ivankelly commented on a change in pull request #832: Issue 620: Close the
fileChannels for read when they are idle
URL: https://github.com/apache/bookkeeper/pull/832#discussion_r174512220
##########
File path:
bookkeeper-server/src/main/java/org/apache/bookkeeper/bookie/FileChannelBackingCache.java
##########
@@ -52,36 +53,33 @@
final ConcurrentHashMap<Long, CachedFileChannel> fileChannels = new
ConcurrentHashMap<>();
CachedFileChannel loadFileChannel(long logId) throws IOException {
- lock.readLock().lock();
- try {
- CachedFileChannel cachedFileChannel = fileChannels.get(logId);
+ CachedFileChannel cachedFileChannel = null;
+ do {
+ fileChannels.computeIfAbsent(logId, logFileId -> {
+ CachedFileChannel cfc = null;
+ try {
+ File file = fileLoader.load(logFileId);
+ // get channel is used to open an existing entry log file
+ // it would be better to open using read mode
+ FileChannel newFc = new RandomAccessFile(file,
"r").getChannel();
+ cfc = new CachedFileChannel(logFileId, newFc);
+ } catch (IOException ioe){
+ throw new UncheckedIOException(ioe);
Review comment:
This will end up doing throwing a RuntimeException. Rather than using a call
to computeIfAbsent(), do:
```
CachedFileChannel cachedFileChannel = null;
do {
CachedFileChannel c = fileChannels.get(logId);
if (c != null) {
if (c.tryRetain()) {
cachedFileChannel = c;
} else {
// this isn't strictly necessary, but it's good defensively to
avoid infinite loop
fileChannels.remove(logId, c);
}
} else {
c = // the construction stuff
CachedFileChannel existing = fileChannels.putIfAbsent(logId, c);
if (existing != null) {
// cleanup c
if (existing.tryRetain()) {
cachedFileChannel = existing;
} else {
fileChannels.remove(logId, existing);
}
}
}
} while (cachedFileChannel == null);
```
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