// limitations under the License.

[[sec:daemon_watch_fs]]
= File System Watching

Gradle maintains a Virtual File System (VFS) to calculate what needs to be rebuilt on repeat builds of a project.
By watching the file system, Gradle keeps the VFS current between builds.

== Enable

Gradle enables file system watching by default for supported operating systems since Gradle 7.

        when:
        FileTree filtered = tree.matching(closure)
        def sourceCollections = (filtered as CompositeFileTree).sourceCollections

        then:
        sourceCollections == [filtered1, filtered2]

        and:
        1 * patternSetFactory.create() >> patterns
        1 * source1.matching(patterns) >> filtered1
        1 * source2.matching(patterns) >> filtered2
    }

        def list = ImmutableFilteredList.allOf([1, 2, 3, 4, 5, 6])

        expect:
        list.matching(x -> x > 2) == [3, 4, 5, 6]
        list.matching(x -> x < 2) == [1]
        list.matching(x -> x > 2).matching(x -> x < 5) == [3, 4]
        list.matching(x -> x != 5).matching(x -> x != 3) == [1, 2, 4, 6]
        list.matching(x -> x != 1).matching(x -> x != 6) == [2, 3, 4, 5]
    }

 * Build root directories are always watchable hierarchies.
 * Watching the build root directories is better since they are less likely to be deleted and
 * nearly no changes to the watched directories are necessary when running builds on the same project.
 *
 * To allow deleting the build root directories, we need to stop watching a build root directory if there are no more snapshots in the VFS inside,

 * // destination directory. Files matching the preserve
 * // filter will not be deleted.
 * task sync(type: Sync) {
 *     from 'source'
 *     into 'dest'
 *     preserve {
 *         include 'extraDir/**'
 *         include 'dir1/**'
 *         exclude 'dir1/extra.txt'
 *     }
 * }
 * </pre>
 */
@DisableCachingByDefault(because = "Not worth caching")
public abstract class Sync extends AbstractCopyTask {

     */
    public static final JvmVendorSpec ADOPTIUM = matching(KnownJvmVendor.ADOPTIUM);

    public static final JvmVendorSpec ADOPTOPENJDK = matching(KnownJvmVendor.ADOPTOPENJDK);

    public static final JvmVendorSpec AMAZON = matching(KnownJvmVendor.AMAZON);

    public static final JvmVendorSpec APPLE = matching(KnownJvmVendor.APPLE);

    public static final JvmVendorSpec AZUL = matching(KnownJvmVendor.AZUL);

} else if (testToolchain == "matchingVendor") {
// tag::toolchain-matching-vendor[]
java {
    toolchain {
        languageVersion = JavaLanguageVersion.of(11)
        vendor = JvmVendorSpec.matching("customString")
    }
}
// end::toolchain-matching-vendor[]

} else if (testToolchain == "matchingImplementation") {
// tag::toolchain-matching-implementation[]
java {
    toolchain {

type resourceMetricsClient struct {
	client resourceclient.PodMetricsesGetter
}

// GetResourceMetric gets the given resource metric (and an associated oldest timestamp)
// for all pods matching the specified selector in the given namespace

    private static final String ENABLED_MESSAGE = "Watching the file system is configured to be enabled"
    private static final String ENABLED_IF_AVAILABLE_MESSAGE = "Watching the file system is configured to be enabled if available"
    private static final String DISABLED_MESSAGE = "Watching the file system is configured to be disabled"

    private static final String ACTIVE_MESSAGE = "File system watching is active"

        new DefaultInternalOptions([:]))

    def setup() {
        _ * startParameter.getSystemPropertiesArgs() >> [:]
        _ * buildAction.startParameter >> startParameter
    }

    def "watching virtual file system is informed about watching the file system being #watchMode.description (VFS logging: #vfsLogging, watch logging: #watchLogging)"() {
        _ * startParameter.watchFileSystemMode >> watchMode