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/***************************************************************************
* include/stxxl/bits/containers/sequence.h
*
* based on include/stxxl/bits/containers/queue.h
*
* Part of the STXXL. See http://stxxl.sourceforge.net
*
* Copyright (C) 2012-2013 Timo Bingmann <tb@panthema.net>
*
* Distributed under the Boost Software License, Version 1.0.
* (See accompanying file LICENSE_1_0.txt or copy at
* http://www.boost.org/LICENSE_1_0.txt)
**************************************************************************/
#ifndef STXXL_CONTAINERS_SEQUENCE_HEADER
#define STXXL_CONTAINERS_SEQUENCE_HEADER
#include <deque>
#include <stxxl/bits/deprecated.h>
#include <stxxl/bits/mng/block_manager.h>
#include <stxxl/bits/mng/typed_block.h>
#include <stxxl/bits/common/tmeta.h>
#include <stxxl/bits/mng/read_write_pool.h>
#include <stxxl/bits/mng/write_pool.h>
#include <stxxl/bits/mng/prefetch_pool.h>
STXXL_BEGIN_NAMESPACE
#ifndef STXXL_VERBOSE_SEQUENCE
#define STXXL_VERBOSE_SEQUENCE STXXL_VERBOSE2
#endif
//! \addtogroup stlcont
//! \{
//! \brief External sequence or deque container without random access. \n
//! <b> Introduction </b> to sequence container: see \ref tutorial_sequence tutorial. \n
//! <b> Design and Internals </b> of sequence container: see \ref design_queue
/**
* Sequence is a primitive container consisting of only a sequence of blocks in
* external memory. The sequence provides appending methods similar to a deque:
* push_back and push_front; and also the corresponding pop functions. However,
* different from stxxl::deque (which is a vector in disguise), the sequence
* does not allow random access. Instead, the sequence can only be iterated
* using streams: either from front to back or in reverse.
*
* As with queue and stack, sequences of pushes and pops are made efficient
* using overlapping or read-ahead via block pools. The stream access likewise
* uses overlapped I/O, just like stream::vector_iterator2stream.
*
* \tparam ValueType type of the contained objects (POD with no references to internal memory)
* \tparam BlockSize size of the external memory block in bytes, default is \c STXXL_DEFAULT_BLOCK_SIZE(ValTp)
* \tparam AllocStr parallel disk allocation strategy, default is \c STXXL_DEFAULT_ALLOC_STRATEGY
* \tparam SizeType size data type, default is \c stxxl::uint64
*/
template <class ValueType,
unsigned BlockSize = STXXL_DEFAULT_BLOCK_SIZE(ValueType),
class AllocStr = STXXL_DEFAULT_ALLOC_STRATEGY,
class SizeType = stxxl::uint64>
class sequence : private noncopyable
{
public:
typedef ValueType value_type;
typedef AllocStr alloc_strategy_type;
typedef SizeType size_type;
enum {
block_size = BlockSize
};
typedef typed_block<block_size, value_type> block_type;
typedef BID<block_size> bid_type;
typedef std::deque<bid_type> bid_deque_type;
private:
typedef read_write_pool<block_type> pool_type;
/// current number of items in the sequence
size_type m_size;
/// whether the m_pool object is own and should be deleted.
bool m_owns_pool;
/// read_write_pool of blocks
pool_type* m_pool;
/// current front block of sequence
block_type* m_front_block;
/// current back block of sequence
block_type* m_back_block;
/// pointer to current front element in m_front_block
value_type* m_front_element;
/// pointer to current back element in m_back_block
value_type* m_back_element;
/// block allocation strategy
alloc_strategy_type m_alloc_strategy;
/// block allocation counter
unsigned_type m_alloc_count;
/// allocated block identifiers
bid_deque_type m_bids;
/// block manager used
block_manager* m_bm;
/// number of blocks to prefetch
unsigned_type m_blocks2prefetch;
public:
//! \name Constructors/Destructors
//! \{
//! Constructs empty sequence with own write and prefetch block pool
//!
//! \param D number of parallel disks, defaulting to the configured number of scratch disks,
//! memory consumption will be 2 * D + 2 blocks
//! (first and last block, D blocks as write cache, D block for prefetching)
explicit sequence(int_type D = -1) :
m_size(0),
m_owns_pool(true),
m_alloc_count(0),
m_bm(block_manager::get_instance())
{
if (D < 1) D = config::get_instance()->disks_number();
STXXL_VERBOSE_SEQUENCE("sequence[" << this << "]::sequence(D)");
m_pool = new pool_type(D, D + 2);
init();
}
//! Constructs empty sequence with own write and prefetch block pool
//!
//! \param w_pool_size number of blocks in the write pool, must be at least 2, recommended at least 3
//! \param p_pool_size number of blocks in the prefetch pool, recommended at least 1
//! \param blocks2prefetch defines the number of blocks to prefetch (\c front side),
//! default is number of block in the prefetch pool
explicit sequence(unsigned_type w_pool_size, unsigned_type p_pool_size, int blocks2prefetch = -1) :
m_size(0),
m_owns_pool(true),
m_alloc_count(0),
m_bm(block_manager::get_instance())
{
STXXL_VERBOSE_SEQUENCE("sequence[" << this << "]::sequence(sizes)");
m_pool = new pool_type(p_pool_size, w_pool_size);
init(blocks2prefetch);
}
//! Constructs empty sequence
//!
//! \param pool block write/prefetch pool
//! \param blocks2prefetch defines the number of blocks to prefetch (\c front side), default is number of blocks in the prefetch pool
//! \warning Number of blocks in the write pool must be at least 2, recommended at least 3
//! \warning Number of blocks in the prefetch pool recommended at least 1
sequence(pool_type& pool, int blocks2prefetch = -1) :
m_size(0),
m_owns_pool(false),
m_pool(&pool),
m_alloc_count(0),
m_bm(block_manager::get_instance())
{
STXXL_VERBOSE_SEQUENCE("sequence[" << this << "]::sequence(pool)");
init(blocks2prefetch);
}
//! \}
//! \name Modifiers
//! \{
void swap(sequence& obj)
{
std::swap(m_size, obj.m_size);
std::swap(m_owns_pool, obj.m_owns_pool);
std::swap(m_pool, obj.m_pool);
std::swap(m_front_block, obj.m_front_block);
std::swap(m_back_block, obj.m_back_block);
std::swap(m_front_element, obj.m_front_element);
std::swap(m_back_element, obj.m_back_element);
std::swap(m_alloc_strategy, obj.m_alloc_strategy);
std::swap(m_alloc_count, obj.m_alloc_count);
std::swap(m_bids, obj.m_bids);
std::swap(m_bm, obj.m_bm);
std::swap(m_blocks2prefetch, obj.m_blocks2prefetch);
}
//! \}
private:
void init(int blocks2prefetch = -1)
{
if (m_pool->size_write() < 2) {
STXXL_ERRMSG("sequence: invalid configuration, not enough blocks (" << m_pool->size_write() <<
") in write pool, at least 2 are needed, resizing to 3");
m_pool->resize_write(3);
}
if (m_pool->size_write() < 3) {
STXXL_MSG("sequence: inefficient configuration, no blocks for buffered writing available");
}
if (m_pool->size_prefetch() < 1) {
STXXL_MSG("sequence: inefficient configuration, no blocks for prefetching available");
}
/// initialize empty sequence
m_front_block = m_back_block = m_pool->steal();
m_back_element = m_back_block->begin() - 1;
m_front_element = m_back_block->begin();
set_prefetch_aggr(blocks2prefetch);
}
public:
//! \name Miscellaneous
//! \{
//! Defines the number of blocks to prefetch (\c front side).
//! This method should be called whenever the prefetch pool is resized
//! \param blocks2prefetch defines the number of blocks to prefetch (\c front side),
//! a negative value means to use the number of blocks in the prefetch pool
void set_prefetch_aggr(int_type blocks2prefetch)
{
if (blocks2prefetch < 0)
m_blocks2prefetch = m_pool->size_prefetch();
else
m_blocks2prefetch = blocks2prefetch;
}
//! Returns the number of blocks prefetched from the \c front side
unsigned_type get_prefetch_aggr() const
{
return m_blocks2prefetch;
}
//! \}
//! \name Modifiers
//! \{
//! Adds an element to the front of the sequence
void push_front(const value_type& val)
{
if (UNLIKELY(m_front_element == m_front_block->begin()))
{
if (m_size == 0)
{
STXXL_VERBOSE1("sequence::push_front Case 0");
assert(m_front_block == m_back_block);
m_front_element = m_back_element = m_front_block->end() - 1;
*m_front_element = val;
++m_size;
return;
}
// front block is completely filled
else if (m_front_block == m_back_block)
{
// can not write the front block because it
// is the same as the back block, must keep it memory
STXXL_VERBOSE1("sequence::push_front Case 1");
}
else if (size() < 2 * block_type::size)
{
STXXL_VERBOSE1("sequence::push_front Case 1.5");
// only two blocks with a gap at the end, move elements within memory
assert(m_bids.empty());
size_t gap = m_back_block->end() - (m_back_element + 1);
assert(gap > 0);
std::copy_backward(m_back_block->begin(), m_back_element + 1, m_back_block->end());
std::copy_backward(m_front_block->end() - gap, m_front_block->end(), m_back_block->begin() + gap);
std::copy_backward(m_front_block->begin(), m_front_block->end() - gap, m_front_block->end());
m_front_element += gap;
m_back_element += gap;
--m_front_element;
*m_front_element = val;
++m_size;
return;
}
else
{
STXXL_VERBOSE1("sequence::push_front Case 2");
// write the front block
// need to allocate new block
bid_type newbid;
m_bm->new_block(m_alloc_strategy, newbid, m_alloc_count++);
STXXL_VERBOSE_SEQUENCE("sequence[" << this << "]: push_front block " << m_front_block << " @ " << FMT_BID(newbid));
m_bids.push_front(newbid);
m_pool->write(m_front_block, newbid);
if (m_bids.size() <= m_blocks2prefetch) {
STXXL_VERBOSE1("sequence::push Case Hints");
m_pool->hint(newbid);
}
}
m_front_block = m_pool->steal();
m_front_element = m_front_block->end() - 1;
*m_front_element = val;
++m_size;
}
else // not at beginning of a block
{
--m_front_element;
*m_front_element = val;
++m_size;
}
}
//! Adds an element to the end of the sequence
void push_back(const value_type& val)
{
if (UNLIKELY(m_back_element == m_back_block->begin() + (block_type::size - 1)))
{
// back block is completely filled
if (m_front_block == m_back_block)
{
// can not write the back block because it
// is the same as the front block, must keep it memory
STXXL_VERBOSE1("sequence::push_back Case 1");
}
else if (size() < 2 * block_type::size)
{
STXXL_VERBOSE1("sequence::push_back Case 1.5");
// only two blocks with a gap in the beginning, move elements within memory
assert(m_bids.empty());
size_t gap = m_front_element - m_front_block->begin();
assert(gap > 0);
std::copy(m_front_element, m_front_block->end(), m_front_block->begin());
std::copy(m_back_block->begin(), m_back_block->begin() + gap, m_front_block->begin() + (block_type::size - gap));
std::copy(m_back_block->begin() + gap, m_back_block->end(), m_back_block->begin());
m_front_element -= gap;
m_back_element -= gap;
++m_back_element;
*m_back_element = val;
++m_size;
return;
}
else
{
STXXL_VERBOSE1("sequence::push_back Case 2");
// write the back block
// need to allocate new block
bid_type newbid;
m_bm->new_block(m_alloc_strategy, newbid, m_alloc_count++);
STXXL_VERBOSE_SEQUENCE("sequence[" << this << "]: push_back block " << m_back_block << " @ " << FMT_BID(newbid));
m_bids.push_back(newbid);
m_pool->write(m_back_block, newbid);
if (m_bids.size() <= m_blocks2prefetch) {
STXXL_VERBOSE1("sequence::push_back Case Hints");
m_pool->hint(newbid);
}
}
m_back_block = m_pool->steal();
m_back_element = m_back_block->begin();
*m_back_element = val;
++m_size;
}
else // not at end of a block
{
++m_back_element;
*m_back_element = val;
++m_size;
}
}
//! Removes element from the front of the sequence
void pop_front()
{
assert(!empty());
if (UNLIKELY(m_front_element == m_front_block->begin() + (block_type::size - 1)))
{
// if there is only one block, it implies ...
if (m_back_block == m_front_block)
{
STXXL_VERBOSE1("sequence::pop_front Case 1");
assert(size() == 1);
assert(m_back_element == m_front_element);
assert(m_bids.empty());
// reset everything
m_back_element = m_back_block->begin() - 1;
m_front_element = m_back_block->begin();
m_size = 0;
return;
}
--m_size;
if (m_size <= block_type::size)
{
STXXL_VERBOSE1("sequence::pop_front Case 2");
assert(m_bids.empty());
// the m_back_block is the next block
m_pool->add(m_front_block);
m_front_block = m_back_block;
m_front_element = m_back_block->begin();
return;
}
STXXL_VERBOSE1("sequence::pop_front Case 3");
assert(!m_bids.empty());
request_ptr req = m_pool->read(m_front_block, m_bids.front());
STXXL_VERBOSE_SEQUENCE("sequence[" << this << "]: pop_front block " << m_front_block << " @ " << FMT_BID(m_bids.front()));
// give prefetching hints
for (unsigned_type i = 0; i < m_blocks2prefetch && i < m_bids.size() - 1; ++i)
{
STXXL_VERBOSE1("sequence::pop_front Case Hints");
m_pool->hint(m_bids[i + 1]);
}
m_front_element = m_front_block->begin();
req->wait();
m_bm->delete_block(m_bids.front());
m_bids.pop_front();
}
else
{
++m_front_element;
--m_size;
}
}
//! Removes element from the back of the sequence
void pop_back()
{
assert(!empty());
if (UNLIKELY(m_back_element == m_back_block->begin()))
{
// if there is only one block, it implies ...
if (m_back_block == m_front_block)
{
STXXL_VERBOSE1("sequence::pop_back Case 1");
assert(size() == 1);
assert(m_back_element == m_front_element);
assert(m_bids.empty());
// reset everything
m_back_element = m_back_block->begin() - 1;
m_front_element = m_back_block->begin();
m_size = 0;
return;
}
--m_size;
if (m_size <= block_type::size)
{
STXXL_VERBOSE1("sequence::pop_back Case 2");
assert(m_bids.empty());
// the m_front_block is the next block
m_pool->add(m_back_block);
m_back_block = m_front_block;
m_back_element = m_back_block->end() - 1;
return;
}
STXXL_VERBOSE1("sequence::pop_back Case 3");
assert(!m_bids.empty());
request_ptr req = m_pool->read(m_back_block, m_bids.back());
STXXL_VERBOSE_SEQUENCE("sequence[" << this << "]: pop_back block " << m_back_block << " @ " << FMT_BID(m_bids.back()));
// give prefetching hints
for (unsigned_type i = 1; i < m_blocks2prefetch && i < m_bids.size() - 1; ++i)
{
STXXL_VERBOSE1("sequence::pop_front Case Hints");
m_pool->hint(m_bids[m_bids.size() - 1 - i]);
}
m_back_element = m_back_block->end() - 1;
req->wait();
m_bm->delete_block(m_bids.back());
m_bids.pop_back();
}
else
{
--m_back_element;
--m_size;
}
}
//! \}
//! \name Capacity
//! \{
//! Returns the size of the sequence
size_type size() const
{
return m_size;
}
//! Returns \c true if sequence is empty
bool empty() const
{
return (m_size == 0);
}
//! \}
//! \name Operators
//! \{
//! Returns a mutable reference at the back of the sequence
value_type & back()
{
assert(!empty());
return *m_back_element;
}
//! Returns a const reference at the back of the sequence
const value_type & back() const
{
assert(!empty());
return *m_back_element;
}
//! Returns a mutable reference at the front of the sequence
value_type & front()
{
assert(!empty());
return *m_front_element;
}
//! Returns a const reference at the front of the sequence
const value_type & front() const
{
assert(!empty());
return *m_front_element;
}
//! \}
//! \name Constructors/Destructors
//! \{
~sequence()
{
if (m_front_block != m_back_block)
m_pool->add(m_back_block);
m_pool->add(m_front_block);
if (m_owns_pool)
delete m_pool;
if (!m_bids.empty())
m_bm->delete_blocks(m_bids.begin(), m_bids.end());
}
//! \}
/********************************************************************************/
class stream
{
public:
typedef typename sequence::value_type value_type;
typedef typename bid_deque_type::const_iterator bid_iter_type;
protected:
const sequence& m_sequence;
size_type m_size;
value_type* m_current_element;
block_type* m_current_block;
bid_iter_type m_next_bid;
public:
stream(const sequence& sequence)
: m_sequence(sequence),
m_size(sequence.size())
{
m_current_block = sequence.m_front_block;
m_current_element = sequence.m_front_element;
m_next_bid = sequence.m_bids.begin();
}
~stream()
{
if (m_current_block != m_sequence.m_front_block &&
m_current_block != m_sequence.m_back_block) // give m_current_block back to pool
m_sequence.m_pool->add(m_current_block);
}
//! return number of element left till end-of-stream.
size_type size() const
{
return m_size;
}
//! standard stream method
bool empty() const
{
return (m_size == 0);
}
//! standard stream method
const value_type& operator * () const
{
assert(!empty());
return *m_current_element;
}
//! standard stream method
stream& operator ++ ()
{
assert(!empty());
if (UNLIKELY(m_current_element == m_current_block->begin() + (block_type::size - 1)))
{
// next item position is beyond end of current block, find next block
--m_size;
if (m_size == 0)
{
STXXL_VERBOSE1("sequence::stream::operator++ last block finished clean at block end");
assert(m_next_bid == m_sequence.m_bids.end());
assert(m_current_block == m_sequence.m_back_block);
// nothing to give back to sequence pool
m_current_element = NULL;
return *this;
}
else if (m_size <= block_type::size) // still items left in last partial block
{
STXXL_VERBOSE1("sequence::stream::operator++ reached last block");
assert(m_next_bid == m_sequence.m_bids.end());
// the m_back_block is the next block
if (m_current_block != m_sequence.m_front_block) // give current_block back to pool
m_sequence.m_pool->add(m_current_block);
m_current_block = m_sequence.m_back_block;
m_current_element = m_current_block->begin();
return *this;
}
else if (m_current_block == m_sequence.m_front_block)
{
STXXL_VERBOSE1("sequence::stream::operator++ first own-block case: steal block from sequence's pool");
m_current_block = m_sequence.m_pool->steal();
}
STXXL_VERBOSE1("sequence::stream::operator++ default case: fetch next block");
assert(m_next_bid != m_sequence.m_bids.end());
request_ptr req = m_sequence.m_pool->read(m_current_block, *m_next_bid);
STXXL_VERBOSE_SEQUENCE("sequence[" << this << "]::stream::operator++ read block " << m_current_block << " @ " << FMT_BID(*m_next_bid));
// give prefetching hints
bid_iter_type bid = m_next_bid + 1;
for (unsigned_type i = 0; i < m_sequence.m_blocks2prefetch && bid != m_sequence.m_bids.end(); ++i, ++bid)
{
STXXL_VERBOSE1("sequence::stream::operator++ giving prefetch hints");
m_sequence.m_pool->hint(*bid);
}
m_current_element = m_current_block->begin();
req->wait();
++m_next_bid;
}
else
{
--m_size;
++m_current_element;
}
return *this;
}
};
//! \name Miscellaneous
//! \{
//! construct a forward stream from this sequence
stream get_stream()
{
return stream(*this);
}
//! \}
/********************************************************************************/
class reverse_stream
{
public:
typedef typename sequence::value_type value_type;
typedef typename bid_deque_type::const_reverse_iterator bid_iter_type;
protected:
const sequence& m_sequence;
size_type m_size;
value_type* m_current_element;
block_type* m_current_block;
bid_iter_type m_next_bid;
public:
reverse_stream(const sequence& sequence)
: m_sequence(sequence),
m_size(sequence.size())
{
m_current_block = sequence.m_back_block;
m_current_element = sequence.m_back_element;
m_next_bid = sequence.m_bids.rbegin();
}
~reverse_stream()
{
if (m_current_block != m_sequence.m_front_block &&
m_current_block != m_sequence.m_back_block) // give m_current_block back to pool
m_sequence.m_pool->add(m_current_block);
}
//! return number of element left till end-of-stream.
size_type size() const
{
return m_size;
}
//! standard stream method
bool empty() const
{
return (m_size == 0);
}
//! standard stream method
const value_type& operator * () const
{
assert(!empty());
return *m_current_element;
}
//! standard stream method
reverse_stream& operator ++ ()
{
assert(!empty());
if (UNLIKELY(m_current_element == m_current_block->begin()))
{
// next item position is beyond begin of current block, find next block
--m_size;
if (m_size == 0)
{
STXXL_VERBOSE1("sequence::reverse_stream::operator++ last block finished clean at block begin");
assert(m_next_bid == m_sequence.m_bids.rend());
assert(m_current_block == m_sequence.m_front_block);
// nothing to give back to sequence pool
m_current_element = NULL;
return *this;
}
else if (m_size <= block_type::size)
{
STXXL_VERBOSE1("sequence::reverse_stream::operator++ reached first block");
assert(m_next_bid == m_sequence.m_bids.rend());
// the m_back_block is the next block
if (m_current_block != m_sequence.m_back_block) // give current_block back to pool
m_sequence.m_pool->add(m_current_block);
m_current_block = m_sequence.m_front_block;
m_current_element = m_current_block->begin() + (block_type::size - 1);
return *this;
}
else if (m_current_block == m_sequence.m_back_block)
{
STXXL_VERBOSE1("sequence::reverse_stream::operator++ first own-block case: steal block from sequence's pool");
m_current_block = m_sequence.m_pool->steal();
}
STXXL_VERBOSE1("sequence::reverse_stream::operator++ default case: fetch previous block");
assert(m_next_bid != m_sequence.m_bids.rend());
request_ptr req = m_sequence.m_pool->read(m_current_block, *m_next_bid);
STXXL_VERBOSE_SEQUENCE("sequence[" << this << "]::reverse_stream::operator++ read block " << m_current_block << " @ " << FMT_BID(*m_next_bid));
// give prefetching hints
bid_iter_type bid = m_next_bid + 1;
for (unsigned_type i = 0; i < m_sequence.m_blocks2prefetch && bid != m_sequence.m_bids.rend(); ++i, ++bid)
{
STXXL_VERBOSE1("sequence::reverse_stream::operator++ giving prefetch hints");
m_sequence.m_pool->hint(*bid);
}
m_current_element = m_current_block->begin() + (block_type::size - 1);
req->wait();
++m_next_bid;
}
else
{
--m_size;
--m_current_element;
}
return *this;
}
};
//! \name Miscellaneous
//! \{
//! construct a reverse stream from this sequence
reverse_stream get_reverse_stream()
{
return reverse_stream(*this);
}
//! \}
};
//! \}
STXXL_END_NAMESPACE
#endif // !STXXL_CONTAINERS_SEQUENCE_HEADER
// vim: et:ts=4:sw=4

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