| //===- MultiOnDiskHashTable.h - Merged set of hash tables -------*- C++ -*-===// |
| // |
| // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. |
| // See https://llvm.org/LICENSE.txt for license information. |
| // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception |
| // |
| //===----------------------------------------------------------------------===// |
| // |
| // This file provides a hash table data structure suitable for incremental and |
| // distributed storage across a set of files. |
| // |
| // Multiple hash tables from different files are implicitly merged to improve |
| // performance, and on reload the merged table will override those from other |
| // files. |
| // |
| //===----------------------------------------------------------------------===// |
| |
| #ifndef LLVM_CLANG_LIB_SERIALIZATION_MULTIONDISKHASHTABLE_H |
| #define LLVM_CLANG_LIB_SERIALIZATION_MULTIONDISKHASHTABLE_H |
| |
| #include "llvm/ADT/DenseMap.h" |
| #include "llvm/ADT/DenseSet.h" |
| #include "llvm/ADT/PointerUnion.h" |
| #include "llvm/ADT/STLExtras.h" |
| #include "llvm/ADT/SmallVector.h" |
| #include "llvm/ADT/TinyPtrVector.h" |
| #include "llvm/ADT/iterator_range.h" |
| #include "llvm/Support/Endian.h" |
| #include "llvm/Support/EndianStream.h" |
| #include "llvm/Support/OnDiskHashTable.h" |
| #include "llvm/Support/raw_ostream.h" |
| #include <algorithm> |
| #include <cstdint> |
| #include <vector> |
| |
| namespace clang { |
| namespace serialization { |
| |
| /// A collection of on-disk hash tables, merged when relevant for performance. |
| template<typename Info> class MultiOnDiskHashTable { |
| public: |
| /// A handle to a file, used when overriding tables. |
| using file_type = typename Info::file_type; |
| |
| /// A pointer to an on-disk representation of the hash table. |
| using storage_type = const unsigned char *; |
| |
| using external_key_type = typename Info::external_key_type; |
| using internal_key_type = typename Info::internal_key_type; |
| using data_type = typename Info::data_type; |
| using data_type_builder = typename Info::data_type_builder; |
| using hash_value_type = unsigned; |
| |
| private: |
| /// The generator is permitted to read our merged table. |
| template<typename ReaderInfo, typename WriterInfo> |
| friend class MultiOnDiskHashTableGenerator; |
| |
| /// A hash table stored on disk. |
| struct OnDiskTable { |
| using HashTable = llvm::OnDiskIterableChainedHashTable<Info>; |
| |
| file_type File; |
| HashTable Table; |
| |
| OnDiskTable(file_type File, unsigned NumBuckets, unsigned NumEntries, |
| storage_type Buckets, storage_type Payload, storage_type Base, |
| const Info &InfoObj) |
| : File(File), |
| Table(NumBuckets, NumEntries, Buckets, Payload, Base, InfoObj) {} |
| }; |
| |
| struct MergedTable { |
| std::vector<file_type> Files; |
| llvm::DenseMap<internal_key_type, data_type> Data; |
| }; |
| |
| using Table = llvm::PointerUnion<OnDiskTable *, MergedTable *>; |
| using TableVector = llvm::TinyPtrVector<void *>; |
| |
| /// The current set of on-disk and merged tables. |
| /// We manually store the opaque value of the Table because TinyPtrVector |
| /// can't cope with holding a PointerUnion directly. |
| /// There can be at most one MergedTable in this vector, and if present, |
| /// it is the first table. |
| TableVector Tables; |
| |
| /// Files corresponding to overridden tables that we've not yet |
| /// discarded. |
| llvm::TinyPtrVector<file_type> PendingOverrides; |
| |
| struct AsOnDiskTable { |
| using result_type = OnDiskTable *; |
| |
| result_type operator()(void *P) const { |
| return Table::getFromOpaqueValue(P).template get<OnDiskTable *>(); |
| } |
| }; |
| |
| using table_iterator = |
| llvm::mapped_iterator<TableVector::iterator, AsOnDiskTable>; |
| using table_range = llvm::iterator_range<table_iterator>; |
| |
| /// The current set of on-disk tables. |
| table_range tables() { |
| auto Begin = Tables.begin(), End = Tables.end(); |
| if (getMergedTable()) |
| ++Begin; |
| return llvm::make_range(llvm::map_iterator(Begin, AsOnDiskTable()), |
| llvm::map_iterator(End, AsOnDiskTable())); |
| } |
| |
| MergedTable *getMergedTable() const { |
| // If we already have a merged table, it's the first one. |
| return Tables.empty() ? nullptr : Table::getFromOpaqueValue(*Tables.begin()) |
| .template dyn_cast<MergedTable*>(); |
| } |
| |
| /// Delete all our current on-disk tables. |
| void clear() { |
| for (auto *T : tables()) |
| delete T; |
| if (auto *M = getMergedTable()) |
| delete M; |
| Tables.clear(); |
| } |
| |
| void removeOverriddenTables() { |
| llvm::DenseSet<file_type> Files; |
| Files.insert(PendingOverrides.begin(), PendingOverrides.end()); |
| // Explicitly capture Files to work around an MSVC 2015 rejects-valid bug. |
| auto ShouldRemove = [&Files](void *T) -> bool { |
| auto *ODT = Table::getFromOpaqueValue(T).template get<OnDiskTable *>(); |
| bool Remove = Files.count(ODT->File); |
| if (Remove) |
| delete ODT; |
| return Remove; |
| }; |
| Tables.erase(std::remove_if(tables().begin().getCurrent(), Tables.end(), |
| ShouldRemove), |
| Tables.end()); |
| PendingOverrides.clear(); |
| } |
| |
| void condense() { |
| MergedTable *Merged = getMergedTable(); |
| if (!Merged) |
| Merged = new MergedTable; |
| |
| // Read in all the tables and merge them together. |
| // FIXME: Be smarter about which tables we merge. |
| for (auto *ODT : tables()) { |
| auto &HT = ODT->Table; |
| Info &InfoObj = HT.getInfoObj(); |
| |
| for (auto I = HT.data_begin(), E = HT.data_end(); I != E; ++I) { |
| auto *LocalPtr = I.getItem(); |
| |
| // FIXME: Don't rely on the OnDiskHashTable format here. |
| auto L = InfoObj.ReadKeyDataLength(LocalPtr); |
| const internal_key_type &Key = InfoObj.ReadKey(LocalPtr, L.first); |
| data_type_builder ValueBuilder(Merged->Data[Key]); |
| InfoObj.ReadDataInto(Key, LocalPtr + L.first, L.second, |
| ValueBuilder); |
| } |
| |
| Merged->Files.push_back(ODT->File); |
| delete ODT; |
| } |
| |
| Tables.clear(); |
| Tables.push_back(Table(Merged).getOpaqueValue()); |
| } |
| |
| public: |
| MultiOnDiskHashTable() = default; |
| |
| MultiOnDiskHashTable(MultiOnDiskHashTable &&O) |
| : Tables(std::move(O.Tables)), |
| PendingOverrides(std::move(O.PendingOverrides)) { |
| O.Tables.clear(); |
| } |
| |
| MultiOnDiskHashTable &operator=(MultiOnDiskHashTable &&O) { |
| if (&O == this) |
| return *this; |
| clear(); |
| Tables = std::move(O.Tables); |
| O.Tables.clear(); |
| PendingOverrides = std::move(O.PendingOverrides); |
| return *this; |
| } |
| |
| ~MultiOnDiskHashTable() { clear(); } |
| |
| /// Add the table \p Data loaded from file \p File. |
| void add(file_type File, storage_type Data, Info InfoObj = Info()) { |
| using namespace llvm::support; |
| |
| storage_type Ptr = Data; |
| |
| uint32_t BucketOffset = endian::readNext<uint32_t, little, unaligned>(Ptr); |
| |
| // Read the list of overridden files. |
| uint32_t NumFiles = endian::readNext<uint32_t, little, unaligned>(Ptr); |
| // FIXME: Add a reserve() to TinyPtrVector so that we don't need to make |
| // an additional copy. |
| llvm::SmallVector<file_type, 16> OverriddenFiles; |
| OverriddenFiles.reserve(NumFiles); |
| for (/**/; NumFiles != 0; --NumFiles) |
| OverriddenFiles.push_back(InfoObj.ReadFileRef(Ptr)); |
| PendingOverrides.insert(PendingOverrides.end(), OverriddenFiles.begin(), |
| OverriddenFiles.end()); |
| |
| // Read the OnDiskChainedHashTable header. |
| storage_type Buckets = Data + BucketOffset; |
| auto NumBucketsAndEntries = |
| OnDiskTable::HashTable::readNumBucketsAndEntries(Buckets); |
| |
| // Register the table. |
| Table NewTable = new OnDiskTable(File, NumBucketsAndEntries.first, |
| NumBucketsAndEntries.second, |
| Buckets, Ptr, Data, std::move(InfoObj)); |
| Tables.push_back(NewTable.getOpaqueValue()); |
| } |
| |
| /// Find and read the lookup results for \p EKey. |
| data_type find(const external_key_type &EKey) { |
| data_type Result; |
| |
| if (!PendingOverrides.empty()) |
| removeOverriddenTables(); |
| |
| if (Tables.size() > static_cast<unsigned>(Info::MaxTables)) |
| condense(); |
| |
| internal_key_type Key = Info::GetInternalKey(EKey); |
| auto KeyHash = Info::ComputeHash(Key); |
| |
| if (MergedTable *M = getMergedTable()) { |
| auto It = M->Data.find(Key); |
| if (It != M->Data.end()) |
| Result = It->second; |
| } |
| |
| data_type_builder ResultBuilder(Result); |
| |
| for (auto *ODT : tables()) { |
| auto &HT = ODT->Table; |
| auto It = HT.find_hashed(Key, KeyHash); |
| if (It != HT.end()) |
| HT.getInfoObj().ReadDataInto(Key, It.getDataPtr(), It.getDataLen(), |
| ResultBuilder); |
| } |
| |
| return Result; |
| } |
| |
| /// Read all the lookup results into a single value. This only makes |
| /// sense if merging values across keys is meaningful. |
| data_type findAll() { |
| data_type Result; |
| data_type_builder ResultBuilder(Result); |
| |
| if (!PendingOverrides.empty()) |
| removeOverriddenTables(); |
| |
| if (MergedTable *M = getMergedTable()) { |
| for (auto &KV : M->Data) |
| Info::MergeDataInto(KV.second, ResultBuilder); |
| } |
| |
| for (auto *ODT : tables()) { |
| auto &HT = ODT->Table; |
| Info &InfoObj = HT.getInfoObj(); |
| for (auto I = HT.data_begin(), E = HT.data_end(); I != E; ++I) { |
| auto *LocalPtr = I.getItem(); |
| |
| // FIXME: Don't rely on the OnDiskHashTable format here. |
| auto L = InfoObj.ReadKeyDataLength(LocalPtr); |
| const internal_key_type &Key = InfoObj.ReadKey(LocalPtr, L.first); |
| InfoObj.ReadDataInto(Key, LocalPtr + L.first, L.second, ResultBuilder); |
| } |
| } |
| |
| return Result; |
| } |
| }; |
| |
| /// Writer for the on-disk hash table. |
| template<typename ReaderInfo, typename WriterInfo> |
| class MultiOnDiskHashTableGenerator { |
| using BaseTable = MultiOnDiskHashTable<ReaderInfo>; |
| using Generator = llvm::OnDiskChainedHashTableGenerator<WriterInfo>; |
| |
| Generator Gen; |
| |
| public: |
| MultiOnDiskHashTableGenerator() : Gen() {} |
| |
| void insert(typename WriterInfo::key_type_ref Key, |
| typename WriterInfo::data_type_ref Data, WriterInfo &Info) { |
| Gen.insert(Key, Data, Info); |
| } |
| |
| void emit(llvm::SmallVectorImpl<char> &Out, WriterInfo &Info, |
| const BaseTable *Base) { |
| using namespace llvm::support; |
| |
| llvm::raw_svector_ostream OutStream(Out); |
| |
| // Write our header information. |
| { |
| endian::Writer Writer(OutStream, little); |
| |
| // Reserve four bytes for the bucket offset. |
| Writer.write<uint32_t>(0); |
| |
| if (auto *Merged = Base ? Base->getMergedTable() : nullptr) { |
| // Write list of overridden files. |
| Writer.write<uint32_t>(Merged->Files.size()); |
| for (const auto &F : Merged->Files) |
| Info.EmitFileRef(OutStream, F); |
| |
| // Add all merged entries from Base to the generator. |
| for (auto &KV : Merged->Data) { |
| if (!Gen.contains(KV.first, Info)) |
| Gen.insert(KV.first, Info.ImportData(KV.second), Info); |
| } |
| } else { |
| Writer.write<uint32_t>(0); |
| } |
| } |
| |
| // Write the table itself. |
| uint32_t BucketOffset = Gen.Emit(OutStream, Info); |
| |
| // Replace the first four bytes with the bucket offset. |
| endian::write32le(Out.data(), BucketOffset); |
| } |
| }; |
| |
| } // namespace serialization |
| } // namespace clang |
| |
| #endif // LLVM_CLANG_LIB_SERIALIZATION_MULTIONDISKHASHTABLE_H |