Example usage for com.google.common.hash HashFunction hashInt

Introduction

In this page you can find the example usage for com.google.common.hash HashFunction hashInt.

Prototype

HashCode hashInt(int input);

Source Link

Document

Shortcut for newHasher().putInt(input).hash() ; returns the hash code for the given int value, interpreted in little-endian byte order.

Usage

From source file:mx.itam.metodos.lshclustering.MinhashEmitMapper.java

@Override
public void map(Text id, IntArrayWritable values, Context context) throws IOException, InterruptedException {
    for (int i = 0; i < functionsCount; i++) {
        hashValues[i] = Integer.MAX_VALUE;
    }// www.  j a  va  2 s.  c  om
    for (int i = 0; i < functionsCount; i++) {
        HashFunction hf = functions[i];
        for (Writable wr : values.get()) {
            IntWritable value = (IntWritable) wr;
            int hash = hf.hashInt(value.get()).asInt();
            if (hash < hashValues[i]) {
                hashValues[i] = hash;
            }
        }
    }
    Text sketch = new Text();
    Hasher hasher = lsh.newHasher();
    int band = 0;
    for (int i = 0; i < functionsCount; i++) {
        hasher.putInt(hashValues[i]);
        if (i > 0 && (i % rows) == 0) {
            sketch.set(band + "-" + hasher.hash().toString());
            context.write(new SecondarySortKey(sketch, id), id);
            hasher = lsh.newHasher();
            band++;
        }
    }
    sketch.set(band + "-" + hasher.hash().toString());
    context.write(new SecondarySortKey(sketch, id), id);
}

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From source file:mx.itam.metodos.minhashing.MinhashMapper.java

@Override
public void map(Text id, IntArrayWritable values, Context ctx) throws IOException, InterruptedException {
    for (int i = 0; i < functionsCount; i++) {
        hashValues[i] = Integer.MAX_VALUE;
    }//from w w w .  j  a va2 s.c  o  m
    for (int i = 0; i < functionsCount; i++) {
        HashFunction hf = functions[i];
        for (Writable wr : values.get()) {
            IntWritable value = (IntWritable) wr;
            int hash = hf.hashInt(value.get()).asInt();
            if (hash < hashValues[i]) {
                hashValues[i] = hash;
            }
        }
    }
    Text sketch = new Text();
    Hasher hasher = lsh.newHasher();
    int band = 0;
    for (int i = 0; i < functionsCount; i++) {
        hasher.putInt(hashValues[i]);
        if (i > 0 && (i % rows) == 0) {
            sketch.set(band + "-" + hasher.hash().toString());
            write(id, sketch, ctx);
            hasher = lsh.newHasher();
            band++;
        }
    }
    sketch.set(band + "-" + hasher.hash().toString());
    write(id, sketch, ctx);
}

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From source file:org.hawkular.alerts.engine.impl.PartitionManagerImpl.java

/**
 * Distribute a new entry across buckets using a consistent hashing strategy.
 *
 * @param newEntry the new entry to distribute
 * @param buckets a table of nodes//from  w ww  .j a  v a 2s. c o  m
 * @return a code of the node which the new entry is placed
 */
public Integer calculateNewEntry(PartitionEntry newEntry, Map<Integer, Integer> buckets) {
    if (newEntry == null) {
        throw new IllegalArgumentException("newEntry must be not null");
    }
    if (isEmpty(buckets)) {
        throw new IllegalArgumentException("buckets must be not null");
    }
    HashFunction md5 = Hashing.md5();
    int numBuckets = buckets.size();
    return buckets.get(Hashing.consistentHash(md5.hashInt(newEntry.hashCode()), numBuckets));
}

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From source file:org.hawkular.alerts.engine.impl.PartitionManagerImpl.java

/**
 * Distribute triggers on nodes using a consistent hashing strategy.
 * This strategy allows to scale and minimize changes and re-distribution when cluster changes.
 *
 * @param entries a list of entries to distribute
 * @param buckets a table of nodes/*from w  w w .  j  a va 2s  .co m*/
 * @return a map of entries distributed across nodes
 */
public Map<PartitionEntry, Integer> calculatePartition(List<PartitionEntry> entries,
        Map<Integer, Integer> buckets) {
    if (entries == null) {
        throw new IllegalArgumentException("entries must be not null");
    }
    if (isEmpty(buckets)) {
        throw new IllegalArgumentException("entries must be not null");
    }
    HashFunction md5 = Hashing.md5();
    int numBuckets = buckets.size();
    Map<PartitionEntry, Integer> newPartition = new HashMap<>();
    for (PartitionEntry entry : entries) {
        newPartition.put(entry, buckets.get(Hashing.consistentHash(md5.hashInt(entry.hashCode()), numBuckets)));
    }
    return newPartition;
}

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