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// Copyright Vespa.ai. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
package com.yahoo.vespa.hosted.node.admin.task.util.file;
import com.yahoo.vespa.hosted.node.admin.component.TaskContext;
import java.nio.file.Path;
import java.time.Instant;
import java.util.Arrays;
import java.util.Optional;
import java.util.logging.Logger;
/**
* Class to minimize resource usage with repetitive and mostly identical, idempotent, and
* mutating file operations, e.g. setting file content, setting owner, etc.
*
* Only changes to the file is logged.
*
* @author hakohall
*/
// @ThreadUnsafe
public class FileSync {
private static final Logger logger = Logger.getLogger(FileSync.class.getName());
private final UnixPath path;
private final FileContentCache contentCache;
private final FileAttributesCache attributesCache;
public FileSync(Path path) {
this.path = new UnixPath(path);
this.contentCache = new FileContentCache(this.path);
this.attributesCache = new FileAttributesCache(this.path);
}
public boolean convergeTo(TaskContext taskContext, PartialFileData partialFileData) {
return convergeTo(taskContext, partialFileData, false);
}
/**
* CPU, I/O, and memory usage is optimized for repeated calls with the same arguments.
*
* @param atomicWrite Whether to write updates to a temporary file in the same directory, and atomically move it
* to path. Ensures the file cannot be read while in the middle of writing it.
* @return true if the system was modified: content was written, or owner was set, etc.
* system is only modified if necessary (different).
*/
public boolean convergeTo(TaskContext taskContext, PartialFileData partialFileData, boolean atomicWrite) {
boolean modifiedSystem = false;
if (partialFileData.getContent().isPresent()) {
modifiedSystem |= convergeTo(taskContext, partialFileData.getContent().get(), atomicWrite, partialFileData.getPermissions());
}
AttributeSync attributeSync = new AttributeSync(path.toPath()).with(partialFileData);
modifiedSystem |= attributeSync.converge(taskContext, this.attributesCache);
return modifiedSystem;
}
/**
* CPU, I/O, and memory usage is optimized for repeated calls with the same argument.
*
* @param atomicWrite Whether to write updates to a temporary file in the same directory, and atomically move it
* to path. Ensures the file cannot be read while in the middle of writing it.
* @param permissions Permissions if the file is created.
* @return true if the content was written. Only modified if necessary (different).
*/
public boolean convergeTo(TaskContext taskContext, byte[] content, boolean atomicWrite, Optional<String> permissions) {
Optional<Instant> lastModifiedTime = attributesCache.forceGet().map(FileAttributes::lastModifiedTime);
if (lastModifiedTime.isEmpty()) {
taskContext.recordSystemModification(logger, "Creating file " + path +
permissions.map(p -> " with permissions " + p).orElse(""));
path.createParents();
writeBytes(content, atomicWrite, permissions);
contentCache.updateWith(content, attributesCache.forceGet().orElseThrow().lastModifiedTime());
return true;
}
if (Arrays.equals(content, contentCache.get(attributesCache.getOrThrow().lastModifiedTime()))) {
return false;
} else {
taskContext.recordSystemModification(logger, "Patching file " + path);
// empty permissions here, because the file already exists and won't be applied anyway
writeBytes(content, atomicWrite, Optional.empty());
contentCache.updateWith(content, attributesCache.forceGet().orElseThrow().lastModifiedTime());
return true;
}
}
private void writeBytes(byte[] content, boolean atomic, Optional<String> permissions) {
if (atomic) {
UnixPath tmpPath = new UnixPath(path.toPath().getFileSystem().getPath(path.toPath().toString() + ".FileSyncTmp"));
if (permissions.isPresent()) {
tmpPath.writeBytes(content, permissions.get());
} else {
tmpPath.writeBytes(content);
}
tmpPath.atomicMove(path.toPath());
} else {
if (permissions.isPresent()) {
path.writeBytes(content, permissions.get());
} else {
path.writeBytes(content);
}
}
}
}
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