/*
* Copyright 2015-present Facebook, Inc.
*
* 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.facebook.buck.util;
import com.google.common.collect.ImmutableList;
import java.util.Iterator;
import java.util.List;
/**
* Splits an argument list into a list of command invocations whose total length will not exceed the
* specified limit if possible. If that is not possible, all arguments that exceed the limit will be
* used in their own invocation separate from all other arguments to minimize the maximal command
* length.
*/
public class CommandSplitter {
private final int desiredLimit;
private final ImmutableList<String> commandPrefix;
private final int commandPrefixLength;
private static final int DEFAULT_DESIRED_LIMIT = 32 * 1024;
public CommandSplitter(List<String> commandPrefix, int desiredLimit) {
this.desiredLimit = desiredLimit;
this.commandPrefix = ImmutableList.copyOf(commandPrefix);
int commandPrefixLength = 0;
for (String argument : commandPrefix) {
commandPrefixLength += argument.length() + 1; // +1 for separator
}
this.commandPrefixLength = commandPrefixLength;
}
public CommandSplitter(List<String> commandPrefix) {
this(commandPrefix, DEFAULT_DESIRED_LIMIT);
}
public ImmutableList<ImmutableList<String>> getCommandsForArguments(Iterable<String> arguments) {
Iterator<String> argumentIterator = arguments.iterator();
if (!argumentIterator.hasNext()) {
return ImmutableList.of();
}
ImmutableList.Builder<ImmutableList<String>> commands = ImmutableList.builder();
ImmutableList.Builder<String> commandBuilder = ImmutableList.builder();
String firstArgument = argumentIterator.next();
commandBuilder.addAll(commandPrefix).add(firstArgument);
int commandLength = commandPrefixLength + firstArgument.length() + 1; // +1 for separator
while (argumentIterator.hasNext()) {
// Loop invariant: commandBuilder contains at least one argument after the command prefix.
String argument = argumentIterator.next();
int updatedCommandLength = commandLength + argument.length() + 1; // +1 for separator
if (updatedCommandLength > desiredLimit) {
// Put the current command into the output list and start building a new command
commands.add(commandBuilder.build());
commandBuilder = ImmutableList.<String>builder().addAll(commandPrefix);
commandLength = commandPrefixLength;
}
commandBuilder.add(argument);
commandLength += argument.length() + 1; // +1 for separator
}
commands.add(commandBuilder.build());
return commands.build();
}
}