Download API upgrade (#955)

* Adds API for fetching manifest only and downloading dataset without stream

* Updates openapi.yaml

* Adds tests for downloading manifest-only and without stream.

* review comments by Giuliano

* updates test clients

codex/rest/api.nim

@@ -53,14 +53,16 @@ proc validate(
   {.gcsafe, raises: [Defect].} =
   0
 
+proc formatManifest(cid: Cid, manifest: Manifest): RestContent =
+  return RestContent.init(cid, manifest)
+
 proc formatManifestBlocks(node: CodexNodeRef): Future[JsonNode] {.async.} =
   var content: seq[RestContent]
 
-  proc formatManifest(cid: Cid, manifest: Manifest) =
+  proc addManifest(cid: Cid, manifest: Manifest) =
-    let restContent = RestContent.init(cid, manifest)
+    content.add(formatManifest(cid, manifest))
-    content.add(restContent)
+  await node.iterateManifests(addManifest)
 
-  await node.iterateManifests(formatManifest)
   return %RestContentList.init(content)
 
 proc retrieveCid(
@@ -207,8 +209,45 @@ proc initDataApi(node: CodexNodeRef, repoStore: RepoStore, router: var RestRoute
       await node.retrieveCid(cid.get(), local = true, resp=resp)
 
   router.api(
-    MethodGet,
+    MethodPost,
     "/api/codex/v1/data/{cid}/network") do (
+      cid: Cid, resp: HttpResponseRef) -> RestApiResponse:
+      ## Download a file from the network to the local node
+      ##
+
+      var headers = buildCorsHeaders("GET", allowedOrigin)
+
+      if cid.isErr:
+        return RestApiResponse.error(
+          Http400,
+          $cid.error(), headers = headers)
+
+      if corsOrigin =? allowedOrigin:
+        resp.setCorsHeaders("GET", corsOrigin)
+        resp.setHeader("Access-Control-Headers", "X-Requested-With")
+
+      without manifest =? (await node.fetchManifest(cid.get())), err:
+        error "Failed to fetch manifest", err = err.msg
+        return RestApiResponse.error(
+          Http404,
+          err.msg, headers = headers)
+
+      proc fetchDatasetAsync(): Future[void] {.async.} =
+        try:
+          if err =? (await node.fetchBatched(manifest)).errorOption:
+            error "Unable to fetch dataset", cid = cid.get(), err = err.msg
+        except CatchableError as exc:
+          error "CatchableError when fetching dataset", cid = cid.get(), exc = exc.msg
+          discard
+
+      asyncSpawn fetchDatasetAsync()
+
+      let json = %formatManifest(cid.get(), manifest)
+      return RestApiResponse.response($json, contentType="application/json")
+
+  router.api(
+    MethodGet,
+    "/api/codex/v1/data/{cid}/network/stream") do (
       cid: Cid, resp: HttpResponseRef) -> RestApiResponse:
       ## Download a file from the network in a streaming
       ## manner
@@ -227,6 +266,33 @@ proc initDataApi(node: CodexNodeRef, repoStore: RepoStore, router: var RestRoute
 
       await node.retrieveCid(cid.get(), local = false, resp=resp)
 
+  router.api(
+    MethodGet,
+    "/api/codex/v1/data/{cid}/network/manifest") do (
+      cid: Cid, resp: HttpResponseRef) -> RestApiResponse:
+      ## Download only the manifest.
+      ##
+
+      var headers = buildCorsHeaders("GET", allowedOrigin)
+
+      if cid.isErr:
+        return RestApiResponse.error(
+          Http400,
+          $cid.error(), headers = headers)
+
+      if corsOrigin =? allowedOrigin:
+        resp.setCorsHeaders("GET", corsOrigin)
+        resp.setHeader("Access-Control-Headers", "X-Requested-With")
+
+      without manifest =? (await node.fetchManifest(cid.get())), err:
+        error "Failed to fetch manifest", err = err.msg
+        return RestApiResponse.error(
+          Http404,
+          err.msg, headers = headers)
+
+      let json = %formatManifest(cid.get(), manifest)
+      return RestApiResponse.response($json, contentType="application/json")
+
   router.api(
     MethodGet,
     "/api/codex/v1/space") do () -> RestApiResponse:

openapi.yaml

@@ -455,10 +455,36 @@ paths:
           description: Well it was bad-bad
 
   "/data/{cid}/network":
+    post:
+      summary: "Download a file from the network to the local node if it's not available locally. Note: Download is performed async. Call can return before download is completed."
+      tags: [ Data ]
+      operationId: downloadNetwork
+      parameters:
+        - in: path
+          name: cid
+          required: true
+          schema:
+              $ref: "#/components/schemas/Cid"
+          description: "File to be downloaded."
+      responses:
+        "200":
+          description: Manifest information for download that has been started.
+          content:
+            application/json:
+              schema:
+                $ref: "#/components/schemas/DataItem"
+        "400":
+          description: Invalid CID is specified
+        "404":
+          description: Failed to download dataset manifest
+        "500":
+          description: Well it was bad-bad
+
+  "/data/{cid}/network/stream":
     get:
       summary: "Download a file from the network in a streaming manner. If the file is not available locally, it will be retrieved from other nodes in the network if able."
       tags: [ Data ]
-      operationId: downloadNetwork
+      operationId: downloadNetworkStream
       parameters:
         - in: path
           name: cid
@@ -481,6 +507,32 @@ paths:
         "500":
           description: Well it was bad-bad
 
+  "/data/{cid}/network/manifest":
+    get:
+      summary: "Download only the dataset manifest from the network to the local node if it's not available locally."
+      tags: [ Data ]
+      operationId: downloadNetworkManifest
+      parameters:
+        - in: path
+          name: cid
+          required: true
+          schema:
+              $ref: "#/components/schemas/Cid"
+          description: "File for which the manifest is to be downloaded."
+      responses:
+        "200":
+          description: Manifest information.
+          content:
+            application/json:
+              schema:
+                $ref: "#/components/schemas/DataItem"
+        "400":
+          description: Invalid CID is specified
+        "404":
+          description: Failed to download dataset manifest
+        "500":
+          description: Well it was bad-bad
+
   "/space":
     get:
       summary: "Gets a summary of the storage space allocation of the node."

tests/integration/codexclient.nim

@@ -46,7 +46,27 @@ proc download*(client: CodexClient, cid: Cid, local = false): ?!string =
   let
     response = client.http.get(
       client.baseurl & "/data/" & $cid &
-      (if local: "" else: "/network"))
+      (if local: "" else: "/network/stream"))
+
+  if response.status != "200 OK":
+    return failure(response.status)
+
+  success response.body
+
+proc downloadManifestOnly*(client: CodexClient, cid: Cid): ?!string =
+  let
+    response = client.http.get(
+      client.baseurl & "/data/" & $cid & "/network/manifest")
+
+  if response.status != "200 OK":
+    return failure(response.status)
+
+  success response.body
+
+proc downloadNoStream*(client: CodexClient, cid: Cid): ?!string =
+  let
+    response = client.http.post(
+      client.baseurl & "/data/" & $cid & "/network")
 
   if response.status != "200 OK":
     return failure(response.status)
@@ -60,7 +80,7 @@ proc downloadBytes*(
 
   let uri = parseUri(
     client.baseurl & "/data/" & $cid &
-    (if local: "" else: "/network")
+    (if local: "" else: "/network/stream")
   )
 
   let (status, bytes) = await client.session.fetch(uri)

tests/integration/testblockexpiration.nim

@@ -47,7 +47,7 @@ ethersuite "Node block expiration tests":
   proc downloadTestFile(contentId: string, local = false): Response =
     let client = newHttpClient(timeout=3000)
     let downloadUrl = baseurl & "/data/" &
-      contentId & (if local: "" else: "/network")
+      contentId & (if local: "" else: "/network/stream")
 
     let content = client.get(downloadUrl)
     client.close()

tests/integration/testupdownload.nim

@@ -1,3 +1,4 @@
+import pkg/codex/rest/json
 import ./twonodes
 
 twonodessuite "Uploads and downloads", debug1 = false, debug2 = false:
@@ -37,3 +38,25 @@ twonodessuite "Uploads and downloads", debug1 = false, debug2 = false:
 
     check:
       resp2.error.msg == "404 Not Found"
+
+  proc checkRestContent(content: ?!string) =
+    let c = content.tryGet()
+    # tried to JSON (very easy) and checking the resulting object (would be much nicer)
+    # spent an hour to try and make it work.
+    check:
+      c == "{\"cid\":\"zDvZRwzm1ePSzKSXt57D5YxHwcSDmsCyYN65wW4HT7fuX9HrzFXy\",\"manifest\":{\"treeCid\":\"zDzSvJTezk7bJNQqFq8k1iHXY84psNuUfZVusA5bBQQUSuyzDSVL\",\"datasetSize\":18,\"blockSize\":65536,\"protected\":false}}"
+
+  test "node allows downloading only manifest":
+    let content1 = "some file contents"
+    let cid1 = client1.upload(content1).get
+    let resp2 = client2.downloadManifestOnly(cid1)
+    checkRestContent(resp2)
+
+  test "node allows downloading content without stream":
+    let content1 = "some file contents"
+    let cid1 = client1.upload(content1).get
+    let resp1 = client2.downloadNoStream(cid1)
+    checkRestContent(resp1)
+    let resp2 = client2.download(cid1, local = true).get
+    check:
+      content1 == resp2