forked from OSchip/llvm-project
Support: Move OnDiskHashTable from clang to llvm
This introduces clang's Basic/OnDiskHashTable.h into llvm as Support/OnDiskHashTable.h. I've taken the opportunity to add doxygen comments and run the file through clang-format, but other than the namespace changing from clang:: to llvm:: the API is identical. llvm-svn: 206438
This commit is contained in:
Justin Bogner
parent
51df0c1965
commit
033135c5eb
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//===--- OnDiskHashTable.h - On-Disk Hash Table Implementation --*- C++ -*-===//
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//
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// The LLVM Compiler Infrastructure
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//
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// This file is distributed under the University of Illinois Open Source
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// License. See LICENSE.TXT for details.
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//
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//===----------------------------------------------------------------------===//
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///
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/// \file
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/// \brief Defines facilities for reading and writing on-disk hash tables.
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///
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//===----------------------------------------------------------------------===//
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#ifndef LLVM_SUPPORT_ON_DISK_HASH_TABLE_H
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#define LLVM_SUPPORT_ON_DISK_HASH_TABLE_H
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#include "llvm/Support/Allocator.h"
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#include "llvm/Support/AlignOf.h"
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#include "llvm/Support/DataTypes.h"
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#include "llvm/Support/EndianStream.h"
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#include "llvm/Support/Host.h"
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#include "llvm/Support/MathExtras.h"
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#include "llvm/Support/raw_ostream.h"
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#include <cassert>
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#include <cstdlib>
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namespace llvm {
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/// \brief Generates an on disk hash table.
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///
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/// This needs an \c Info that handles storing values into the hash table's
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/// payload and computes the hash for a given key. This should provide the
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/// following interface:
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///
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/// \code
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/// class ExampleInfo {
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/// public:
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/// typedef ExampleKey key_type; // Must be copy constructible
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/// typedef ExampleKey &key_type_ref;
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/// typedef ExampleData data_type; // Must be copy constructible
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/// typedef ExampleData &data_type_ref;
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///
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/// /// Calculate the hash for Key
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/// static unsigned ComputeHash(key_type_ref Key);
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/// /// Return the lengths, in bytes, of the given Key/Data pair.
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/// static std::pair<unsigned, unsigned>
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/// EmitKeyDataLength(raw_ostream &Out, key_type_ref Key, data_type_ref Data);
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/// /// Write Key to Out. KeyLen is the length from EmitKeyDataLength.
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/// static void EmitKey(raw_ostream &Out, key_type_ref Key, unsigned KeyLen);
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/// /// Write Data to Out. DataLen is the length from EmitKeyDataLength.
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/// static void EmitData(raw_ostream &Out, key_type_ref Key,
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/// data_type_ref Data, unsigned DataLen);
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/// };
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/// \endcode
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template <typename Info> class OnDiskChainedHashTableGenerator {
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unsigned NumBuckets;
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unsigned NumEntries;
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llvm::BumpPtrAllocator BA;
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/// \brief A single item in the hash table.
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class Item {
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public:
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typename Info::key_type Key;
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typename Info::data_type Data;
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Item *Next;
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const uint32_t Hash;
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Item(typename Info::key_type_ref Key, typename Info::data_type_ref Data,
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Info &InfoObj)
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: Key(Key), Data(Data), Next(0), Hash(InfoObj.ComputeHash(Key)) {}
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};
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/// \brief A linked list of values in a particular hash bucket.
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class Bucket {
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public:
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uint32_t Off;
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Item *Head;
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unsigned Length;
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Bucket() {}
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};
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Bucket *Buckets;
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private:
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/// \brief Insert an item into the appropriate hash bucket.
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void insert(Bucket *Buckets, size_t Size, Item *E) {
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Bucket &B = Buckets[E->Hash & (Size - 1)];
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E->Next = B.Head;
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++B.Length;
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B.Head = E;
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}
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/// \brief Resize the hash table, moving the old entries into the new buckets.
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void resize(size_t NewSize) {
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Bucket *NewBuckets = (Bucket *)std::calloc(NewSize, sizeof(Bucket));
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// Populate NewBuckets with the old entries.
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for (unsigned I = 0; I < NumBuckets; ++I)
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for (Item *E = Buckets[I].Head; E;) {
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Item *N = E->Next;
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E->Next = 0;
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insert(NewBuckets, NewSize, E);
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E = N;
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}
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free(Buckets);
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NumBuckets = NewSize;
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Buckets = NewBuckets;
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}
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public:
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/// \brief Insert an entry into the table.
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void insert(typename Info::key_type_ref Key,
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typename Info::data_type_ref Data) {
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Info InfoObj;
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insert(Key, Data, InfoObj);
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}
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/// \brief Insert an entry into the table.
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///
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/// Uses the provided Info instead of a stack allocated one.
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void insert(typename Info::key_type_ref Key,
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typename Info::data_type_ref Data, Info &InfoObj) {
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++NumEntries;
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if (4 * NumEntries >= 3 * NumBuckets)
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resize(NumBuckets * 2);
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insert(Buckets, NumBuckets,
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new (BA.Allocate<Item>()) Item(Key, Data, InfoObj));
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}
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/// \brief Emit the table to Out, which must not be at offset 0.
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uint32_t Emit(raw_ostream &Out) {
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Info InfoObj;
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return Emit(Out, InfoObj);
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}
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/// \brief Emit the table to Out, which must not be at offset 0.
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///
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/// Uses the provided Info instead of a stack allocated one.
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uint32_t Emit(raw_ostream &Out, Info &InfoObj) {
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using namespace llvm::support;
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endian::Writer<little> LE(Out);
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// Emit the payload of the table.
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for (unsigned I = 0; I < NumBuckets; ++I) {
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Bucket &B = Buckets[I];
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if (!B.Head)
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continue;
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// Store the offset for the data of this bucket.
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B.Off = Out.tell();
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assert(B.Off && "Cannot write a bucket at offset 0. Please add padding.");
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// Write out the number of items in the bucket.
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LE.write<uint16_t>(B.Length);
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assert(B.Length != 0 && "Bucket has a head but zero length?");
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// Write out the entries in the bucket.
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for (Item *I = B.Head; I; I = I->Next) {
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LE.write<uint32_t>(I->Hash);
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const std::pair<unsigned, unsigned> &Len =
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InfoObj.EmitKeyDataLength(Out, I->Key, I->Data);
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InfoObj.EmitKey(Out, I->Key, Len.first);
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InfoObj.EmitData(Out, I->Key, I->Data, Len.second);
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}
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}
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// Pad with zeros so that we can start the hashtable at an aligned address.
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uint32_t TableOff = Out.tell();
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uint64_t N = llvm::OffsetToAlignment(TableOff, alignOf<uint32_t>());
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TableOff += N;
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while (N--)
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LE.write<uint8_t>(0);
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// Emit the hashtable itself.
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LE.write<uint32_t>(NumBuckets);
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LE.write<uint32_t>(NumEntries);
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for (unsigned I = 0; I < NumBuckets; ++I)
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LE.write<uint32_t>(Buckets[I].Off);
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return TableOff;
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}
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OnDiskChainedHashTableGenerator() {
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NumEntries = 0;
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NumBuckets = 64;
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// Note that we do not need to run the constructors of the individual
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// Bucket objects since 'calloc' returns bytes that are all 0.
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Buckets = (Bucket *)std::calloc(NumBuckets, sizeof(Bucket));
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}
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~OnDiskChainedHashTableGenerator() { std::free(Buckets); }
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};
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/// \brief Provides lookup on an on disk hash table.
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///
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/// This needs an \c Info that handles reading values from the hash table's
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/// payload and computes the hash for a given key. This should provide the
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/// following interface:
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///
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/// \code
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/// class ExampleLookupInfo {
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/// public:
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/// typedef ExampleData data_type;
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/// typedef ExampleInternalKey internal_key_type; // The stored key type.
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/// typedef ExampleKey external_key_type; // The type to pass to find().
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///
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/// /// Compare two keys for equality.
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/// static bool EqualKey(internal_key_type &Key1, internal_key_type &Key2);
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/// /// Calculate the hash for the given key.
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/// static unsigned ComputeHash(internal_key_type &IKey);
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/// /// Translate from the semantic type of a key in the hash table to the
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/// /// type that is actually stored and used for hashing and comparisons.
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/// /// The internal and external types are often the same, in which case this
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/// /// can simply return the passed in value.
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/// static const internal_key_type &GetInternalKey(external_key_type &EKey);
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/// /// Read the key and data length from Buffer, leaving it pointing at the
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/// /// following byte.
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/// static std::pair<unsigned, unsigned>
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/// ReadKeyDataLength(const unsigned char *&Buffer);
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/// /// Read the key from Buffer, given the KeyLen as reported from
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/// /// ReadKeyDataLength.
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/// const internal_key_type &ReadKey(const unsigned char *Buffer,
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/// unsigned KeyLen);
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/// /// Read the data for Key from Buffer, given the DataLen as reported from
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/// /// ReadKeyDataLength.
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/// data_type ReadData(StringRef Key, const unsigned char *Buffer,
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/// unsigned DataLen);
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/// };
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/// \endcode
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template <typename Info> class OnDiskChainedHashTable {
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const unsigned NumBuckets;
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const unsigned NumEntries;
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const unsigned char *const Buckets;
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const unsigned char *const Base;
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Info InfoObj;
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public:
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typedef typename Info::internal_key_type internal_key_type;
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typedef typename Info::external_key_type external_key_type;
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typedef typename Info::data_type data_type;
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OnDiskChainedHashTable(unsigned NumBuckets, unsigned NumEntries,
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const unsigned char *Buckets,
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const unsigned char *Base,
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const Info &InfoObj = Info())
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: NumBuckets(NumBuckets), NumEntries(NumEntries), Buckets(Buckets),
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Base(Base), InfoObj(InfoObj) {
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assert((reinterpret_cast<uintptr_t>(Buckets) & 0x3) == 0 &&
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"'buckets' must have a 4-byte alignment");
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}
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unsigned getNumBuckets() const { return NumBuckets; }
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unsigned getNumEntries() const { return NumEntries; }
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const unsigned char *getBase() const { return Base; }
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const unsigned char *getBuckets() const { return Buckets; }
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bool isEmpty() const { return NumEntries == 0; }
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class iterator {
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internal_key_type Key;
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const unsigned char *const Data;
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const unsigned Len;
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Info *InfoObj;
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public:
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iterator() : Data(0), Len(0) {}
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iterator(const internal_key_type K, const unsigned char *D, unsigned L,
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Info *InfoObj)
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: Key(K), Data(D), Len(L), InfoObj(InfoObj) {}
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data_type operator*() const { return InfoObj->ReadData(Key, Data, Len); }
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bool operator==(const iterator &X) const { return X.Data == Data; }
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bool operator!=(const iterator &X) const { return X.Data != Data; }
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};
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/// \brief Look up the stored data for a particular key.
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iterator find(const external_key_type &EKey, Info *InfoPtr = 0) {
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if (!InfoPtr)
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InfoPtr = &InfoObj;
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using namespace llvm::support;
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const internal_key_type &IKey = InfoObj.GetInternalKey(EKey);
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unsigned KeyHash = InfoObj.ComputeHash(IKey);
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// Each bucket is just a 32-bit offset into the hash table file.
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unsigned Idx = KeyHash & (NumBuckets - 1);
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const unsigned char *Bucket = Buckets + sizeof(uint32_t) * Idx;
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unsigned Offset = endian::readNext<uint32_t, little, aligned>(Bucket);
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if (Offset == 0)
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return iterator(); // Empty bucket.
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const unsigned char *Items = Base + Offset;
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// 'Items' starts with a 16-bit unsigned integer representing the
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// number of items in this bucket.
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unsigned Len = endian::readNext<uint16_t, little, unaligned>(Items);
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for (unsigned i = 0; i < Len; ++i) {
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// Read the hash.
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uint32_t ItemHash = endian::readNext<uint32_t, little, unaligned>(Items);
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// Determine the length of the key and the data.
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const std::pair<unsigned, unsigned> &L = Info::ReadKeyDataLength(Items);
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unsigned ItemLen = L.first + L.second;
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// Compare the hashes. If they are not the same, skip the entry entirely.
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if (ItemHash != KeyHash) {
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Items += ItemLen;
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continue;
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}
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// Read the key.
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const internal_key_type &X =
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InfoPtr->ReadKey((const unsigned char *const)Items, L.first);
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// If the key doesn't match just skip reading the value.
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if (!InfoPtr->EqualKey(X, IKey)) {
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Items += ItemLen;
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continue;
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}
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// The key matches!
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return iterator(X, Items + L.first, L.second, InfoPtr);
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}
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return iterator();
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}
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iterator end() const { return iterator(); }
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Info &getInfoObj() { return InfoObj; }
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/// \brief Create the hash table.
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///
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/// \param Buckets is the beginning of the hash table itself, which follows
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/// the payload of entire structure. This is the value returned by
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/// OnDiskHashTableGenerator::Emit.
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///
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/// \param Base is the point from which all offsets into the structure are
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/// based. This is offset 0 in the stream that was used when Emitting the
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/// table.
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static OnDiskChainedHashTable *Create(const unsigned char *Buckets,
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const unsigned char *const Base,
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const Info &InfoObj = Info()) {
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using namespace llvm::support;
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assert(Buckets > Base);
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assert((reinterpret_cast<uintptr_t>(Buckets) & 0x3) == 0 &&
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"buckets should be 4-byte aligned.");
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unsigned NumBuckets = endian::readNext<uint32_t, little, aligned>(Buckets);
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unsigned NumEntries = endian::readNext<uint32_t, little, aligned>(Buckets);
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return new OnDiskChainedHashTable<Info>(NumBuckets, NumEntries, Buckets,
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Base, InfoObj);
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}
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};
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/// \brief Provides lookup and iteration over an on disk hash table.
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///
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/// \copydetails llvm::OnDiskChainedHashTable
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template <typename Info>
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class OnDiskIterableChainedHashTable : public OnDiskChainedHashTable<Info> {
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const unsigned char *Payload;
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public:
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typedef OnDiskChainedHashTable<Info> base_type;
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typedef typename base_type::internal_key_type internal_key_type;
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typedef typename base_type::external_key_type external_key_type;
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typedef typename base_type::data_type data_type;
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OnDiskIterableChainedHashTable(unsigned NumBuckets, unsigned NumEntries,
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const unsigned char *Buckets,
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const unsigned char *Payload,
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const unsigned char *Base,
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const Info &InfoObj = Info())
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: base_type(NumBuckets, NumEntries, Buckets, Base, InfoObj),
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Payload(Payload) {}
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/// \brief Iterates over all of the keys in the table.
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class key_iterator {
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const unsigned char *Ptr;
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unsigned NumItemsInBucketLeft;
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unsigned NumEntriesLeft;
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Info *InfoObj;
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public:
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typedef external_key_type value_type;
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key_iterator(const unsigned char *const Ptr, unsigned NumEntries,
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Info *InfoObj)
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: Ptr(Ptr), NumItemsInBucketLeft(0), NumEntriesLeft(NumEntries),
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InfoObj(InfoObj) {}
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key_iterator()
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: Ptr(0), NumItemsInBucketLeft(0), NumEntriesLeft(0), InfoObj(0) {}
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friend bool operator==(const key_iterator &X, const key_iterator &Y) {
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return X.NumEntriesLeft == Y.NumEntriesLeft;
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}
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friend bool operator!=(const key_iterator &X, const key_iterator &Y) {
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return X.NumEntriesLeft != Y.NumEntriesLeft;
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}
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key_iterator &operator++() { // Preincrement
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using namespace llvm::support;
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if (!NumItemsInBucketLeft) {
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// 'Items' starts with a 16-bit unsigned integer representing the
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// number of items in this bucket.
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NumItemsInBucketLeft =
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endian::readNext<uint16_t, little, unaligned>(Ptr);
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}
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Ptr += 4; // Skip the hash.
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// Determine the length of the key and the data.
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const std::pair<unsigned, unsigned> &L = Info::ReadKeyDataLength(Ptr);
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Ptr += L.first + L.second;
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assert(NumItemsInBucketLeft);
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--NumItemsInBucketLeft;
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assert(NumEntriesLeft);
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--NumEntriesLeft;
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return *this;
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}
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key_iterator operator++(int) { // Postincrement
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key_iterator tmp = *this; ++*this; return tmp;
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}
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value_type operator*() const {
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const unsigned char *LocalPtr = Ptr;
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if (!NumItemsInBucketLeft)
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LocalPtr += 2; // number of items in bucket
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LocalPtr += 4; // Skip the hash.
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// Determine the length of the key and the data.
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const std::pair<unsigned, unsigned> &L =
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Info::ReadKeyDataLength(LocalPtr);
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// Read the key.
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const internal_key_type &Key = InfoObj->ReadKey(LocalPtr, L.first);
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return InfoObj->GetExternalKey(Key);
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}
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};
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key_iterator key_begin() {
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return key_iterator(Payload, this->getNumEntries(), &this->getInfoObj());
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}
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key_iterator key_end() { return key_iterator(); }
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/// \brief Iterates over all the entries in the table, returning the data.
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class data_iterator {
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const unsigned char *Ptr;
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unsigned NumItemsInBucketLeft;
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unsigned NumEntriesLeft;
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Info *InfoObj;
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public:
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typedef data_type value_type;
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data_iterator(const unsigned char *const Ptr, unsigned NumEntries,
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Info *InfoObj)
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: Ptr(Ptr), NumItemsInBucketLeft(0), NumEntriesLeft(NumEntries),
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InfoObj(InfoObj) {}
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data_iterator()
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: Ptr(0), NumItemsInBucketLeft(0), NumEntriesLeft(0), InfoObj(0) {}
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||||
|
||||
bool operator==(const data_iterator &X) const {
|
||||
return X.NumEntriesLeft == NumEntriesLeft;
|
||||
}
|
||||
bool operator!=(const data_iterator &X) const {
|
||||
return X.NumEntriesLeft != NumEntriesLeft;
|
||||
}
|
||||
|
||||
data_iterator &operator++() { // Preincrement
|
||||
using namespace llvm::support;
|
||||
if (!NumItemsInBucketLeft) {
|
||||
// 'Items' starts with a 16-bit unsigned integer representing the
|
||||
// number of items in this bucket.
|
||||
NumItemsInBucketLeft =
|
||||
endian::readNext<uint16_t, little, unaligned>(Ptr);
|
||||
}
|
||||
Ptr += 4; // Skip the hash.
|
||||
// Determine the length of the key and the data.
|
||||
const std::pair<unsigned, unsigned> &L = Info::ReadKeyDataLength(Ptr);
|
||||
Ptr += L.first + L.second;
|
||||
assert(NumItemsInBucketLeft);
|
||||
--NumItemsInBucketLeft;
|
||||
assert(NumEntriesLeft);
|
||||
--NumEntriesLeft;
|
||||
return *this;
|
||||
}
|
||||
data_iterator operator++(int) { // Postincrement
|
||||
data_iterator tmp = *this; ++*this; return tmp;
|
||||
}
|
||||
|
||||
value_type operator*() const {
|
||||
const unsigned char *LocalPtr = Ptr;
|
||||
if (!NumItemsInBucketLeft)
|
||||
LocalPtr += 2; // number of items in bucket
|
||||
LocalPtr += 4; // Skip the hash.
|
||||
|
||||
// Determine the length of the key and the data.
|
||||
const std::pair<unsigned, unsigned> &L =
|
||||
Info::ReadKeyDataLength(LocalPtr);
|
||||
|
||||
// Read the key.
|
||||
const internal_key_type &Key = InfoObj->ReadKey(LocalPtr, L.first);
|
||||
return InfoObj->ReadData(Key, LocalPtr + L.first, L.second);
|
||||
}
|
||||
};
|
||||
|
||||
data_iterator data_begin() {
|
||||
return data_iterator(Payload, this->getNumEntries(), &this->getInfoObj());
|
||||
}
|
||||
data_iterator data_end() { return data_iterator(); }
|
||||
|
||||
/// \brief Create the hash table.
|
||||
///
|
||||
/// \param Buckets is the beginning of the hash table itself, which follows
|
||||
/// the payload of entire structure. This is the value returned by
|
||||
/// OnDiskHashTableGenerator::Emit.
|
||||
///
|
||||
/// \param Payload is the beginning of the data contained in the table. This
|
||||
/// is Base plus any padding or header data that was stored, ie, the offset
|
||||
/// that the stream was at when calling Emit.
|
||||
///
|
||||
/// \param Base is the point from which all offsets into the structure are
|
||||
/// based. This is offset 0 in the stream that was used when Emitting the
|
||||
/// table.
|
||||
static OnDiskIterableChainedHashTable *
|
||||
Create(const unsigned char *Buckets, const unsigned char *const Payload,
|
||||
const unsigned char *const Base, const Info &InfoObj = Info()) {
|
||||
using namespace llvm::support;
|
||||
assert(Buckets > Base);
|
||||
assert((reinterpret_cast<uintptr_t>(Buckets) & 0x3) == 0 &&
|
||||
"buckets should be 4-byte aligned.");
|
||||
|
||||
unsigned NumBuckets = endian::readNext<uint32_t, little, aligned>(Buckets);
|
||||
unsigned NumEntries = endian::readNext<uint32_t, little, aligned>(Buckets);
|
||||
return new OnDiskIterableChainedHashTable<Info>(
|
||||
NumBuckets, NumEntries, Buckets, Payload, Base, InfoObj);
|
||||
}
|
||||
};
|
||||
|
||||
} // end namespace llvm
|
||||
|
||||
#endif // LLVM_SUPPORT_ON_DISK_HASH_TABLE_H
|
||||
Loading…
Reference in New Issue