datafusion_datasource/write/

mod.rs

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// to you under the Apache License, Version 2.0 (the
// "License"); you may not use this file except in compliance
// with the License.  You may obtain a copy of the License at
//
//   http://www.apache.org/licenses/LICENSE-2.0
//
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// KIND, either express or implied.  See the License for the
// specific language governing permissions and limitations
// under the License.

//! Module containing helper methods/traits related to enabling
//! write support for the various file formats

use std::io::Write;
use std::sync::Arc;

use crate::file_compression_type::FileCompressionType;
use crate::file_sink_config::FileSinkConfig;
use datafusion_common::error::Result;

use arrow::array::RecordBatch;
use arrow::datatypes::Schema;
use bytes::Bytes;
use object_store::buffered::BufWriter;
use object_store::path::Path;
use object_store::ObjectStore;
use tokio::io::AsyncWrite;

pub mod demux;
pub mod orchestration;

/// A buffer with interior mutability shared by the SerializedFileWriter and
/// ObjectStore writer
#[derive(Clone)]
pub struct SharedBuffer {
    /// The inner buffer for reading and writing
    ///
    /// The lock is used to obtain internal mutability, so no worry about the
    /// lock contention.
    pub buffer: Arc<futures::lock::Mutex<Vec<u8>>>,
}

impl SharedBuffer {
    pub fn new(capacity: usize) -> Self {
        Self {
            buffer: Arc::new(futures::lock::Mutex::new(Vec::with_capacity(capacity))),
        }
    }
}

impl Write for SharedBuffer {
    fn write(&mut self, buf: &[u8]) -> std::io::Result<usize> {
        let mut buffer = self.buffer.try_lock().unwrap();
        Write::write(&mut *buffer, buf)
    }

    fn flush(&mut self) -> std::io::Result<()> {
        let mut buffer = self.buffer.try_lock().unwrap();
        Write::flush(&mut *buffer)
    }
}

/// A trait that defines the methods required for a RecordBatch serializer.
pub trait BatchSerializer: Sync + Send {
    /// Asynchronously serializes a `RecordBatch` and returns the serialized bytes.
    /// Parameter `initial` signals whether the given batch is the first batch.
    /// This distinction is important for certain serializers (like CSV).
    fn serialize(&self, batch: RecordBatch, initial: bool) -> Result<Bytes>;
}

/// Returns an [`AsyncWrite`] which writes to the given object store location
/// with the specified compression.
///
/// The writer will have a default buffer size as chosen by [`BufWriter::new`].
///
/// We drop the `AbortableWrite` struct and the writer will not try to cleanup on failure.
/// Users can configure automatic cleanup with their cloud provider.
#[deprecated(since = "48.0.0", note = "Use ObjectWriterBuilder::new(...) instead")]
pub async fn create_writer(
    file_compression_type: FileCompressionType,
    location: &Path,
    object_store: Arc<dyn ObjectStore>,
) -> Result<Box<dyn AsyncWrite + Send + Unpin>> {
    ObjectWriterBuilder::new(file_compression_type, location, object_store).build()
}

/// Converts table schema to writer schema, which may differ in the case
/// of hive style partitioning where some columns are removed from the
/// underlying files.
pub fn get_writer_schema(config: &FileSinkConfig) -> Arc<Schema> {
    if !config.table_partition_cols.is_empty() && !config.keep_partition_by_columns {
        let schema = config.output_schema();
        let partition_names: Vec<_> =
            config.table_partition_cols.iter().map(|(s, _)| s).collect();
        Arc::new(Schema::new_with_metadata(
            schema
                .fields()
                .iter()
                .filter(|f| !partition_names.contains(&f.name()))
                .map(|f| (**f).clone())
                .collect::<Vec<_>>(),
            schema.metadata().clone(),
        ))
    } else {
        Arc::clone(config.output_schema())
    }
}

/// A builder for an [`AsyncWrite`] that writes to an object store location.
///
/// This can be used to specify file compression on the writer. The writer
/// will have a default buffer size unless altered. The specific default size
/// is chosen by [`BufWriter::new`].
///
/// We drop the `AbortableWrite` struct and the writer will not try to cleanup on failure.
/// Users can configure automatic cleanup with their cloud provider.
#[derive(Debug)]
pub struct ObjectWriterBuilder {
    /// Compression type for object writer.
    file_compression_type: FileCompressionType,
    /// Output path
    location: Path,
    /// The related store that handles the given path
    object_store: Arc<dyn ObjectStore>,
    /// The size of the buffer for the object writer.
    buffer_size: Option<usize>,
}

impl ObjectWriterBuilder {
    /// Create a new [`ObjectWriterBuilder`] for the specified path and compression type.
    pub fn new(
        file_compression_type: FileCompressionType,
        location: &Path,
        object_store: Arc<dyn ObjectStore>,
    ) -> Self {
        Self {
            file_compression_type,
            location: location.clone(),
            object_store,
            buffer_size: None,
        }
    }

    /// Set buffer size in bytes for object writer.
    ///
    /// # Example
    /// ```
    /// # use datafusion_datasource::file_compression_type::FileCompressionType;
    /// # use datafusion_datasource::write::ObjectWriterBuilder;
    /// # use object_store::memory::InMemory;
    /// # use object_store::path::Path;
    /// # use std::sync::Arc;
    /// # let compression_type = FileCompressionType::UNCOMPRESSED;
    /// # let location = Path::from("/foo/bar");
    /// # let object_store = Arc::new(InMemory::new());
    /// let mut builder = ObjectWriterBuilder::new(compression_type, &location, object_store);
    /// builder.set_buffer_size(Some(20 * 1024 * 1024)); //20 MiB
    /// assert_eq!(builder.get_buffer_size(), Some(20 * 1024 * 1024), "Internal error: Builder buffer size doesn't match");
    /// ```
    pub fn set_buffer_size(&mut self, buffer_size: Option<usize>) {
        self.buffer_size = buffer_size;
    }

    /// Set buffer size in bytes for object writer, returning the builder.
    ///
    /// # Example
    /// ```
    /// # use datafusion_datasource::file_compression_type::FileCompressionType;
    /// # use datafusion_datasource::write::ObjectWriterBuilder;
    /// # use object_store::memory::InMemory;
    /// # use object_store::path::Path;
    /// # use std::sync::Arc;
    /// # let compression_type = FileCompressionType::UNCOMPRESSED;
    /// # let location = Path::from("/foo/bar");
    /// # let object_store = Arc::new(InMemory::new());
    /// let builder = ObjectWriterBuilder::new(compression_type, &location, object_store)
    ///     .with_buffer_size(Some(20 * 1024 * 1024)); //20 MiB
    /// assert_eq!(builder.get_buffer_size(), Some(20 * 1024 * 1024), "Internal error: Builder buffer size doesn't match");
    /// ```
    pub fn with_buffer_size(mut self, buffer_size: Option<usize>) -> Self {
        self.buffer_size = buffer_size;
        self
    }

    /// Currently specified buffer size in bytes.
    pub fn get_buffer_size(&self) -> Option<usize> {
        self.buffer_size
    }

    /// Return a writer object that writes to the object store location.
    ///
    /// If a buffer size has not been set, the default buffer buffer size will
    /// be used.
    ///
    /// # Errors
    /// If there is an error applying the compression type.
    pub fn build(self) -> Result<Box<dyn AsyncWrite + Send + Unpin>> {
        let Self {
            file_compression_type,
            location,
            object_store,
            buffer_size,
        } = self;

        let buf_writer = match buffer_size {
            Some(size) => BufWriter::with_capacity(object_store, location, size),
            None => BufWriter::new(object_store, location),
        };

        file_compression_type.convert_async_writer(buf_writer)
    }
}