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-rw-r--r--vendor/exr/src/block/writer.rs468
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+//! Composable structures to handle writing an image.
+
+
+use std::fmt::Debug;
+use std::io::Seek;
+use std::iter::Peekable;
+use std::ops::Not;
+use rayon_core::{ThreadPool, ThreadPoolBuildError};
+
+use smallvec::alloc::collections::BTreeMap;
+
+use crate::block::UncompressedBlock;
+use crate::block::chunk::{Chunk};
+use crate::compression::Compression;
+use crate::error::{Error, Result, UnitResult, usize_to_u64};
+use crate::io::{Data, Tracking, Write};
+use crate::meta::{Headers, MetaData, OffsetTables};
+use crate::meta::attribute::LineOrder;
+
+/// Write an exr file by writing one chunk after another in a closure.
+/// In the closure, you are provided a chunk writer, which should be used to write all the chunks.
+/// Assumes the your write destination is buffered.
+pub fn write_chunks_with<W: Write + Seek>(
+ buffered_write: W, headers: Headers, pedantic: bool,
+ write_chunks: impl FnOnce(MetaData, &mut ChunkWriter<W>) -> UnitResult
+) -> UnitResult {
+ // this closure approach ensures that after writing all chunks, the file is always completed and checked and flushed
+ let (meta, mut writer) = ChunkWriter::new_for_buffered(buffered_write, headers, pedantic)?;
+ write_chunks(meta, &mut writer)?;
+ writer.complete_meta_data()
+}
+
+/// Can consume compressed pixel chunks, writing them a file.
+/// Use `sequential_blocks_compressor` or `parallel_blocks_compressor` to compress your data,
+/// or use `compress_all_blocks_sequential` or `compress_all_blocks_parallel`.
+/// Use `on_progress` to obtain a new writer
+/// that triggers a callback for each block.
+// #[must_use]
+#[derive(Debug)]
+#[must_use]
+pub struct ChunkWriter<W> {
+ header_count: usize,
+ byte_writer: Tracking<W>,
+ chunk_indices_byte_location: std::ops::Range<usize>,
+ chunk_indices_increasing_y: OffsetTables,
+ chunk_count: usize, // TODO compose?
+}
+
+/// A new writer that triggers a callback
+/// for each block written to the inner writer.
+#[derive(Debug)]
+#[must_use]
+pub struct OnProgressChunkWriter<'w, W, F> {
+ chunk_writer: &'w mut W,
+ written_chunks: usize,
+ on_progress: F,
+}
+
+/// Write chunks to a byte destination.
+/// Then write each chunk with `writer.write_chunk(chunk)`.
+pub trait ChunksWriter: Sized {
+
+ /// The total number of chunks that the complete file will contain.
+ fn total_chunks_count(&self) -> usize;
+
+ /// Any more calls will result in an error and have no effect.
+ /// If writing results in an error, the file and the writer
+ /// may remain in an invalid state and should not be used further.
+ /// Errors when the chunk at this index was already written.
+ fn write_chunk(&mut self, index_in_header_increasing_y: usize, chunk: Chunk) -> UnitResult;
+
+ /// Obtain a new writer that calls the specified closure for each block that is written to this writer.
+ fn on_progress<F>(&mut self, on_progress: F) -> OnProgressChunkWriter<'_, Self, F> where F: FnMut(f64) {
+ OnProgressChunkWriter { chunk_writer: self, written_chunks: 0, on_progress }
+ }
+
+ /// Obtain a new writer that can compress blocks to chunks, which are then passed to this writer.
+ fn sequential_blocks_compressor<'w>(&'w mut self, meta: &'w MetaData) -> SequentialBlocksCompressor<'w, Self> {
+ SequentialBlocksCompressor::new(meta, self)
+ }
+
+ /// Obtain a new writer that can compress blocks to chunks on multiple threads, which are then passed to this writer.
+ /// Returns none if the sequential compressor should be used instead (thread pool creation failure or too large performance overhead).
+ fn parallel_blocks_compressor<'w>(&'w mut self, meta: &'w MetaData) -> Option<ParallelBlocksCompressor<'w, Self>> {
+ ParallelBlocksCompressor::new(meta, self)
+ }
+
+ /// Compresses all blocks to the file.
+ /// The index of the block must be in increasing line order within the header.
+ /// Obtain iterator with `MetaData::collect_ordered_blocks(...)` or similar methods.
+ fn compress_all_blocks_sequential(mut self, meta: &MetaData, blocks: impl Iterator<Item=(usize, UncompressedBlock)>) -> UnitResult {
+ let mut writer = self.sequential_blocks_compressor(meta);
+
+ // TODO check block order if line order is not unspecified!
+ for (index_in_header_increasing_y, block) in blocks {
+ writer.compress_block(index_in_header_increasing_y, block)?;
+ }
+
+ // TODO debug_assert_eq!(self.is_complete());
+ Ok(())
+ }
+
+ /// Compresses all blocks to the file.
+ /// The index of the block must be in increasing line order within the header.
+ /// Obtain iterator with `MetaData::collect_ordered_blocks(...)` or similar methods.
+ /// Will fallback to sequential processing where threads are not available, or where it would not speed up the process.
+ fn compress_all_blocks_parallel(mut self, meta: &MetaData, blocks: impl Iterator<Item=(usize, UncompressedBlock)>) -> UnitResult {
+ let mut parallel_writer = match self.parallel_blocks_compressor(meta) {
+ None => return self.compress_all_blocks_sequential(meta, blocks),
+ Some(writer) => writer,
+ };
+
+ // TODO check block order if line order is not unspecified!
+ for (index_in_header_increasing_y, block) in blocks {
+ parallel_writer.add_block_to_compression_queue(index_in_header_increasing_y, block)?;
+ }
+
+ // TODO debug_assert_eq!(self.is_complete());
+ Ok(())
+ }
+}
+
+
+impl<W> ChunksWriter for ChunkWriter<W> where W: Write + Seek {
+
+ /// The total number of chunks that the complete file will contain.
+ fn total_chunks_count(&self) -> usize { self.chunk_count }
+
+ /// Any more calls will result in an error and have no effect.
+ /// If writing results in an error, the file and the writer
+ /// may remain in an invalid state and should not be used further.
+ /// Errors when the chunk at this index was already written.
+ fn write_chunk(&mut self, index_in_header_increasing_y: usize, chunk: Chunk) -> UnitResult {
+ let header_chunk_indices = &mut self.chunk_indices_increasing_y[chunk.layer_index];
+
+ if index_in_header_increasing_y >= header_chunk_indices.len() {
+ return Err(Error::invalid("too large chunk index"));
+ }
+
+ let chunk_index_slot = &mut header_chunk_indices[index_in_header_increasing_y];
+ if *chunk_index_slot != 0 {
+ return Err(Error::invalid(format!("chunk at index {} is already written", index_in_header_increasing_y)));
+ }
+
+ *chunk_index_slot = usize_to_u64(self.byte_writer.byte_position());
+ chunk.write(&mut self.byte_writer, self.header_count)?;
+ Ok(())
+ }
+}
+
+impl<W> ChunkWriter<W> where W: Write + Seek {
+ // -- the following functions are private, because they must be called in a strict order --
+
+ /// Writes the meta data and zeroed offset tables as a placeholder.
+ fn new_for_buffered(buffered_byte_writer: W, headers: Headers, pedantic: bool) -> Result<(MetaData, Self)> {
+ let mut write = Tracking::new(buffered_byte_writer);
+ let requirements = MetaData::write_validating_to_buffered(&mut write, headers.as_slice(), pedantic)?;
+
+ // TODO: use increasing line order where possible, but this requires us to know whether we want to be parallel right now
+ /*// if non-parallel compression, we always use increasing order anyways
+ if !parallel || !has_compression {
+ for header in &mut headers {
+ if header.line_order == LineOrder::Unspecified {
+ header.line_order = LineOrder::Increasing;
+ }
+ }
+ }*/
+
+ let offset_table_size: usize = headers.iter().map(|header| header.chunk_count).sum();
+
+ let offset_table_start_byte = write.byte_position();
+ let offset_table_end_byte = write.byte_position() + offset_table_size * u64::BYTE_SIZE;
+
+ // skip offset tables, filling with 0, will be updated after the last chunk has been written
+ write.seek_write_to(offset_table_end_byte)?;
+
+ let header_count = headers.len();
+ let chunk_indices_increasing_y = headers.iter()
+ .map(|header| vec![0_u64; header.chunk_count]).collect();
+
+ let meta_data = MetaData { requirements, headers };
+
+ Ok((meta_data, ChunkWriter {
+ header_count,
+ byte_writer: write,
+ chunk_count: offset_table_size,
+ chunk_indices_byte_location: offset_table_start_byte .. offset_table_end_byte,
+ chunk_indices_increasing_y,
+ }))
+ }
+
+ /// Seek back to the meta data, write offset tables, and flush the byte writer.
+ /// Leaves the writer seeked to the middle of the file.
+ fn complete_meta_data(mut self) -> UnitResult {
+ if self.chunk_indices_increasing_y.iter().flatten().any(|&index| index == 0) {
+ return Err(Error::invalid("some chunks are not written yet"))
+ }
+
+ // write all offset tables
+ debug_assert_ne!(self.byte_writer.byte_position(), self.chunk_indices_byte_location.end, "offset table has already been updated");
+ self.byte_writer.seek_write_to(self.chunk_indices_byte_location.start)?;
+
+ for table in self.chunk_indices_increasing_y {
+ u64::write_slice(&mut self.byte_writer, table.as_slice())?;
+ }
+
+ self.byte_writer.flush()?; // make sure we catch all (possibly delayed) io errors before returning
+ Ok(())
+ }
+
+}
+
+
+impl<'w, W, F> ChunksWriter for OnProgressChunkWriter<'w, W, F> where W: 'w + ChunksWriter, F: FnMut(f64) {
+ fn total_chunks_count(&self) -> usize {
+ self.chunk_writer.total_chunks_count()
+ }
+
+ fn write_chunk(&mut self, index_in_header_increasing_y: usize, chunk: Chunk) -> UnitResult {
+ let total_chunks = self.total_chunks_count();
+ let on_progress = &mut self.on_progress;
+
+ // guarantee on_progress being called with 0 once
+ if self.written_chunks == 0 { on_progress(0.0); }
+
+ self.chunk_writer.write_chunk(index_in_header_increasing_y, chunk)?;
+
+ self.written_chunks += 1;
+
+ on_progress({
+ // guarantee finishing with progress 1.0 for last block at least once, float division might slightly differ from 1.0
+ if self.written_chunks == total_chunks { 1.0 }
+ else { self.written_chunks as f64 / total_chunks as f64 }
+ });
+
+ Ok(())
+ }
+}
+
+
+/// Write blocks that appear in any order and reorder them before writing.
+#[derive(Debug)]
+#[must_use]
+pub struct SortedBlocksWriter<'w, W> {
+ chunk_writer: &'w mut W,
+ pending_chunks: BTreeMap<usize, (usize, Chunk)>,
+ unwritten_chunk_indices: Peekable<std::ops::Range<usize>>,
+ requires_sorting: bool, // using this instead of Option, because of borrowing
+}
+
+
+impl<'w, W> SortedBlocksWriter<'w, W> where W: ChunksWriter {
+
+ /// New sorting writer. Returns `None` if sorting is not required.
+ pub fn new(meta_data: &MetaData, chunk_writer: &'w mut W) -> SortedBlocksWriter<'w, W> {
+ let requires_sorting = meta_data.headers.iter()
+ .any(|header| header.line_order != LineOrder::Unspecified);
+
+ let total_chunk_count = chunk_writer.total_chunks_count();
+
+ SortedBlocksWriter {
+ pending_chunks: BTreeMap::new(),
+ unwritten_chunk_indices: (0 .. total_chunk_count).peekable(),
+ requires_sorting,
+ chunk_writer
+ }
+ }
+
+ /// Write the chunk or stash it. In the closure, write all chunks that can be written now.
+ pub fn write_or_stash_chunk(&mut self, chunk_index_in_file: usize, chunk_y_index: usize, chunk: Chunk) -> UnitResult {
+ if self.requires_sorting.not() {
+ return self.chunk_writer.write_chunk(chunk_y_index, chunk);
+ }
+
+ // write this chunk now if possible
+ if self.unwritten_chunk_indices.peek() == Some(&chunk_index_in_file){
+ self.chunk_writer.write_chunk(chunk_y_index, chunk)?;
+ self.unwritten_chunk_indices.next().expect("peeked chunk index is missing");
+
+ // write all pending blocks that are immediate successors of this block
+ while let Some((next_chunk_y_index, next_chunk)) = self
+ .unwritten_chunk_indices.peek().cloned()
+ .and_then(|id| self.pending_chunks.remove(&id))
+ {
+ self.chunk_writer.write_chunk(next_chunk_y_index, next_chunk)?;
+ self.unwritten_chunk_indices.next().expect("peeked chunk index is missing");
+ }
+ }
+
+ else {
+ // the argument block is not to be written now,
+ // and all the pending blocks are not next up either,
+ // so just stash this block
+ self.pending_chunks.insert(chunk_index_in_file, (chunk_y_index, chunk));
+ }
+
+ Ok(())
+ }
+
+ /// Where the chunks will be written to.
+ pub fn inner_chunks_writer(&self) -> &W {
+ &self.chunk_writer
+ }
+}
+
+
+
+/// Compress blocks to a chunk writer in this thread.
+#[derive(Debug)]
+#[must_use]
+pub struct SequentialBlocksCompressor<'w, W> {
+ meta: &'w MetaData,
+ chunks_writer: &'w mut W,
+}
+
+impl<'w, W> SequentialBlocksCompressor<'w, W> where W: 'w + ChunksWriter {
+
+ /// New blocks writer.
+ pub fn new(meta: &'w MetaData, chunks_writer: &'w mut W) -> Self { Self { meta, chunks_writer, } }
+
+ /// This is where the compressed blocks are written to.
+ pub fn inner_chunks_writer(&'w self) -> &'w W { self.chunks_writer }
+
+ /// Compress a single block immediately. The index of the block must be in increasing line order.
+ pub fn compress_block(&mut self, index_in_header_increasing_y: usize, block: UncompressedBlock) -> UnitResult {
+ self.chunks_writer.write_chunk(
+ index_in_header_increasing_y,
+ block.compress_to_chunk(&self.meta.headers)?
+ )
+ }
+}
+
+/// Compress blocks to a chunk writer with multiple threads.
+#[derive(Debug)]
+#[must_use]
+pub struct ParallelBlocksCompressor<'w, W> {
+ meta: &'w MetaData,
+ sorted_writer: SortedBlocksWriter<'w, W>,
+
+ sender: flume::Sender<Result<(usize, usize, Chunk)>>,
+ receiver: flume::Receiver<Result<(usize, usize, Chunk)>>,
+ pool: rayon_core::ThreadPool,
+
+ currently_compressing_count: usize,
+ written_chunk_count: usize, // used to check for last chunk
+ max_threads: usize,
+ next_incoming_chunk_index: usize, // used to remember original chunk order
+}
+
+impl<'w, W> ParallelBlocksCompressor<'w, W> where W: 'w + ChunksWriter {
+
+ /// New blocks writer. Returns none if sequential compression should be used.
+ /// Use `new_with_thread_pool` to customize the threadpool.
+ pub fn new(meta: &'w MetaData, chunks_writer: &'w mut W) -> Option<Self> {
+ Self::new_with_thread_pool(meta, chunks_writer, ||{
+ rayon_core::ThreadPoolBuilder::new()
+ .thread_name(|index| format!("OpenEXR Block Compressor Thread #{}", index))
+ .build()
+ })
+ }
+
+ /// New blocks writer. Returns none if sequential compression should be used.
+ pub fn new_with_thread_pool<CreatePool>(
+ meta: &'w MetaData, chunks_writer: &'w mut W, try_create_thread_pool: CreatePool)
+ -> Option<Self>
+ where CreatePool: FnOnce() -> std::result::Result<ThreadPool, ThreadPoolBuildError>
+ {
+ if meta.headers.iter().all(|head|head.compression == Compression::Uncompressed) {
+ return None;
+ }
+
+ // in case thread pool creation fails (for example on WASM currently),
+ // we revert to sequential compression
+ let pool = match try_create_thread_pool() {
+ Ok(pool) => pool,
+
+ // TODO print warning?
+ Err(_) => return None,
+ };
+
+ let max_threads = pool.current_num_threads().max(1).min(chunks_writer.total_chunks_count()) + 2; // ca one block for each thread at all times
+ let (send, recv) = flume::unbounded(); // TODO bounded channel simplifies logic?
+
+ Some(Self {
+ sorted_writer: SortedBlocksWriter::new(meta, chunks_writer),
+ next_incoming_chunk_index: 0,
+ currently_compressing_count: 0,
+ written_chunk_count: 0,
+ sender: send,
+ receiver: recv,
+ max_threads,
+ pool,
+ meta,
+ })
+ }
+
+ /// This is where the compressed blocks are written to.
+ pub fn inner_chunks_writer(&'w self) -> &'w W { self.sorted_writer.inner_chunks_writer() }
+
+ // private, as may underflow counter in release mode
+ fn write_next_queued_chunk(&mut self) -> UnitResult {
+ debug_assert!(self.currently_compressing_count > 0, "cannot wait for chunks as there are none left");
+
+ let some_compressed_chunk = self.receiver.recv()
+ .expect("cannot receive compressed block");
+
+ self.currently_compressing_count -= 1;
+ let (chunk_file_index, chunk_y_index, chunk) = some_compressed_chunk?;
+ self.sorted_writer.write_or_stash_chunk(chunk_file_index, chunk_y_index, chunk)?;
+
+ self.written_chunk_count += 1;
+ Ok(())
+ }
+
+ /// Wait until all currently compressing chunks in the compressor have been written.
+ pub fn write_all_queued_chunks(&mut self) -> UnitResult {
+ while self.currently_compressing_count > 0 {
+ self.write_next_queued_chunk()?;
+ }
+
+ debug_assert_eq!(self.currently_compressing_count, 0, "counter does not match block count");
+ Ok(())
+ }
+
+ /// Add a single block to the compressor queue. The index of the block must be in increasing line order.
+ /// When calling this function for the last block, this method waits until all the blocks have been written.
+ /// This only works when you write as many blocks as the image expects, otherwise you can use `wait_for_all_remaining_chunks`.
+ /// Waits for a block from the queue to be written, if the queue already has enough items.
+ pub fn add_block_to_compression_queue(&mut self, index_in_header_increasing_y: usize, block: UncompressedBlock) -> UnitResult {
+
+ // if pipe is full, block to wait for a slot to free up
+ if self.currently_compressing_count >= self.max_threads {
+ self.write_next_queued_chunk()?;
+ }
+
+ // add the argument chunk to the compression queueue
+ let index_in_file = self.next_incoming_chunk_index;
+ let sender = self.sender.clone();
+ let meta = self.meta.clone();
+
+ self.pool.spawn(move ||{
+ let compressed_or_err = block.compress_to_chunk(&meta.headers);
+
+ // by now, decompressing could have failed in another thread.
+ // the error is then already handled, so we simply
+ // don't send the decompressed block and do nothing
+ let _ = sender.send(compressed_or_err.map(move |compressed| (index_in_file, index_in_header_increasing_y, compressed)));
+ });
+
+ self.currently_compressing_count += 1;
+ self.next_incoming_chunk_index += 1;
+
+ // if this is the last chunk, wait for all chunks to complete before returning
+ if self.written_chunk_count + self.currently_compressing_count == self.inner_chunks_writer().total_chunks_count() {
+ self.write_all_queued_chunks()?;
+ debug_assert_eq!(
+ self.written_chunk_count, self.inner_chunks_writer().total_chunks_count(),
+ "written chunk count mismatch"
+ );
+ }
+
+
+ Ok(())
+ }
+}
+
+
+
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