gitaly_client: Implement support for `#list_blobs`

The new `#list_blobs` RPC allows the caller to enumerate blobs via a set
of revisions. It's thus a more flexible sibling to `#get_new_blobs`,
which only allows a single positive revision and will automatically add
`--not --all`.

Add support for this new RPC via a new `#list_blobs` function in the
`BlobService`.

lib/gitlab/gitaly_client/blob_service.rb

@@ -19,6 +19,25 @@ module Gitlab
         consume_blob_response(response)
       end
 
+      def list_blobs(revisions, limit: 0, bytes_limit: 0, dynamic_timeout: nil)
+        request = Gitaly::ListBlobsRequest.new(
+          repository: @gitaly_repo,
+          revisions: Array.wrap(revisions),
+          limit: limit,
+          bytes_limit: bytes_limit
+        )
+
+        timeout =
+          if dynamic_timeout
+            [dynamic_timeout, GitalyClient.medium_timeout].min
+          else
+            GitalyClient.medium_timeout
+          end
+
+        response = GitalyClient.call(@gitaly_repo.storage_name, :blob_service, :list_blobs, request, timeout: timeout)
+        GitalyClient::BlobsStitcher.new(GitalyClient::ListBlobsAdapter.new(response))
+      end
+
       def batch_lfs_pointers(blob_ids)
         return [] if blob_ids.empty?
 

lib/gitlab/gitaly_client/list_blobs_adapter.rb

+# frozen_string_literal: true
+
+module Gitlab
+  module GitalyClient
+    class ListBlobsAdapter
+      include Enumerable
+
+      def initialize(rpc_response)
+        @rpc_response = rpc_response
+      end
+
+      def each
+        @rpc_response.each do |msg|
+          msg.blobs.each do |blob|
+            yield blob
+          end
+        end
+      end
+    end
+  end
+end

spec/lib/gitlab/gitaly_client/blob_service_spec.rb

@@ -88,4 +88,104 @@ RSpec.describe Gitlab::GitalyClient::BlobService do
       subject
     end
   end
+
+  describe '#list_blobs' do
+    let(:limit) { 0 }
+    let(:bytes_limit) { 0 }
+    let(:expected_params) { { revisions: revisions, limit: limit, bytes_limit: bytes_limit } }
+
+    before do
+      ::Gitlab::GitalyClient.clear_stubs!
+    end
+
+    subject { client.list_blobs(revisions, limit: limit, bytes_limit: bytes_limit) }
+
+    context 'with a single revision' do
+      let(:revisions) { ['master'] }
+
+      it 'sends a list_blobs message' do
+        expect_next_instance_of(Gitaly::BlobService::Stub) do |service|
+          expect(service)
+            .to receive(:list_blobs)
+            .with(gitaly_request_with_params(expected_params), kind_of(Hash))
+            .and_return([])
+        end
+
+        subject
+      end
+    end
+
+    context 'with multiple revisions' do
+      let(:revisions) { ['master', '--not', '--all'] }
+
+      it 'sends a list_blobs message' do
+        expect_next_instance_of(Gitaly::BlobService::Stub) do |service|
+          expect(service)
+            .to receive(:list_blobs)
+            .with(gitaly_request_with_params(expected_params), kind_of(Hash))
+            .and_return([])
+        end
+
+        subject
+      end
+    end
+
+    context 'with multiple revisions and limits' do
+      let(:revisions) { ['master', '--not', '--all'] }
+      let(:limit) { 10 }
+      let(:bytes_lmit) { 1024 }
+
+      it 'sends a list_blobs message' do
+        expect_next_instance_of(Gitaly::BlobService::Stub) do |service|
+          expect(service)
+            .to receive(:list_blobs)
+            .with(gitaly_request_with_params(expected_params), kind_of(Hash))
+            .and_return([])
+        end
+
+        subject
+      end
+    end
+
+    context 'with split contents' do
+      let(:revisions) { ['master'] }
+
+      it 'sends a list_blobs message', :aggregate_failures do
+        expect_next_instance_of(Gitaly::BlobService::Stub) do |service|
+          expect(service)
+            .to receive(:list_blobs)
+            .with(gitaly_request_with_params(expected_params), kind_of(Hash))
+            .and_return([
+              Gitaly::ListBlobsResponse.new(blobs: [
+                Gitaly::ListBlobsResponse::Blob.new(oid: "012345", size: 8, data: "0x01"),
+                Gitaly::ListBlobsResponse::Blob.new(data: "23")
+              ]),
+              Gitaly::ListBlobsResponse.new(blobs: [
+                Gitaly::ListBlobsResponse::Blob.new(data: "45"),
+                Gitaly::ListBlobsResponse::Blob.new(oid: "56", size: 4, data: "0x5"),
+                Gitaly::ListBlobsResponse::Blob.new(data: "6")
+              ]),
+              Gitaly::ListBlobsResponse.new(blobs: [
+                Gitaly::ListBlobsResponse::Blob.new(oid: "78", size: 4, data: "0x78")
+              ])
+            ])
+        end
+
+        blobs = subject.to_a
+        expect(blobs.size).to be(3)
+
+        expect(blobs[0].id).to eq('012345')
+        expect(blobs[0].size).to eq(8)
+        expect(blobs[0].data).to eq('0x012345')
+
+        expect(blobs[1].id).to eq('56')
+        expect(blobs[1].size).to eq(4)
+        expect(blobs[1].data).to eq('0x56')
+
+        expect(blobs[2].id).to eq('78')
+        expect(blobs[2].size).to eq(4)
+        expect(blobs[2].data).to eq('0x78')
+      end
+    end
+  end
 end