// Copyright 2015 The Bazel Authors. All rights reserved.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//    http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
package com.google.devtools.build.lib.actions;

import static com.google.common.truth.Truth.assertThat;
import static org.junit.Assert.fail;

import com.google.common.collect.ImmutableList;
import com.google.common.collect.ImmutableSet;
import com.google.devtools.build.lib.actions.ResourceManager.ResourceHandle;
import com.google.devtools.build.lib.analysis.platform.PlatformInfo;
import com.google.devtools.build.lib.testutil.TestThread;
import com.google.devtools.build.lib.testutil.TestUtils;
import java.util.concurrent.CyclicBarrier;
import java.util.concurrent.TimeUnit;
import java.util.concurrent.atomic.AtomicInteger;
import javax.annotation.Nullable;
import org.junit.Before;
import org.junit.Test;
import org.junit.runner.RunWith;
import org.junit.runners.JUnit4;

/**
 *
 * Tests for @{link ResourceManager}.
 */
@RunWith(JUnit4.class)
public class ResourceManagerTest {

  private final ActionExecutionMetadata resourceOwner = new ResourceOwnerStub();
  private final ResourceManager rm = ResourceManager.instanceForTestingOnly();
  private AtomicInteger counter;
  CyclicBarrier sync;
  CyclicBarrier sync2;

  @Before
  public final void configureResourceManager() throws Exception  {
    rm.setRamUtilizationPercentage(100);
    rm.setAvailableResources(
        ResourceSet.create(/*memoryMb=*/ 1000, /*cpuUsage=*/ 1, /* localTestCount= */ 2));
    counter = new AtomicInteger(0);
    sync = new CyclicBarrier(2);
    sync2 = new CyclicBarrier(2);
    rm.resetResourceUsage();
  }

  private ResourceHandle acquire(double ram, double cpu, int tests)
      throws InterruptedException {
    return rm.acquireResources(resourceOwner, ResourceSet.create(ram, cpu, tests));
  }

  private ResourceHandle acquireNonblocking(double ram, double cpu, int tests) {
    return rm.tryAcquire(resourceOwner, ResourceSet.create(ram, cpu, tests));
  }

  private void release(double ram, double cpu, int tests) {
    rm.releaseResources(resourceOwner, ResourceSet.create(ram, cpu, tests));
  }

  private void validate(int count) {
    assertThat(counter.incrementAndGet()).isEqualTo(count);
  }

  @Test
  public void testOverBudgetRequests() throws Exception {
    assertThat(rm.inUse()).isFalse();

    // When nothing is consuming RAM,
    // Then Resource Manager will successfully acquire an over-budget request for RAM:
    double bigRam = 10000.0;
    acquire(bigRam, 0, 0);
    // When RAM is consumed,
    // Then Resource Manager will be "in use":
    assertThat(rm.inUse()).isTrue();
    release(bigRam, 0, 0);
    // When that RAM is released,
    // Then Resource Manager will not be "in use":
    assertThat(rm.inUse()).isFalse();

    // Ditto, for CPU:
    double bigCpu = 10.0;
    acquire(0, bigCpu, 0);
    assertThat(rm.inUse()).isTrue();
    release(0, bigCpu, 0);
    assertThat(rm.inUse()).isFalse();

    // Ditto, for tests:
    int bigTests = 10;
    acquire(0, 0, bigTests);
    assertThat(rm.inUse()).isTrue();
    release(0, 0, bigTests);
    assertThat(rm.inUse()).isFalse();
  }

  @Test
  public void testThatCpuCanBeOverallocated() throws Exception {
    assertThat(rm.inUse()).isFalse();

    // Given CPU is partially acquired:
    acquire(0, 0.5, 0);

    // When a request for CPU is made that would slightly overallocate CPU,
    // Then the request succeeds:
    TestThread thread1 =
        new TestThread() {
          @Override
          public void runTest() throws Exception {
            assertThat(acquireNonblocking(0, 0.6, 0)).isNotNull();
          }
        };
    thread1.start();
    thread1.joinAndAssertState(10000);
  }

  @Test
  public void testThatCpuAllocationIsNoncommutative() throws Exception {
    assertThat(rm.inUse()).isFalse();

    // Given that CPU has a small initial allocation:
    acquire(0, 0.099, 0);

    // When a request for a large CPU allocation is made,
    // Then the request succeeds:
    TestThread thread1 =
        new TestThread() {
          @Override
          public void runTest() throws Exception {
            assertThat(acquireNonblocking(0, 0.99, 0)).isNotNull();
            // Cleanup
            release(0, 0.99, 0);
          }
        };
    thread1.start();
    thread1.joinAndAssertState(10000);

    // Cleanup
    release(0, 0.099, 0);
    assertThat(rm.inUse()).isFalse();

    // Given that CPU has a large initial allocation:
    acquire(0, 0.99, 0);

    // When a request for a small CPU allocation is made,
    // Then the request fails:
    TestThread thread2 =
        new TestThread() {
          @Override
          public void runTest() throws Exception {
            assertThat(acquireNonblocking(0, 0.099, 0)).isNull();
          }
        };
    thread2.start();
    thread2.joinAndAssertState(10000);
    // Note that this behavior is surprising and probably not intended.
  }

  @Test
  public void testThatRamCannotBeOverallocated() throws Exception {
    assertThat(rm.inUse()).isFalse();

    // Given RAM is partially acquired:
    acquire(500, 0, 0);

    // When a request for RAM is made that would slightly overallocate RAM,
    // Then the request fails:
    TestThread thread1 =
        new TestThread() {
          @Override
          public void runTest() throws Exception {
            assertThat(acquireNonblocking(600, 0, 0)).isNull();
          }
        };
    thread1.start();
    thread1.joinAndAssertState(10000);
  }

  @Test
  public void testThatTestsCannotBeOverallocated() throws Exception {
    assertThat(rm.inUse()).isFalse();

    // Given test count is partially acquired:
    acquire(0, 0, 1);

    // When a request for tests is made that would slightly overallocate tests,
    // Then the request fails:
    TestThread thread1 =
        new TestThread() {
          @Override
          public void runTest() throws Exception {
            assertThat(acquireNonblocking(0, 0, 2)).isNull();
          }
        };
    thread1.start();
    thread1.joinAndAssertState(10000);
  }

  @Test
  public void testHasResources() throws Exception {
    assertThat(rm.inUse()).isFalse();
    assertThat(rm.threadHasResources()).isFalse();
    acquire(1, 0.1, 1);
    assertThat(rm.threadHasResources()).isTrue();

    // We have resources in this thread - make sure other threads
    // are not affected.
    TestThread thread1 =
        new TestThread() {
          @Override
          public void runTest() throws Exception {
            assertThat(rm.threadHasResources()).isFalse();
            acquire(1, 0, 0);
            assertThat(rm.threadHasResources()).isTrue();
            release(1, 0, 0);
            assertThat(rm.threadHasResources()).isFalse();
            acquire(0, 0.1, 0);
            assertThat(rm.threadHasResources()).isTrue();
            release(0, 0.1, 0);
            assertThat(rm.threadHasResources()).isFalse();
            acquire(0, 0, 1);
            assertThat(rm.threadHasResources()).isTrue();
            release(0, 0, 1);
            assertThat(rm.threadHasResources()).isFalse();
          }
        };
    thread1.start();
    thread1.joinAndAssertState(10000);

    release(1, 0.1, 1);
    assertThat(rm.threadHasResources()).isFalse();
    assertThat(rm.inUse()).isFalse();
  }

  @Test
  public void testConcurrentLargeRequests() throws Exception {
    assertThat(rm.inUse()).isFalse();
    TestThread thread1 =
        new TestThread() {
          @Override
          public void runTest() throws Exception {
            acquire(2000, 2, 0);
            sync.await();
            validate(1);
            sync.await();
            // Wait till other thread will be locked.
            while (rm.getWaitCount() == 0) {
              Thread.yield();
            }
            release(2000, 2, 0);
            assertThat(rm.getWaitCount()).isEqualTo(0);
            acquire(2000, 2, 0); // Will be blocked by the thread2.
            validate(3);
            release(2000, 2, 0);
          }
        };
    TestThread thread2 =
        new TestThread() {
          @Override
          public void runTest() throws Exception {
            sync2.await();
            assertThat(rm.isAvailable(2000, 2, 0)).isFalse();
            acquire(2000, 2, 0); // Will be blocked by the thread1.
            validate(2);
            sync2.await();
            // Wait till other thread will be locked.
            while (rm.getWaitCount() == 0) {
              Thread.yield();
            }
            release(2000, 2, 0);
          }
        };

    thread1.start();
    thread2.start();
    sync.await(1, TimeUnit.SECONDS);
    assertThat(rm.inUse()).isTrue();
    assertThat(rm.getWaitCount()).isEqualTo(0);
    sync2.await(1, TimeUnit.SECONDS);
    sync.await(1, TimeUnit.SECONDS);
    sync2.await(1, TimeUnit.SECONDS);
    thread1.joinAndAssertState(1000);
    thread2.joinAndAssertState(1000);
    assertThat(rm.inUse()).isFalse();
  }

  @Test
  public void testInterruptedAcquisitionClearsResources() throws Exception {
    assertThat(rm.inUse()).isFalse();
    // Acquire a small amount of resources so that future requests can block (the initial request
    // always succeeds even if it's for too much).
    TestThread smallThread =
        new TestThread() {
          @Override
          public void runTest() throws InterruptedException {
            acquire(1, 0, 0);
          }
        };
    smallThread.start();
    smallThread.joinAndAssertState(TestUtils.WAIT_TIMEOUT_MILLISECONDS);
    TestThread thread1 =
        new TestThread() {
          @Override
          public void runTest() {
            Thread.currentThread().interrupt();
            try {
              acquire(1999, 0, 0);
              fail("Didn't throw interrupted exception");
            } catch (InterruptedException e) {
              // Expected.
            }
          }
        };
    thread1.start();
    thread1.joinAndAssertState(TestUtils.WAIT_TIMEOUT_MILLISECONDS);
    // This should process the queue. If the request from above is still present, it will take all
    // the available memory. But it shouldn't.
    rm.setAvailableResources(
        ResourceSet.create(/*memoryMb=*/ 2000, /*cpuUsage=*/ 1, /* localTestCount= */ 2));
    TestThread thread2 =
        new TestThread() {
          @Override
          public void runTest() throws InterruptedException {
            acquire(1999, 0, 0);
            release(1999, 0, 0);
          }
        };
    thread2.start();
    thread2.joinAndAssertState(TestUtils.WAIT_TIMEOUT_MILLISECONDS);
  }

  @Test
  public void testOutOfOrderAllocation() throws Exception {
    final CyclicBarrier sync3 = new CyclicBarrier(2);
    final CyclicBarrier sync4 = new CyclicBarrier(2);

    assertThat(rm.inUse()).isFalse();

    TestThread thread1 = new TestThread () {
      @Override public void runTest() throws Exception {
        sync.await();
        acquire(900, 0.5, 0); // Will be blocked by the main thread.
        validate(5);
        release(900, 0.5, 0);
        sync.await();
      }
    };

    TestThread thread2 = new TestThread() {
      @Override public void runTest() throws Exception {
        // Wait till other thread will be locked
        while (rm.getWaitCount() == 0) {
          Thread.yield();
        }
        acquire(100, 0.1, 0);
        validate(2);
        release(100, 0.1, 0);
        sync2.await();
        acquire(200, 0.5, 0);
        validate(4);
        sync2.await();
        release(200, 0.5, 0);
      }
    };

    TestThread thread3 =
        new TestThread() {
          @Override
          public void runTest() throws Exception {
            acquire(100, 0.4, 0);
            sync3.await();
            sync3.await();
            release(100, 0.4, 0);
          }
        };

    TestThread thread4 =
        new TestThread() {
          @Override
          public void runTest() throws Exception {
            acquire(750, 0.3, 0);
            sync4.await();
            sync4.await();
            release(750, 0.3, 0);
          }
        };

    // Lock 900 MB, 0.9 CPU in total (spread over three threads so that we can individually release
    // parts of it).
    acquire(50, 0.2, 0);
    thread3.start();
    thread4.start();
    sync3.await(1, TimeUnit.SECONDS);
    sync4.await(1, TimeUnit.SECONDS);
    validate(1);

    // Start thread1, which will try to acquire 900 MB, 0.5 CPU, but can't, so it has to wait.
    thread1.start();
    sync.await(1, TimeUnit.SECONDS);

    // Start thread2, which will successfully acquire and release 100 MB, 0.1 CPU.
    thread2.start();
    // Signal thread2 to acquire 200 MB and 0.5 CPU, which will block.
    sync2.await(1, TimeUnit.SECONDS);

    // Waiting till both threads are locked.
    while (rm.getWaitCount() < 2) {
      Thread.yield();
    }

    validate(3); // Thread1 is now first in the queue and Thread2 is second.

    // Release 100 MB, 0.4 CPU. This allows Thread2 to continue out of order.
    sync3.await(1, TimeUnit.SECONDS);
    sync2.await(1, TimeUnit.SECONDS);

    // Release 750 MB, 0.3 CPU. At this point thread1 will finally acquire resources.
    sync4.await(1, TimeUnit.SECONDS);
    sync.await(1, TimeUnit.SECONDS);

    // Release all remaining resources.
    release(50, 0.2, 0);
    thread1.join();
    thread2.join();
    thread3.join();
    thread4.join();

    assertThat(rm.inUse()).isFalse();
  }

  private static class ResourceOwnerStub implements ActionExecutionMetadata {

    @Override
    @Nullable
    public String getProgressMessage() {
      throw new IllegalStateException();
    }

    @Override
    public ActionOwner getOwner() {
      throw new IllegalStateException();
    }

    @Override
    public boolean isShareable() {
      throw new IllegalStateException();
    }

    @Override
    public String prettyPrint() {
      throw new IllegalStateException();
    }

    @Override
    public String getMnemonic() {
      throw new IllegalStateException();
    }

    @Override
    public boolean inputsDiscovered() {
      throw new IllegalStateException();
    }

    @Override
    public boolean discoversInputs() {
      throw new IllegalStateException();
    }

    @Override
    public Iterable<Artifact> getTools() {
      throw new IllegalStateException();
    }

    @Override
    public Iterable<Artifact> getInputs() {
      throw new IllegalStateException();
    }

    @Override
    public Iterable<String> getClientEnvironmentVariables() {
      throw new IllegalStateException();
    }

    @Override
    public RunfilesSupplier getRunfilesSupplier() {
      throw new IllegalStateException();
    }

    @Override
    public ImmutableSet<Artifact> getOutputs() {
      throw new IllegalStateException();
    }

    @Override
    public Artifact getPrimaryInput() {
      throw new IllegalStateException();
    }

    @Override
    public Artifact getPrimaryOutput() {
      throw new IllegalStateException();
    }

    @Override
    public Iterable<Artifact> getMandatoryInputs() {
      throw new IllegalStateException();
    }

    @Override
    public Iterable<Artifact> getInputFilesForExtraAction(
      ActionExecutionContext actionExecutionContext) {
    return ImmutableList.of();
  }

    @Override
    public String getKey(ActionKeyContext actionKeyContext) {
      throw new IllegalStateException();
    }

    @Override
    @Nullable
    public String describeKey() {
      throw new IllegalStateException();
    }

    @Override
    public String describe() {
      return "ResourceOwnerStubAction";
    }

    @Override
    public ImmutableSet<Artifact> getMandatoryOutputs() {
      return ImmutableSet.of();
    }

    @Override
    public boolean shouldReportPathPrefixConflict(ActionAnalysisMetadata action) {
      throw new IllegalStateException();
    }

    @Override
    public MiddlemanType getActionType() {
      throw new IllegalStateException();
    }

    @Nullable
    @Override
    public PlatformInfo getExecutionPlatform() {
      throw new IllegalStateException();
    }
  }
}