[push, lfs] Tell the pre-push hook whether the push is a dry run

This is a feature that does not exist in C git: an external pre-push
hook doesn't know whether the push is run as a dry run. But for
internal hooks written in Java it is entirely possible to give a hook
this information.

In JGit with its internal LFS implementation, this enables us to not
perform LFS uploads in a dry run. This is kind of important because
EGit frequently does a dry-run before doing the actual push to give the
user a way to review what would be pushed before it actually happens.

Doing an LFS upload of potentially huge files during a dry-run is
wasteful, makes the dry run not actually a dry run, and leads to
uploading the same file twice if followed by a real push.

Use the information in the LfsPrePushHook to only do the initial call
to the LFS server, but then skipping the actual upload if the push is
a dry run. That way, a failure to contact the LFS server leads to an
error in the dry run, as it should.

Bug: 546567
Change-Id: I155430f27c4979d91096ba72fd95c3775dd3f28b
Signed-off-by: Thomas Wolf <thomas.wolf@paranor.ch>

1 files changed, 5 insertions, 3 deletions

diff --git a/org.eclipse.jgit.lfs/src/org/eclipse/jgit/lfs/LfsPrePushHook.java b/org.eclipse.jgit.lfs/src/org/eclipse/jgit/lfs/LfsPrePushHook.java
index ebf46e080e..9b3d60812a 100644
--- a/org.eclipse.jgit.lfs/src/org/eclipse/jgit/lfs/LfsPrePushHook.java
+++ b/org.eclipse.jgit.lfs/src/org/eclipse/jgit/lfs/LfsPrePushHook.java
@@ -1,5 +1,5 @@
 /*
- * Copyright (C) 2017, Markus Duft <markus.duft@ssi-schaefer.com> and others
+ * Copyright (C) 2017, 2022 Markus Duft <markus.duft@ssi-schaefer.com> and others
  *
  * This program and the accompanying materials are made available under the
  * terms of the Eclipse Distribution License v. 1.0 which is available at
@@ -101,8 +101,10 @@ public class LfsPrePushHook extends PrePushHook {
 		}
 		HttpConnection api = LfsConnectionFactory.getLfsConnection(
 				getRepository(), METHOD_POST, OPERATION_UPLOAD);
-		Map<String, LfsPointer> oid2ptr = requestBatchUpload(api, toPush);
-		uploadContents(api, oid2ptr);
+		if (!isDryRun()) {
+			Map<String, LfsPointer> oid2ptr = requestBatchUpload(api, toPush);
+			uploadContents(api, oid2ptr);
+		}
 		return EMPTY;
 
 	}