Specify and implement reverse for ReadIndex and ReadBatch

doc/drafts/k2v-spec.md

@@ -379,6 +379,7 @@ Query parameters:
 | `start` | `null` | First partition key to list, in lexicographical order |
 | `end` | `null` | Last partition key to list (excluded) |
 | `limit` | `null` | Maximum number of partition keys to list |
+| `reverse` | `false` | Iterate in reverse lexicographical order |
 
 The response consists in a JSON object that repeats the parameters of the query and gives the result (see below).
 
@@ -415,6 +416,7 @@ HTTP/1.1 200 OK
   start: null,
   end: null,
   limit: null,
+  reverse: false,
   partitionKeys: [
     { pk: "keys", n: 3043 },
     { pk: "mailbox:INBOX", n: 42 },
@@ -485,13 +487,14 @@ JSON struct with the following fields:
 | `start` | `null` | The sort key of the first item to read |
 | `end` | `null` | The sort key of the last item to read (excluded) |
 | `limit` | `null` | The maximum number of items to return |
+| `reverse` | `false` | Iterate in reverse lexicographical order on sort keys |
 | `singleItem` | `false` | Whether to return only the item with sort key `start` |
 | `conflictsOnly` | `false` | Whether to return only items that have several concurrent values |
 | `tombstones` | `false` | Whether or not to return tombstone lines to indicate the presence of old deleted items |
 
 
 For each of the searches, triplets are listed and returned separately. The
-semantics of `prefix`, `start`, `end` and `limit` are the same as for ReadIndex. The
+semantics of `prefix`, `start`, `end`, `limit` and `reverse` are the same as for ReadIndex. The
 additionnal parameter `singleItem` allows to get a single item, whose sort key
 is the one given in `start`. Parameters `conflictsOnly` and `tombstones`
 control additional filters on the items that are returned.
@@ -553,6 +556,7 @@ HTTP/1.1 200 OK
     start: null,
     end: null,
     limit: null,
+    reverse: false,
     conflictsOnly: false,
     tombstones: false,
     singleItem: false,
@@ -570,6 +574,7 @@ HTTP/1.1 200 OK
     start: "001892831",
     end: null,
     limit: 3,
+    reverse: false,
     conflictsOnly: false,
     tombstones: false,
     singleItem: false,
@@ -589,6 +594,7 @@ HTTP/1.1 200 OK
     conflictsOnly: false,
     tombstones: false,
     limit: null,
+    reverse: false,
     singleItem: true,
     items: [
       { sk: "0", ct: "opaquetoken999", v: ["b64binarystuff999"] },

src/api/k2v/api_server.rs

@@ -164,7 +164,8 @@ impl ApiHandler for K2VApiServer {
 				start,
 				end,
 				limit,
-			} => handle_read_index(garage, bucket_id, prefix, start, end, limit).await,
+				reverse,
+			} => handle_read_index(garage, bucket_id, prefix, start, end, limit, reverse).await,
 			Endpoint::InsertBatch {} => handle_insert_batch(garage, bucket_id, req).await,
 			Endpoint::ReadBatch {} => handle_read_batch(garage, bucket_id, req).await,
 			Endpoint::DeleteBatch {} => handle_delete_batch(garage, bucket_id, req).await,

src/api/k2v/batch.rs

@@ -115,7 +115,7 @@ async fn handle_read_batch_query(
 			&query.end,
 			query.limit,
 			Some(filter),
-			EnumerationOrder::Forward,
+			EnumerationOrder::from_reverse(query.reverse),
 		)
 		.await?;
 
@@ -133,6 +133,7 @@ async fn handle_read_batch_query(
 		start: query.start,
 		end: query.end,
 		limit: query.limit,
+		reverse: query.reverse,
 		single_item: query.single_item,
 		conflicts_only: query.conflicts_only,
 		tombstones: query.tombstones,
@@ -278,6 +279,8 @@ struct ReadBatchQuery {
 	end: Option<String>,
 	#[serde(default)]
 	limit: Option<u64>,
+	#[serde(default)]
+	reverse: bool,
 	#[serde(default, rename = "singleItem")]
 	single_item: bool,
 	#[serde(default, rename = "conflictsOnly")]
@@ -294,6 +297,7 @@ struct ReadBatchResponse {
 	start: Option<String>,
 	end: Option<String>,
 	limit: Option<u64>,
+	reverse: bool,
 	#[serde(rename = "singleItem")]
 	single_item: bool,
 	#[serde(rename = "conflictsOnly")]

src/api/k2v/index.rs

@@ -22,7 +22,10 @@ pub async fn handle_read_index(
 	start: Option<String>,
 	end: Option<String>,
 	limit: Option<u64>,
+	reverse: Option<bool>,
 ) -> Result<Response<Body>, Error> {
+	let reverse = reverse.unwrap_or(false);
+
 	let ring: Arc<Ring> = garage.system.ring.borrow().clone();
 
 	let (partition_keys, more, next_start) = read_range(
@@ -33,7 +36,7 @@ pub async fn handle_read_index(
 		&end,
 		limit,
 		Some((DeletedFilter::NotDeleted, ring.layout.node_id_vec.clone())),
-		EnumerationOrder::Forward,
+		EnumerationOrder::from_reverse(reverse),
 	)
 	.await?;
 
@@ -47,6 +50,7 @@ pub async fn handle_read_index(
 		start,
 		end,
 		limit,
+		reverse,
 		partition_keys: partition_keys
 			.into_iter()
 			.map(|part| {
@@ -76,6 +80,7 @@ struct ReadIndexResponse {
 	start: Option<String>,
 	end: Option<String>,
 	limit: Option<u64>,
+	reverse: bool,
 
 	#[serde(rename = "partitionKeys")]
 	partition_keys: Vec<ReadIndexResponseEntry>,

src/api/k2v/router.rs

@@ -39,6 +39,7 @@ pub enum Endpoint {
 		start: Option<String>,
 		end: Option<String>,
 		limit: Option<u64>,
+		reverse: Option<bool>,
 	},
 	ReadItem {
 		partition_key: String,
@@ -101,7 +102,7 @@ impl Endpoint {
 				EMPTY => ReadItem (query::sort_key),
 			],
 			no_key: [
-				EMPTY => ReadIndex (query_opt::prefix, query_opt::start, query_opt::end, opt_parse::limit),
+				EMPTY => ReadIndex (query_opt::prefix, query_opt::start, query_opt::end, opt_parse::limit, opt_parse::reverse),
 			]
 		}
 	}
@@ -236,6 +237,7 @@ generateQueryParameters! {
 	"causality_token" => causality_token,
 	"end" => end,
 	"limit" => limit,
+	"reverse" => reverse,
 	"sort_key" => sort_key,
 	"timeout" => timeout
 }

src/garage/tests/k2v/batch.rs

@@ -112,6 +112,7 @@ async fn test_batch() {
 				"start": null,
 				"end": null,
 				"limit": null,
+				"reverse": false,
 				"conflictsOnly": false,
 				"tombstones": false,
 				"singleItem": false,
@@ -132,6 +133,7 @@ async fn test_batch() {
 				"start": "c",
 				"end": null,
 				"limit": null,
+				"reverse": false,
 				"conflictsOnly": false,
 				"tombstones": false,
 				"singleItem": false,
@@ -150,6 +152,7 @@ async fn test_batch() {
 				"start": null,
 				"end": null,
 				"limit": 1,
+				"reverse": false,
 				"conflictsOnly": false,
 				"tombstones": false,
 				"singleItem": false,
@@ -165,6 +168,7 @@ async fn test_batch() {
 				"start": null,
 				"end": null,
 				"limit": null,
+				"reverse": false,
 				"conflictsOnly": false,
 				"tombstones": false,
 				"singleItem": false,
@@ -267,6 +271,7 @@ async fn test_batch() {
 				"start": null,
 				"end": null,
 				"limit": null,
+				"reverse": false,
 				"conflictsOnly": false,
 				"tombstones": false,
 				"singleItem": false,
@@ -286,6 +291,7 @@ async fn test_batch() {
 				"start": null,
 				"end": null,
 				"limit": null,
+				"reverse": false,
 				"conflictsOnly": false,
 				"tombstones": false,
 				"singleItem": false,
@@ -302,6 +308,7 @@ async fn test_batch() {
 				"start": null,
 				"end": "d.2",
 				"limit": null,
+				"reverse": false,
 				"conflictsOnly": false,
 				"tombstones": false,
 				"singleItem": false,
@@ -317,6 +324,7 @@ async fn test_batch() {
 				"start": null,
 				"end": null,
 				"limit": 1,
+				"reverse": false,
 				"conflictsOnly": false,
 				"tombstones": false,
 				"singleItem": false,
@@ -332,6 +340,7 @@ async fn test_batch() {
 				"start": "d.2",
 				"end": null,
 				"limit": 1,
+				"reverse": false,
 				"conflictsOnly": false,
 				"tombstones": false,
 				"singleItem": false,
@@ -347,6 +356,7 @@ async fn test_batch() {
 				"start": null,
 				"end": null,
 				"limit": 2,
+				"reverse": false,
 				"conflictsOnly": false,
 				"tombstones": false,
 				"singleItem": false,
@@ -427,6 +437,7 @@ async fn test_batch() {
 				"start": null,
 				"end": null,
 				"limit": null,
+				"reverse": false,
 				"conflictsOnly": false,
 				"tombstones": false,
 				"singleItem": false,

src/garage/tests/k2v/item.rs

@@ -27,6 +27,7 @@ async fn test_items_and_indices() {
 			"start": null,
 			"end": null,
 			"limit": null,
+			"reverse": false,
 			"partitionKeys": [],
 			"more": false,
 			"nextStart": null
@@ -100,6 +101,7 @@ async fn test_items_and_indices() {
 				"start": null,
 				"end": null,
 				"limit": null,
+				"reverse": false,
 				"partitionKeys": [
 				{
 					"pk": "root",
@@ -167,6 +169,7 @@ async fn test_items_and_indices() {
 				"start": null,
 				"end": null,
 				"limit": null,
+				"reverse": false,
 				"partitionKeys": [
 				{
 					"pk": "root",
@@ -234,6 +237,7 @@ async fn test_items_and_indices() {
 				"start": null,
 				"end": null,
 				"limit": null,
+				"reverse": false,
 				"partitionKeys": [
 				{
 					"pk": "root",
@@ -302,6 +306,7 @@ async fn test_items_and_indices() {
 					"start": null,
 					"end": null,
 					"limit": null,
+					"reverse": false,
 					"partitionKeys": [
 					{
 						"pk": "root",
@@ -323,6 +328,7 @@ async fn test_items_and_indices() {
 					"start": null,
 					"end": null,
 					"limit": null,
+					"reverse": false,
 					"partitionKeys": [],
 					"more": false,
 					"nextStart": null