+++ /dev/null
-// -*- mode:C++; tab-width:8; c-basic-offset:2; indent-tabs-mode:t -*-
-// vim: ts=8 sw=2 smarttab
-/*
- * Ceph - scalable distributed file system
- *
- * Copyright (C) 2013- Sage Weil <sage@inktank.com>
- *
- * This is free software; you can redistribute it and/or
- * modify it under the terms of the GNU Lesser General Public
- * License version 2.1, as published by the Free Software
- * Foundation. See file COPYING.
- *
- */
-
-#ifndef CEPH_PAGESET_H
-#define CEPH_PAGESET_H
-
-#include <algorithm>
-#include <atomic>
-#include <cassert>
-#include <mutex>
-#include <vector>
-#include <boost/intrusive/avl_set.hpp>
-#include <boost/intrusive_ptr.hpp>
-
-#include "include/encoding.h"
-#include "include/Spinlock.h"
-
-
-struct Page {
- char *const data;
- boost::intrusive::avl_set_member_hook<> hook;
- uint64_t offset;
-
- // avoid RefCountedObject because it has a virtual destructor
- std::atomic<uint16_t> nrefs;
- void get() { ++nrefs; }
- void put() { if (--nrefs == 0) delete this; }
-
- typedef boost::intrusive_ptr<Page> Ref;
- friend void intrusive_ptr_add_ref(Page *p) { p->get(); }
- friend void intrusive_ptr_release(Page *p) { p->put(); }
-
- // key-value comparison functor for avl
- struct Less {
- bool operator()(uint64_t offset, const Page &page) const {
- return offset < page.offset;
- }
- bool operator()(const Page &page, uint64_t offset) const {
- return page.offset < offset;
- }
- bool operator()(const Page &lhs, const Page &rhs) const {
- return lhs.offset < rhs.offset;
- }
- };
- void encode(bufferlist &bl, size_t page_size) const {
- bl.append(buffer::copy(data, page_size));
- ::encode(offset, bl);
- }
- void decode(bufferlist::iterator &p, size_t page_size) {
- p.copy(page_size, data);
- ::decode(offset, p);
- }
-
- static Ref create(size_t page_size, uint64_t offset = 0) {
- // ensure proper alignment of the Page
- const auto align = alignof(Page);
- page_size = (page_size + align - 1) & ~(align - 1);
- // allocate the Page and its data in a single buffer
- auto buffer = new char[page_size + sizeof(Page)];
- // place the Page structure at the end of the buffer
- return new (buffer + page_size) Page(buffer, offset);
- }
-
- // copy disabled
- Page(const Page&) = delete;
- const Page& operator=(const Page&) = delete;
-
- private: // private constructor, use create() instead
- Page(char *data, uint64_t offset) : data(data), offset(offset), nrefs(1) {}
-
- static void operator delete(void *p) {
- delete[] reinterpret_cast<Page*>(p)->data;
- }
-};
-
-class PageSet {
- public:
- // alloc_range() and get_range() return page refs in a vector
- typedef std::vector<Page::Ref> page_vector;
-
- private:
- // store pages in a boost intrusive avl_set
- typedef Page::Less page_cmp;
- typedef boost::intrusive::member_hook<Page,
- boost::intrusive::avl_set_member_hook<>,
- &Page::hook> member_option;
- typedef boost::intrusive::avl_set<Page,
- boost::intrusive::compare<page_cmp>, member_option> page_set;
-
- typedef typename page_set::iterator iterator;
-
- page_set pages;
- uint64_t page_size;
-
- typedef Spinlock lock_type;
- lock_type mutex;
-
- void free_pages(iterator cur, iterator end) {
- while (cur != end) {
- Page *page = &*cur;
- cur = pages.erase(cur);
- page->put();
- }
- }
-
- int count_pages(uint64_t offset, uint64_t len) const {
- // count the overlapping pages
- int count = 0;
- if (offset % page_size) {
- count++;
- size_t rem = page_size - offset % page_size;
- len = len <= rem ? 0 : len - rem;
- }
- count += len / page_size;
- if (len % page_size)
- count++;
- return count;
- }
-
- public:
- explicit PageSet(size_t page_size) : page_size(page_size) {}
- PageSet(PageSet &&rhs)
- : pages(std::move(rhs.pages)), page_size(rhs.page_size) {}
- ~PageSet() {
- free_pages(pages.begin(), pages.end());
- }
-
- // disable copy
- PageSet(const PageSet&) = delete;
- const PageSet& operator=(const PageSet&) = delete;
-
- bool empty() const { return pages.empty(); }
- size_t size() const { return pages.size(); }
- size_t get_page_size() const { return page_size; }
-
- // allocate all pages that intersect the range [offset,length)
- void alloc_range(uint64_t offset, uint64_t length, page_vector &range) {
- // loop in reverse so we can provide hints to avl_set::insert_check()
- // and get O(1) insertions after the first
- uint64_t position = offset + length - 1;
-
- range.resize(count_pages(offset, length));
- auto out = range.rbegin();
-
- std::lock_guard<lock_type> lock(mutex);
- iterator cur = pages.end();
- while (length) {
- const uint64_t page_offset = position & ~(page_size-1);
-
- typename page_set::insert_commit_data commit;
- auto insert = pages.insert_check(cur, page_offset, page_cmp(), commit);
- if (insert.second) {
- auto page = Page::create(page_size, page_offset);
- cur = pages.insert_commit(*page, commit);
-
- // assume that the caller will write to the range [offset,length),
- // so we only need to zero memory outside of this range
-
- // zero end of page past offset + length
- if (offset + length < page->offset + page_size)
- std::fill(page->data + offset + length - page->offset,
- page->data + page_size, 0);
- // zero front of page between page_offset and offset
- if (offset > page->offset)
- std::fill(page->data, page->data + offset - page->offset, 0);
- } else { // exists
- cur = insert.first;
- }
- // add a reference to output vector
- out->reset(&*cur);
- ++out;
-
- auto c = std::min(length, (position & (page_size-1)) + 1);
- position -= c;
- length -= c;
- }
- // make sure we sized the vector correctly
- assert(out == range.rend());
- }
-
- // return all allocated pages that intersect the range [offset,length)
- void get_range(uint64_t offset, uint64_t length, page_vector &range) {
- auto cur = pages.lower_bound(offset & ~(page_size-1), page_cmp());
- while (cur != pages.end() && cur->offset < offset + length)
- range.push_back(&*cur++);
- }
-
- void free_pages_after(uint64_t offset) {
- std::lock_guard<lock_type> lock(mutex);
- auto cur = pages.lower_bound(offset & ~(page_size-1), page_cmp());
- if (cur == pages.end())
- return;
- if (cur->offset < offset)
- cur++;
- free_pages(cur, pages.end());
- }
-
- void encode(bufferlist &bl) const {
- ::encode(page_size, bl);
- unsigned count = pages.size();
- ::encode(count, bl);
- for (auto p = pages.rbegin(); p != pages.rend(); ++p)
- p->encode(bl, page_size);
- }
- void decode(bufferlist::iterator &p) {
- assert(empty());
- ::decode(page_size, p);
- unsigned count;
- ::decode(count, p);
- auto cur = pages.end();
- for (unsigned i = 0; i < count; i++) {
- auto page = Page::create(page_size);
- page->decode(p, page_size);
- cur = pages.insert_before(cur, *page);
- }
- }
-};
-
-#endif // CEPH_PAGESET_H
Code Review / stor4nfv.git / blobdiff