xichen01 commented on code in PR #6383:
URL: https://github.com/apache/ozone/pull/6383#discussion_r1605683734
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hadoop-hdds/common/src/main/java/org/apache/hadoop/hdds/fs/CachingSpaceUsageSource.java:
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@@ -76,42 +81,65 @@ public CachingSpaceUsageSource(SpaceUsageCheckParams
params) {
@Override
public long getCapacity() {
- return source.getCapacity();
+ try (AutoCloseableLock ignored = lock.readLock(null, null)) {
+ return cachedCapacity;
+ }
}
@Override
public long getAvailable() {
- return source.getAvailable();
+ try (AutoCloseableLock ignored = lock.readLock(null, null)) {
+ return cachedAvailable;
+ }
}
@Override
public long getUsedSpace() {
- return cachedValue.get();
+ try (AutoCloseableLock ignored = lock.readLock(null, null)) {
+ return cachedUsedSpace;
+ }
+ }
+
+ @Override
+ public SpaceUsageSource snapshot() {
+ try (AutoCloseableLock ignored = lock.readLock(null, null)) {
+ return new Fixed(cachedCapacity, cachedAvailable, cachedUsedSpace);
+ }
}
public void incrementUsedSpace(long usedSpace) {
- cachedValue.addAndGet(usedSpace);
+ final long current, change;
+ try (AutoCloseableLock ignored = lock.writeLock(null, null)) {
+ current = cachedAvailable;
+ change = Math.min(current, usedSpace);
+ cachedAvailable -= change;
+ cachedUsedSpace += change;
+ }
+
+ if (change != usedSpace) {
+ LOG.warn("Attempted to decrement available space to a negative value.
Current: {}, Decrement: {}, Source: {}",
+ current, usedSpace, source);
+ }
}
public void decrementUsedSpace(long reclaimedSpace) {
- cachedValue.updateAndGet(current -> {
- long newValue = current - reclaimedSpace;
- if (newValue < 0) {
- if (current > 0) {
- LOG.warn("Attempted to decrement used space to a negative value. " +
- "Current: {}, Decrement: {}, Source: {}",
- current, reclaimedSpace, source);
- }
- return 0;
- } else {
- return newValue;
- }
- });
+ final long current, change;
+ try (AutoCloseableLock ignored = lock.writeLock(null, null)) {
+ current = cachedUsedSpace;
+ change = Math.min(current, reclaimedSpace);
+ cachedUsedSpace -= change;
+ cachedAvailable += change;
+ }
+
+ if (change != reclaimedSpace) {
+ LOG.warn("Attempted to decrement used space to a negative value.
Current: {}, Decrement: {}, Source: {}",
+ current, reclaimedSpace, source);
+ }
}
public void start() {
if (executor != null) {
- long initialDelay = cachedValue.get() > 0 ? refresh.toMillis() : 0;
+ long initialDelay = getUsedSpace() > 0 ? refresh.toMillis() : 0;
Review Comment:
Yes, the `capacity` usually not changes, However, `available` may change for
other reasons, such as multiple volumes sharing a physical disk, or other data
being written to the disk. In this case, the actual `available` may differ from
the value calculated by `increment/decrementUsedSpace`.
However, if there is a lot of disk space left, I think this “difference” is
acceptable, but when there is less disk space left, is there something that can
be done to reduce the possible "difference"? Like an update thread or a
fallback to get the `filesystem.available` every time instead of getting it
from the `cache`.
But it's a more delicate operation, not a must, what do you think?
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