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178 lines
5.8 KiB
178 lines
5.8 KiB
/* -*- mode: C++; c-basic-offset: 4; indent-tabs-mode: nil -*- */
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// vim: ft=cpp:expandtab:ts=8:sw=4:softtabstop=4:
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#ident "$Id$"
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/*======
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This file is part of PerconaFT.
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Copyright (c) 2006, 2015, Percona and/or its affiliates. All rights reserved.
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PerconaFT is free software: you can redistribute it and/or modify
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it under the terms of the GNU General Public License, version 2,
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as published by the Free Software Foundation.
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PerconaFT is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with PerconaFT. If not, see <http://www.gnu.org/licenses/>.
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----------------------------------------
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PerconaFT is free software: you can redistribute it and/or modify
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it under the terms of the GNU Affero General Public License, version 3,
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as published by the Free Software Foundation.
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PerconaFT is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU Affero General Public License for more details.
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You should have received a copy of the GNU Affero General Public License
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along with PerconaFT. If not, see <http://www.gnu.org/licenses/>.
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----------------------------------------
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Licensed under the Apache License, Version 2.0 (the "License");
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you may not use this file except in compliance with the License.
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You may obtain a copy of the License at
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http://www.apache.org/licenses/LICENSE-2.0
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Unless required by applicable law or agreed to in writing, software
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distributed under the License is distributed on an "AS IS" BASIS,
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WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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See the License for the specific language governing permissions and
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limitations under the License.
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======= */
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#ident \
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"Copyright (c) 2006, 2015, Percona and/or its affiliates. All rights reserved."
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#pragma once
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#include <inttypes.h>
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#include <stdint.h>
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#include "../util/dbt.h"
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#include "../util/memarena.h"
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namespace toku {
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// a key range buffer represents a set of key ranges that can
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// be stored, iterated over, and then destroyed all at once.
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class range_buffer {
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private:
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// the key range buffer is a bunch of records in a row.
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// each record has the following header, followed by the
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// left key and right key data payload, if applicable.
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// we limit keys to be 2^16, since we store lengths as 2 bytes.
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static const size_t MAX_KEY_SIZE = 1 << 16;
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struct record_header {
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bool left_neg_inf;
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bool left_pos_inf;
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bool right_pos_inf;
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bool right_neg_inf;
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uint16_t left_key_size;
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uint16_t right_key_size;
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bool is_exclusive_lock;
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bool left_is_infinite(void) const;
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bool right_is_infinite(void) const;
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void init(const DBT *left_key, const DBT *right_key, bool is_exclusive);
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};
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// PORT static_assert(sizeof(record_header) == 8, "record header format is
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// off");
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public:
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// the iterator abstracts reading over a buffer of variable length
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// records one by one until there are no more left.
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class iterator {
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public:
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iterator();
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iterator(const range_buffer *buffer);
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// a record represents the user-view of a serialized key range.
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// it handles positive and negative infinity and the optimized
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// point range case, where left and right points share memory.
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class record {
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public:
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// get a read-only pointer to the left key of this record's range
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const DBT *get_left_key(void) const;
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// get a read-only pointer to the right key of this record's range
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const DBT *get_right_key(void) const;
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// how big is this record? this tells us where the next record is
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size_t size(void) const;
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bool get_exclusive_flag() const { return _header.is_exclusive_lock; }
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// populate a record header and point our DBT's
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// buffers into ours if they are not infinite.
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void deserialize(const char *buf);
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private:
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record_header _header;
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DBT _left_key;
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DBT _right_key;
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};
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// populate the given record object with the current
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// the memory referred to by record is valid for only
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// as long as the record exists.
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bool current(record *rec);
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// move the iterator to the next record in the buffer
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void next(void);
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private:
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void reset_current_chunk();
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// the key range buffer we are iterating over, the current
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// offset in that buffer, and the size of the current record.
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memarena::chunk_iterator _ma_chunk_iterator;
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const void *_current_chunk_base;
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size_t _current_chunk_offset;
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size_t _current_chunk_max;
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size_t _current_rec_size;
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};
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// allocate buffer space lazily instead of on creation. this way,
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// no malloc/free is done if the transaction ends up taking no locks.
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void create(void);
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// append a left/right key range to the buffer.
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// if the keys are equal, then only one copy is stored.
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void append(const DBT *left_key, const DBT *right_key,
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bool is_write_request = false);
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// is this range buffer empty?
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bool is_empty(void) const;
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// how much memory is being used by this range buffer?
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uint64_t total_memory_size(void) const;
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// how many ranges are stored in this range buffer?
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int get_num_ranges(void) const;
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void destroy(void);
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private:
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memarena _arena;
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int _num_ranges;
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void append_range(const DBT *left_key, const DBT *right_key,
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bool is_write_request);
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// append a point to the buffer. this is the space/time saving
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// optimization for key ranges where left == right.
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void append_point(const DBT *key, bool is_write_request);
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};
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} /* namespace toku */
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