Gradle copies all the files if at least one is not up-to-date - gradle

Question

For instance, I've got the following task:
task testCopy(type: Copy) {
from ("folder/copy_from")
into ("folder/copy_to")
eachFile {println it.name}
}
Unless the inner files of the folder copy_from are touched, task works fine. As soon as I change, let's say one file in the folder copy_from, then Gradle begins to copy all the files from copy_from folder into copy_to instead of copying only one changed/added file.
Is this behaviour expected? Is there a way to make Gradle copy only changed/added file?

Answer 1

Yes based on this github issue and gradle discuss:
The build is incremental in the sense that the copy task only executes
when things have changed but it isn’t incremental itself, in that it
only copies inputs that have been modified.
I couldn't find a propper solution, but one solution is just splitting your task into smaller ones with specific types.
task copy1(type: Copy) {
into 'build/out'
from ('src') {
include 'docs/*.txt'
}
eachFile {println it.name}
}
task copy2(type: Copy) {
into 'build/out'
from ('src') {
include 'docs/*.md'
}
eachFile {println it.name}
}
task copy3 {
dependsOn copy1, copy2
}
It's not exactly what you want but it improves the performance by reducing files to copy.
when you change a text file and run gradle copy3 it just copies the text files not md files.
UPDATE:
Ant copy task doesn't have this problem
from it's documentation:
By default, files are only copied if the source file is newer than the destination file, or when the destination file does not exist. However, you can explicitly overwrite files with the overwrite attribute
So you can use ant copy task instead, as we can use ant tasks from gradle:
task copyFromAnt {
doLast {
ant.copy(todir: 'build/out') {
fileset(dir: 'src')
}
}
}
ant logs the files it copies so you can check the log with help of gradle -d and grep:
gradle copyFromAnt -d | grep "\[ant:copy\]"
and to see just the files it copies with out up-to-dat and etc. you can use the below command:
gradle copyFromAnt -d | grep "\[ant:copy\] Copying"