import org.gradle.api.internal.file.FileOperations;
import org.gradle.api.internal.tasks.compile.incremental.IncrementalCompilerFactory;
import org.gradle.api.internal.tasks.compile.incremental.analyzer.CachingClassDependenciesAnalyzer;
import org.gradle.api.internal.tasks.compile.incremental.analyzer.ClassDependenciesAnalyzer;
import org.gradle.api.internal.tasks.compile.incremental.analyzer.DefaultClassDependenciesAnalyzer;

        when:
        file("build/output2/overlapping.txt").text = "overlapping"
        waitForChangesToBePickedUp()
        withWatchFs().run ":incremental", "-DoutputDir=output2"
        then:
        executedAndNotSkipped(":incremental")
        file("build/output1").assertDoesNotExist()

        when:
        waitForChangesToBePickedUp()

        """.stripIndent()
    }

    def "incremental analysis cache file is not generated with incremental analysis disabled"() {
        buildFile << 'pmd { incrementalAnalysis = false }'
        goodCode()

        expect:
        succeeds("check", "-i")
        !file("build/tmp/pmdMain/incremental.cache").exists()
    }

    def "incremental analysis can be enabled"() {
        given:

        with (taskFailureResult(':failingTask')) {
            !executionReasons.empty
            failures[0].description.contains("task failed intentionally")
        }
    }

    def "reports incremental task as incremental"() {
        given:
        file('src').mkdir()
        def supportsInputChanges = targetVersion > GradleVersion.version("5.4")

import org.gradle.language.internal.DefaultNativeComponentFactory;
import org.gradle.language.nativeplatform.internal.incremental.DefaultCompilationStateCacheFactory;
import org.gradle.language.nativeplatform.internal.incremental.DefaultIncrementalCompilerBuilder;
import org.gradle.language.nativeplatform.internal.incremental.sourceparser.CachingCSourceParser;
import org.gradle.language.nativeplatform.internal.toolchains.DefaultToolChainSelector;

// limitations under the License.

[[part5_gradle_inc_builds]]
= Part 5: Exploring Incremental Builds

++++
<div class="badge-wrapper">
    <a class="badge" href="https://dpeuniversity.gradle.com/app/courses/ec69d0b8-9171-4969-ac3e-82dea16f87b0/" target="_blank">
        <span class="badge-type button--blue">LEARN</span>
        <span class="badge-text">Incremental Builds and Build Caching with Gradle&nbsp;&nbsp;&nbsp;&gt;</span>
    </a>
</div>

 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.gradle.java.compile.incremental

import org.gradle.api.JavaVersion
import org.gradle.api.internal.cache.StringInterner
import org.gradle.api.internal.tasks.compile.incremental.recomp.PreviousCompilationAccess
import org.gradle.integtests.fixtures.AvailableJavaHomes
import org.gradle.integtests.fixtures.CompiledLanguage

upgradeNotes:
  - title: Delta xDS on by default
    content: |
      In previous versions, Istio used the "State of the world" xDS protocol to configure Envoy.
      In this release, the ["Delta"](https://www.envoyproxy.io/docs/envoy/latest/api-docs/xds_protocol#incremental-xds) xDS protocol is enabled by default.

</div>
++++

Gradle uses two main features to reduce build time: *incremental builds* and *build caching*.

image::gradle-basic-8.png[]

== Incremental builds

An *incremental build* is a build that avoids running tasks whose inputs have not changed since the previous build.
Re-executing such tasks is unnecessary if they would only re-produce the same output.

For incremental builds to work, tasks must define their inputs and outputs.

import org.gradle.language.nativeplatform.internal.incremental.sourceparser.CSourceParser;
import org.gradle.language.nativeplatform.internal.incremental.sourceparser.DefaultIncludeDirectives;
import org.gradle.language.nativeplatform.internal.incremental.sourceparser.MacroWithSimpleExpression;
import org.gradle.language.nativeplatform.internal.incremental.sourceparser.RegexBackedCSourceParser;