1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
|
// Copyright Epic Games, Inc. All Rights Reserved.
#include "zenstore/cidstore.h"
#include <zencore/compress.h>
#include <zencore/filesystem.h>
#include <zencore/logging.h>
#include <zenstore/CAS.h>
#include <zenstore/caslog.h>
#include <filesystem>
namespace zen {
struct CidStore::CidState
{
CidState(CasStore& InCasStore) : m_CasStore(InCasStore) {}
struct IndexEntry
{
IoHash Uncompressed;
IoHash Compressed;
};
CasStore& m_CasStore;
TCasLogFile<IndexEntry> m_LogFile;
RwLock m_Lock;
tsl::robin_map<IoHash, IoHash> m_CidMap;
CidStore::InsertResult AddChunk(CompressedBuffer& ChunkData)
{
const IoHash DecompressedId = IoHash::FromBLAKE3(ChunkData.GetRawHash());
IoBuffer Payload = ChunkData.GetCompressed().Flatten().AsIoBuffer();
IoHash CompressedHash = IoHash::HashBuffer(Payload.Data(), Payload.Size());
CasStore::InsertResult Result = m_CasStore.InsertChunk(Payload, CompressedHash);
AddCompressedCid(DecompressedId, CompressedHash);
return {.DecompressedId = DecompressedId, .CompressedHash = CompressedHash, .New = Result.New};
}
void AddCompressedCid(const IoHash& DecompressedId, const IoHash& Compressed)
{
RwLock::ExclusiveLockScope _(m_Lock);
m_CidMap.insert_or_assign(DecompressedId, Compressed);
// TODO: it's pretty wasteful to log even idempotent updates
// however we can't simply use the boolean returned by insert_or_assign
// since there's not a 1:1 mapping between compressed and uncompressed
// so if we want a last-write-wins policy then we have to log each update
m_LogFile.Append({.Uncompressed = DecompressedId, .Compressed = Compressed});
}
IoBuffer FindChunkByCid(const IoHash& DecompressedId)
{
IoHash CompressedHash;
{
RwLock::SharedLockScope _(m_Lock);
if (auto It = m_CidMap.find(DecompressedId); It != m_CidMap.end())
{
CompressedHash = It->second;
}
}
if (CompressedHash != IoHash::Zero)
{
return m_CasStore.FindChunk(CompressedHash);
}
return IoBuffer();
}
bool ContainsChunk(const IoHash& DecompressedId)
{
RwLock::SharedLockScope _(m_Lock);
// Note that we do not check CAS here. This is optimistic but usually
// what we want.
return m_CidMap.find(DecompressedId) != m_CidMap.end();
}
void InitializeIndex(const std::filesystem::path& RootDir)
{
CreateDirectories(RootDir);
std::filesystem::path SlogPath{RootDir / "cid.slog"};
bool IsNew = !std::filesystem::exists(SlogPath);
m_LogFile.Open(SlogPath, IsNew);
m_LogFile.Replay([&](const IndexEntry& Ie) {
if (Ie.Compressed != IoHash::Zero)
{
// Update
m_CidMap.insert_or_assign(Ie.Uncompressed, Ie.Compressed);
}
else
{
// Tombstone
m_CidMap.erase(Ie.Uncompressed);
}
});
ZEN_DEBUG("CID index initialized: {} entries found", m_CidMap.size());
}
void Flush() { m_LogFile.Flush(); }
void Scrub(ScrubContext& Ctx)
{
CasChunkSet ChunkSet;
{
RwLock::SharedLockScope _(m_Lock);
for (auto& Kv : m_CidMap)
{
ChunkSet.AddChunk(Kv.second);
}
}
m_CasStore.FilterChunks(ChunkSet);
if (ChunkSet.IsEmpty())
{
// All good - we have all the chunks
return;
}
ZEN_ERROR("Scrubbing found that {} cid mappings mapped to non-existent CAS chunks", ChunkSet.GetChunkSet().size());
// Erase all mappings to chunks which are not present in the underlying CAS store
// we do this by removing mappings from the in-memory lookup structure and also
// by emitting tombstone records to the commit log
const auto& MissingChunks = ChunkSet.GetChunkSet();
std::vector<IoHash> BadChunks;
{
RwLock::SharedLockScope _(m_Lock);
for (auto It = begin(m_CidMap), ItEnd = end(m_CidMap); It != ItEnd;)
{
if (auto MissingIt = MissingChunks.find(It->second); MissingIt != MissingChunks.end())
{
const IoHash& BadHash = It->first;
// Log a tombstone record
m_LogFile.Append({.Uncompressed = BadHash, .Compressed = IoHash::Zero});
BadChunks.push_back(BadHash);
It = m_CidMap.erase(It);
}
else
{
++It;
}
}
}
m_LogFile.Flush();
// TODO: Should compute a snapshot index here
Ctx.ReportBadChunks(BadChunks);
}
};
//////////////////////////////////////////////////////////////////////////
CidStore::CidStore(CasStore& InCasStore, const std::filesystem::path& RootDir) : m_Impl(std::make_unique<CidState>(InCasStore))
{
m_Impl->InitializeIndex(RootDir);
}
CidStore::~CidStore()
{
}
CidStore::InsertResult
CidStore::AddChunk(CompressedBuffer& ChunkData)
{
return m_Impl->AddChunk(ChunkData);
}
void
CidStore::AddCompressedCid(const IoHash& DecompressedId, const IoHash& Compressed)
{
m_Impl->AddCompressedCid(DecompressedId, Compressed);
}
IoBuffer
CidStore::FindChunkByCid(const IoHash& DecompressedId)
{
return m_Impl->FindChunkByCid(DecompressedId);
}
bool
CidStore::ContainsChunk(const IoHash& DecompressedId)
{
return m_Impl->ContainsChunk(DecompressedId);
}
void
CidStore::Flush()
{
m_Impl->Flush();
}
void
CidStore::Scrub(ScrubContext& Ctx)
{
m_Impl->Scrub(Ctx);
}
} // namespace zen
|