Teach independent negotiation (no pack file) using an option "wait-for-done"

From Git commit 9c1e657a8f:
  Currently, the packfile negotiation step within a Git fetch cannot be
  done independent of sending the packfile, even though there is at
  least one application wherein this is useful - push negotiation.
  Therefore, make it possible for this negotiation step to be done
  independently.

  This feature is for protocol v2 only.

  In the protocol, the main hindrance towards independent negotiation is
  that the server can unilaterally decide to send the packfile. This is
  solved by a "wait-for-done" argument: the server will then wait for
  the client to say "done". In practice, the client will never say it;
  instead it will cease requests once it is satisfied.

Advertising the server capability option "wait-for-done" is behind the
transport config: uploadpack.advertisewaitfordone, which by default is
false.

Change-Id: I5ebd3e99ad76b8943597216e23ced2ed38eb5224

1 files changed, 102 insertions, 0 deletions

diff --git a/org.eclipse.jgit.test/tst/org/eclipse/jgit/transport/UploadPackTest.java b/org.eclipse.jgit.test/tst/org/eclipse/jgit/transport/UploadPackTest.java
index 5045e9464e..b0b5f68efa 100644
--- a/org.eclipse.jgit.test/tst/org/eclipse/jgit/transport/UploadPackTest.java
+++ b/org.eclipse.jgit.test/tst/org/eclipse/jgit/transport/UploadPackTest.java
@@ -999,6 +999,108 @@ public class UploadPackTest {
 	}
 
 	@Test
+	public void testV2FetchWithoutWaitForDoneReceivesPackfile()
+			throws Exception {
+		String commonInBlob = "abcdefghijklmnopqrstuvwxyz";
+
+		RevBlob parentBlob = remote.blob(commonInBlob + "a");
+		RevCommit parent = remote
+				.commit(remote.tree(remote.file("foo", parentBlob)));
+		remote.update("branch1", parent);
+
+		RevCommit localParent = null;
+		RevCommit localChild = null;
+		try (TestRepository<InMemoryRepository> local = new TestRepository<>(
+				client)) {
+			RevBlob localParentBlob = local.blob(commonInBlob + "a");
+			localParent = local
+					.commit(local.tree(local.file("foo", localParentBlob)));
+			RevBlob localChildBlob = local.blob(commonInBlob + "b");
+			localChild = local.commit(
+					local.tree(local.file("foo", localChildBlob)), localParent);
+			local.update("branch1", localChild);
+		}
+
+		ByteArrayInputStream recvStream = uploadPackV2("command=fetch\n",
+				PacketLineIn.delimiter(),
+				"have " + localParent.toObjectId().getName() + "\n",
+				"have " + localChild.toObjectId().getName() + "\n",
+				PacketLineIn.end());
+		PacketLineIn pckIn = new PacketLineIn(recvStream);
+		assertThat(pckIn.readString(), is("acknowledgments"));
+		assertThat(Arrays.asList(pckIn.readString()),
+				hasItems("ACK " + parent.toObjectId().getName()));
+		assertThat(pckIn.readString(), is("ready"));
+		assertTrue(PacketLineIn.isDelimiter(pckIn.readString()));
+		assertThat(pckIn.readString(), is("packfile"));
+		parsePack(recvStream);
+	}
+
+	@Test
+	public void testV2FetchWithWaitForDoneOnlyDoesNegotiation()
+			throws Exception {
+		String commonInBlob = "abcdefghijklmnopqrstuvwxyz";
+
+		RevBlob parentBlob = remote.blob(commonInBlob + "a");
+		RevCommit parent = remote
+				.commit(remote.tree(remote.file("foo", parentBlob)));
+		remote.update("branch1", parent);
+
+		RevCommit localParent = null;
+		RevCommit localChild = null;
+		try (TestRepository<InMemoryRepository> local = new TestRepository<>(
+				client)) {
+			RevBlob localParentBlob = local.blob(commonInBlob + "a");
+			localParent = local
+					.commit(local.tree(local.file("foo", localParentBlob)));
+			RevBlob localChildBlob = local.blob(commonInBlob + "b");
+			localChild = local.commit(
+					local.tree(local.file("foo", localChildBlob)), localParent);
+			local.update("branch1", localChild);
+		}
+
+		ByteArrayInputStream recvStream = uploadPackV2("command=fetch\n",
+				PacketLineIn.delimiter(), "wait-for-done\n",
+				"have " + localParent.toObjectId().getName() + "\n",
+				"have " + localChild.toObjectId().getName() + "\n",
+				PacketLineIn.end());
+		PacketLineIn pckIn = new PacketLineIn(recvStream);
+		assertThat(pckIn.readString(), is("acknowledgments"));
+		assertThat(Arrays.asList(pckIn.readString()),
+				hasItems("ACK " + parent.toObjectId().getName()));
+		assertTrue(PacketLineIn.isEnd(pckIn.readString()));
+	}
+
+	@Test
+	public void testV2FetchWithWaitForDoneOnlyDoesNegotiationAndNothingToAck()
+			throws Exception {
+		String commonInBlob = "abcdefghijklmnopqrstuvwxyz";
+
+		RevCommit localParent = null;
+		RevCommit localChild = null;
+		try (TestRepository<InMemoryRepository> local = new TestRepository<>(
+				client)) {
+			RevBlob localParentBlob = local.blob(commonInBlob + "a");
+			localParent = local
+					.commit(local.tree(local.file("foo", localParentBlob)));
+			RevBlob localChildBlob = local.blob(commonInBlob + "b");
+			localChild = local.commit(
+					local.tree(local.file("foo", localChildBlob)), localParent);
+			local.update("branch1", localChild);
+		}
+
+		ByteArrayInputStream recvStream = uploadPackV2("command=fetch\n",
+				PacketLineIn.delimiter(), "wait-for-done\n",
+				"have " + localParent.toObjectId().getName() + "\n",
+				"have " + localChild.toObjectId().getName() + "\n",
+				PacketLineIn.end());
+		PacketLineIn pckIn = new PacketLineIn(recvStream);
+		assertThat(pckIn.readString(), is("acknowledgments"));
+		assertThat(pckIn.readString(), is("NAK"));
+		assertTrue(PacketLineIn.isEnd(pckIn.readString()));
+	}
+
+	@Test
 	public void testV2FetchThinPack() throws Exception {
 		String commonInBlob = "abcdefghijklmnopqrstuvwxyz";