_distribution.items():
+                full_block_frames = file_frames.blocks * frames_per_block
+                v_source = h5py.VirtualSource(
+                    f"{path / prefix}_{str(file_number).zfill(6)}.h5",
+                    name=dataset_name,
+                    shape=(file_frames.frames, frame_shape[0], frame_shape[1]),
+                    dtype=dtype,
+                )
+                if file_frames.blocks:
+                    source = v_source[:full_block_frames, :, :]
+                    v_layout[
+                        h5py.MultiBlockSlice(
+                            start=file_frames.start,
+                            stride=stride,
+                            count=file_frames.blocks,
+                            block=frames_per_block,
+                        ),
+                        :,
+                        :,
+                    ] = source
+                if file_frames.remainder_frames:
+                    # Last few frames that don't fit into a block
+                    source = v_source[full_block_frames : file_frames.frames, :, :]
+                    v_layout[
+                        frame_count - file_frames.remainder_frames : frame_count, :, :
+                    ] = source
+
+            f.create_virtual_dataset(dataset_name, v_layout)