// Copyright 2014 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.runtime.commands;

import static com.google.devtools.build.lib.runtime.Command.BuildPhase.NONE;

import com.google.devtools.build.lib.runtime.BlazeCommand;
import com.google.devtools.build.lib.runtime.BlazeCommandResult;
import com.google.devtools.build.lib.runtime.Command;
import com.google.devtools.build.lib.runtime.CommandEnvironment;
import com.google.devtools.common.options.Option;
import com.google.devtools.common.options.OptionDocumentationCategory;
import com.google.devtools.common.options.OptionEffectTag;
import com.google.devtools.common.options.OptionsBase;
import com.google.devtools.common.options.OptionsClass;
import com.google.devtools.common.options.OptionsParser;
import com.google.devtools.common.options.OptionsParsingResult;

/** The 'blaze shutdown' command. */
@Command(
    name = "shutdown",
    buildPhase = NONE,
    options = {ShutdownCommand.Options.class},
    allowResidue = false,
    mustRunInWorkspace = false,
    shortDescription = "Stops the %{product} server.",
    help =
        "This command shuts down the memory resident %{product} server process.\n" + "%{options}")
public final class ShutdownCommand implements BlazeCommand {

  /** Options for the {@code shutdown} command. */
  @OptionsClass
  public abstract static class Options extends OptionsBase {

    @Option(
        name = "iff_heap_size_greater_than",
        defaultValue = "0",
        documentationCategory = OptionDocumentationCategory.OUTPUT_SELECTION,
        effectTags = {OptionEffectTag.LOSES_INCREMENTAL_STATE, OptionEffectTag.EAGERNESS_TO_EXIT},
        help =
            "Iff non-zero, then shutdown will only shut down the server if the total memory (in MB)"
                + " consumed by the JVM exceeds this value.")
    public abstract int getHeapSizeLimit();
  }

  @Override
  public void editOptions(OptionsParser optionsParser) {}

  @Override
  public BlazeCommandResult exec(CommandEnvironment env, OptionsParsingResult options) {
    int limit = options.getOptions(Options.class).getHeapSizeLimit();

    // Iff limit is non-zero, shut down the server if total memory exceeds the
    // limit. totalMemory is the actual heap size that the VM currently uses
    // *from the OS perspective*. That is, it's not the size occupied by all
    // objects (which is totalMemory() - freeMemory()), and not the -Xmx
    // (which is maxMemory()). It's really how much memory this process
    // currently consumes, in addition to the JVM code and C heap.

    if (limit == 0 ||
        Runtime.getRuntime().totalMemory() > limit * 1000L * 1000) {
      return BlazeCommandResult.shutdownOnSuccess();
    }

    return BlazeCommandResult.success();
  }

}
