Method put

output/java_guava/1.4.18/LocalCache.java:2917–2985

(K key, int hash, V value, boolean onlyIfAbsent)

    }

    @Nullable
    V put(K key, int hash, V value, boolean onlyIfAbsent) {
      lock();
      try {
        long now = map.ticker.read();
        preWriteCleanup(now);
        int newCount = this.count + 1;
        if (newCount > this.threshold) { // ensure capacity
          expand();
          newCount = this.count + 1;
        }
        AtomicReferenceArray<ReferenceEntry<K, V>> table = this.table;
        int index = hash & (table.length() - 1);
        ReferenceEntry<K, V> first = table.get(index);

        // Look for an existing entry.
        for (ReferenceEntry<K, V> e = first; e != null; e = e.getNext()) {
          K entryKey = e.getKey();
          if (e.getHash() == hash && entryKey != null
              && map.keyEquivalence.equivalent(key, entryKey)) {
            // We found an existing entry.
            ValueReference<K, V> valueReference = e.getValueReference();
            V entryValue = valueReference.get();
            if (entryValue == null) {
              ++modCount;
              if (valueReference.isActive()) {
                enqueueNotification(key, hash, entryValue, valueReference.getWeight(), RemovalCause.COLLECTED);
                setValue(e, key, value, now);
                newCount = this.count; // count remains unchanged
              } else {
                setValue(e, key, value, now);
                newCount = this.count + 1;
              }
              this.count = newCount; // write-volatile
              evictEntries(e);
              return null;
            }
            else if (onlyIfAbsent) {
              // Mimic
              // "if (!map.containsKey(key)) ...
              // else return map.get(key);
              recordLockedRead(e, now);
              return entryValue;
            } else {
              // clobber existing entry, count remains unchanged
              ++modCount;
              enqueueNotification(key, hash, entryValue, valueReference.getWeight(), RemovalCause.REPLACED);
              setValue(e, key, value, now);
              evictEntries(e);
              return entryValue;
            }
          }
        }

        // Create a new entry.

        ++modCount;
        ReferenceEntry<K, V> newEntry = newEntry(key, hash, first);