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[C#] MemOnlyCache sample: improved size tracking, including read cache (
#800) * Improved cache size tracking, including read cache * Rename MemOnlyCache to ResizableCacheStore. * update doc * fixes * Updates
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,101 @@ | ||
| // Copyright (c) Microsoft Corporation. All rights reserved. | ||
| // Licensed under the MIT license. | ||
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| using FASTER.core; | ||
| using System; | ||
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| namespace ResizableCacheStore | ||
| { | ||
| /// <summary> | ||
| /// Cache size tracker | ||
| /// </summary> | ||
| public class CacheSizeTracker | ||
| { | ||
| readonly FasterKV<CacheKey, CacheValue> store; | ||
|
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| /// <summary> | ||
| /// Total size (bytes) used by FASTER including index and log | ||
| /// </summary> | ||
| public long TotalSizeBytes => | ||
| IndexSizeBytes + | ||
| mainLog.TotalSizeBytes + | ||
| (readCache != null ? readCache.TotalSizeBytes : 0); | ||
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| public long IndexSizeBytes => | ||
| store.IndexSize * 64 + | ||
| store.OverflowBucketCount * 64; | ||
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| public long LogSizeBytes => mainLog.TotalSizeBytes; | ||
| public long ReadCacheSizeBytes => readCache != null ? readCache.TotalSizeBytes : 0; | ||
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| readonly LogSizeTracker<CacheKey, CacheValue> mainLog; | ||
| readonly LogSizeTracker<CacheKey, CacheValue> readCache; | ||
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| public void PrintStats() | ||
| { | ||
| Console.WriteLine("Sizes: [store]: {0,8:N2}KB [index]: {1,9:N2}KB [hylog]: {2,8:N2}KB ({3,7} objs) [rcach]: {4,9:N2}KB ({5,7} objs)", | ||
| TotalSizeBytes / 1024.0, | ||
| IndexSizeBytes / 1024.0, | ||
| LogSizeBytes / 1024.0, | ||
| mainLog.NumRecords, | ||
| ReadCacheSizeBytes / 1024.0, | ||
| readCache != null ? readCache.NumRecords : 0 | ||
| ); | ||
| } | ||
|
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| /// <summary> | ||
| /// Class to track and update cache size | ||
| /// </summary> | ||
| /// <param name="store">FASTER store instance</param> | ||
| /// <param name="targetMemoryBytes">Initial target memory size of FASTER in bytes</param> | ||
| public CacheSizeTracker(FasterKV<CacheKey, CacheValue> store, long targetMemoryBytes = long.MaxValue) | ||
| { | ||
| this.store = store; | ||
| this.mainLog = new LogSizeTracker<CacheKey, CacheValue>(store.Log, "mnlog"); | ||
| if (store.ReadCache != null) | ||
| this.readCache = new LogSizeTracker<CacheKey, CacheValue>(store.ReadCache, "readc"); | ||
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| if (targetMemoryBytes < long.MaxValue) | ||
| { | ||
| Console.WriteLine("**** Setting initial target memory: {0,11:N2}KB", targetMemoryBytes / 1024.0); | ||
| SetTargetSizeBytes(targetMemoryBytes); | ||
| } | ||
|
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| PrintStats(); | ||
| } | ||
|
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| /// <summary> | ||
| /// Set target total memory size (in bytes) for the FASTER store | ||
| /// </summary> | ||
| /// <param name="newTargetSize">Target size</param> | ||
| public void SetTargetSizeBytes(long newTargetSize) | ||
| { | ||
| // In this sample, we split the residual space equally between the log and the read cache | ||
| long residual = newTargetSize - IndexSizeBytes; | ||
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| if (residual > 0) | ||
| { | ||
| if (readCache == null) | ||
| mainLog.SetTargetSizeBytes(residual); | ||
| else | ||
| { | ||
| mainLog.SetTargetSizeBytes(residual / 2); | ||
| readCache.SetTargetSizeBytes(residual / 2); | ||
| } | ||
| } | ||
| } | ||
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| /// <summary> | ||
| /// Add to the tracked size of FASTER. This is called by IFunctions as well as the subscriber to evictions (OnNext) | ||
| /// </summary> | ||
| /// <param name="size"></param> | ||
| public void AddTrackedSize(int size, bool isReadCache = false) | ||
| { | ||
| if (isReadCache) | ||
| readCache.AddTrackedSize(size); | ||
| else | ||
| mainLog.AddTrackedSize(size); | ||
| } | ||
| } | ||
| } |
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,10 @@ | ||
| // Copyright (c) Microsoft Corporation. All rights reserved. | ||
| // Licensed under the MIT license. | ||
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| namespace ResizableCacheStore | ||
| { | ||
| public interface ISizeTracker | ||
| { | ||
| int GetSize { get; } | ||
| } | ||
| } |
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,115 @@ | ||
| // Copyright (c) Microsoft Corporation. All rights reserved. | ||
| // Licensed under the MIT license. | ||
|
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| using FASTER.core; | ||
| using System; | ||
| using System.Threading; | ||
|
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| namespace ResizableCacheStore | ||
| { | ||
| public class LogSizeTracker<TCacheKey, TCacheValue> : IObserver<IFasterScanIterator<TCacheKey, TCacheValue>> | ||
| where TCacheKey : ISizeTracker | ||
| where TCacheValue : ISizeTracker | ||
| { | ||
| readonly string name; | ||
|
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| /// <summary> | ||
| /// Number of records in the log | ||
| /// </summary> | ||
| public int NumRecords; | ||
|
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| /// <summary> | ||
| /// Total size occupied by log, including heap | ||
| /// </summary> | ||
| public long TotalSizeBytes => Log.MemorySizeBytes + heapSize; | ||
|
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| /// <summary> | ||
| /// Target size request for FASTER | ||
| /// </summary> | ||
| public long TargetSizeBytes { get; private set; } | ||
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|
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| int heapSize; | ||
| readonly LogAccessor<TCacheKey, TCacheValue> Log; | ||
|
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| public LogSizeTracker(LogAccessor<TCacheKey, TCacheValue> log, string name) | ||
| { | ||
| this.name = name; | ||
| Log = log; | ||
|
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| // Register subscriber to receive notifications of log evictions from memory | ||
| Log.SubscribeEvictions(this); | ||
| } | ||
|
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| /// <summary> | ||
| /// Add to the tracked size of FASTER. This is called by IFunctions as well as the subscriber to evictions (OnNext) | ||
| /// </summary> | ||
| /// <param name="size"></param> | ||
| public void AddTrackedSize(int size) | ||
| { | ||
| Interlocked.Add(ref heapSize, size); | ||
| if (size > 0) Interlocked.Increment(ref NumRecords); | ||
| else Interlocked.Decrement(ref NumRecords); | ||
| } | ||
|
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| /// <summary> | ||
| /// Set target total memory size (in bytes) for the FASTER store | ||
| /// </summary> | ||
| /// <param name="newTargetSize">Target size</param> | ||
| public void SetTargetSizeBytes(long newTargetSize) | ||
| { | ||
| TargetSizeBytes = newTargetSize; | ||
| AdjustAllocation(); | ||
| } | ||
| public void OnNext(IFasterScanIterator<TCacheKey, TCacheValue> iter) | ||
| { | ||
| int size = 0; | ||
| int count = 0; | ||
| while (iter.GetNext(out RecordInfo info, out TCacheKey key, out TCacheValue value)) | ||
| { | ||
| size += key.GetSize; | ||
| count++; | ||
| if (!info.Tombstone) // ignore deleted values being evicted (they are accounted for by ConcurrentDeleter) | ||
| size += value.GetSize; | ||
| } | ||
| Interlocked.Add(ref heapSize, -size); | ||
| Interlocked.Add(ref NumRecords, -count); | ||
| AdjustAllocation(); | ||
| } | ||
|
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| public void OnCompleted() { } | ||
|
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| public void OnError(Exception error) { } | ||
|
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| void AdjustAllocation() | ||
| { | ||
| const long Delta = 1L << 15; | ||
| if (TotalSizeBytes > TargetSizeBytes + Delta) | ||
| { | ||
| while (TotalSizeBytes > TargetSizeBytes + Delta) | ||
| { | ||
| if (Log.AllocatedPageCount > Log.BufferSize - Log.EmptyPageCount + 1) | ||
| { | ||
| // Console.WriteLine($"{name}: {Log.EmptyPageCount} (wait++)"); | ||
| return; // wait for allocation to stabilize | ||
| } | ||
| Log.EmptyPageCount++; | ||
| // Console.WriteLine($"{name}: {Log.EmptyPageCount} (++)"); | ||
| } | ||
| } | ||
| else if (TotalSizeBytes < TargetSizeBytes - Delta) | ||
| { | ||
| while (TotalSizeBytes < TargetSizeBytes - Delta) | ||
| { | ||
| if (Log.AllocatedPageCount < Log.BufferSize - Log.EmptyPageCount - 1) | ||
| { | ||
| // Console.WriteLine($"{name}: {Log.EmptyPageCount} (wait--)"); | ||
| return; // wait for allocation to stabilize | ||
| } | ||
| Log.EmptyPageCount--; | ||
| // Console.WriteLine($"{name}: {Log.EmptyPageCount} (--)"); | ||
| } | ||
| } | ||
| } | ||
| } | ||
| } |
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