From dc589650427f2ab444a7ebf78fb59ee751a4c2c8 Mon Sep 17 00:00:00 2001
From: Dan Engelbrecht <dan.engelbrecht@epicgames.com>
Date: Mon, 2 May 2022 10:53:41 +0200
Subject: use std::vector<std::pair>> instead of map

---
 zenserver/cache/structuredcachestore.cpp | 22 ++--------------------
 zenstore/blockstore.cpp                  |  8 ++++----
 zenstore/compactcas.cpp                  | 20 ++------------------
 zenstore/include/zenstore/blockstore.h   |  8 ++++----
 4 files changed, 12 insertions(+), 46 deletions(-)

diff --git a/zenserver/cache/structuredcachestore.cpp b/zenserver/cache/structuredcachestore.cpp
index e9c051f88..9cfb5fbf3 100644
--- a/zenserver/cache/structuredcachestore.cpp
+++ b/zenserver/cache/structuredcachestore.cpp
@@ -156,24 +156,6 @@ namespace {
 		return BucketDir / (std::string("zen") + LegacyDataExtension);
 	}
 
-	std::vector<DiskIndexEntry> MakeDiskIndexEntries(const std::unordered_map<IoHash, DiskLocation>& MovedChunks,
-													 const std::vector<IoHash>&						 DeletedChunks)
-	{
-		std::vector<DiskIndexEntry> result;
-		result.reserve(MovedChunks.size());
-		for (const auto& MovedEntry : MovedChunks)
-		{
-			result.push_back({.Key = MovedEntry.first, .Location = MovedEntry.second});
-		}
-		for (const IoHash& ChunkHash : DeletedChunks)
-		{
-			DiskLocation Location;
-			Location.Flags |= DiskLocation::kTombStone;
-			result.push_back({.Key = ChunkHash, .Location = Location});
-		}
-		return result;
-	}
-
 	bool ValidateLegacyEntry(const LegacyDiskIndexEntry& Entry, std::string& OutReason)
 	{
 		if (Entry.Key == IoHash::Zero)
@@ -1659,8 +1641,8 @@ ZenCacheDiskLayer::CacheBucket::CollectGarbage(GcContext& GcCtx)
 		m_PayloadAlignment,
 		false,
 		[this, &DeletedChunks, &ChunkIndexToChunkHash, &Index, &ReadBlockTimeUs, &ReadBlockLongestTimeUs](
-			const std::unordered_map<size_t, BlockStoreLocation>& MovedChunks,
-			const std::vector<size_t>&							  RemovedChunks) {
+			const std::vector<std::pair<size_t, BlockStoreLocation>>& MovedChunks,
+			const std::vector<size_t>&								  RemovedChunks) {
 			std::vector<DiskIndexEntry> LogEntries;
 			LogEntries.reserve(MovedChunks.size() + RemovedChunks.size());
 			for (const auto& Entry : MovedChunks)
diff --git a/zenstore/blockstore.cpp b/zenstore/blockstore.cpp
index 3358075ec..593ccc529 100644
--- a/zenstore/blockstore.cpp
+++ b/zenstore/blockstore.cpp
@@ -459,8 +459,8 @@ BlockStore::ReclaimSpace(const ReclaimSnapshotState&			Snapshot,
 			continue;
 		}
 
-		std::unordered_map<size_t, BlockStoreLocation> MovedChunks;
-		std::vector<uint8_t>						   Chunk;
+		std::vector<std::pair<size_t, BlockStoreLocation>> MovedChunks;
+		std::vector<uint8_t>							   Chunk;
 		for (const size_t& ChunkIndex : KeepMap)
 		{
 			const BlockStoreLocation ChunkLocation = ChunkLocations[ChunkIndex];
@@ -541,8 +541,8 @@ BlockStore::ReclaimSpace(const ReclaimSnapshotState&			Snapshot,
 			}
 
 			NewBlockFile->Write(Chunk.data(), Chunk.size(), WriteOffset);
-			MovedChunks[ChunkIndex] = {.BlockIndex = NewBlockIndex, .Offset = WriteOffset, .Size = Chunk.size()};
-			WriteOffset				= RoundUp(WriteOffset + Chunk.size(), PayloadAlignment);
+			MovedChunks.push_back({ChunkIndex, {.BlockIndex = NewBlockIndex, .Offset = WriteOffset, .Size = Chunk.size()}});
+			WriteOffset = RoundUp(WriteOffset + Chunk.size(), PayloadAlignment);
 		}
 		Chunk.clear();
 		if (NewBlockFile)
diff --git a/zenstore/compactcas.cpp b/zenstore/compactcas.cpp
index 8d90ba186..6a9cba817 100644
--- a/zenstore/compactcas.cpp
+++ b/zenstore/compactcas.cpp
@@ -48,22 +48,6 @@ struct CasDiskIndexHeader
 static_assert(sizeof(CasDiskIndexHeader) == 32);
 
 namespace {
-	std::vector<CasDiskIndexEntry> MakeCasDiskEntries(const std::unordered_map<IoHash, BlockStoreDiskLocation>& MovedChunks,
-													  const std::vector<IoHash>&								DeletedChunks)
-	{
-		std::vector<CasDiskIndexEntry> result;
-		result.reserve(MovedChunks.size());
-		for (const auto& MovedEntry : MovedChunks)
-		{
-			result.push_back({.Key = MovedEntry.first, .Location = MovedEntry.second});
-		}
-		for (const IoHash& ChunkHash : DeletedChunks)
-		{
-			result.push_back({.Key = ChunkHash, .Flags = CasDiskIndexEntry::kTombstone});
-		}
-		return result;
-	}
-
 	const char* IndexExtension = ".uidx";
 	const char* LogExtension   = ".ulog";
 
@@ -493,8 +477,8 @@ CasContainerStrategy::CollectGarbage(GcContext& GcCtx)
 		m_PayloadAlignment,
 		false,
 		[this, &DeletedChunks, &ChunkIndexToChunkHash, &LocationMap, &ReadBlockTimeUs, &ReadBlockLongestTimeUs](
-			const std::unordered_map<size_t, BlockStoreLocation>& MovedChunks,
-			const std::vector<size_t>&							  RemovedChunks) {
+			const std::vector<std::pair<size_t, BlockStoreLocation>>& MovedChunks,
+			const std::vector<size_t>&								  RemovedChunks) {
 			std::vector<CasDiskIndexEntry> LogEntries;
 			LogEntries.reserve(MovedChunks.size() + RemovedChunks.size());
 			for (const auto& Entry : MovedChunks)
diff --git a/zenstore/include/zenstore/blockstore.h b/zenstore/include/zenstore/blockstore.h
index 0cef7600f..17f4e090e 100644
--- a/zenstore/include/zenstore/blockstore.h
+++ b/zenstore/include/zenstore/blockstore.h
@@ -117,13 +117,13 @@ public:
 		std::unordered_set<uint32_t> ExcludeBlockIndexes;
 		size_t						 BlockCount;
 	};
-	typedef std::function<void(const std::unordered_map<size_t, BlockStoreLocation>& MovedChunks, const std::vector<size_t>& RemovedChunks)>
+	typedef std::function<void(const std::vector<std::pair<size_t, BlockStoreLocation>>& MovedChunks,
+							   const std::vector<size_t>&								 RemovedChunks)>
 																										 ReclaimCallback;
 	typedef std::function<void(const BlockStoreLocation& Location)>										 WriteChunkCallback;
 	typedef std::function<void(size_t ChunkIndex, const void* Data, uint64_t Size)>						 IterateChunksSmallSizeCallback;
 	typedef std::function<void(size_t ChunkIndex, BasicFile& BlockFile, uint64_t Offset, uint64_t Size)> IterateChunksLargeSizeCallback;
-
-	typedef std::function<void(const std::vector<std::pair<size_t, BlockStoreLocation>>& MovedChunks)> SplitCallback;
+	typedef std::function<void(const std::vector<std::pair<size_t, BlockStoreLocation>>& MovedChunks)>	 SplitCallback;
 
 	void Initialize(const std::filesystem::path&		   BlocksBasePath,
 					uint64_t							   MaxBlockSize,
@@ -144,7 +144,7 @@ public:
 						const std::vector<size_t>&			   KeepChunkIndexes,
 						uint64_t							   PayloadAlignment,
 						bool								   DryRun,
-						const ReclaimCallback& Callback = [](const std::unordered_map<size_t, BlockStoreLocation>&, const std::vector<size_t>&) {});
+						const ReclaimCallback& Callback = [](const std::vector<std::pair<size_t, BlockStoreLocation>>&, const std::vector<size_t>&) {});
 	void		IterateChunks(const std::vector<BlockStoreLocation>& ChunkLocations,
 							  IterateChunksSmallSizeCallback		 SmallSizeCallback,
 							  IterateChunksLargeSizeCallback		 LargeSizeCallback);
-- 
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