src/main/java/com/google/devtools/build/lib/actions/SpawnResult.java - bazel - Git at Google

 // Copyright 2017 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 com.google.common.base.Preconditions;
 import com.google.common.base.Strings;
 import com.google.devtools.build.lib.concurrent.ThreadSafety.Immutable;
 import com.google.devtools.build.lib.concurrent.ThreadSafety.ThreadSafe;
 import com.google.devtools.build.lib.server.FailureDetails.FailureDetail;
 import com.google.devtools.build.lib.shell.TerminationStatus;
 import com.google.devtools.build.lib.vfs.Path;
 import com.google.protobuf.ByteString;
 import java.io.InputStream;
 import java.time.Duration;
 import java.util.Locale;
 import java.util.Optional;
 import javax.annotation.Nullable;

 /** The result of a {@link Spawn}'s execution. */
 public interface SpawnResult {

   int POSIX_TIMEOUT_EXIT_CODE = /*SIGNAL_BASE=*/ 128 + /*SIGALRM=*/ 14;

   /** The status of the attempted Spawn execution. */
   enum Status {
     /** Subprocess executed successfully, and returned a zero exit code. */
     SUCCESS,

     /** Subprocess executed successfully, but returned a non-zero exit code. */
     NON_ZERO_EXIT(true),

     /** Subprocess execution timed out. */
     TIMEOUT(true),

     /**
      * The subprocess ran out of memory. On Linux systems, the kernel may kill processes in
      * low-memory situations, and this status is intended to report such a case back to Bazel.
      */
     OUT_OF_MEMORY(true),

     /**
      * Subprocess did not execute, it's not the user's fault, and the error is not catastrophic. If
      * keep_going is enabled then Bazel will try to continue the build, possibly will attempt to
      * rerun the same spawn, and possibly will attempt to run other actions.
      */
     EXECUTION_FAILED,

     /**
      * Subprocess did not execute, it's not the user's fault, and the error is catastrophic. Bazel
      * will not rerun this spawn. Bazel will attempt to not run other actions (regardless of whether
      * keep_going is enabled).
      */
     EXECUTION_FAILED_CATASTROPHICALLY,

     /**
      * Subprocess did not execute, it may be the user's fault, and the error is not catastrophic.
      * The user may be able to fix it. For example, a remote system may have denied the execution
      * due to too many inputs or too large inputs.
      */
     EXECUTION_DENIED(true),

     /**
      * Subprocess did not execute, it may be the user's fault, and the error is catastrophic. The
      * user may be able to prevent it from reoccurring. For example, an input file's contents may
      * have been modified by the user intra-build.
      */
     EXECUTION_DENIED_CATASTROPHICALLY(true),

     /**
      * The result of the remotely executed Spawn could not be retrieved due to errors in the remote
      * caching layer.
      */
     REMOTE_CACHE_FAILED;

     private final boolean isUserError;

     Status(boolean isUserError) {
       this.isUserError = isUserError;
     }

     Status() {
       this(false);
     }

     public boolean isConsideredUserError() {
       return isUserError;
     }
   }

   /**
    * Returns whether the spawn was actually run, regardless of the exit code. I.e., returns {@code
    * true} if {@link #status} is any of {@link Status#SUCCESS}, {@link Status#NON_ZERO_EXIT}, {@link
    * Status#TIMEOUT} or {@link Status#OUT_OF_MEMORY}.
    *
    * <p>Returns false if there were errors that prevented the spawn from being run, such as network
    * errors, missing local files, errors setting up sandboxing, etc.
    */
   default boolean setupSuccess() {
     Status status = status();
     return status == Status.SUCCESS
         || status == Status.NON_ZERO_EXIT
         || status == Status.TIMEOUT
         || status == Status.OUT_OF_MEMORY;
   }

   /**
    * Returns true if the status was {@link Status#EXECUTION_FAILED_CATASTROPHICALLY} or {@link
    * Status#EXECUTION_DENIED_CATASTROPHICALLY}.
    */
   default boolean isCatastrophe() {
     return status() == Status.EXECUTION_FAILED_CATASTROPHICALLY
         || status() == Status.EXECUTION_DENIED_CATASTROPHICALLY;
   }

   /** Returns the status of the attempted Spawn execution. */
   Status status();

   /**
    * Returns the exit code of the subprocess if the subprocess was executed.
    *
    * <p>Returns zero if {@link #status} returns {@link Status#SUCCESS}.
    *
    * <p>Returns non-zero if {@link #status} returns {@link Status#NON_ZERO_EXIT} or {@link
    * Status#OUT_OF_MEMORY}.
    *
    * <p>Returns 128 + 14 (corresponding to the Unix signal SIGALRM) if {@link #status} returns
    * {@link Status#TIMEOUT}.
    *
    * <p>Otherwise, the returned value is not meaningful.
    */
   // TODO(mschaller): clean up all uses of this method when {@code !this.setupSuccess()}
   int exitCode();

   /**
    * A detailed representation of what failed if {@link #status} is not {@link Status#SUCCESS}, and
    * {@code null} otherwise.
    */
   @Nullable
   FailureDetail failureDetail();

   /**
    * Returns the host name of the executor or {@code null}. This information is intended for
    * debugging purposes, especially for remote execution systems. Remote caches usually do not store
    * the original host name, so this is generally {@code null} for cache hits.
    */
   @Nullable
   String getExecutorHostName();

   /**
    * Returns the name of the SpawnRunner that executed the spawn. It should always be defined,
    * unless isCacheHit is true, in which case the spawn was not actually run.
    */
   String getRunnerName();

   /**
    * Returns the wall time taken by the {@link Spawn}'s execution.
    *
    * @return the measurement, or empty in case of execution errors or when the measurement is not
    *     implemented for the current platform
    */
   Optional<Duration> getWallTime();

   /**
    * Returns the user time taken by the {@link Spawn}'s execution.
    *
    * @return the measurement, or empty in case of execution errors or when the measurement is not
    *     implemented for the current platform
    */
   Optional<Duration> getUserTime();

   /**
    * Returns the system time taken by the {@link Spawn}'s execution.
    *
    * @return the measurement, or empty in case of execution errors or when the measurement is not
    *     implemented for the current platform
    */
   Optional<Duration> getSystemTime();

   /**
    * Returns the number of block output operations during the {@link Spawn}'s execution.
    *
    * @return the measurement, or empty in case of execution errors or when the measurement is not
    *     implemented for the current platform
    */
   Optional<Long> getNumBlockOutputOperations();

   /**
    * Returns the number of block input operations during the {@link Spawn}'s execution.
    *
    * @return the measurement, or empty in case of execution errors or when the measurement is not
    *     implemented for the current platform
    */
   Optional<Long> getNumBlockInputOperations();

   /**
    * Returns the number of involuntary context switches during the {@link Spawn}'s execution.
    *
    * @return the measurement, or empty in case of execution errors or when the measurement is not
    *     implemented for the current platform
    */
   Optional<Long> getNumInvoluntaryContextSwitches();

   SpawnMetrics getMetrics();

   /** Returns whether the spawn result was a cache hit. */
   boolean isCacheHit();

   /** Returns an optional custom failure message for the result. */
   default String getFailureMessage() {
     return "";
   }

   /**
    * Returns a {@link Spawn}'s output in-memory, if supported and available.
    *
    * <p>This behavior may be triggered with {@link
    * ExecutionRequirements#REMOTE_EXECUTION_INLINE_OUTPUTS}.
    */
   @Nullable
   default InputStream getInMemoryOutput(ActionInput output) {
     return null;
   }

   String getDetailMessage(
       String messagePrefix,
       String message,
       boolean verboseFailures,
       boolean catastrophe,
       boolean forciblyRunRemotely);

   /** Returns a file path to the action metadata log. */
   Optional<MetadataLog> getActionMetadataLog();

   /** Whether the spawn result was obtained through remote strategy. */
   boolean wasRemote();

   /** Basic implementation of {@link SpawnResult}. */
   @Immutable
   @ThreadSafe
   final class SimpleSpawnResult implements SpawnResult {
     private final int exitCode;
     private final Status status;
     @Nullable private final FailureDetail failureDetail;
     private final String executorHostName;
     private final String runnerName;
     private final SpawnMetrics spawnMetrics;
     private final Optional<Duration> wallTime;
     private final Optional<Duration> userTime;
     private final Optional<Duration> systemTime;
     private final Optional<Long> numBlockOutputOperations;
     private final Optional<Long> numBlockInputOperations;
     private final Optional<Long> numInvoluntaryContextSwitches;
     private final Optional<MetadataLog> actionMetadataLog;
     private final boolean cacheHit;
     private final String failureMessage;

     // Invariant: Either both have a value or both are null.
     @Nullable private final ActionInput inMemoryOutputFile;
     @Nullable private final ByteString inMemoryContents;
     private final boolean remote;

     SimpleSpawnResult(Builder builder) {
       this.exitCode = builder.exitCode;
       this.status = Preconditions.checkNotNull(builder.status);
       this.failureDetail = builder.failureDetail;
       this.executorHostName = builder.executorHostName;
       this.runnerName = builder.runnerName;
       this.spawnMetrics = builder.spawnMetrics != null
           ? builder.spawnMetrics
           : SpawnMetrics.forLocalExecution(builder.wallTime.orElse(Duration.ZERO));
       this.wallTime = builder.wallTime;
       this.userTime = builder.userTime;
       this.systemTime = builder.systemTime;
       this.numBlockOutputOperations = builder.numBlockOutputOperations;
       this.numBlockInputOperations = builder.numBlockInputOperations;
       this.numInvoluntaryContextSwitches = builder.numInvoluntaryContextSwitches;
       this.cacheHit = builder.cacheHit;
       this.failureMessage = builder.failureMessage;
       this.inMemoryOutputFile = builder.inMemoryOutputFile;
       this.inMemoryContents = builder.inMemoryContents;
       this.actionMetadataLog = builder.actionMetadataLog;
       this.remote = builder.remote;
     }

     @Override
     public int exitCode() {
       return exitCode;
     }

     @Override
     public Status status() {
       return status;
     }

     @Override
     @Nullable
     public FailureDetail failureDetail() {
       return failureDetail;
     }

     @Override
     public String getExecutorHostName() {
       return executorHostName;
     }

     @Override
     public String getRunnerName() {
       return runnerName;
     }

     @Override
     public SpawnMetrics getMetrics() {
       return spawnMetrics;
     }

     @Override
     public Optional<Duration> getWallTime() {
       return wallTime;
     }

     @Override
     public Optional<Duration> getUserTime() {
       return userTime;
     }

     @Override
     public Optional<Duration> getSystemTime() {
       return systemTime;
     }

     @Override
     public Optional<Long> getNumBlockOutputOperations() {
       return numBlockOutputOperations;
     }

     @Override
     public Optional<Long> getNumBlockInputOperations() {
       return numBlockInputOperations;
     }

     @Override
     public Optional<Long> getNumInvoluntaryContextSwitches() {
       return numInvoluntaryContextSwitches;
     }

     @Override
     public boolean isCacheHit() {
       return cacheHit;
     }

     @Override
     public String getFailureMessage() {
       return failureMessage;
     }

     @Override
     public String getDetailMessage(
         String messagePrefix,
         String message,
         boolean verboseFailures,
         boolean catastrophe,
         boolean forciblyRunRemotely) {
       TerminationStatus status = new TerminationStatus(
           exitCode(), status() == Status.TIMEOUT);
       String reason = " (" + status.toShortString() + ")"; // e.g " (Exit 1)"
       // Include the command line as error message if --verbose_failures is enabled or
       // the command line didn't exit normally.
       String explanation = verboseFailures || !status.exited() ? ": " + message : "";

       if (!status().isConsideredUserError()) {
         String errorDetail = status().name().toLowerCase(Locale.US)
             .replace('_', ' ');
         explanation += ". Note: Remote connection/protocol failed with: " + errorDetail;
       }
       if (status() == Status.TIMEOUT) {
         if (getWallTime().isPresent()) {
           explanation +=
               String.format(
                   Locale.US,
                   " (failed due to timeout after %.2f seconds.)",
                   getWallTime().get().toMillis() / 1000.0);
         } else {
           explanation += " (failed due to timeout.)";
         }
       } else if (status() == Status.OUT_OF_MEMORY) {
         explanation += " (Remote action was terminated due to Out of Memory.)";
       }
       if (status() != Status.TIMEOUT && forciblyRunRemotely) {
         explanation += " Action tagged as local was forcibly run remotely and failed - it's "
             + "possible that the action simply doesn't work remotely";
       }
       if (!Strings.isNullOrEmpty(failureMessage)) {
         explanation += " " + failureMessage;
       }
       return messagePrefix + " failed" + reason + explanation;
     }

     @Nullable
     @Override
     public InputStream getInMemoryOutput(ActionInput output) {
       if (inMemoryOutputFile != null && inMemoryOutputFile.equals(output)) {
         return inMemoryContents.newInput();
       }
       return null;
     }

     @Override
     public Optional<MetadataLog> getActionMetadataLog() {
       return actionMetadataLog;
     }

     @Override
     public boolean wasRemote() {
       return remote;
     }
   }

   /** Builder class for {@link SpawnResult}. */
   final class Builder {
     private int exitCode;
     private Status status;
     private FailureDetail failureDetail;
     private String executorHostName;
     private String runnerName = "";
     private SpawnMetrics spawnMetrics;
     private Optional<Duration> wallTime = Optional.empty();
     private Optional<Duration> userTime = Optional.empty();
     private Optional<Duration> systemTime = Optional.empty();
     private Optional<Long> numBlockOutputOperations = Optional.empty();
     private Optional<Long> numBlockInputOperations = Optional.empty();
     private Optional<Long> numInvoluntaryContextSwitches = Optional.empty();
     private Optional<MetadataLog> actionMetadataLog = Optional.empty();
     private boolean cacheHit;
     private String failureMessage = "";

     // Invariant: Either both have a value or both are null.
     @Nullable private ActionInput inMemoryOutputFile;
     @Nullable private ByteString inMemoryContents;
     private boolean remote;

     public SpawnResult build() {
       Preconditions.checkArgument(!runnerName.isEmpty());

       if (status == Status.SUCCESS) {
         Preconditions.checkArgument(exitCode == 0, exitCode);
       } else if (status == Status.TIMEOUT) {
         Preconditions.checkArgument(exitCode == POSIX_TIMEOUT_EXIT_CODE, exitCode);
       } else if (status == Status.NON_ZERO_EXIT || status == Status.OUT_OF_MEMORY) {
         Preconditions.checkArgument(exitCode != 0, exitCode);
       }

       // TODO(mschaller): Once SimpleSpawnResult.Builder's uses have picked up FailureDetails for
       //  unsuccessful spawns, add a precondition that asserts failureDetail's nullity is the same
       //  as whether status is SUCCESS.

       return new SimpleSpawnResult(this);
     }

     public Builder setExitCode(int exitCode) {
       this.exitCode = exitCode;
       return this;
     }

     public Builder setStatus(Status status) {
       this.status = status;
       return this;
     }

     public Builder setFailureDetail(FailureDetail failureDetail) {
       this.failureDetail = failureDetail;
       return this;
     }

     public Builder setExecutorHostname(String executorHostName) {
       this.executorHostName = executorHostName;
       return this;
     }

     public Builder setRunnerName(String runnerName) {
       this.runnerName = runnerName;
       return this;
     }

     public Builder setSpawnMetrics(SpawnMetrics spawnMetrics) {
       this.spawnMetrics = spawnMetrics;
       return this;
     }

     public Builder setWallTime(Duration wallTime) {
       this.wallTime = Optional.of(wallTime);
       return this;
     }

     public Builder setUserTime(Duration userTime) {
       this.userTime = Optional.of(userTime);
       return this;
     }

     public Builder setSystemTime(Duration systemTime) {
       this.systemTime = Optional.of(systemTime);
       return this;
     }

     public Builder setNumBlockOutputOperations(long numBlockOutputOperations) {
       this.numBlockOutputOperations = Optional.of(numBlockOutputOperations);
       return this;
     }

     public Builder setNumBlockInputOperations(long numBlockInputOperations) {
       this.numBlockInputOperations = Optional.of(numBlockInputOperations);
       return this;
     }

     public Builder setNumInvoluntaryContextSwitches(long numInvoluntaryContextSwitches) {
       this.numInvoluntaryContextSwitches = Optional.of(numInvoluntaryContextSwitches);
       return this;
     }

     public Builder setCacheHit(boolean cacheHit) {
       this.cacheHit = cacheHit;
       return this;
     }

     public Builder setFailureMessage(String failureMessage) {
       this.failureMessage = failureMessage;
       return this;
     }

     public Builder setInMemoryOutput(ActionInput outputFile, ByteString contents) {
       this.inMemoryOutputFile = Preconditions.checkNotNull(outputFile);
       this.inMemoryContents = Preconditions.checkNotNull(contents);
       return this;
     }

     Builder setActionMetadataLog(MetadataLog actionMetadataLog) {
       this.actionMetadataLog = Optional.of(actionMetadataLog);
       return this;
     }

     public Builder setRemote(boolean remote) {
       this.remote = remote;
       return this;
     }
   }

   /** A {@link Spawn}'s metadata name and {@link Path}. */
   final class MetadataLog {
     private final String name;
     private final Path filePath;

     public MetadataLog(String name, Path filePath) {
       this.name = name;
       this.filePath = filePath;
     }

     public String getName() {
       return this.name;
     }

     public Path getFilePath() {
       return this.filePath;
     }
   }
 }
	// Copyright 2017 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 com.google.common.base.Preconditions;
	import com.google.common.base.Strings;
	import com.google.devtools.build.lib.concurrent.ThreadSafety.Immutable;
	import com.google.devtools.build.lib.concurrent.ThreadSafety.ThreadSafe;
	import com.google.devtools.build.lib.server.FailureDetails.FailureDetail;
	import com.google.devtools.build.lib.shell.TerminationStatus;
	import com.google.devtools.build.lib.vfs.Path;
	import com.google.protobuf.ByteString;
	import java.io.InputStream;
	import java.time.Duration;
	import java.util.Locale;
	import java.util.Optional;
	import javax.annotation.Nullable;

	/** The result of a {@link Spawn}'s execution. */
	public interface SpawnResult {

	int POSIX_TIMEOUT_EXIT_CODE = /SIGNAL_BASE=/ 128 + /SIGALRM=/ 14;

	/** The status of the attempted Spawn execution. */
	enum Status {
	/** Subprocess executed successfully, and returned a zero exit code. */
	SUCCESS,

	/** Subprocess executed successfully, but returned a non-zero exit code. */
	NON_ZERO_EXIT(true),

	/** Subprocess execution timed out. */
	TIMEOUT(true),

	/**
	* The subprocess ran out of memory. On Linux systems, the kernel may kill processes in
	* low-memory situations, and this status is intended to report such a case back to Bazel.
	*/
	OUT_OF_MEMORY(true),

	/**
	* Subprocess did not execute, it's not the user's fault, and the error is not catastrophic. If
	* keep_going is enabled then Bazel will try to continue the build, possibly will attempt to
	* rerun the same spawn, and possibly will attempt to run other actions.
	*/
	EXECUTION_FAILED,

	/**
	* Subprocess did not execute, it's not the user's fault, and the error is catastrophic. Bazel
	* will not rerun this spawn. Bazel will attempt to not run other actions (regardless of whether
	* keep_going is enabled).
	*/
	EXECUTION_FAILED_CATASTROPHICALLY,

	/**
	* Subprocess did not execute, it may be the user's fault, and the error is not catastrophic.
	* The user may be able to fix it. For example, a remote system may have denied the execution
	* due to too many inputs or too large inputs.
	*/
	EXECUTION_DENIED(true),

	/**
	* Subprocess did not execute, it may be the user's fault, and the error is catastrophic. The
	* user may be able to prevent it from reoccurring. For example, an input file's contents may
	* have been modified by the user intra-build.
	*/
	EXECUTION_DENIED_CATASTROPHICALLY(true),

	/**
	* The result of the remotely executed Spawn could not be retrieved due to errors in the remote
	* caching layer.
	*/
	REMOTE_CACHE_FAILED;

	private final boolean isUserError;

	Status(boolean isUserError) {
	this.isUserError = isUserError;
	}

	Status() {
	this(false);
	}

	public boolean isConsideredUserError() {
	return isUserError;
	}
	}

	/**
	* Returns whether the spawn was actually run, regardless of the exit code. I.e., returns {@code
	* true} if {@link #status} is any of {@link Status#SUCCESS}, {@link Status#NON_ZERO_EXIT}, {@link
	* Status#TIMEOUT} or {@link Status#OUT_OF_MEMORY}.
	*
	* <p>Returns false if there were errors that prevented the spawn from being run, such as network
	* errors, missing local files, errors setting up sandboxing, etc.
	*/
	default boolean setupSuccess() {
	Status status = status();
	return status == Status.SUCCESS
	\|\| status == Status.NON_ZERO_EXIT
	\|\| status == Status.TIMEOUT
	\|\| status == Status.OUT_OF_MEMORY;
	}

	/**
	* Returns true if the status was {@link Status#EXECUTION_FAILED_CATASTROPHICALLY} or {@link
	* Status#EXECUTION_DENIED_CATASTROPHICALLY}.
	*/
	default boolean isCatastrophe() {
	return status() == Status.EXECUTION_FAILED_CATASTROPHICALLY
	\|\| status() == Status.EXECUTION_DENIED_CATASTROPHICALLY;
	}

	/** Returns the status of the attempted Spawn execution. */
	Status status();

	/**
	* Returns the exit code of the subprocess if the subprocess was executed.
	*
	* <p>Returns zero if {@link #status} returns {@link Status#SUCCESS}.
	*
	* <p>Returns non-zero if {@link #status} returns {@link Status#NON_ZERO_EXIT} or {@link
	* Status#OUT_OF_MEMORY}.
	*
	* <p>Returns 128 + 14 (corresponding to the Unix signal SIGALRM) if {@link #status} returns
	* {@link Status#TIMEOUT}.
	*
	* <p>Otherwise, the returned value is not meaningful.
	*/
	// TODO(mschaller): clean up all uses of this method when {@code !this.setupSuccess()}
	int exitCode();

	/**
	* A detailed representation of what failed if {@link #status} is not {@link Status#SUCCESS}, and
	* {@code null} otherwise.
	*/
	@Nullable
	FailureDetail failureDetail();

	/**
	* Returns the host name of the executor or {@code null}. This information is intended for
	* debugging purposes, especially for remote execution systems. Remote caches usually do not store
	* the original host name, so this is generally {@code null} for cache hits.
	*/
	@Nullable
	String getExecutorHostName();

	/**
	* Returns the name of the SpawnRunner that executed the spawn. It should always be defined,
	* unless isCacheHit is true, in which case the spawn was not actually run.
	*/
	String getRunnerName();

	/**
	* Returns the wall time taken by the {@link Spawn}'s execution.
	*
	* @return the measurement, or empty in case of execution errors or when the measurement is not
	* implemented for the current platform
	*/
	Optional<Duration> getWallTime();

	/**
	* Returns the user time taken by the {@link Spawn}'s execution.
	*
	* @return the measurement, or empty in case of execution errors or when the measurement is not
	* implemented for the current platform
	*/
	Optional<Duration> getUserTime();

	/**
	* Returns the system time taken by the {@link Spawn}'s execution.
	*
	* @return the measurement, or empty in case of execution errors or when the measurement is not
	* implemented for the current platform
	*/
	Optional<Duration> getSystemTime();

	/**
	* Returns the number of block output operations during the {@link Spawn}'s execution.
	*
	* @return the measurement, or empty in case of execution errors or when the measurement is not
	* implemented for the current platform
	*/
	Optional<Long> getNumBlockOutputOperations();

	/**
	* Returns the number of block input operations during the {@link Spawn}'s execution.
	*
	* @return the measurement, or empty in case of execution errors or when the measurement is not
	* implemented for the current platform
	*/
	Optional<Long> getNumBlockInputOperations();

	/**
	* Returns the number of involuntary context switches during the {@link Spawn}'s execution.
	*
	* @return the measurement, or empty in case of execution errors or when the measurement is not
	* implemented for the current platform
	*/
	Optional<Long> getNumInvoluntaryContextSwitches();

	SpawnMetrics getMetrics();

	/** Returns whether the spawn result was a cache hit. */
	boolean isCacheHit();

	/** Returns an optional custom failure message for the result. */
	default String getFailureMessage() {
	return "";
	}

	/**
	* Returns a {@link Spawn}'s output in-memory, if supported and available.
	*
	* <p>This behavior may be triggered with {@link
	* ExecutionRequirements#REMOTE_EXECUTION_INLINE_OUTPUTS}.
	*/
	@Nullable
	default InputStream getInMemoryOutput(ActionInput output) {
	return null;
	}

	String getDetailMessage(
	String messagePrefix,
	String message,
	boolean verboseFailures,
	boolean catastrophe,
	boolean forciblyRunRemotely);

	/** Returns a file path to the action metadata log. */
	Optional<MetadataLog> getActionMetadataLog();

	/** Whether the spawn result was obtained through remote strategy. */
	boolean wasRemote();

	/** Basic implementation of {@link SpawnResult}. */
	@Immutable
	@ThreadSafe
	final class SimpleSpawnResult implements SpawnResult {
	private final int exitCode;
	private final Status status;
	@Nullable private final FailureDetail failureDetail;
	private final String executorHostName;
	private final String runnerName;
	private final SpawnMetrics spawnMetrics;
	private final Optional<Duration> wallTime;
	private final Optional<Duration> userTime;
	private final Optional<Duration> systemTime;
	private final Optional<Long> numBlockOutputOperations;
	private final Optional<Long> numBlockInputOperations;
	private final Optional<Long> numInvoluntaryContextSwitches;
	private final Optional<MetadataLog> actionMetadataLog;
	private final boolean cacheHit;
	private final String failureMessage;

	// Invariant: Either both have a value or both are null.
	@Nullable private final ActionInput inMemoryOutputFile;
	@Nullable private final ByteString inMemoryContents;
	private final boolean remote;

	SimpleSpawnResult(Builder builder) {
	this.exitCode = builder.exitCode;
	this.status = Preconditions.checkNotNull(builder.status);
	this.failureDetail = builder.failureDetail;
	this.executorHostName = builder.executorHostName;
	this.runnerName = builder.runnerName;
	this.spawnMetrics = builder.spawnMetrics != null
	? builder.spawnMetrics
	: SpawnMetrics.forLocalExecution(builder.wallTime.orElse(Duration.ZERO));
	this.wallTime = builder.wallTime;
	this.userTime = builder.userTime;
	this.systemTime = builder.systemTime;
	this.numBlockOutputOperations = builder.numBlockOutputOperations;
	this.numBlockInputOperations = builder.numBlockInputOperations;
	this.numInvoluntaryContextSwitches = builder.numInvoluntaryContextSwitches;
	this.cacheHit = builder.cacheHit;
	this.failureMessage = builder.failureMessage;
	this.inMemoryOutputFile = builder.inMemoryOutputFile;
	this.inMemoryContents = builder.inMemoryContents;
	this.actionMetadataLog = builder.actionMetadataLog;
	this.remote = builder.remote;
	}

	@Override
	public int exitCode() {
	return exitCode;
	}

	@Override
	public Status status() {
	return status;
	}

	@Override
	@Nullable
	public FailureDetail failureDetail() {
	return failureDetail;
	}

	@Override
	public String getExecutorHostName() {
	return executorHostName;
	}

	@Override
	public String getRunnerName() {
	return runnerName;
	}

	@Override
	public SpawnMetrics getMetrics() {
	return spawnMetrics;
	}

	@Override
	public Optional<Duration> getWallTime() {
	return wallTime;
	}

	@Override
	public Optional<Duration> getUserTime() {
	return userTime;
	}

	@Override
	public Optional<Duration> getSystemTime() {
	return systemTime;
	}

	@Override
	public Optional<Long> getNumBlockOutputOperations() {
	return numBlockOutputOperations;
	}

	@Override
	public Optional<Long> getNumBlockInputOperations() {
	return numBlockInputOperations;
	}

	@Override
	public Optional<Long> getNumInvoluntaryContextSwitches() {
	return numInvoluntaryContextSwitches;
	}

	@Override
	public boolean isCacheHit() {
	return cacheHit;
	}

	@Override
	public String getFailureMessage() {
	return failureMessage;
	}

	@Override
	public String getDetailMessage(
	String messagePrefix,
	String message,
	boolean verboseFailures,
	boolean catastrophe,
	boolean forciblyRunRemotely) {
	TerminationStatus status = new TerminationStatus(
	exitCode(), status() == Status.TIMEOUT);
	String reason = " (" + status.toShortString() + ")"; // e.g " (Exit 1)"
	// Include the command line as error message if --verbose_failures is enabled or
	// the command line didn't exit normally.
	String explanation = verboseFailures \|\| !status.exited() ? ": " + message : "";

	if (!status().isConsideredUserError()) {
	String errorDetail = status().name().toLowerCase(Locale.US)
	.replace('_', ' ');
	explanation += ". Note: Remote connection/protocol failed with: " + errorDetail;
	}
	if (status() == Status.TIMEOUT) {
	if (getWallTime().isPresent()) {
	explanation +=
	String.format(
	Locale.US,
	" (failed due to timeout after %.2f seconds.)",
	getWallTime().get().toMillis() / 1000.0);
	} else {
	explanation += " (failed due to timeout.)";
	}
	} else if (status() == Status.OUT_OF_MEMORY) {
	explanation += " (Remote action was terminated due to Out of Memory.)";
	}
	if (status() != Status.TIMEOUT && forciblyRunRemotely) {
	explanation += " Action tagged as local was forcibly run remotely and failed - it's "
	+ "possible that the action simply doesn't work remotely";
	}
	if (!Strings.isNullOrEmpty(failureMessage)) {
	explanation += " " + failureMessage;
	}
	return messagePrefix + " failed" + reason + explanation;
	}

	@Nullable
	@Override
	public InputStream getInMemoryOutput(ActionInput output) {
	if (inMemoryOutputFile != null && inMemoryOutputFile.equals(output)) {
	return inMemoryContents.newInput();
	}
	return null;
	}

	@Override
	public Optional<MetadataLog> getActionMetadataLog() {
	return actionMetadataLog;
	}

	@Override
	public boolean wasRemote() {
	return remote;
	}
	}

	/** Builder class for {@link SpawnResult}. */
	final class Builder {
	private int exitCode;
	private Status status;
	private FailureDetail failureDetail;
	private String executorHostName;
	private String runnerName = "";
	private SpawnMetrics spawnMetrics;
	private Optional<Duration> wallTime = Optional.empty();
	private Optional<Duration> userTime = Optional.empty();
	private Optional<Duration> systemTime = Optional.empty();
	private Optional<Long> numBlockOutputOperations = Optional.empty();
	private Optional<Long> numBlockInputOperations = Optional.empty();
	private Optional<Long> numInvoluntaryContextSwitches = Optional.empty();
	private Optional<MetadataLog> actionMetadataLog = Optional.empty();
	private boolean cacheHit;
	private String failureMessage = "";

	// Invariant: Either both have a value or both are null.
	@Nullable private ActionInput inMemoryOutputFile;
	@Nullable private ByteString inMemoryContents;
	private boolean remote;

	public SpawnResult build() {
	Preconditions.checkArgument(!runnerName.isEmpty());

	if (status == Status.SUCCESS) {
	Preconditions.checkArgument(exitCode == 0, exitCode);
	} else if (status == Status.TIMEOUT) {
	Preconditions.checkArgument(exitCode == POSIX_TIMEOUT_EXIT_CODE, exitCode);
	} else if (status == Status.NON_ZERO_EXIT \|\| status == Status.OUT_OF_MEMORY) {
	Preconditions.checkArgument(exitCode != 0, exitCode);
	}

	// TODO(mschaller): Once SimpleSpawnResult.Builder's uses have picked up FailureDetails for
	// unsuccessful spawns, add a precondition that asserts failureDetail's nullity is the same
	// as whether status is SUCCESS.

	return new SimpleSpawnResult(this);
	}

	public Builder setExitCode(int exitCode) {
	this.exitCode = exitCode;
	return this;
	}

	public Builder setStatus(Status status) {
	this.status = status;
	return this;
	}

	public Builder setFailureDetail(FailureDetail failureDetail) {
	this.failureDetail = failureDetail;
	return this;
	}

	public Builder setExecutorHostname(String executorHostName) {
	this.executorHostName = executorHostName;
	return this;
	}

	public Builder setRunnerName(String runnerName) {
	this.runnerName = runnerName;
	return this;
	}

	public Builder setSpawnMetrics(SpawnMetrics spawnMetrics) {
	this.spawnMetrics = spawnMetrics;
	return this;
	}

	public Builder setWallTime(Duration wallTime) {
	this.wallTime = Optional.of(wallTime);
	return this;
	}

	public Builder setUserTime(Duration userTime) {
	this.userTime = Optional.of(userTime);
	return this;
	}

	public Builder setSystemTime(Duration systemTime) {
	this.systemTime = Optional.of(systemTime);
	return this;
	}

	public Builder setNumBlockOutputOperations(long numBlockOutputOperations) {
	this.numBlockOutputOperations = Optional.of(numBlockOutputOperations);
	return this;
	}

	public Builder setNumBlockInputOperations(long numBlockInputOperations) {
	this.numBlockInputOperations = Optional.of(numBlockInputOperations);
	return this;
	}

	public Builder setNumInvoluntaryContextSwitches(long numInvoluntaryContextSwitches) {
	this.numInvoluntaryContextSwitches = Optional.of(numInvoluntaryContextSwitches);
	return this;
	}

	public Builder setCacheHit(boolean cacheHit) {
	this.cacheHit = cacheHit;
	return this;
	}

	public Builder setFailureMessage(String failureMessage) {
	this.failureMessage = failureMessage;
	return this;
	}

	public Builder setInMemoryOutput(ActionInput outputFile, ByteString contents) {
	this.inMemoryOutputFile = Preconditions.checkNotNull(outputFile);
	this.inMemoryContents = Preconditions.checkNotNull(contents);
	return this;
	}

	Builder setActionMetadataLog(MetadataLog actionMetadataLog) {
	this.actionMetadataLog = Optional.of(actionMetadataLog);
	return this;
	}

	public Builder setRemote(boolean remote) {
	this.remote = remote;
	return this;
	}
	}

	/** A {@link Spawn}'s metadata name and {@link Path}. */
	final class MetadataLog {
	private final String name;
	private final Path filePath;

	public MetadataLog(String name, Path filePath) {
	this.name = name;
	this.filePath = filePath;
	}

	public String getName() {
	return this.name;
	}

	public Path getFilePath() {
	return this.filePath;
	}
	}
	}