RUST-1392 Add GridFS support: Implement public API with placeholder code (#688)

Create the public API for GridFS in the driver

Author: sanav33

src/db/mod.rs

@@ -19,6 +19,12 @@ use crate::{
     concern::{ReadConcern, WriteConcern},
     cursor::Cursor,
     error::{Error, ErrorKind, Result},
+    gridfs::{
+        options::GridFsBucketOptions,
+        GridFsBucket,
+        DEFAULT_BUCKET_NAME,
+        DEFAULT_CHUNK_SIZE_BYTES,
+    },
     operation::{Aggregate, AggregateTarget, Create, DropDatabase, ListCollections, RunCommand},
     options::{
         AggregateOptions,
@@ -564,4 +570,26 @@ impl Database {
             .execute_watch_with_session(pipeline, options, target, None, session)
             .await
     }
+
+    /// Creates a new GridFsBucket in the database with the given options.
+    pub fn gridfs_bucket(&self, options: impl Into<Option<GridFsBucketOptions>>) -> GridFsBucket {
+        let mut options = options.into().unwrap_or_default();
+        options.read_concern = options
+            .read_concern
+            .or_else(|| self.read_concern().cloned());
+        options.write_concern = options
+            .write_concern
+            .or_else(|| self.write_concern().cloned());
+        options.selection_criteria = options
+            .selection_criteria
+            .or_else(|| self.selection_criteria().cloned());
+        options.bucket_name = options
+            .bucket_name
+            .or_else(|| Some(DEFAULT_BUCKET_NAME.to_string()));
+        options.chunk_size_bytes = options.chunk_size_bytes.or(Some(DEFAULT_CHUNK_SIZE_BYTES));
+        GridFsBucket {
+            db: self.clone(),
+            options,
+        }
+    }
 }

src/gridfs.rs

@@ -0,0 +1,331 @@
+pub mod options;
+
+use core::task::{Context, Poll};
+use std::pin::Pin;
+
+use crate::{
+    concern::{ReadConcern, WriteConcern},
+    cursor::Cursor,
+    error::Result,
+    selection_criteria::SelectionCriteria,
+    Database,
+};
+use bson::{oid::ObjectId, Bson, DateTime, Document};
+use options::*;
+use serde::{Deserialize, Serialize};
+use tokio::io::ReadBuf;
+
+pub const DEFAULT_BUCKET_NAME: &str = "fs";
+pub const DEFAULT_CHUNK_SIZE_BYTES: u32 = 255 * 1024;
+
+// Contained in a "chunks" collection for each user file
+struct Chunk {
+    id: ObjectId,
+    files_id: Bson,
+    n: u32,
+    // default size is 255 KiB
+    data: Vec<u8>,
+}
+
+/// A collection in which information about stored files is stored. There will be one files
+/// collection document per stored file.
+#[derive(Serialize, Deserialize)]
+pub struct FilesCollectionDocument {
+    id: Bson,
+    length: i64,
+    chunk_size: u32,
+    upload_date: DateTime,
+    filename: String,
+    metadata: Document,
+}
+
+/// Struct for storing GridFS managed files within a [`Database`].
+pub struct GridFsBucket {
+    // Contains a "chunks" collection
+    pub(crate) db: Database,
+    pub(crate) options: GridFsBucketOptions,
+}
+
+// TODO: RUST-1395 Add documentation and example code for this struct.
+pub struct GridFsUploadStream {
+    files_id: Bson,
+}
+
+impl GridFsUploadStream {
+    /// Gets the file `id` for the stream.
+    pub fn files_id(&self) -> &Bson {
+        &self.files_id
+    }
+
+    /// Consumes the stream and uploads data in the stream to the server.
+    pub async fn finish(self) {
+        todo!()
+    }
+
+    /// Aborts the upload and discards the upload stream.
+    pub async fn abort(self) {
+        todo!()
+    }
+}
+
+impl tokio::io::AsyncWrite for GridFsUploadStream {
+    fn poll_write(
+        self: Pin<&mut Self>,
+        cx: &mut Context<'_>,
+        buf: &[u8],
+    ) -> Poll<tokio::io::Result<usize>> {
+        todo!()
+    }
+
+    fn poll_flush(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<tokio::io::Result<()>> {
+        todo!()
+    }
+
+    fn poll_shutdown(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<tokio::io::Result<()>> {
+        todo!()
+    }
+}
+
+impl futures_util::AsyncWrite for GridFsUploadStream {
+    fn poll_write(
+        self: Pin<&mut Self>,
+        cx: &mut Context<'_>,
+        buf: &[u8],
+    ) -> Poll<core::result::Result<usize, futures_util::io::Error>> {
+        todo!()
+    }
+
+    fn poll_flush(
+        self: Pin<&mut Self>,
+        cx: &mut Context<'_>,
+    ) -> Poll<core::result::Result<(), futures_util::io::Error>> {
+        todo!()
+    }
+
+    fn poll_close(
+        self: Pin<&mut Self>,
+        cx: &mut Context<'_>,
+    ) -> Poll<core::result::Result<(), futures_util::io::Error>> {
+        todo!()
+    }
+}
+
+pub struct GridFsDownloadStream {
+    files_id: Bson,
+}
+
+impl GridFsDownloadStream {
+    /// Gets the file `id` for the stream.
+    pub fn files_id(&self) -> &Bson {
+        &self.files_id
+    }
+}
+
+impl tokio::io::AsyncRead for GridFsDownloadStream {
+    fn poll_read(
+        self: Pin<&mut Self>,
+        cx: &mut Context<'_>,
+        buf: &mut ReadBuf<'_>,
+    ) -> Poll<tokio::io::Result<()>> {
+        todo!()
+    }
+}
+
+impl futures_util::io::AsyncRead for GridFsDownloadStream {
+    fn poll_read(
+        self: Pin<&mut Self>,
+        cx: &mut Context<'_>,
+        buf: &mut [u8],
+    ) -> Poll<core::result::Result<usize, futures_util::io::Error>> {
+        todo!()
+    }
+}
+
+impl GridFsBucket {
+    /// Gets the read concern of the [`GridFsBucket`].
+    pub fn read_concern(&self) -> Option<&ReadConcern> {
+        self.options.read_concern.as_ref()
+    }
+
+    /// Gets the write concern of the [`GridFsBucket`].
+    pub fn write_concern(&self) -> Option<&WriteConcern> {
+        self.options.write_concern.as_ref()
+    }
+
+    /// Gets the selection criteria of the [`GridFsBucket`].
+    pub fn selection_criteria(&self) -> Option<&SelectionCriteria> {
+        self.options.selection_criteria.as_ref()
+    }
+
+    /// Opens a [`GridFsUploadStream`] that the application can write the contents of the file to.
+    /// The application provides a custom file id.
+    ///
+    /// Returns a [`GridFsUploadStream`] to which the application will write the contents.
+    pub async fn open_upload_stream_with_id(
+        &self,
+        id: Bson,
+        filename: String,
+        options: impl Into<Option<GridFsUploadOptions>>,
+    ) -> Result<GridFsUploadStream> {
+        todo!()
+    }
+
+    /// Opens a [`GridFsUploadStream`] that the application can write the contents of the file to.
+    /// The driver generates a unique [`Bson::ObjectId`] for the file id.
+    ///
+    /// Returns a [`GridFsUploadStream`] to which the application will write the contents.
+    pub async fn open_upload_stream(
+        &self,
+        filename: String,
+        options: impl Into<Option<GridFsUploadOptions>>,
+    ) -> Result<GridFsUploadStream> {
+        self.open_upload_stream_with_id(Bson::ObjectId(ObjectId::new()), filename, options)
+            .await
+    }
+
+    /// Uploads a user file to a GridFS bucket. The application supplies a custom file id. Uses the
+    /// `tokio` crate's `AsyncRead` trait for the `source`.
+    pub async fn upload_from_tokio_reader_with_id(
+        &self,
+        id: Bson,
+        filename: String,
+        source: impl tokio::io::AsyncRead,
+        options: impl Into<Option<GridFsUploadOptions>>,
+    ) {
+        todo!()
+    }
+
+    /// Uploads a user file to a GridFS bucket. The application supplies a custom file id. Uses the
+    /// `futures-0.3` crate's `AsyncRead` trait for the `source`.
+    pub async fn upload_from_futures_0_3_reader_with_id(
+        &self,
+        id: Bson,
+        filename: String,
+        source: impl futures_util::AsyncRead,
+        options: impl Into<Option<GridFsUploadOptions>>,
+    ) {
+        todo!()
+    }
+
+    /// Uploads a user file to a GridFS bucket. The driver generates a unique [`Bson::ObjectId`] for
+    /// the file id. Uses the `tokio` crate's `AsyncRead` trait for the `source`.
+    pub async fn upload_from_tokio_reader(
+        &self,
+        filename: String,
+        source: impl tokio::io::AsyncRead,
+        options: impl Into<Option<GridFsUploadOptions>>,
+    ) {
+        self.upload_from_tokio_reader_with_id(
+            Bson::ObjectId(ObjectId::new()),
+            filename,
+            source,
+            options,
+        )
+        .await
+    }
+
+    /// Uploads a user file to a GridFS bucket. The driver generates a unique [`Bson::ObjectId`] for
+    /// the file id. Uses the `futures-0.3` crate's `AsyncRead` trait for the `source`.
+    pub async fn upload_from_futures_0_3_reader(
+        &self,
+        filename: String,
+        source: impl futures_util::AsyncRead,
+        options: impl Into<Option<GridFsUploadOptions>>,
+    ) {
+        self.upload_from_futures_0_3_reader_with_id(
+            Bson::ObjectId(ObjectId::new()),
+            filename,
+            source,
+            options,
+        )
+        .await
+    }
+
+    /// Opens and returns a [`GridFsDownloadStream`] from which the application can read
+    /// the contents of the stored file specified by `id`.
+    pub async fn open_download_stream(&self, id: Bson) -> Result<GridFsDownloadStream> {
+        todo!()
+    }
+
+    /// Opens and returns a [`GridFsDownloadStream`] from which the application can read
+    /// the contents of the stored file specified by `filename` and the revision
+    /// in `options`.
+    pub async fn open_download_stream_by_name(
+        &self,
+        filename: String,
+        options: impl Into<Option<GridFsDownloadByNameOptions>>,
+    ) -> Result<GridFsDownloadStream> {
+        todo!()
+    }
+
+    /// Downloads the contents of the stored file specified by `id` and writes
+    /// the contents to the `destination`. Uses the `tokio` crate's `AsyncWrite`
+    /// trait for the `destination`.
+    pub async fn download_to_tokio_writer(
+        &self,
+        id: Bson,
+        destination: impl tokio::io::AsyncWrite,
+    ) {
+        todo!()
+    }
+
+    /// Downloads the contents of the stored file specified by `id` and writes
+    /// the contents to the `destination`. Uses the `futures-0.3` crate's `AsyncWrite`
+    /// trait for the `destination`.
+    pub async fn download_to_futures_0_3_writer(
+        &self,
+        id: Bson,
+        destination: impl futures_util::AsyncWrite,
+    ) {
+        todo!()
+    }
+
+    /// Downloads the contents of the stored file specified by `filename` and by
+    /// the revision in `options` and writes the contents to the `destination`. Uses the
+    /// `tokio` crate's `AsyncWrite` trait for the `destination`.
+    pub async fn download_to_tokio_writer_by_name(
+        &self,
+        filename: String,
+        destination: impl tokio::io::AsyncWrite,
+        options: impl Into<Option<GridFsDownloadByNameOptions>>,
+    ) {
+        todo!()
+    }
+
+    /// Downloads the contents of the stored file specified by `filename` and by
+    /// the revision in `options` and writes the contents to the `destination`. Uses the
+    /// `futures-0.3` crate's `AsyncWrite` trait for the `destination`.
+    pub async fn download_to_futures_0_3_writer_by_name(
+        &self,
+        filename: String,
+        destination: impl futures_util::AsyncWrite,
+        options: impl Into<Option<GridFsDownloadByNameOptions>>,
+    ) {
+        todo!()
+    }
+
+    /// Given an `id`, deletes the stored file's files collection document and
+    /// associated chunks from a [`GridFsBucket`].
+    pub async fn delete(&self, id: Bson) {
+        todo!()
+    }
+
+    /// Finds and returns the files collection documents that match the filter.
+    pub async fn find(
+        &self,
+        filter: Document,
+        options: impl Into<Option<GridFsBucketOptions>>,
+    ) -> Result<Cursor<FilesCollectionDocument>> {
+        todo!()
+    }
+
+    /// Renames the stored file with the specified `id`.
+    pub async fn rename(&self, id: Bson, new_filename: String) {
+        todo!()
+    }
+
+    /// Drops the files associated with this bucket.
+    pub async fn drop(&self) {
+        todo!()
+    }
+}