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=tes since 2.4.x requires Java8, we can drop LongAdder and Striped copies

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Konrad Malawski 2015-07-14 15:51:28 +02:00 • committed by Konrad Malawski
parent f3c6ff5665
commit efe2459875
3 changed files with 2 additions and 551 deletions
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197
akka-testkit/src/test/java/akka/testkit/metrics/LongAdder.java
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@ -1,197 +0,0 @@
/*
* Written by Doug Lea with assistance from members of JCP JSR-166
* Expert Group and released to the public domain, as explained at
* http://creativecommons.org/publicdomain/zero/1.0/
*
* http://gee.cs.oswego.edu/cgi-bin/viewcvs.cgi/jsr166/src/jsr166e/LongAdder.java?revision=1.14&view=markup
*/
package akka.testkit.metrics;
import java.io.Serializable;
import java.util.concurrent.atomic.AtomicLong;
// CHECKSTYLE:OFF
/**
* One or more variables that together maintain an initially zero {@code long} sum. When updates
* (method {@link #add}) are contended across threads, the set of variables may grow dynamically to
* reduce contention. Method {@link #sum} (or, equivalently, {@link #longValue}) returns the current
* total combined across the variables maintaining the sum.
* <p/>
* <p>This class is usually preferable to {@link AtomicLong} when multiple threads update a common
* sum that is used for purposes such as collecting statistics, not for fine-grained synchronization
* control. Under low update contention, the two classes have similar characteristics. But under
* high contention, expected throughput of this class is significantly higher, at the expense of
* higher space consumption.
* <p/>
* <p>This class extends {@link Number}, but does <em>not</em> define methods such as {@code
* equals}, {@code hashCode} and {@code compareTo} because instances are expected to be mutated, and
* so are not useful as collection keys.
* <p/>
* <p><em>jsr166e note: This class is targeted to be placed in java.util.concurrent.atomic.</em>
*
* @author Doug Lea
* @since 1.8
*/
@SuppressWarnings("all")
class LongAdder extends Striped64 implements Serializable {
private static final long serialVersionUID = 7249069246863182397L;
/**
* Version of plus for use in retryUpdate
*/
final long fn(long v, long x) {
return v + x;
}
/**
* Creates a new adder with initial sum of zero.
*/
LongAdder() {
}
/**
* Adds the given value.
*
* @param x the value to add
*/
public void add(long x) {
Cell[] as;
long b, v;
HashCode hc;
Cell a;
int n;
if ((as = cells) != null || !casBase(b = base, b + x)) {
boolean uncontended = true;
int h = (hc = threadHashCode.get()).code;
if (as == null || (n = as.length) < 1 ||
(a = as[(n - 1) & h]) == null ||
!(uncontended = a.cas(v = a.value, v + x)))
retryUpdate(x, hc, uncontended);
}
}
/**
* Equivalent to {@code add(1)}.
*/
public void increment() {
add(1L);
}
/**
* Equivalent to {@code add(-1)}.
*/
public void decrement() {
add(-1L);
}
/**
* Returns the current sum. The returned value is <em>NOT</em> an atomic snapshot; invocation
* in the absence of concurrent updates returns an accurate result, but concurrent updates that
* occur while the sum is being calculated might not be incorporated.
*
* @return the sum
*/
public long sum() {
long sum = base;
Cell[] as = cells;
if (as != null) {
int n = as.length;
for (int i = 0; i < n; ++i) {
Cell a = as[i];
if (a != null)
sum += a.value;
}
}
return sum;
}
/**
* Resets variables maintaining the sum to zero. This method may be a useful alternative to
* creating a new adder, but is only effective if there are no concurrent updates. Because this
* method is intrinsically racy, it should only be used when it is known that no threads are
* concurrently updating.
*/
public void reset() {
internalReset(0L);
}
/**
* Equivalent in effect to {@link #sum} followed by {@link #reset}. This method may apply for
* example during quiescent points between multithreaded computations. If there are updates
* concurrent with this method, the returned value is <em>not</em> guaranteed to be the final
* value occurring before the reset.
*
* @return the sum
*/
public long sumThenReset() {
long sum = base;
Cell[] as = cells;
base = 0L;
if (as != null) {
int n = as.length;
for (int i = 0; i < n; ++i) {
Cell a = as[i];
if (a != null) {
sum += a.value;
a.value = 0L;
}
}
}
return sum;
}
/**
* Returns the String representation of the {@link #sum}.
*
* @return the String representation of the {@link #sum}
*/
public String toString() {
return Long.toString(sum());
}
/**
* Equivalent to {@link #sum}.
*
* @return the sum
*/
public long longValue() {
return sum();
}
/**
* Returns the {@link #sum} as an {@code int} after a narrowing primitive conversion.
*/
public int intValue() {
return (int) sum();
}
/**
* Returns the {@link #sum} as a {@code float} after a widening primitive conversion.
*/
public float floatValue() {
return (float) sum();
}
/**
* Returns the {@link #sum} as a {@code double} after a widening primitive conversion.
*/
public double doubleValue() {
return (double) sum();
}
private void writeObject(java.io.ObjectOutputStream s)
throws java.io.IOException {
s.defaultWriteObject();
s.writeLong(sum());
}
private void readObject(java.io.ObjectInputStream s)
throws java.io.IOException, ClassNotFoundException {
s.defaultReadObject();
busy = 0;
cells = null;
base = s.readLong();
}
}
// CHECKSTYLE:ON

354
akka-testkit/src/test/java/akka/testkit/metrics/Striped64.java
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@ -1,354 +0,0 @@
/*
* Written by Doug Lea with assistance from members of JCP JSR-166
* Expert Group and released to the public domain, as explained at
* http://creativecommons.org/publicdomain/zero/1.0/
*
* http://gee.cs.oswego.edu/cgi-bin/viewcvs.cgi/jsr166/src/jsr166e/Striped64.java?revision=1.8&view=markup
*/
package akka.testkit.metrics;
import java.util.Random;
// CHECKSTYLE:OFF
/**
* A package-local class holding common representation and mechanics for classes supporting dynamic
* striping on 64bit values. The class extends Number so that concrete subclasses must publicly do
* so.
*/
@SuppressWarnings("all")
abstract class Striped64 extends Number {
/*
* This class maintains a lazily-initialized table of atomically
* updated variables, plus an extra "base" field. The table size
* is a power of two. Indexing uses masked per-thread hash codes.
* Nearly all declarations in this class are package-private,
* accessed directly by subclasses.
*
* Table entries are of class Cell; a variant of AtomicLong padded
* to reduce cache contention on most processors. Padding is
* overkill for most Atomics because they are usually irregularly
* scattered in memory and thus don't interfere much with each
* other. But Atomic objects residing in arrays will tend to be
* placed adjacent to each other, and so will most often share
* cache lines (with a huge negative performance impact) without
* this precaution.
*
* In part because Cells are relatively large, we avoid creating
* them until they are needed. When there is no contention, all
* updates are made to the base field. Upon first contention (a
* failed CAS on base update), the table is initialized to size 2.
* The table size is doubled upon further contention until
* reaching the nearest power of two greater than or equal to the
* number of CPUS. Table slots remain empty (null) until they are
* needed.
*
* A single spinlock ("busy") is used for initializing and
* resizing the table, as well as populating slots with new Cells.
* There is no need for a blocking lock; when the lock is not
* available, threads try other slots (or the base). During these
* retries, there is increased contention and reduced locality,
* which is still better than alternatives.
*
* Per-thread hash codes are initialized to random values.
* Contention and/or table collisions are indicated by failed
* CASes when performing an update operation (see method
* retryUpdate). Upon a collision, if the table size is less than
* the capacity, it is doubled in size unless some other thread
* holds the lock. If a hashed slot is empty, and lock is
* available, a new Cell is created. Otherwise, if the slot
* exists, a CAS is tried. Retries proceed by "double hashing",
* using a secondary hash (Marsaglia XorShift) to try to find a
* free slot.
*
* The table size is capped because, when there are more threads
* than CPUs, supposing that each thread were bound to a CPU,
* there would exist a perfect hash function mapping threads to
* slots that eliminates collisions. When we reach capacity, we
* search for this mapping by randomly varying the hash codes of
* colliding threads. Because search is random, and collisions
* only become known via CAS failures, convergence can be slow,
* and because threads are typically not bound to CPUS forever,
* may not occur at all. However, despite these limitations,
* observed contention rates are typically low in these cases.
*
* It is possible for a Cell to become unused when threads that
* once hashed to it terminate, as well as in the case where
* doubling the table causes no thread to hash to it under
* expanded mask. We do not try to detect or remove such cells,
* under the assumption that for long-running instances, observed
* contention levels will recur, so the cells will eventually be
* needed again; and for short-lived ones, it does not matter.
*/
/**
* Padded variant of AtomicLong supporting only raw accesses plus CAS. The value field is placed
* between pads, hoping that the JVM doesn't reorder them.
* <p/>
* JVM intrinsics note: It would be possible to use a release-only form of CAS here, if it were
* provided.
*/
static final class Cell {
volatile long p0, p1, p2, p3, p4, p5, p6;
volatile long value;
volatile long q0, q1, q2, q3, q4, q5, q6;
Cell(long x) {
value = x;
}
final boolean cas(long cmp, long val) {
return UNSAFE.compareAndSwapLong(this, valueOffset, cmp, val);
}
// Unsafe mechanics
private static final sun.misc.Unsafe UNSAFE;
private static final long valueOffset;
static {
try {
UNSAFE = getUnsafe();
Class<?> ak = Cell.class;
valueOffset = UNSAFE.objectFieldOffset
(ak.getDeclaredField("value"));
} catch (Exception e) {
throw new Error(e);
}
}
}
/**
* Holder for the thread-local hash code. The code is initially random, but may be set to a
* different value upon collisions.
*/
static final class HashCode {
static final Random rng = new Random();
int code;
HashCode() {
int h = rng.nextInt(); // Avoid zero to allow xorShift rehash
code = (h == 0) ? 1 : h;
}
}
/**
* The corresponding ThreadLocal class
*/
static final class ThreadHashCode extends ThreadLocal<HashCode> {
public HashCode initialValue() {
return new HashCode();
}
}
/**
* Static per-thread hash codes. Shared across all instances to reduce ThreadLocal pollution and
* because adjustments due to collisions in one table are likely to be appropriate for others.
*/
static final ThreadHashCode threadHashCode = new ThreadHashCode();
/**
* Number of CPUS, to place bound on table size
*/
static final int NCPU = Runtime.getRuntime().availableProcessors();
/**
* Table of cells. When non-null, size is a power of 2.
*/
transient volatile Cell[] cells;
/**
* Base value, used mainly when there is no contention, but also as a fallback during table
* initialization races. Updated via CAS.
*/
transient volatile long base;
/**
* Spinlock (locked via CAS) used when resizing and/or creating Cells.
*/
transient volatile int busy;
/**
* Package-private default constructor
*/
Striped64() {
}
/**
* CASes the base field.
*/
final boolean casBase(long cmp, long val) {
return UNSAFE.compareAndSwapLong(this, baseOffset, cmp, val);
}
/**
* CASes the busy field from 0 to 1 to acquire lock.
*/
final boolean casBusy() {
return UNSAFE.compareAndSwapInt(this, busyOffset, 0, 1);
}
/**
* Computes the function of current and new value. Subclasses should open-code this update
* function for most uses, but the virtualized form is needed within retryUpdate.
*
* @param currentValue the current value (of either base or a cell)
* @param newValue the argument from a user update call
* @return result of the update function
*/
abstract long fn(long currentValue, long newValue);
/**
* Handles cases of updates involving initialization, resizing, creating new Cells, and/or
* contention. See above for explanation. This method suffers the usual non-modularity problems
* of optimistic retry code, relying on rechecked sets of reads.
*
* @param x the value
* @param hc the hash code holder
* @param wasUncontended false if CAS failed before call
*/
final void retryUpdate(long x, HashCode hc, boolean wasUncontended) {
int h = hc.code;
boolean collide = false; // True if last slot nonempty
for (; ; ) {
Cell[] as;
Cell a;
int n;
long v;
if ((as = cells) != null && (n = as.length) > 0) {
if ((a = as[(n - 1) & h]) == null) {
if (busy == 0) { // Try to attach new Cell
Cell r = new Cell(x); // Optimistically create
if (busy == 0 && casBusy()) {
boolean created = false;
try { // Recheck under lock
Cell[] rs;
int m, j;
if ((rs = cells) != null &&
(m = rs.length) > 0 &&
rs[j = (m - 1) & h] == null) {
rs[j] = r;
created = true;
}
} finally {
busy = 0;
}
if (created)
break;
continue; // Slot is now non-empty
}
}
collide = false;
} else if (!wasUncontended) // CAS already known to fail
wasUncontended = true; // Continue after rehash
else if (a.cas(v = a.value, fn(v, x)))
break;
else if (n >= NCPU || cells != as)
collide = false; // At max size or stale
else if (!collide)
collide = true;
else if (busy == 0 && casBusy()) {
try {
if (cells == as) { // Expand table unless stale
Cell[] rs = new Cell[n << 1];
for (int i = 0; i < n; ++i)
rs[i] = as[i];
cells = rs;
}
} finally {
busy = 0;
}
collide = false;
continue; // Retry with expanded table
}
h ^= h << 13; // Rehash
h ^= h >>> 17;
h ^= h << 5;
} else if (busy == 0 && cells == as && casBusy()) {
boolean init = false;
try { // Initialize table
if (cells == as) {
Cell[] rs = new Cell[2];
rs[h & 1] = new Cell(x);
cells = rs;
init = true;
}
} finally {
busy = 0;
}
if (init)
break;
} else if (casBase(v = base, fn(v, x)))
break; // Fall back on using base
}
hc.code = h; // Record index for next time
}
/**
* Sets base and all cells to the given value.
*/
final void internalReset(long initialValue) {
Cell[] as = cells;
base = initialValue;
if (as != null) {
int n = as.length;
for (int i = 0; i < n; ++i) {
Cell a = as[i];
if (a != null)
a.value = initialValue;
}
}
}
// Unsafe mechanics
private static final sun.misc.Unsafe UNSAFE;
private static final long baseOffset;
private static final long busyOffset;
static {
try {
UNSAFE = getUnsafe();
Class<?> sk = Striped64.class;
baseOffset = UNSAFE.objectFieldOffset
(sk.getDeclaredField("base"));
busyOffset = UNSAFE.objectFieldOffset
(sk.getDeclaredField("busy"));
} catch (Exception e) {
throw new Error(e);
}
}
/**
* Returns a sun.misc.Unsafe. Suitable for use in a 3rd party package. Replace with a simple
* call to Unsafe.getUnsafe when integrating into a jdk.
*
* @return a sun.misc.Unsafe
*/
private static sun.misc.Unsafe getUnsafe() {
try {
return sun.misc.Unsafe.getUnsafe();
} catch (SecurityException ignored) {
}
try {
return java.security.AccessController.doPrivileged
(new java.security.PrivilegedExceptionAction<sun.misc.Unsafe>() {
public sun.misc.Unsafe run() throws Exception {
Class<sun.misc.Unsafe> k = sun.misc.Unsafe.class;
for (java.lang.reflect.Field f : k.getDeclaredFields()) {
f.setAccessible(true);
Object x = f.get(null);
if (k.isInstance(x))
return k.cast(x);
}
throw new NoSuchFieldError("the Unsafe");
}
});
} catch (java.security.PrivilegedActionException e) {
throw new RuntimeException("Could not initialize intrinsics",
e.getCause());
}
}
}
// CHECKSTYLE:ON

2
akka-testkit/src/test/scala/akka/testkit/metrics/AveragingGauge.scala
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@ -3,6 +3,8 @@
*/
package akka.testkit.metrics
import java.util.concurrent.atomic.LongAdder
import com.codahale.metrics.Gauge
/**