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>

1 files changed, 22 insertions, 42 deletions

diff --git a/org.eclipse.jgit/src/org/eclipse/jgit/util/FS_POSIX.java b/org.eclipse.jgit/src/org/eclipse/jgit/util/FS_POSIX.java
index 1c42f78577..eda8afb10f 100644
--- a/org.eclipse.jgit/src/org/eclipse/jgit/util/FS_POSIX.java
+++ b/org.eclipse.jgit/src/org/eclipse/jgit/util/FS_POSIX.java
@@ -42,6 +42,9 @@
  */
 package org.eclipse.jgit.util;
 
+import static org.eclipse.jgit.lib.ConfigConstants.CONFIG_CORE_SECTION;
+import static org.eclipse.jgit.lib.ConfigConstants.CONFIG_KEY_SUPPORTSATOMICFILECREATION;
+
 import java.io.BufferedReader;
 import java.io.File;
 import java.io.IOException;
@@ -67,10 +70,9 @@ import org.eclipse.jgit.api.errors.JGitInternalException;
 import org.eclipse.jgit.errors.CommandFailedException;
 import org.eclipse.jgit.errors.ConfigInvalidException;
 import org.eclipse.jgit.internal.JGitText;
-import org.eclipse.jgit.lib.ConfigConstants;
 import org.eclipse.jgit.lib.Constants;
 import org.eclipse.jgit.lib.Repository;
-import org.eclipse.jgit.storage.file.FileBasedConfig;
+import org.eclipse.jgit.lib.StoredConfig;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
@@ -87,7 +89,7 @@ public class FS_POSIX extends FS {
 
 	private volatile boolean supportsUnixNLink = true;
 
-	private volatile AtomicFileCreation supportsAtomicCreateNewFile = AtomicFileCreation.UNDEFINED;
+	private volatile AtomicFileCreation supportsAtomicFileCreation = AtomicFileCreation.UNDEFINED;
 
 	private enum AtomicFileCreation {
 		SUPPORTED, NOT_SUPPORTED, UNDEFINED
@@ -112,42 +114,6 @@ public class FS_POSIX extends FS {
 		}
 	}
 
-	private void determineAtomicFileCreationSupport() {
-		// @TODO: enhance SystemReader to support this without copying code
-		AtomicFileCreation ret = getAtomicFileCreationSupportOption(
-				SystemReader.getInstance().openUserConfig(null, this));
-		if (ret == AtomicFileCreation.UNDEFINED
-				&& StringUtils.isEmptyOrNull(SystemReader.getInstance()
-						.getenv(Constants.GIT_CONFIG_NOSYSTEM_KEY))) {
-			ret = getAtomicFileCreationSupportOption(
-					SystemReader.getInstance().openSystemConfig(null, this));
-		}
-
-		if (ret == AtomicFileCreation.UNDEFINED) {
-			ret = AtomicFileCreation.SUPPORTED;
-		}
-		supportsAtomicCreateNewFile = ret;
-	}
-
-	private AtomicFileCreation getAtomicFileCreationSupportOption(
-			FileBasedConfig config) {
-		try {
-			config.load();
-			String value = config.getString(ConfigConstants.CONFIG_CORE_SECTION,
-					null,
-					ConfigConstants.CONFIG_KEY_SUPPORTSATOMICFILECREATION);
-			if (value == null) {
-				return AtomicFileCreation.UNDEFINED;
-			}
-			return StringUtils.toBoolean(value)
-					? AtomicFileCreation.SUPPORTED
-					: AtomicFileCreation.NOT_SUPPORTED;
-		} catch (IOException | ConfigInvalidException e) {
-			LOG.error(e.getMessage(), e);
-			return AtomicFileCreation.UNDEFINED;
-		}
-	}
-
 	/** {@inheritDoc} */
 	@Override
 	public FS newInstance() {
@@ -362,10 +328,24 @@ public class FS_POSIX extends FS {
 	/** {@inheritDoc} */
 	@Override
 	public boolean supportsAtomicCreateNewFile() {
-		if (supportsAtomicCreateNewFile == AtomicFileCreation.UNDEFINED) {
-			determineAtomicFileCreationSupport();
+		if (supportsAtomicFileCreation == AtomicFileCreation.UNDEFINED) {
+			try {
+				StoredConfig config = SystemReader.getInstance().getUserConfig();
+				String value = config.getString(CONFIG_CORE_SECTION, null,
+						CONFIG_KEY_SUPPORTSATOMICFILECREATION);
+				if (value != null) {
+					supportsAtomicFileCreation = StringUtils.toBoolean(value)
+							? AtomicFileCreation.SUPPORTED
+							: AtomicFileCreation.NOT_SUPPORTED;
+				} else {
+					supportsAtomicFileCreation = AtomicFileCreation.SUPPORTED;
+				}
+			} catch (IOException | ConfigInvalidException e) {
+				LOG.warn(JGitText.get().assumeAtomicCreateNewFile, e);
+				supportsAtomicFileCreation = AtomicFileCreation.SUPPORTED;
+			}
 		}
-		return supportsAtomicCreateNewFile == AtomicFileCreation.SUPPORTED;
+		return supportsAtomicFileCreation == AtomicFileCreation.SUPPORTED;
 	}
 
 	@Override