Cache user global and system-wide git configurations

So far the git configuration and the system wide git configuration were
always reloaded when jgit accessed these global configuration files to
access global configuration options which are not in the context of a
single git repository. Cache these configurations in SystemReader and
only reload them if their file metadata observed using FileSnapshot
indicates a modification.

Change-Id: I092fe11a5d95f1c5799273cacfc7a415d0b7786c
Signed-off-by: Matthias Sohn <matthias.sohn@sap.com>
Signed-off-by: Thomas Wolf <thomas.wolf@paranor.ch>

2 files changed, 45 insertions, 5 deletions

diff --git a/org.eclipse.jgit.junit/src/org/eclipse/jgit/junit/LocalDiskRepositoryTestCase.java b/org.eclipse.jgit.junit/src/org/eclipse/jgit/junit/LocalDiskRepositoryTestCase.java
index f8f0c18cba..29579d007f 100644
--- a/org.eclipse.jgit.junit/src/org/eclipse/jgit/junit/LocalDiskRepositoryTestCase.java
+++ b/org.eclipse.jgit.junit/src/org/eclipse/jgit/junit/LocalDiskRepositoryTestCase.java
@@ -137,14 +137,15 @@ public abstract class LocalDiskRepositoryTestCase {
 		// the same one here
 		FS.getFileStoreAttributes(tmp.toPath().getParent());
 
-		mockSystemReader.userGitConfig = new FileBasedConfig(new File(tmp,
-				"usergitconfig"), FS.DETECTED);
+		FileBasedConfig userConfig = new FileBasedConfig(
+				new File(tmp, "usergitconfig"), FS.DETECTED);
 		// We have to set autoDetach to false for tests, because tests expect to be able
 		// to clean up by recursively removing the repository, and background GC might be
 		// in the middle of writing or deleting files, which would disrupt this.
-		mockSystemReader.userGitConfig.setBoolean(ConfigConstants.CONFIG_GC_SECTION,
+		userConfig.setBoolean(ConfigConstants.CONFIG_GC_SECTION,
 				null, ConfigConstants.CONFIG_KEY_AUTODETACH, false);
-		mockSystemReader.userGitConfig.save();
+		userConfig.save();
+		mockSystemReader.setUserGitConfig(userConfig);
 		ceilTestDirectories(getCeilings());
 
 		author = new PersonIdent("J. Author", "jauthor@example.com");
diff --git a/org.eclipse.jgit.junit/src/org/eclipse/jgit/junit/MockSystemReader.java b/org.eclipse.jgit.junit/src/org/eclipse/jgit/junit/MockSystemReader.java
index 92b531d191..123fdb305f 100644
--- a/org.eclipse.jgit.junit/src/org/eclipse/jgit/junit/MockSystemReader.java
+++ b/org.eclipse.jgit.junit/src/org/eclipse/jgit/junit/MockSystemReader.java
@@ -60,6 +60,7 @@ import java.util.concurrent.TimeUnit;
 import org.eclipse.jgit.errors.ConfigInvalidException;
 import org.eclipse.jgit.lib.Config;
 import org.eclipse.jgit.lib.Constants;
+import org.eclipse.jgit.lib.StoredConfig;
 import org.eclipse.jgit.storage.file.FileBasedConfig;
 import org.eclipse.jgit.util.FS;
 import org.eclipse.jgit.util.SystemReader;
@@ -100,11 +101,37 @@ public class MockSystemReader extends SystemReader {
 
 	final Map<String, String> values = new HashMap<>();
 
-	FileBasedConfig userGitConfig;
+	private FileBasedConfig userGitConfig;
 
 	FileBasedConfig systemGitConfig;
 
 	/**
+	 * Set the user-level git config
+	 *
+	 * @param userGitConfig
+	 *            set another user-level git config
+	 * @return the old user-level git config
+	 */
+	public FileBasedConfig setUserGitConfig(FileBasedConfig userGitConfig) {
+		FileBasedConfig old = this.userGitConfig;
+		this.userGitConfig = userGitConfig;
+		return old;
+	}
+
+	/**
+	 * Set the system-level git config
+	 *
+	 * @param systemGitConfig
+	 *            the new system-level git config
+	 * @return the old system-level config
+	 */
+	public FileBasedConfig setSystemGitConfig(FileBasedConfig systemGitConfig) {
+		FileBasedConfig old = this.systemGitConfig;
+		this.systemGitConfig = systemGitConfig;
+		return old;
+	}
+
+	/**
 	 * Constructor for <code>MockSystemReader</code>
 	 */
 	public MockSystemReader() {
@@ -166,6 +193,18 @@ public class MockSystemReader extends SystemReader {
 		return systemGitConfig;
 	}
 
+	@Override
+	public StoredConfig getUserConfig()
+			throws IOException, ConfigInvalidException {
+		return userGitConfig;
+	}
+
+	@Override
+	public StoredConfig getSystemConfig()
+			throws IOException, ConfigInvalidException {
+		return systemGitConfig;
+	}
+
 	/** {@inheritDoc} */
 	@Override
 	public String getHostname() {