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Code Issues Actions 12 Packages Projects Releases Wiki Activity

Improve crash consistency on Linux (#8815) 

* Improve crash consistency

* `fsync` the correct parent directory

* More flexibility

* Add reference to man page

* fix formatting

---------

Co-authored-by: Tim Jacomb <21194782+timja@users.noreply.github.com>
This commit is contained in:
Basil Crow 2024-01-03 01:27:32 -08:00 committed by GitHub
parent d75833e5e0
commit 444f2de993
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1 changed files with 17 additions and 0 deletions
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17
core/src/main/java/hudson/util/AtomicFileWriter.java
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@ -26,11 +26,13 @@ package hudson.util;
import edu.umd.cs.findbugs.annotations.NonNull;
import edu.umd.cs.findbugs.annotations.Nullable;
import hudson.Functions;
import java.io.File;
import java.io.FileWriter;
import java.io.IOException;
import java.io.Writer;
import java.lang.ref.Cleaner;
import java.nio.channels.FileChannel;
import java.nio.charset.Charset;
import java.nio.charset.StandardCharsets;
import java.nio.file.AtomicMoveNotSupportedException;
@ -62,6 +64,9 @@ public class AtomicFileWriter extends Writer {
private static /* final */ boolean DISABLE_FORCED_FLUSH = SystemProperties.getBoolean(
AtomicFileWriter.class.getName() + ".DISABLE_FORCED_FLUSH");
private static /* final */ boolean REQUIRES_DIR_FSYNC = SystemProperties.getBoolean(
AtomicFileWriter.class.getName() + ".REQUIRES_DIR_FSYNC", !Functions.isWindows());
static {
if (DISABLE_FORCED_FLUSH) {
LOGGER.log(Level.WARNING, "DISABLE_FORCED_FLUSH flag used, this could result in dataloss if failures happen in your storage subsystem.");
@ -234,6 +239,18 @@ public class AtomicFileWriter extends Writer {
throw replaceFailed;
}
}
/*
* From fsync(2) on Linux:
*
* Calling fsync() does not necessarily ensure that the entry in the directory containing the file has also
* reached disk. For that an explicit fsync() on a file descriptor for the directory is also needed.
*/
if (!DISABLE_FORCED_FLUSH && REQUIRES_DIR_FSYNC) {
try (FileChannel parentChannel = FileChannel.open(destPath.getParent())) {
parentChannel.force(true);
}
}
}
private static final class CleanupChecker implements Runnable {