/**
* Grow the key array. All of the values in the current array must be re-hashed and added to the
* new array.
*/
private void growKeyArray() {
AtomicLongArray newKeys = emptyKeyArray(pointersAndOrdinals.length() * 2);
long valuesToAdd[] = new long[size];
int counter = 0;
/// do not iterate over these values in the same order in which they appear in the hashed array.
/// if we do so, we cause large clusters of collisions to appear (because we resolve collisions
// with linear probing).
for (int i = 0; i < pointersAndOrdinals.length(); i++) {
long key = pointersAndOrdinals.get(i);
if (key != EMPTY_BUCKET_VALUE) {
valuesToAdd[counter++] = key;
}
}
Arrays.sort(valuesToAdd);
populateNewHashArray(newKeys, valuesToAdd);
/// 70% load factor
sizeBeforeGrow = (newKeys.length() * 7) / 10;
pointersAndOrdinals = newKeys;
}
/**
* Create an array mapping the ordinals to pointers, so that they can be easily looked up when
* writing to blob streams.
*
* @return the maximum length, in bytes, of any byte sequence in this map.
*/
public int prepareForWrite() {
int maxOrdinal = 0;
int maxLength = 0;
for (int i = 0; i < pointersAndOrdinals.length(); i++) {
long key = pointersAndOrdinals.get(i);
if (key != EMPTY_BUCKET_VALUE) {
int ordinal = (int) (key >> 32);
if (ordinal > maxOrdinal) maxOrdinal = ordinal;
}
}
pointersByOrdinal = new int[maxOrdinal + 1];
Arrays.fill(pointersByOrdinal, -1);
for (int i = 0; i < pointersAndOrdinals.length(); i++) {
long key = pointersAndOrdinals.get(i);
if (key != EMPTY_BUCKET_VALUE) {
int ordinal = (int) (key >> 32);
pointersByOrdinal[ordinal] = (int) key;
int dataLength = VarInt.readVInt(byteData.getUnderlyingArray(), pointersByOrdinal[ordinal]);
if (dataLength > maxLength) maxLength = dataLength;
}
}
return maxLength;
}
/**
* This is used to store the server's SerializationState, so that it may resume the delta chain
* after a new server is brought back up.
*
* @param os
* @throws IOException
*/
public void serializeTo(OutputStream os) throws IOException {
/// write the hashed key array size
VarInt.writeVInt(os, pointersAndOrdinals.length());
/// write the keys in sorted ordinal order to the stream
long keys[] = new long[size];
int counter = 0;
for (int i = 0; i < pointersAndOrdinals.length(); i++) {
long key = pointersAndOrdinals.get(i);
if (key != EMPTY_BUCKET_VALUE) {
keys[counter++] = key;
}
}
Arrays.sort(keys);
VarInt.writeVInt(os, keys.length);
for (int i = 0; i < keys.length; i++) {
VarInt.writeVInt(os, (int) (keys[i] >> 32));
VarInt.writeVInt(os, (int) (keys[i]));
}
/// write the byte data to the stream
VarInt.writeVInt(os, byteData.length());
for (int i = 0; i < byteData.length(); i++) {
os.write(byteData.get(i) & 0xFF);
}
/// write the freeOrdinalTracker to the stream
freeOrdinalTracker.serializeTo(os);
}
/**
* Assign a predefined ordinal to a serialized representation.
*
* <p>WARNING: THIS OPERATION IS NOT THREAD-SAFE.
*
* <p>This is intended for use in the client-side heap-safe double snapshot load.
*/
public void put(ByteDataBuffer serializedRepresentation, int ordinal) {
if (size > sizeBeforeGrow) growKeyArray();
int hash = SegmentedByteArrayHasher.hashCode(serializedRepresentation);
int modBitmask = pointersAndOrdinals.length() - 1;
int bucket = hash & modBitmask;
long key = pointersAndOrdinals.get(bucket);
while (key != EMPTY_BUCKET_VALUE) {
if (compare(serializedRepresentation, key)) return;
bucket = (bucket + 1) & modBitmask;
key = pointersAndOrdinals.get(bucket);
}
int pointer = byteData.length();
VarInt.writeVInt(byteData, serializedRepresentation.length());
serializedRepresentation.copyTo(byteData);
key = ((long) ordinal << 32) | pointer;
size++;
pointersAndOrdinals.set(bucket, key);
}
/**
* Create an AtomicLongArray of the specified size, each value in the array will be
* EMPTY_BUCKET_VALUE
*/
private AtomicLongArray emptyKeyArray(int size) {
AtomicLongArray arr = new AtomicLongArray(size);
for (int i = 0; i < arr.length(); i++) {
arr.set(i, EMPTY_BUCKET_VALUE);
}
return arr;
}
/**
* Remove all entries from this map, but reuse the existing arrays when populating the map next
* time.
*
* <p>This is intended for use in the client-side heap-safe double snapshot load.
*/
public void clear() {
for (int i = 0; i < pointersAndOrdinals.length(); i++) {
pointersAndOrdinals.set(i, EMPTY_BUCKET_VALUE);
}
byteData.reset();
size = 0;
}
/**
* Reclaim space in the byte array used in the previous cycle, but not referenced in this cycle.
*
* <p>This is achieved by shifting all used byte sequences down in the byte array, then updating
* the key array to reflect the new pointers and exclude the removed entries. This is also where
* ordinals which are unused are returned to the pool.
*
* <p>
*
* @param usedOrdinals a bit set representing the ordinals which are currently referenced by any
* image.
*/
public void compact(ThreadSafeBitSet usedOrdinals) {
long populatedReverseKeys[] = new long[size];
int counter = 0;
for (int i = 0; i < pointersAndOrdinals.length(); i++) {
long key = pointersAndOrdinals.get(i);
if (key != EMPTY_BUCKET_VALUE) {
populatedReverseKeys[counter++] = key << 32 | key >>> 32;
}
}
Arrays.sort(populatedReverseKeys);
SegmentedByteArray arr = byteData.getUnderlyingArray();
int currentCopyPointer = 0;
for (int i = 0; i < populatedReverseKeys.length; i++) {
int ordinal = (int) populatedReverseKeys[i];
if (usedOrdinals.get(ordinal)) {
int pointer = (int) (populatedReverseKeys[i] >> 32);
int length = VarInt.readVInt(arr, pointer);
length += VarInt.sizeOfVInt(length);
if (currentCopyPointer != pointer) arr.copy(arr, pointer, currentCopyPointer, length);
populatedReverseKeys[i] = populatedReverseKeys[i] << 32 | currentCopyPointer;
currentCopyPointer += length;
} else {
freeOrdinalTracker.returnOrdinalToPool(ordinal);
populatedReverseKeys[i] = EMPTY_BUCKET_VALUE;
}
}
byteData.setPosition(currentCopyPointer);
for (int i = 0; i < pointersAndOrdinals.length(); i++) {
pointersAndOrdinals.set(i, EMPTY_BUCKET_VALUE);
}
populateNewHashArray(pointersAndOrdinals, populatedReverseKeys);
size = usedOrdinals.cardinality();
pointersByOrdinal = null;
}
/**
* @return the largest value that could have been added to this histogram. If the histogram
* overflowed, returns Long.MAX_VALUE.
*/
public long max() {
int lastBucket = buckets.length() - 1;
if (buckets.get(lastBucket) > 0) return Long.MAX_VALUE;
for (int i = lastBucket - 1; i >= 0; i--) {
if (buckets.get(i) > 0) return bucketOffsets[i];
}
return 0;
}
/**
* @param reset zero out buckets afterwards if true
* @return a long[] containing the current histogram buckets
*/
public long[] getBuckets(boolean reset) {
final int len = buckets.length();
long[] rv = new long[len];
if (reset) for (int i = 0; i < len; i++) rv[i] = buckets.getAndSet(i, 0L);
else for (int i = 0; i < len; i++) rv[i] = buckets.get(i);
return rv;
}
/**
* Hash all of the existing values specified by the keys in the supplied long array into the
* supplied AtomicLongArray.
*/
private void populateNewHashArray(AtomicLongArray newKeys, long[] valuesToAdd) {
int modBitmask = newKeys.length() - 1;
for (int i = 0; i < valuesToAdd.length; i++) {
if (valuesToAdd[i] != EMPTY_BUCKET_VALUE) {
int hash = rehashPreviouslyAddedData(valuesToAdd[i]);
int bucket = hash & modBitmask;
while (newKeys.get(bucket) != EMPTY_BUCKET_VALUE) bucket = (bucket + 1) & modBitmask;
newKeys.set(bucket, valuesToAdd[i]);
}
}
}
Consumer<S> check(long maxTime, PooledFatPipe parent) {
if (parent != null && parent.group == null) return null;
AtomicLongArray outUse = this.outUse;
Consumer<S>[] consumers = this.consumers;
long now = System.nanoTime();
if (consumers.length > outUse.length()) {
logger.warn("skipping check " + outUse.length() + "/" + consumers.length);
return null;
}
try {
for (int i = 0; i < consumers.length; i++) {
long time = outUse.get(i);
if (time == 0) continue;
if (time == -1) continue;
if (now < time + maxTime * 1_000_000) continue;
if (parent != null) parent.group.list();
return consumers[i];
}
} catch (Exception e) {
logger.error("check", e);
}
return null;
}
/**
* log.debug() every record in the histogram
*
* @param log
*/
public void log(Logger log) {
// only print overflow if there is any
int nameCount;
if (buckets.get(buckets.length() - 1) == 0) nameCount = buckets.length() - 1;
else nameCount = buckets.length();
String[] names = new String[nameCount];
int maxNameLength = 0;
for (int i = 0; i < nameCount; i++) {
names[i] = nameOfRange(bucketOffsets, i);
maxNameLength = Math.max(maxNameLength, names[i].length());
}
// emit log records
String formatstr = "%" + maxNameLength + "s: %d";
for (int i = 0; i < nameCount; i++) {
long count = buckets.get(i);
// sort-of-hack to not print empty ranges at the start that are only used to demarcate the
// first populated range. for code clarity we don't omit this record from the maxNameLength
// calculation, and accept the unnecessary whitespace prefixes that will occasionally occur
if (i == 0 && count == 0) continue;
log.debug(String.format(formatstr, names[i], count));
}
}
/**
* @return the mean histogram value (average of bucket offsets, weighted by count)
* @throws IllegalStateException if any values were greater than the largest bucket threshold
*/
public long mean() {
int lastBucket = buckets.length() - 1;
if (buckets.get(lastBucket) > 0)
throw new IllegalStateException(
"Unable to compute ceiling for max when histogram overflowed");
long elements = 0;
long sum = 0;
for (int i = 0; i < lastBucket; i++) {
long bCount = buckets.get(i);
elements += bCount;
sum += bCount * bucketOffsets[i];
}
return (long) Math.ceil((double) sum / elements);
}
/**
* @param percentile
* @return estimated value at given percentile
*/
public long percentile(double percentile) {
assert percentile >= 0 && percentile <= 1.0;
int lastBucket = buckets.length() - 1;
if (buckets.get(lastBucket) > 0)
throw new IllegalStateException("Unable to compute when histogram overflowed");
long pcount = (long) Math.floor(count() * percentile);
if (pcount == 0) return 0;
long elements = 0;
for (int i = 0; i < lastBucket; i++) {
elements += buckets.get(i);
if (elements >= pcount) return bucketOffsets[i];
}
return 0;
}
/**
* Add a sequence of bytes to this map. If the sequence of bytes has already been added to this
* map, return the originally assigned ordinal. If the sequence of bytes has not been added to
* this map, assign and return a new ordinal. This operation is thread-safe.
*/
public int getOrAssignOrdinal(ByteDataBuffer serializedRepresentation) {
int hash = SegmentedByteArrayHasher.hashCode(serializedRepresentation);
int modBitmask = pointersAndOrdinals.length() - 1;
int bucket = hash & modBitmask;
long key = pointersAndOrdinals.get(bucket);
/// linear probing to resolve collisions.
while (key != EMPTY_BUCKET_VALUE) {
if (compare(serializedRepresentation, key)) {
return (int) (key >> 32);
}
bucket = (bucket + 1) & modBitmask;
key = pointersAndOrdinals.get(bucket);
}
return assignOrdinal(serializedRepresentation, hash);
}
/// acquire the lock before writing.
private synchronized int assignOrdinal(ByteDataBuffer serializedRepresentation, int hash) {
if (size > sizeBeforeGrow) growKeyArray();
/// check to make sure that after acquiring the lock, the element still does not exist.
/// this operation is akin to double-checked locking which is 'fixed' with the JSR 133 memory
// model in JVM >= 1.5.
int modBitmask = pointersAndOrdinals.length() - 1;
int bucket = hash & modBitmask;
long key = pointersAndOrdinals.get(bucket);
while (key != EMPTY_BUCKET_VALUE) {
if (compare(serializedRepresentation, key)) {
return (int) (key >> 32);
}
bucket = (bucket + 1) & modBitmask;
key = pointersAndOrdinals.get(bucket);
}
/// the ordinal for this object still does not exist in the list, even after the lock has been
// acquired.
/// it is up to this thread to add it at the current bucket position.
int ordinal = freeOrdinalTracker.getFreeOrdinal();
int pointer = byteData.length();
VarInt.writeVInt(byteData, serializedRepresentation.length());
serializedRepresentation.copyTo(byteData);
key = ((long) ordinal << 32) | pointer;
size++;
/// this set on the AtomicLongArray has volatile semantics (i.e. behaves like a monitor
// release).
/// Any other thread reading this element in the AtomicLongArray will have visibility to all
// memory writes this thread has made up to this point.
/// This means the entire byte sequence is guaranteed to be visible to any thread which reads
// the pointer to that data.
pointersAndOrdinals.set(bucket, key);
return ordinal;
}
private int getNextIndex(Object caller) {
long now = System.currentTimeMillis();
if (this.policy == LoadBalancerPolicy.ROUND_ROBIN) {
// Try all endpoints if some are suspended
int count = endpointCount;
int[] tried = new int[endpointCount];
while (count > 0) {
// Increment index and convert negative values to positive if need be
int index = indexGenerator.getAndIncrement() % endpointCount;
if (index < 0) {
index += endpointCount;
}
// Don't retry same index
if (tried[index] == 0) {
// Return index if endpoint is not suspended
if (suspensionTimes.get(index) < now) {
return index;
}
tried[index] = 1;
count--;
}
}
} else if (this.policy == LoadBalancerPolicy.LATENCY_LAST) {
int index = -1;
for (int i = 0; i < latencyTimes.length(); i++) {
long current = latencyTimes.get(i);
long smallest = Long.MAX_VALUE;
if (current < smallest && suspensionTimes.get(i) < now) {
smallest = current;
index = i;
}
}
return index;
}
return -1;
}
private void getIdentitiesOfFiles() throws IOException {
for (int i = 0; i < fileIds.length(); i++) {
fileIds.set(i, buffer.openFile(fileNames[i]));
}
}
/** @return the smallest value that could have been added to this histogram */
public long min() {
for (int i = 0; i < buckets.length(); i++) {
if (buckets.get(i) > 0) return i == 0 ? 0 : 1 + bucketOffsets[i - 1];
}
return 0;
}
/** @return the total number of non-zero values */
public long count() {
long sum = 0L;
for (int i = 0; i < buckets.length(); i++) sum += buckets.get(i);
return sum;
}
/**
* @return true if this histogram has overflowed -- that is, a value larger than our largest
* bucket could bound was added
*/
public boolean isOverflowed() {
return buckets.get(buckets.length() - 1) > 0;
}
/**
* @param product
* @param sequence
* @return false if there is an error
*/
boolean consume(S product, long sequence, long sleep) {
if (product == null) return true;
// make copies
Consumer<S>[] consumers = this.consumers;
AtomicLongArray outUse = this.outUse;
long[] consumerSeqs = this.consumerSeqs;
if (outUse.length() != consumers.length) return false;
for (int j = 0; j < consumers.length; j++) {
if (!consumers[j].isConsuming()) continue;
long time = System.nanoTime();
if (!outUse.compareAndSet(j, 0, time)) continue;
try {
if (sequence <= consumerSeqs[j]) {
outUse.lazySet(j, 0);
if (outUse != this.outUse) resetConsumer(consumers[j]);
break;
}
consumerSeqs[j] = sequence;
consumers[j].consume(product, time);
if (sleep > 0) Thread.sleep(sleep);
outUse.lazySet(j, 0);
if (outUse != this.outUse) {
resetConsumer(consumers[j]);
break;
}
} catch (Exception e) {
if (listener == null) logger.error("consume", e);
else listener.exceptionThrown(e);
}
}
finishConsuming(product, sequence);
return true;
}
