sdk/fidl/fuchsia.pkg/cache.fidl - fuchsia - Git at Google

 // Copyright 2018 The Fuchsia Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 library fuchsia.pkg;

 using fuchsia.fxfs;
 using fuchsia.io;
 using zx;

 /// This manages the system package cache.
 ///
 /// This is intended to be implemented by the package manager component and used by
 /// package resolver components.
 @discoverable
 closed protocol PackageCache {
     /// Gets the package directory if it is present on the local system. If it is not, the
     /// `missing_blobs` iterator will provide all the blobs in the package that are missing from
     /// the system, and the ability to write those blobs to blobfs. If all the missing blobs are
     /// downloaded and written to by the client, the `dir` directory will be resolved. This method
     /// will return successfully when the package has been fully resolved, or return an error if
     /// the client closes `needed_blobs` or `dir` handle before the package has been resolved.
     ///
     /// This method does not guarantee the missing blobs have been persisted. In order to guarantee
     /// missing blobs are persisted, clients should call ['Sync'].
     ///
     /// Clients must not make concurrent `Get()` calls for the same `meta_far_blob`, even across
     /// different `PackageCache` connections, *unless* the `meta_far_blob` is in base or already
     /// active in the dynamic index. Violating this may result in `Get()` errors.
     ///
     /// + request `meta_far_blob` the blob info for the package's meta.far.
     /// + request `needed_blobs` an iterator over all the blobs in the package that
     ///   are not present on the system.
     /// + request `dir` the channel on which the package directory will be served.
     /// * error a zx_status value indicating failure. One of the following:
     ///     * `ZX_ERR_UNAVAILABLE` if the client closed `needed_blobs` handles before
     ///       all the missing blobs were downloaded to the system.
     strict Get(resource struct {
         meta_far_blob BlobInfo;
         gc_protection GcProtection;
         needed_blobs server_end:NeededBlobs;
         dir server_end:<fuchsia.io.Directory>;
     }) -> () error zx.Status;

     /// Gets the package directory for a subpackage.
     /// The connection to the superpackage's package directory must still be open when this is
     /// called.
     /// The returned package will be protected by open package tracking.
     ///
     /// + request `superpackage` the hash of the superpackage's meta.far.
     /// + request `subpackage` the relative package URL of the subpackage.
     /// + request `dir` the channel on which the package directory will be served.
     /// * error a GetSubpackageError value indicating failure.
     strict GetSubpackage(resource struct {
         superpackage BlobId;
         subpackage PackageUrl;
         dir server_end:<fuchsia.io.Directory>;
     }) -> () error GetSubpackageError;

     /// Retrieves a chunk iterator to the base package index.
     ///
     /// + request `iterator` a request for the `PackageIndexIterator` that will return sets of
     ///   `PackageIndexEntry` objects until all packages in the base index have been iterated.
     strict BasePackageIndex(resource struct {
         iterator server_end:PackageIndexIterator;
     });

     /// Retrieves a chunk iterator to the cache package index.
     ///
     /// + request `iterator` a request for the `PackageIndexIterator` that will return sets of
     ///   `PackageIndexEntry` objects until all packages in the cache index have been iterated.
     strict CachePackageIndex(resource struct {
         iterator server_end:PackageIndexIterator;
     });

     /// Synchronizes updates to the cached packages to the underlying persistent storage.
     ///
     /// * error a zx_status value indicating failure. One of the following:
     ///     * `ZX_ERR_INTERNAL` if the sync fails.
     strict Sync() -> () error zx.Status;
 };

 /// How the package served by [`PackageCache.Get`] should be protected from GC.
 type GcProtection = strict enum {
     /// Package will be protected from GC as long as there is an open connection to the directory.
     OPEN_PACKAGE_TRACKING = 1;

     /// Package will be protected from GC as long as it is in the Retained index, which is
     /// controlled by the [`RetainedPackages`] protocol. Client is responsible for ensuring
     /// the package is in the Retained index.
     RETAINED = 2;
 };

 /// Error type for [`PackageCache.GetSubpackage`].
 type GetSubpackageError = strict enum {
     /// The superpackage was not open.
     SUPERPACKAGE_CLOSED = 1;

     /// The requested subpackage does not exist.
     DOES_NOT_EXIST = 2;

     /// An unspecified error occurred.
     INTERNAL = 3;
 };

 /// Error type for [`NeededBlobs.OpenMetaBlob`] and [`NeededBlobs.OpenBlob`].
 type OpenBlobError = strict enum {
     /// There is insufficient storage space available to persist this blob.
     OUT_OF_SPACE = 1;

     /// This blob is already open for write by another cache operation.
     CONCURRENT_WRITE = 2;

     /// An unspecified error occurred during underlying I/O.
     UNSPECIFIED_IO = 3;

     /// An unspecified error occurred.
     INTERNAL = 4;
 };

 /// Error type for [`NeededBlobs.BlobWritten`].
 type BlobWrittenError = strict enum {
     /// Client called BlobWritten but blob was not readable in blobfs.
     NOT_WRITTEN = 1;

     /// Client called BlobWritten for a blob it has not yet opened.
     UNOPENED_BLOB = 2;
 };

 /// Represents the transaction for caching a particular package.
 ///
 /// Server expects client to follow the normal operation sequence defined below.
 /// Violating the protocol (e.g. calling wrong methods at the wrong time) will result
 /// in the channel being closed by the package cache with a `ZX_ERR_BAD_STATE` epitaph
 /// and aborting the package cache operation.
 /// If a fatal error occurs at any step, server will close the channel, and client
 /// should not proceed with the sequence.
 /// Non-fatal errors could be retried, as long as the channel remains open.
 ///
 /// Normal operation sequence:
 /// 1. Clients should start by requesting to `OpenMetaBlob()`, and fetch and write
 /// the metadata blob if needed, calling `BlobWritten()` when done to indicate the
 /// write is complete.
 /// 2. `GetMissingBlobs()` should be used to determine which blobs need to be
 /// fetched and written.
 /// 3. Each of the missing blobs needs to be written using `OpenBlob()` and
 /// `BlobWritten()` should be called after each blob is written.
 ///
 /// Clients are responsible for avoiding concurrent creation of the same blob if the underlying
 /// blobstore does not support it.
 /// This manifests as the following constraints (applied per `BlobId`):
 /// 1. If the `BlobWriter` returned by calls to `Open[Meta]Blob` is the `file` variant, once Clients
 ///    call Resize on a file, they must close *all* file connections obtained from `Open[Meta]Blob`
 ///    before calling `Open[Meta]Blob` again.
 /// 2. If the `BlobWriter` returned by calls to `Open[Meta]Blob` is the `writer` variant, Clients
 ///    must not write all the bytes to more than one of the `writer`s.
 /// This applies per `BlobId` to all `BlobWriter`s returned by all calls to `Open[Meta]Blob` across
 /// all `NeededBlobs` connections across all `PackageCache` connections.
 /// Once c++blobfs support is removed and fxblob is changed to support duplicate concurrent creation
 /// requests (https://fxbug.dev/335870456#comment9), this requirement can be dropped.
 ///
 /// Once all needed blobs are written by the client, the package cache will
 /// complete the pending [`PackageCache.Get`] request and close this channel
 /// with a `ZX_OK` epitaph.
 closed protocol NeededBlobs {
     /// Opens the package's metadata blob for writing. `GetMissingBlobs()`
     /// should not be called until writing the meta blob or this request
     /// responds with `false`.
     ///
     /// If the package was already cached, server will close the channel with a
     /// `ZX_OK` epitaph.
     ///
     /// - response `writer` is used to write the blob. If `writer` is absent,
     ///   the blob is already cached and so does not need to be written.
     /// * error an OpenBlobError indicating failure. Clients may retry this
     ///   request, though the server end may abort this cache operation on
     ///   errors it considers to be fatal.
     strict OpenMetaBlob() -> (resource struct {
         writer BlobWriter:optional;
     }) error OpenBlobError;

     /// Returns an iterator of blobs that are not present on the system that
     /// must be written using the `OpenBlob` request before the package will be
     /// fully cached.
     ///
     /// Client should call `OpenMetaBlob`, and write it if needed, before
     /// calling `GetMissingBlobs`.
     ///
     /// A client should make this request no more than once per `NeededBlobs`
     /// connection. Once all blobs yielded by this iterator are written, the
     /// package open request will complete.
     ///
     /// New items may be added to the obtained `BlobInfoIterator` as the client
     /// calls `OpenBlob`, so, to guaranatee termination of the iterator, clients
     /// should call `OpenBlob` concurrently with reading the iterator.
     ///
     /// + request `iterator` a request for an iterator of [`BlobInfo`] of blobs
     ///   that the client should try to write.
     strict GetMissingBlobs(resource struct {
         iterator server_end:BlobInfoIterator;
     });

     /// Opens a blob for writing.
     ///
     /// + request `blob_id` the blob id describing this blob.
     /// - response `writer` is used to write the blob. If `writer` is absent,
     ///   the blob is already cached and so does not need to be written.
     /// * error an OpenBlobError indicating failure. Clients may retry this
     ///   request, though the server end may abort this cache operation on
     ///   errors it considers to be fatal.
     strict OpenBlob(struct {
         blob_id BlobId;
     }) -> (resource struct {
         writer BlobWriter:optional;
     }) error OpenBlobError;

     /// Indicates that a blob opened by `Open[Meta]Blob` has been successfully
     /// written.
     ///
     /// A client should call this once the blob has been fully written using
     /// the `writer` returned by `Open[Meta]Blob`.
     ///
     /// + request `blob_id` the blob id describing this blob.
     /// * error a BlobWrittenError indicating failure. Clients may retry the
     ///   `Open[Meta]Blob` request that prompted this call, though the server
     ///   end may abort this cache operation on errors it considers to be fatal.
     strict BlobWritten(struct {
         blob_id BlobId;
     }) -> () error BlobWrittenError;

     /// Aborts this caching operation for the package.
     ///
     /// Any open blobs and any missing blobs iterator will be closed. Any `dir`
     /// provided to the associated [`PackageCache.Get`] request will also be
     /// closed. Once this request is acknowledged, this channel will be closed.
     ///
     /// Note, dropping this NeededBlobs channel without writing all needed blobs
     /// will also abort the package cache operation. However, this API provides
     /// the ability to wait for the operation to be torn down.
     strict Abort() -> ();
 };

 /// Used to write a blob to the underlying storage.
 type BlobWriter = strict resource union {
     /// To write a blob with `file`:
     ///   1. If the blob is uncompressed, use `fuchsia.io/File.Resize` to set
     ///      the blob's uncompressed size.
     ///   2. Use `fuchsia.io/File.Write` to write the blob's contents from
     ///      start to finish (seeks are not supported).
     /// A corrupt blob is indicated by a `Write()` (usually the final write),
     /// failing with `ZX_ERR_IO_DATA_INTEGRITY`.
     1: file client_end:fuchsia.io.File;
     /// To write a blob with `writer`, follow the instructions on the
     /// `fuchsia.fxfs.BlobWriter` protocol.
     2: writer client_end:fuchsia.fxfs.BlobWriter;
 };

 /// A chunked iterator of [`BlobInfo`], allowing transfer of more [`BlobInfo`]s
 /// that can fit in a single FIDL message.
 closed protocol BlobInfoIterator {
     /// Responds with the next chunk of [`BlobInfo`]s. When the iterator is
     /// exhausted, responds with an empty vector and closes the connection.
     ///
     /// - response `blobs` the next chunk of [`BlobInfo`]s.
     strict Next() -> (struct {
         blobs vector<BlobInfo>:MAX;
     });
 };

 /// A chunk iterator for the package index. This is required because it is possible for the
 /// package index to be too large to send over in a single request (over 64KiB).
 closed protocol PackageIndexIterator {
     /// Returns the next chunk of package index entries. When the iterator is exhausted,
     /// this returns an empty vector.
     ///
     /// - response `entries` the next chunk of entries in the package index.
     strict Next() -> (struct {
         entries vector<PackageIndexEntry>:MAX;
     });
 };

 /// Manages the set of retained packages.
 ///
 /// Retained packages will not be removed from the package cache, even if they
 /// aren't fully present. There is only a single set active at once, and the
 /// provided APIs for configuring the set atomically replace that set. On boot,
 /// the retained package set is always initialized to the empty set.
 /// Documentation on [garbage collection](
 /// https://fuchsia.dev/fuchsia-src/concepts/packages/garbage_collection) contains
 /// details on various types of package indexes (static, retained, etc) and
 /// describes when a package will be garbage collected or retained.
 @discoverable
 closed protocol RetainedPackages {
     /// Atomically clear the retained package set, releasing any previously
     /// retained packages.
     strict Clear() -> ();

     /// Atomically replace the retained package set with the [package hashes](
     /// https://fuchsia.dev/fuchsia-src/concepts/packages/package_url#package-hash)
     /// provided by the given iterator.
     /// Duplicate IDs provided will be merged and processed as a single one.
     ///
     /// + request `iterator` an iterator of package blob IDs that should be
     ///   retained.
     strict Replace(resource struct {
         iterator client_end:BlobIdIterator;
     }) -> ();
 };

 /// A chunked iterator of blob IDs, allowing transfer of more blob IDs that can
 /// fit in a single FIDL message.
 closed protocol BlobIdIterator {
     /// Responds with the next chunk of blob IDs. When the iterator is
     /// exhausted, responds with an empty vector and closes the connection.
     ///
     /// - response `blobs` the next chunk of blob IDs.
     strict Next() -> (struct {
         blobs vector<BlobId>:MAX;
     });
 };
	// Copyright 2018 The Fuchsia Authors. All rights reserved.
	// Use of this source code is governed by a BSD-style license that can be
	// found in the LICENSE file.
	library fuchsia.pkg;

	using fuchsia.fxfs;
	using fuchsia.io;
	using zx;

	/// This manages the system package cache.
	///
	/// This is intended to be implemented by the package manager component and used by
	/// package resolver components.
	@discoverable
	closed protocol PackageCache {
	/// Gets the package directory if it is present on the local system. If it is not, the
	/// `missing_blobs` iterator will provide all the blobs in the package that are missing from
	/// the system, and the ability to write those blobs to blobfs. If all the missing blobs are
	/// downloaded and written to by the client, the `dir` directory will be resolved. This method
	/// will return successfully when the package has been fully resolved, or return an error if
	/// the client closes `needed_blobs` or `dir` handle before the package has been resolved.
	///
	/// This method does not guarantee the missing blobs have been persisted. In order to guarantee
	/// missing blobs are persisted, clients should call ['Sync'].
	///
	/// Clients must not make concurrent `Get()` calls for the same `meta_far_blob`, even across
	/// different `PackageCache` connections, unless the `meta_far_blob` is in base or already
	/// active in the dynamic index. Violating this may result in `Get()` errors.
	///
	/// + request `meta_far_blob` the blob info for the package's meta.far.
	/// + request `needed_blobs` an iterator over all the blobs in the package that
	/// are not present on the system.
	/// + request `dir` the channel on which the package directory will be served.
	/// * error a zx_status value indicating failure. One of the following:
	/// * `ZX_ERR_UNAVAILABLE` if the client closed `needed_blobs` handles before
	/// all the missing blobs were downloaded to the system.
	strict Get(resource struct {
	meta_far_blob BlobInfo;
	gc_protection GcProtection;
	needed_blobs server_end:NeededBlobs;
	dir server_end:<fuchsia.io.Directory>;
	}) -> () error zx.Status;

	/// Gets the package directory for a subpackage.
	/// The connection to the superpackage's package directory must still be open when this is
	/// called.
	/// The returned package will be protected by open package tracking.
	///
	/// + request `superpackage` the hash of the superpackage's meta.far.
	/// + request `subpackage` the relative package URL of the subpackage.
	/// + request `dir` the channel on which the package directory will be served.
	/// * error a GetSubpackageError value indicating failure.
	strict GetSubpackage(resource struct {
	superpackage BlobId;
	subpackage PackageUrl;
	dir server_end:<fuchsia.io.Directory>;
	}) -> () error GetSubpackageError;

	/// Retrieves a chunk iterator to the base package index.
	///
	/// + request `iterator` a request for the `PackageIndexIterator` that will return sets of
	/// `PackageIndexEntry` objects until all packages in the base index have been iterated.
	strict BasePackageIndex(resource struct {
	iterator server_end:PackageIndexIterator;
	});

	/// Retrieves a chunk iterator to the cache package index.
	///
	/// + request `iterator` a request for the `PackageIndexIterator` that will return sets of
	/// `PackageIndexEntry` objects until all packages in the cache index have been iterated.
	strict CachePackageIndex(resource struct {
	iterator server_end:PackageIndexIterator;
	});

	/// Synchronizes updates to the cached packages to the underlying persistent storage.
	///
	/// * error a zx_status value indicating failure. One of the following:
	/// * `ZX_ERR_INTERNAL` if the sync fails.
	strict Sync() -> () error zx.Status;
	};

	/// How the package served by [`PackageCache.Get`] should be protected from GC.
	type GcProtection = strict enum {
	/// Package will be protected from GC as long as there is an open connection to the directory.
	OPEN_PACKAGE_TRACKING = 1;

	/// Package will be protected from GC as long as it is in the Retained index, which is
	/// controlled by the [`RetainedPackages`] protocol. Client is responsible for ensuring
	/// the package is in the Retained index.
	RETAINED = 2;
	};

	/// Error type for [`PackageCache.GetSubpackage`].
	type GetSubpackageError = strict enum {
	/// The superpackage was not open.
	SUPERPACKAGE_CLOSED = 1;

	/// The requested subpackage does not exist.
	DOES_NOT_EXIST = 2;

	/// An unspecified error occurred.
	INTERNAL = 3;
	};

	/// Error type for [`NeededBlobs.OpenMetaBlob`] and [`NeededBlobs.OpenBlob`].
	type OpenBlobError = strict enum {
	/// There is insufficient storage space available to persist this blob.
	OUT_OF_SPACE = 1;

	/// This blob is already open for write by another cache operation.
	CONCURRENT_WRITE = 2;

	/// An unspecified error occurred during underlying I/O.
	UNSPECIFIED_IO = 3;

	/// An unspecified error occurred.
	INTERNAL = 4;
	};

	/// Error type for [`NeededBlobs.BlobWritten`].
	type BlobWrittenError = strict enum {
	/// Client called BlobWritten but blob was not readable in blobfs.
	NOT_WRITTEN = 1;

	/// Client called BlobWritten for a blob it has not yet opened.
	UNOPENED_BLOB = 2;
	};

	/// Represents the transaction for caching a particular package.
	///
	/// Server expects client to follow the normal operation sequence defined below.
	/// Violating the protocol (e.g. calling wrong methods at the wrong time) will result
	/// in the channel being closed by the package cache with a `ZX_ERR_BAD_STATE` epitaph
	/// and aborting the package cache operation.
	/// If a fatal error occurs at any step, server will close the channel, and client
	/// should not proceed with the sequence.
	/// Non-fatal errors could be retried, as long as the channel remains open.
	///
	/// Normal operation sequence:
	/// 1. Clients should start by requesting to `OpenMetaBlob()`, and fetch and write
	/// the metadata blob if needed, calling `BlobWritten()` when done to indicate the
	/// write is complete.
	/// 2. `GetMissingBlobs()` should be used to determine which blobs need to be
	/// fetched and written.
	/// 3. Each of the missing blobs needs to be written using `OpenBlob()` and
	/// `BlobWritten()` should be called after each blob is written.
	///
	/// Clients are responsible for avoiding concurrent creation of the same blob if the underlying
	/// blobstore does not support it.
	/// This manifests as the following constraints (applied per `BlobId`):
	/// 1. If the `BlobWriter` returned by calls to `Open[Meta]Blob` is the `file` variant, once Clients
	/// call Resize on a file, they must close all file connections obtained from `Open[Meta]Blob`
	/// before calling `Open[Meta]Blob` again.
	/// 2. If the `BlobWriter` returned by calls to `Open[Meta]Blob` is the `writer` variant, Clients
	/// must not write all the bytes to more than one of the `writer`s.
	/// This applies per `BlobId` to all `BlobWriter`s returned by all calls to `Open[Meta]Blob` across
	/// all `NeededBlobs` connections across all `PackageCache` connections.
	/// Once c++blobfs support is removed and fxblob is changed to support duplicate concurrent creation
	/// requests (https://fxbug.dev/335870456#comment9), this requirement can be dropped.
	///
	/// Once all needed blobs are written by the client, the package cache will
	/// complete the pending [`PackageCache.Get`] request and close this channel
	/// with a `ZX_OK` epitaph.
	closed protocol NeededBlobs {
	/// Opens the package's metadata blob for writing. `GetMissingBlobs()`
	/// should not be called until writing the meta blob or this request
	/// responds with `false`.
	///
	/// If the package was already cached, server will close the channel with a
	/// `ZX_OK` epitaph.
	///
	/// - response `writer` is used to write the blob. If `writer` is absent,
	/// the blob is already cached and so does not need to be written.
	/// * error an OpenBlobError indicating failure. Clients may retry this
	/// request, though the server end may abort this cache operation on
	/// errors it considers to be fatal.
	strict OpenMetaBlob() -> (resource struct {
	writer BlobWriter:optional;
	}) error OpenBlobError;

	/// Returns an iterator of blobs that are not present on the system that
	/// must be written using the `OpenBlob` request before the package will be
	/// fully cached.
	///
	/// Client should call `OpenMetaBlob`, and write it if needed, before
	/// calling `GetMissingBlobs`.
	///
	/// A client should make this request no more than once per `NeededBlobs`
	/// connection. Once all blobs yielded by this iterator are written, the
	/// package open request will complete.
	///
	/// New items may be added to the obtained `BlobInfoIterator` as the client
	/// calls `OpenBlob`, so, to guaranatee termination of the iterator, clients
	/// should call `OpenBlob` concurrently with reading the iterator.
	///
	/// + request `iterator` a request for an iterator of [`BlobInfo`] of blobs
	/// that the client should try to write.
	strict GetMissingBlobs(resource struct {
	iterator server_end:BlobInfoIterator;
	});

	/// Opens a blob for writing.
	///
	/// + request `blob_id` the blob id describing this blob.
	/// - response `writer` is used to write the blob. If `writer` is absent,
	/// the blob is already cached and so does not need to be written.
	/// * error an OpenBlobError indicating failure. Clients may retry this
	/// request, though the server end may abort this cache operation on
	/// errors it considers to be fatal.
	strict OpenBlob(struct {
	blob_id BlobId;
	}) -> (resource struct {
	writer BlobWriter:optional;
	}) error OpenBlobError;

	/// Indicates that a blob opened by `Open[Meta]Blob` has been successfully
	/// written.
	///
	/// A client should call this once the blob has been fully written using
	/// the `writer` returned by `Open[Meta]Blob`.
	///
	/// + request `blob_id` the blob id describing this blob.
	/// * error a BlobWrittenError indicating failure. Clients may retry the
	/// `Open[Meta]Blob` request that prompted this call, though the server
	/// end may abort this cache operation on errors it considers to be fatal.
	strict BlobWritten(struct {
	blob_id BlobId;
	}) -> () error BlobWrittenError;

	/// Aborts this caching operation for the package.
	///
	/// Any open blobs and any missing blobs iterator will be closed. Any `dir`
	/// provided to the associated [`PackageCache.Get`] request will also be
	/// closed. Once this request is acknowledged, this channel will be closed.
	///
	/// Note, dropping this NeededBlobs channel without writing all needed blobs
	/// will also abort the package cache operation. However, this API provides
	/// the ability to wait for the operation to be torn down.
	strict Abort() -> ();
	};

	/// Used to write a blob to the underlying storage.
	type BlobWriter = strict resource union {
	/// To write a blob with `file`:
	/// 1. If the blob is uncompressed, use `fuchsia.io/File.Resize` to set
	/// the blob's uncompressed size.
	/// 2. Use `fuchsia.io/File.Write` to write the blob's contents from
	/// start to finish (seeks are not supported).
	/// A corrupt blob is indicated by a `Write()` (usually the final write),
	/// failing with `ZX_ERR_IO_DATA_INTEGRITY`.
	1: file client_end:fuchsia.io.File;
	/// To write a blob with `writer`, follow the instructions on the
	/// `fuchsia.fxfs.BlobWriter` protocol.
	2: writer client_end:fuchsia.fxfs.BlobWriter;
	};

	/// A chunked iterator of [`BlobInfo`], allowing transfer of more [`BlobInfo`]s
	/// that can fit in a single FIDL message.
	closed protocol BlobInfoIterator {
	/// Responds with the next chunk of [`BlobInfo`]s. When the iterator is
	/// exhausted, responds with an empty vector and closes the connection.
	///
	/// - response `blobs` the next chunk of [`BlobInfo`]s.
	strict Next() -> (struct {
	blobs vector<BlobInfo>:MAX;
	});
	};

	/// A chunk iterator for the package index. This is required because it is possible for the
	/// package index to be too large to send over in a single request (over 64KiB).
	closed protocol PackageIndexIterator {
	/// Returns the next chunk of package index entries. When the iterator is exhausted,
	/// this returns an empty vector.
	///
	/// - response `entries` the next chunk of entries in the package index.
	strict Next() -> (struct {
	entries vector<PackageIndexEntry>:MAX;
	});
	};

	/// Manages the set of retained packages.
	///
	/// Retained packages will not be removed from the package cache, even if they
	/// aren't fully present. There is only a single set active at once, and the
	/// provided APIs for configuring the set atomically replace that set. On boot,
	/// the retained package set is always initialized to the empty set.
	/// Documentation on [garbage collection](
	/// https://fuchsia.dev/fuchsia-src/concepts/packages/garbage_collection) contains
	/// details on various types of package indexes (static, retained, etc) and
	/// describes when a package will be garbage collected or retained.
	@discoverable
	closed protocol RetainedPackages {
	/// Atomically clear the retained package set, releasing any previously
	/// retained packages.
	strict Clear() -> ();

	/// Atomically replace the retained package set with the [package hashes](
	/// https://fuchsia.dev/fuchsia-src/concepts/packages/package_url#package-hash)
	/// provided by the given iterator.
	/// Duplicate IDs provided will be merged and processed as a single one.
	///
	/// + request `iterator` an iterator of package blob IDs that should be
	/// retained.
	strict Replace(resource struct {
	iterator client_end:BlobIdIterator;
	}) -> ();
	};

	/// A chunked iterator of blob IDs, allowing transfer of more blob IDs that can
	/// fit in a single FIDL message.
	closed protocol BlobIdIterator {
	/// Responds with the next chunk of blob IDs. When the iterator is
	/// exhausted, responds with an empty vector and closes the connection.
	///
	/// - response `blobs` the next chunk of blob IDs.
	strict Next() -> (struct {
	blobs vector<BlobId>:MAX;
	});
	};