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[C#] Sample as a memory-only cache (#396)
* Initial sample + minor mods to support use case * cleanup * added zipf distribution to example. moved to samples folder. * updates * Change CopyReadsToTail from bool to enum. * Add support for CopyReadsToTail to copy to tail when read from ReadOnly region. * updated sample, use container to store value being reinserted. * Added support for SubscribeEvictions * updated sample to ignore tombstones
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| <Project Sdk="Microsoft.NET.Sdk"> | ||
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| <PropertyGroup> | ||
| <OutputType>Exe</OutputType> | ||
| <AllowUnsafeBlocks>true</AllowUnsafeBlocks> | ||
| <TargetFramework>netcoreapp3.1</TargetFramework> | ||
| <Platforms>x64</Platforms> | ||
| <RuntimeIdentifier>win7-x64</RuntimeIdentifier> | ||
| </PropertyGroup> | ||
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| <ItemGroup> | ||
| <ProjectReference Include="..\..\src\core\FASTER.core.csproj" /> | ||
| </ItemGroup> | ||
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| </Project> |
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| // Copyright (c) Microsoft Corporation. All rights reserved. | ||
| // Licensed under the MIT license. | ||
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| using FASTER.core; | ||
| using System; | ||
| using System.Diagnostics; | ||
| using System.Threading; | ||
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| #pragma warning disable IDE0079 // Remove unnecessary suppression | ||
| #pragma warning disable CS0162 // Unreachable code detected | ||
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| namespace MemOnlyCache | ||
| { | ||
| class Program | ||
| { | ||
| /// <summary> | ||
| /// Total database size | ||
| /// </summary> | ||
| const int DbSize = 10_000_000; | ||
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| /// <summary> | ||
| /// Number of threads accessing FASTER instances | ||
| /// </summary> | ||
| const int kNumThreads = 1; | ||
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| /// <summary> | ||
| /// Percentage of writes in incoming workload requests (remaining are reads) | ||
| /// </summary> | ||
| const int WritePercent = 0; | ||
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| /// <summary> | ||
| /// Uniform random distribution (true) or Zipf distribution (false) of requests | ||
| /// </summary> | ||
| const bool UseUniform = false; | ||
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| /// <summary> | ||
| /// Skew factor (theta) of Zipf distribution | ||
| /// </summary> | ||
| const double Theta = 0.99; | ||
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| /// <summary> | ||
| /// Whether to upsert the data automatically on a cache miss | ||
| /// </summary> | ||
| const bool UpsertOnCacheMiss = true; | ||
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| static FasterKV<CacheKey, CacheValue> h; | ||
| static long totalReads = 0; | ||
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| static void Main() | ||
| { | ||
| // This sample shows the use of FASTER as a concurrent pure in-memory cache | ||
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| var log = new NullDevice(); // no storage involved | ||
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| // Define settings for log | ||
| var logSettings = new LogSettings | ||
| { | ||
| LogDevice = log, ObjectLogDevice = log, | ||
| MutableFraction = 0.9, // 10% of memory log is "read-only region" | ||
| CopyReadsToTail = CopyReadsToTail.FromReadOnly, // reads in read-only region are copied to tail | ||
| PageSizeBits = 14, // Each page is sized at 2^14 bytes | ||
| MemorySizeBits = 25, // (2^25 / 24) = ~1.39M key-value pairs (log uses 24 bytes per KV pair) | ||
| }; | ||
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| // Number of records in memory, assuming class keys and values and x64 platform | ||
| // (8-byte key + 8-byte value + 8-byte header = 24 bytes per record) | ||
| int numRecords = (int)(Math.Pow(2, logSettings.MemorySizeBits) / 24); | ||
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| // Targeting 1 record per bucket | ||
| var numBucketBits = (int)Math.Ceiling(Math.Log2(numRecords)); | ||
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| h = new FasterKV<CacheKey, CacheValue>(1L << numBucketBits, logSettings, comparer: new CacheKey()); | ||
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| // Register subscriber to receive notifications of log evictions from memory | ||
| h.Log.SubscribeEvictions(new LogObserver()); | ||
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| PopulateStore(numRecords); | ||
| ContinuousRandomWorkload(); | ||
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| h.Dispose(); | ||
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| Console.WriteLine("Press <ENTER> to end"); | ||
| Console.ReadLine(); | ||
| } | ||
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| private static void PopulateStore(int count) | ||
| { | ||
| using var s = h.For(new CacheFunctions()).NewSession<CacheFunctions>(); | ||
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| Random r = new Random(0); | ||
| Console.WriteLine("Writing random keys to fill cache"); | ||
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| for (int i = 0; i < count; i++) | ||
| { | ||
| int k = r.Next(DbSize); | ||
| var key = new CacheKey(k); | ||
| var value = new CacheValue(k); | ||
| s.Upsert(ref key, ref value); | ||
| } | ||
| } | ||
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| private static void ContinuousRandomWorkload() | ||
| { | ||
| var threads = new Thread[kNumThreads]; | ||
| for (int i = 0; i < kNumThreads; i++) | ||
| { | ||
| var x = i; | ||
| threads[i] = new Thread(() => RandomWorkload(x)); | ||
| } | ||
| for (int i = 0; i < kNumThreads; i++) | ||
| threads[i].Start(); | ||
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| Stopwatch sw = new Stopwatch(); | ||
| sw.Start(); | ||
| var _lastReads = totalReads; | ||
| var _lastTime = sw.ElapsedMilliseconds; | ||
| while (true) | ||
| { | ||
| Thread.Sleep(1000); | ||
| var tmp = totalReads; | ||
| var tmp2 = sw.ElapsedMilliseconds; | ||
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| Console.WriteLine("Throughput: {0:0.00}K ops/sec", (_lastReads - tmp) / (double)(_lastTime - tmp2)); | ||
| _lastReads = tmp; | ||
| _lastTime = tmp2; | ||
| } | ||
| } | ||
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| private static void RandomWorkload(int threadid) | ||
| { | ||
| Console.WriteLine("Issuing {0} random read workload of {1} reads from thread {2}", UseUniform ? "uniform" : "zipf", DbSize, threadid); | ||
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| using var session = h.For(new CacheFunctions()).NewSession<CacheFunctions>(); | ||
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| var rnd = new Random(threadid); | ||
| var zipf = new ZipfGenerator(rnd, DbSize, Theta); | ||
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| int statusNotFound = 0; | ||
| int statusFound = 0; | ||
| CacheValue output = default; | ||
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| int i = 0; | ||
| while (true) | ||
| { | ||
| if ((i % 256 == 0) && (i > 0)) | ||
| { | ||
| Interlocked.Add(ref totalReads, 256); | ||
| if (i % (1024 * 1024 * 16) == 0) // report after every 16M ops | ||
| Console.WriteLine("Hit rate: {0:N2}; Evict count: {1}", statusFound / (double)(statusFound + statusNotFound), LogObserver.EvictCount); | ||
| } | ||
| int op = WritePercent == 0 ? 0 : rnd.Next(100); | ||
| long k = UseUniform ? rnd.Next(DbSize) : zipf.Next(); | ||
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| var key = new CacheKey(k); | ||
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| if (op < WritePercent) | ||
| { | ||
| var value = new CacheValue(k); | ||
| session.Upsert(ref key, ref value); | ||
| } | ||
| else | ||
| { | ||
| var status = session.Read(ref key, ref output); | ||
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| switch (status) | ||
| { | ||
| case Status.NOTFOUND: | ||
| statusNotFound++; | ||
| if (UpsertOnCacheMiss) | ||
| { | ||
| var value = new CacheValue(k); | ||
| session.Upsert(ref key, ref value); | ||
| } | ||
| break; | ||
| case Status.OK: | ||
| statusFound++; | ||
| if (output.value != key.key) | ||
| throw new Exception("Read error!"); | ||
| break; | ||
| default: | ||
| throw new Exception("Error!"); | ||
| } | ||
| } | ||
| i++; | ||
| } | ||
| } | ||
| } | ||
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| class LogObserver : IObserver<IFasterScanIterator<CacheKey, CacheValue>> | ||
| { | ||
| public static int EvictCount = 0; | ||
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| public void OnCompleted() { } | ||
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| public void OnError(Exception error) { } | ||
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| public void OnNext(IFasterScanIterator<CacheKey, CacheValue> iter) | ||
| { | ||
| int cnt = 0; | ||
| while (iter.GetNext(out RecordInfo info, out CacheKey _, out CacheValue _)) | ||
| { | ||
| if (!info.Tombstone) // ignore deleted records being evicted | ||
| cnt++; | ||
| } | ||
| Interlocked.Add(ref EvictCount, cnt); | ||
| } | ||
| } | ||
| } |
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| // Copyright (c) Microsoft Corporation. All rights reserved. | ||
| // Licensed under the MIT license. | ||
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| using FASTER.core; | ||
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| namespace MemOnlyCache | ||
| { | ||
| public sealed class CacheKey : IFasterEqualityComparer<CacheKey> | ||
| { | ||
| public long key; | ||
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| public CacheKey() { } | ||
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| public CacheKey(long first) | ||
| { | ||
| key = first; | ||
| } | ||
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| public long GetHashCode64(ref CacheKey key) => Utility.GetHashCode(key.key); | ||
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| public bool Equals(ref CacheKey k1, ref CacheKey k2) => k1.key == k2.key; | ||
| } | ||
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| public sealed class CacheValue | ||
| { | ||
| public long value; | ||
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| public CacheValue(long first) | ||
| { | ||
| value = first; | ||
| } | ||
| } | ||
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| /// <summary> | ||
| /// Callback for FASTER operations | ||
| /// </summary> | ||
| public sealed class CacheFunctions : SimpleFunctions<CacheKey, CacheValue> { } | ||
| } |
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| Original file line number | Diff line number | Diff line change |
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| // Copyright (c) Microsoft Corporation. All rights reserved. | ||
| // Licensed under the MIT license. | ||
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| using System; | ||
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| namespace MemOnlyCache | ||
| { | ||
| public class ZipfGenerator | ||
| { | ||
| // Based on "Quickly Generating Billion-Record Synthetic Databases", Jim Gray et al., SIGMOD 1994. | ||
| readonly Random rng; | ||
| readonly private int size; | ||
| readonly double theta; | ||
| readonly double zetaN, alpha, cutoff2, eta; | ||
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| public ZipfGenerator(Random rng, int size, double theta = 0.99) | ||
| { | ||
| this.rng = rng; | ||
| this.size = size; | ||
| this.theta = theta; | ||
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| zetaN = Zeta(size, this.theta); | ||
| alpha = 1.0 / (1.0 - this.theta); | ||
| cutoff2 = Math.Pow(0.5, this.theta); | ||
| var zeta2 = Zeta(2, this.theta); | ||
| eta = (1.0 - Math.Pow(2.0 / size, 1.0 - this.theta)) / (1.0 - zeta2 / zetaN); | ||
| } | ||
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| private static double Zeta(int count, double theta) | ||
| { | ||
| double zetaN = 0.0; | ||
| for (var ii = 1; ii <= count; ++ii) | ||
| zetaN += 1.0 / Math.Pow(ii, theta); | ||
| return zetaN; | ||
| } | ||
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| public int Next() | ||
| { | ||
| double u = (double)rng.Next(int.MaxValue) / int.MaxValue; | ||
| double uz = u * zetaN; | ||
| if (uz < 1) | ||
| return 0; | ||
| if (uz < 1 + cutoff2) | ||
| return 1; | ||
| return (int)(size * Math.Pow(eta * u - eta + 1, alpha)); | ||
| } | ||
| } | ||
| } |
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