UploadPack: support custom packfile-to-URI mapping

Teach UploadPack to take a provider of URIs corresponding to cached
packs. When fetching, if the client supports the packfile-uri feature,
and if such a cached pack were to be streamed, instead send the
corresponding URI.

This packfile-uri feature is implemented in the jt/fetch-cdn-offload
branch of Git. There is interest in this feature [1], but it is not yet
merged.

[1] https://public-inbox.org/git/cover.1552073690.git.jonathantanmy@google.com/

Change-Id: I9a32dae131c9c56ad2ff4a8a9638ae3b5e44dc15
Signed-off-by: Jonathan Tan <jonathantanmy@google.com>

1 files changed, 28 insertions, 1 deletions

diff --git a/org.eclipse.jgit/src/org/eclipse/jgit/transport/UploadPack.java b/org.eclipse.jgit/src/org/eclipse/jgit/transport/UploadPack.java
index 2194f2f304..1e49c7b01f 100644
--- a/org.eclipse.jgit/src/org/eclipse/jgit/transport/UploadPack.java
+++ b/org.eclipse.jgit/src/org/eclipse/jgit/transport/UploadPack.java
@@ -93,6 +93,7 @@ import org.eclipse.jgit.errors.IncorrectObjectTypeException;
 import org.eclipse.jgit.errors.MissingObjectException;
 import org.eclipse.jgit.errors.PackProtocolException;
 import org.eclipse.jgit.internal.JGitText;
+import org.eclipse.jgit.internal.storage.pack.CachedPackUriProvider;
 import org.eclipse.jgit.internal.storage.pack.PackWriter;
 import org.eclipse.jgit.internal.transport.parser.FirstWant;
 import org.eclipse.jgit.lib.BitmapIndex;
@@ -359,6 +360,8 @@ public class UploadPack {
 	 */
 	private FetchRequest currentRequest;
 
+	private CachedPackUriProvider cachedPackUriProvider;
+
 	/**
 	 * Create a new pack upload for an open repository.
 	 *
@@ -736,6 +739,15 @@ public class UploadPack {
 		this.clientRequestedV2 = params.contains("version=2"); //$NON-NLS-1$
 	}
 
+	/**
+	 * @param p provider of URIs corresponding to cached packs (to support
+	 *     the packfile URIs feature)
+	 * @since 5.5
+	 */
+	public void setCachedPackUriProvider(@Nullable CachedPackUriProvider p) {
+		cachedPackUriProvider = p;
+	}
+
 	private boolean useProtocolV2() {
 		return ProtocolVersion.V2.equals(transferConfig.protocolVersion)
 				&& clientRequestedV2;
@@ -1285,6 +1297,7 @@ public class UploadPack {
 				(transferConfig.isAllowFilter() ? OPTION_FILTER + ' ' : "") + //$NON-NLS-1$
 				(advertiseRefInWant ? CAPABILITY_REF_IN_WANT + ' ' : "") + //$NON-NLS-1$
 				(transferConfig.isAllowSidebandAll() ? OPTION_SIDEBAND_ALL + ' ' : "") + //$NON-NLS-1$
+				(cachedPackUriProvider != null ? "packfile-uris " : "") + // $NON-NLS-1$
 				OPTION_SHALLOW);
 		caps.add(CAPABILITY_SERVER_OPTION);
 		return caps;
@@ -2298,7 +2311,21 @@ public class UploadPack {
 			}
 
 			if (pckOut.isUsingSideband()) {
-				pckOut.writeString("packfile\n"); //$NON-NLS-1$
+				if (req instanceof FetchV2Request &&
+						cachedPackUriProvider != null &&
+						!((FetchV2Request) req).getPackfileUriProtocols().isEmpty()) {
+					FetchV2Request reqV2 = (FetchV2Request) req;
+					pw.setPackfileUriConfig(new PackWriter.PackfileUriConfig(
+							pckOut,
+							reqV2.getPackfileUriProtocols(),
+							cachedPackUriProvider));
+				} else {
+					// PackWriter will write "packfile-uris\n" and "packfile\n"
+					// for us if provided a PackfileUriConfig. In this case, we
+					// are not providing a PackfileUriConfig, so we have to
+					// write this line ourselves.
+					pckOut.writeString("packfile\n"); //$NON-NLS-1$
+				}
 			}
 			pw.writePack(pm, NullProgressMonitor.INSTANCE, packOut);