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// 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.unix;
import com.google.common.annotations.VisibleForTesting;
import com.google.common.base.CharMatcher;
import com.google.common.collect.ImmutableMap;
import com.google.common.io.Files;
import java.io.File;
import java.io.IOException;
import java.nio.charset.Charset;
import java.util.List;
import java.util.Map;
/**
* Parse and return information from /proc/meminfo.
*/
public class ProcMeminfoParser {
public static final String FILE = "/proc/meminfo";
private final Map<String, Long> memInfo;
/**
* Populates memory information by reading /proc/meminfo.
* @throws IOException if reading the file failed.
*/
public ProcMeminfoParser() throws IOException {
this(FILE);
}
@VisibleForTesting
public ProcMeminfoParser(String fileName) throws IOException {
List<String> lines = Files.readLines(new File(fileName), Charset.defaultCharset());
ImmutableMap.Builder<String, Long> builder = ImmutableMap.builder();
for (String line : lines) {
int colon = line.indexOf(':');
if (colon == -1) {
continue;
}
String keyword = line.substring(0, colon);
String valString = line.substring(colon + 1);
try {
long val = Long.parseLong(CharMatcher.inRange('0', '9').retainFrom(valString));
builder.put(keyword, val);
} catch (NumberFormatException e) {
// Ignore: we'll fail later if somebody tries to capture this value.
}
}
memInfo = builder.build();
}
/** Gets a named field in KB. */
long getRamKb(String keyword) throws KeywordNotFoundException {
Long val = memInfo.get(keyword);
if (val == null) {
throw new KeywordNotFoundException(keyword);
}
return val;
}
/** Return the total physical memory. */
public long getTotalKb() throws KeywordNotFoundException {
return getRamKb("MemTotal");
}
/**
* Convert KB to MB.
*/
public static double kbToMb(long kb) {
return kb >> 10;
}
/**
* Reads the amount of *available* memory as reported by the kernel. See https://goo.gl/ABn283 for
* why this is better than trying to figure it out ourselves. This corresponds to the MemAvailable
* line in /proc/meminfo.
*/
public long getFreeRamKb() throws KeywordNotFoundException {
if (memInfo.containsKey("MemAvailable")) {
return getRamKb("MemAvailable");
}
// We have no MemAvailable in /proc/meminfo; fall back to the previous estimation.
return getRamKb("MemTotal")
- getRamKb("Active")
// Blaze doesn't want to use more than a third of inactive ram...
- (long) (getRamKb("Inactive") * 0.3)
// ...and doesn't want to assume more than 80% of the slab memory can be reallocated.
- (long) (getRamKb("Slab") * 0.8);
// That said, this estimate will be more inaccurate as it diverges from kernel internals.
}
/** Exception thrown when /proc/meminfo does not have a requested key. Should be tolerated. */
public static class KeywordNotFoundException extends Exception {
private KeywordNotFoundException(String keyword) {
super("Can't locate " + keyword + " in the /proc/meminfo");
}
}
}
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