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From jacques-n <...@git.apache.org>
Subject [GitHub] drill pull request: DRILL-4134: Allocator updates
Date Fri, 18 Dec 2015 17:59:48 GMT
Github user jacques-n commented on a diff in the pull request:

    https://github.com/apache/drill/pull/283#discussion_r48051385
  
    --- Diff: exec/memory/base/src/main/java/org/apache/drill/exec/memory/Accountant.java
---
    @@ -0,0 +1,269 @@
    +/**
    + * Licensed to the Apache Software Foundation (ASF) under one
    + * or more contributor license agreements.  See the NOTICE file
    + * distributed with this work for additional information
    + * regarding copyright ownership.  The ASF licenses this file
    + * to you under the Apache License, Version 2.0 (the
    + * "License"); you may not use this file except in compliance
    + * with the License.  You may obtain a copy of the License at
    + *
    + * http://www.apache.org/licenses/LICENSE-2.0
    + *
    + * Unless required by applicable law or agreed to in writing, software
    + * distributed under the License is distributed on an "AS IS" BASIS,
    + * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    + * See the License for the specific language governing permissions and
    + * limitations under the License.
    + */
    +package org.apache.drill.exec.memory;
    +
    +import java.util.concurrent.atomic.AtomicLong;
    +
    +import javax.annotation.concurrent.ThreadSafe;
    +
    +import org.apache.drill.exec.exception.OutOfMemoryException;
    +
    +import com.google.common.base.Preconditions;
    +
    +/**
    + * Provides a concurrent way to manage account for memory usage without locking. Used
as basis for Allocators. All
    + * operations are threadsafe (except for close).
    + */
    +@ThreadSafe
    +class Accountant implements AutoCloseable {
    +  // private static final org.slf4j.Logger logger = org.slf4j.LoggerFactory.getLogger(Accountant.class);
    +
    +  /**
    +   * The parent allocator
    +   */
    +  protected final Accountant parent;
    +
    +  /**
    +   * The amount of memory reserved for this allocator. Releases below this amount of
memory will not be returned to the
    +   * parent Accountant until this Accountant is closed.
    +   */
    +  protected final long reservation;
    +
    +  private final AtomicLong peakAllocation = new AtomicLong();
    +
    +  /**
    +   * Maximum local memory that can be held. This can be externally updated. Changing
it won't cause past memory to
    +   * change but will change responses to future allocation efforts
    +   */
    +  private final AtomicLong allocationLimit = new AtomicLong();
    +
    +  /**
    +   * Currently allocated amount of memory;
    +   */
    +  private final AtomicLong locallyHeldMemory = new AtomicLong();
    +
    +  public Accountant(Accountant parent, long reservation, long maxAllocation) {
    +    Preconditions.checkArgument(reservation >= 0, "The initial reservation size must
be non-negative.");
    +    Preconditions.checkArgument(maxAllocation >= 0, "The maximum allocation limit
must be non-negative.");
    +    Preconditions.checkArgument(reservation <= maxAllocation,
    +        "The initial reservation size must be <= the maximum allocation.");
    +    Preconditions.checkArgument(reservation == 0 || parent != null, "The root accountant
can't reserve memory.");
    +
    +    this.parent = parent;
    +    this.reservation = reservation;
    +    this.allocationLimit.set(maxAllocation);
    +
    +    if (reservation != 0) {
    +      // we will allocate a reservation from our parent.
    +      final AllocationOutcome outcome = parent.allocateBytes(reservation);
    +      if (!outcome.isOk()) {
    +        throw new OutOfMemoryException(String.format(
    +            "Failure trying to allocate initial reservation for Allocator. "
    +                + "Attempted to allocate %d bytes and received an outcome of %s.", reservation,
outcome.name()));
    +      }
    +    }
    +  }
    +
    +  /**
    +   * Attempt to allocate the requested amount of memory. Either completely succeeds or
completely fails. Constructs a a
    +   * log of delta
    +   *
    +   * If it fails, no changes are made to accounting.
    +   *
    +   * @param size
    +   *          The amount of memory to reserve in bytes.
    +   * @return True if the allocation was successful, false if the allocation failed.
    +   */
    +  AllocationOutcome allocateBytes(long size) {
    +    final AllocationOutcome outcome = allocate(size, true, false);
    +    if (!outcome.isOk()) {
    +      releaseBytes(size);
    +    }
    +    return outcome;
    +  }
    +
    +  private void updatePeak() {
    +    final long currentMemory = locallyHeldMemory.get();
    +
    +    long previousPeak;
    +    do {
    +      previousPeak = peakAllocation.get();
    +      if (peakAllocation.compareAndSet(previousPeak, currentMemory)) {
    --- End diff --
    
    oops. will fix. how does everything else look?


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