private void executeImp()

in org.eclipse.jgit/src/org/eclipse/jgit/transport/FetchProcess.java [124:250]
110 lines of code
36 McCabe index (conditional complexity)

	private void executeImp(final ProgressMonitor monitor,
			final FetchResult result, String initialBranch)
			throws NotSupportedException, TransportException {
		final TagOpt tagopt = transport.getTagOpt();
		String getTags = (tagopt == TagOpt.NO_TAGS) ? null : Constants.R_TAGS;
		String getHead = null;
		try {
			// If we don't have a HEAD yet, we're cloning and need to get the
			// upstream HEAD, too.
			Ref head = transport.local.exactRef(Constants.HEAD);
			ObjectId id = head != null ? head.getObjectId() : null;
			if (id == null || id.equals(ObjectId.zeroId())) {
				getHead = Constants.HEAD;
			}
		} catch (IOException e) {
			// Ignore
		}
		conn = transport.openFetch(toFetch, getTags, getHead);
		try {
			Map<String, Ref> refsMap = conn.getRefsMap();
			if (isInitialBranchMissing(refsMap, initialBranch)) {
				throw new TransportException(MessageFormat.format(
						JGitText.get().remoteBranchNotFound, initialBranch));
			}
			result.setAdvertisedRefs(transport.getURI(), refsMap);
			result.peerUserAgent = conn.getPeerUserAgent();
			final Set<Ref> matched = new HashSet<>();
			for (RefSpec spec : toFetch) {
				if (spec.getSource() == null)
					throw new TransportException(MessageFormat.format(
							JGitText.get().sourceRefNotSpecifiedForRefspec, spec));

				if (spec.isWildcard())
					expandWildcard(spec, matched);
				else
					expandSingle(spec, matched);
			}

			Collection<Ref> additionalTags = Collections.<Ref> emptyList();
			if (tagopt == TagOpt.AUTO_FOLLOW)
				additionalTags = expandAutoFollowTags();
			else if (tagopt == TagOpt.FETCH_TAGS)
				expandFetchTags();

			final boolean includedTags;
			if (!askFor.isEmpty() && !askForIsComplete()) {
				fetchObjects(monitor);
				includedTags = conn.didFetchIncludeTags();

				// Connection was used for object transfer. If we
				// do another fetch we must open a new connection.
				//
				closeConnection(result);
			} else {
				includedTags = false;
			}

			if (tagopt == TagOpt.AUTO_FOLLOW && !additionalTags.isEmpty()) {
				// There are more tags that we want to follow, but
				// not all were asked for on the initial request.
				//
				have.addAll(askFor.keySet());
				askFor.clear();
				for (Ref r : additionalTags) {
					ObjectId id = r.getPeeledObjectId();
					if (id == null)
						id = r.getObjectId();
					if (localHasObject(id))
						wantTag(r);
				}

				if (!askFor.isEmpty() && (!includedTags || !askForIsComplete())) {
					reopenConnection();
					if (!askFor.isEmpty())
						fetchObjects(monitor);
				}
			}
		} finally {
			closeConnection(result);
		}

		BatchRefUpdate batch = transport.local.getRefDatabase()
				.newBatchUpdate()
				.setAllowNonFastForwards(true)
				.setRefLogMessage("fetch", true); //$NON-NLS-1$
		try (RevWalk walk = new RevWalk(transport.local)) {
			walk.setRetainBody(false);
			if (monitor instanceof BatchingProgressMonitor) {
				((BatchingProgressMonitor) monitor).setDelayStart(
						250, TimeUnit.MILLISECONDS);
			}
			if (transport.isRemoveDeletedRefs()) {
				deleteStaleTrackingRefs(result, batch);
			}
			addUpdateBatchCommands(result, batch);
			for (ReceiveCommand cmd : batch.getCommands()) {
				cmd.updateType(walk);
				if (cmd.getType() == UPDATE_NONFASTFORWARD
						&& cmd instanceof TrackingRefUpdate.Command
						&& !((TrackingRefUpdate.Command) cmd).canForceUpdate())
					cmd.setResult(REJECTED_NONFASTFORWARD);
			}
			if (transport.isDryRun()) {
				for (ReceiveCommand cmd : batch.getCommands()) {
					if (cmd.getResult() == NOT_ATTEMPTED)
						cmd.setResult(OK);
				}
			} else {
				batch.execute(walk, monitor);
			}
		} catch (TransportException e) {
			throw e;
		} catch (IOException err) {
			throw new TransportException(MessageFormat.format(
					JGitText.get().failureUpdatingTrackingRef,
					getFirstFailedRefName(batch), err.getMessage()), err);
		}

		if (!fetchHeadUpdates.isEmpty()) {
			try {
				updateFETCH_HEAD(result);
			} catch (IOException err) {
				throw new TransportException(MessageFormat.format(
						JGitText.get().failureUpdatingFETCH_HEAD, err.getMessage()), err);
			}
		}
	}