X-Git-Url: https://gerrit.opnfv.org/gerrit/gitweb?a=blobdiff_plain;f=src%2Fceph%2Fsrc%2Fos%2Fmemstore%2FPageSet.h;fp=src%2Fceph%2Fsrc%2Fos%2Fmemstore%2FPageSet.h;h=a40b86425ec1f47cb6c13cf0be47dc2217195a32;hb=812ff6ca9fcd3e629e49d4328905f33eee8ca3f5;hp=0000000000000000000000000000000000000000;hpb=15280273faafb77777eab341909a3f495cf248d9;p=stor4nfv.git

diff --git a/src/ceph/src/os/memstore/PageSet.h b/src/ceph/src/os/memstore/PageSet.h
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+++ b/src/ceph/src/os/memstore/PageSet.h
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+// -*- 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