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122 lines
4.9 KiB
C++
122 lines
4.9 KiB
C++
/* -*- 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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#ident "Copyright (c) 2007-2012 Tokutek Inc. All rights reserved."
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#ident "The technology is licensed by the Massachusetts Institute of Technology, Rutgers State University of New Jersey, and the Research Foundation of State University of New York at Stony Brook under United States of America Serial No. 11/760379 and to the patents and/or patent applications resulting from it."
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#ifndef CONCURRENT_TREE_H
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#define CONCURRENT_TREE_H
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#include <ft/comparator.h>
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#include "treenode.h"
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#include "keyrange.h"
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namespace toku {
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// A concurrent_tree stores non-overlapping ranges.
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// Access to disjoint parts of the tree usually occurs concurrently.
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class concurrent_tree {
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public:
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// A locked_keyrange gives you exclusive access to read and write
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// operations that occur on any keys in that range. You only have
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// the right to operate on keys in that range or keys that were read
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// from the keyrange using iterate()
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//
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// Access model:
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// - user prepares a locked keyrange. all threads serialize behind prepare().
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// - user breaks the serialzation point by acquiring a range, or releasing.
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// - one thread operates on a certain locked_keyrange object at a time.
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// - when the thread is finished, it releases
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class locked_keyrange {
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public:
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// effect: prepare to acquire a locked keyrange over the given
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// concurrent_tree, preventing other threads from preparing
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// until this thread either does acquire() or release().
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// note: operations performed on a prepared keyrange are equivalent
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// to ones performed on an acquired keyrange over -inf, +inf.
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// rationale: this provides the user with a serialization point for descending
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// or modifying the the tree. it also proives a convenient way of
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// doing serializable operations on the tree.
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// There are two valid sequences of calls:
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// - prepare, acquire, [operations], release
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// - prepare, [operations],release
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void prepare(concurrent_tree *tree);
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// requires: the locked keyrange was prepare()'d
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// effect: acquire a locked keyrange over the given concurrent_tree.
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// the locked keyrange represents the range of keys overlapped
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// by the given range
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void acquire(const keyrange &range);
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// effect: releases a locked keyrange and the mutex it holds
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void release(void);
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// effect: iterate over each range this locked_keyrange represents,
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// calling function->fn() on each node's keyrange and txnid
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// until there are no more or the function returns false
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template <class F>
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void iterate(F *function) const;
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// inserts the given range into the tree, with an associated txnid.
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// requires: range does not overlap with anything in this locked_keyrange
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// rationale: caller is responsible for only inserting unique ranges
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void insert(const keyrange &range, TXNID txnid);
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// effect: removes the given range from the tree
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// requires: range exists exactly in this locked_keyrange
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// rationale: caller is responsible for only removing existing ranges
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void remove(const keyrange &range);
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// effect: removes all of the keys represented by this locked keyrange
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// rationale: we'd like a fast way to empty out a tree
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void remove_all(void);
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private:
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// the concurrent tree this locked keyrange is for
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concurrent_tree *m_tree;
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// the range of keys this locked keyrange represents
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keyrange m_range;
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// the subtree under which all overlapping ranges exist
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treenode *m_subtree;
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friend class concurrent_tree_unit_test;
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};
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// effect: initialize the tree to an empty state
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void create(comparator *cmp);
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// effect: destroy the tree.
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// requires: tree is empty
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void destroy(void);
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// returns: true iff the tree is empty
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bool is_empty(void);
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// returns: the memory overhead of a single insertion into the tree
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static uint64_t get_insertion_memory_overhead(void);
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private:
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// the root needs to always exist so there's a lock to grab
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// even if the tree is empty. that's why we store a treenode
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// here and not a pointer to one.
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treenode m_root;
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friend class concurrent_tree_unit_test;
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};
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// include the implementation here so we can use templated member
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// functions in locked_keyrange, which are expanded and defined in the
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// compilation unit that includes "concurrent_tree.h". if we didn't
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// include the source here, then there would be problems with multiple
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// definitions of the tree functions
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#include "concurrent_tree.cc"
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} /* namespace toku */
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#endif /* CONCURRENT_TREE_H */
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