ndb - wl#1497 add LinearPool

storage/ndb/src/kernel/vm/LinearPool.hpp

+/* Copyright (C) 2003 MySQL AB
+
+   This program is free software; you can redistribute it and/or modify
+   it under the terms of the GNU General Public License as published by
+   the Free Software Foundation; either version 2 of the License, or
+   (at your option) any later version.
+
+   This program is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with this program; if not, write to the Free Software
+   Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA */
+
+#ifndef LINEAR_POOL_HPP
+#define LINEAR_POOL_HPP
+
+#include <SuperPool.hpp>
+
+/*
+ * LinearPool - indexed record pool
+ *
+ * LinearPool implements a pool where each record has a 0-based index.
+ * Any index value (up to 2^32-1) is allowed.  Normal efficient usage is
+ * to assign index values in sequence and to re-use any values which
+ * have become free.  This is default seize/release behaviour.
+ *
+ * LinearPool has 2 internal RecordPool instances:
+ *
+ * (a) record pool of T (the template argument class)
+ * (b) record pool of "maps" (array of Uint32)
+ *
+ * The maps translate an index into an i-value in (a).  Each map has
+ * a level.  Level 0 maps point to i-values.  Level N+1 maps point to
+ * level N maps.  There is a unique "root map" at top.
+ *
+ * This works exactly like numbers in a given base.  Each map has base
+ * size entries.  For implementation convenience the base must be power
+ * of 2 and is given as its log2 value.
+ *
+ * There is a doubly linked list of available maps (some free entries)
+ * on each level.  There is a singly linked free list within each map.
+ *
+ * Level 0 free entry has space for one record.  Level N free entry
+ * implies space for base^N records.  The implied levels are created and
+ * removed on demand.  Completely empty maps are removed.
+ *
+ * Default base is 256 (log2 = 8) which requires maximum 4 levels or
+ * "digits" (similar to ip address).
+ *
+ * TODO
+ *
+ * - move most of the inline code to LinearPool.cpp
+ * - add methods to check / seize user-specified index
+ */
+
+#include "SuperPool.hpp"
+
+template <class T, Uint32 LogBase = 8>
+class LinearPool {
+  typedef SuperPool::PtrI PtrI;
+
+  // Base.
+  STATIC_CONST( Base = 1 << LogBase );
+
+  // Digit mask.
+  STATIC_CONST( DigitMask = Base - 1 );
+
+  // Max possible levels (0 to max root level).
+  STATIC_CONST( MaxLevels = (32 + LogBase - 1) / LogBase );
+
+  // Map.
+  struct Map {
+    Uint32 m_level;
+    Uint32 m_occup;     // number of used entries
+    Uint32 m_firstfree; // position of first free entry
+    PtrI m_parent;      // parent map
+    Uint32 m_index;     // from root to here
+    PtrI m_nextavail;
+    PtrI m_prevavail;
+    PtrI m_entry[Base];
+  };
+
+public:
+
+  // Constructor.
+  LinearPool(GroupPool& gp);
+
+  // Destructor.
+  ~LinearPool();
+
+  // Update pointer ptr.p according to index value ptr.i.
+  void getPtr(Ptr<T>& ptr);
+
+  // Allocate record from the pool.  Reuses free index if possible.
+  bool seize(Ptr<T>& ptr);
+
+  // Return record to the pool.
+  void release(Ptr<T>& ptr);
+
+  // Verify (debugging).
+  void verify();
+
+private:
+
+  // Given index find the bottom map.
+  void get_map(Ptr<Map>& map_ptr, Uint32 index);
+
+  // Add new root map and increase level
+  bool add_root();
+
+  // Add new non-root map.
+  bool add_map(Ptr<Map>& map_ptr, Ptr<Map> parent_ptr, Uint32 digit);
+
+  // Remove entry and map if it becomes empty.
+  void remove_entry(Ptr<Map> map_ptr, Uint32 digit);
+
+  // Remove map and all parents which become empty.
+  void remove_map(Ptr<Map> map_ptr);
+
+  // Add map to available list.
+  void add_avail(Ptr<Map> map_ptr);
+
+  // Remove map from available list.
+  void remove_avail(Ptr<Map> map_ptr);
+
+  // Verify map (recursive).
+  void verify(Ptr<Map> map_ptr, Uint32 level);
+
+  RecordPool<T> m_records;
+  RecordPool<Map> m_maps;
+  Uint32 m_levels;              // 0 means empty pool
+  PtrI m_root;
+  PtrI m_avail[MaxLevels];
+};
+
+template <class T, Uint32 LogBase>
+inline
+LinearPool<T, LogBase>::LinearPool(GroupPool& gp) :
+  m_records(gp),
+  m_maps(gp),
+  m_levels(0),
+  m_root(RNIL)
+{
+  Uint32 n;
+  for (n = 0; n < MaxLevels; n++)
+    m_avail[n] = RNIL;
+}
+
+template <class T, Uint32 LogBase>
+inline
+LinearPool<T, LogBase>::~LinearPool()
+{
+}
+
+template <class T, Uint32 LogBase>
+inline void
+LinearPool<T, LogBase>::getPtr(Ptr<T>& ptr)
+{
+  Uint32 index = ptr.i;
+  // get level 0 map
+  Ptr<Map> map_ptr;
+  get_map(map_ptr, index);
+  // get record
+  Ptr<T> rec_ptr;
+  Uint32 digit = index & DigitMask;
+  rec_ptr.i = map_ptr.p->m_entry[digit];
+  m_records.getPtr(rec_ptr);
+  ptr.p = rec_ptr.p;
+}
+
+template <class T, Uint32 LogBase>
+inline bool
+LinearPool<T, LogBase>::seize(Ptr<T>& ptr)
+{
+  // look for free list on some level
+  Ptr<Map> map_ptr;
+  map_ptr.i = RNIL;
+  Uint32 n = 0;
+  while (n < m_levels) {
+    if ((map_ptr.i = m_avail[n]) != RNIL)
+      break;
+    n++;
+  }
+  if (map_ptr.i == RNIL) {
+    // add new level with available maps
+    if (! add_root())
+      return false;
+    assert(n < m_levels);
+    map_ptr.i = m_avail[n];
+  }
+  m_maps.getPtr(map_ptr);
+  // walk down creating missing levels and using an entry on each
+  Uint32 firstfree;
+  while (true) {
+    assert(map_ptr.p->m_occup < Base);
+    map_ptr.p->m_occup++;
+    firstfree = map_ptr.p->m_firstfree;
+    assert(firstfree < Base);
+    map_ptr.p->m_firstfree = map_ptr.p->m_entry[firstfree];
+    if (map_ptr.p->m_occup == Base) {
+      assert(map_ptr.p->m_firstfree == Base);
+      // remove from available list
+      remove_avail(map_ptr);
+    }
+    if (n == 0)
+      break;
+    Ptr<Map> child_ptr;
+    if (! add_map(child_ptr, map_ptr, firstfree)) {
+      remove_entry(map_ptr, firstfree);
+      return false;
+    }
+    map_ptr.p->m_entry[firstfree] = child_ptr.i;
+    map_ptr = child_ptr;
+    n--;
+  }
+  // now on level 0
+  assert(map_ptr.p->m_level == 0);
+  Ptr<T> rec_ptr;
+  if (! m_records.seize(rec_ptr)) {
+    remove_entry(map_ptr, firstfree);
+    return false;
+  }
+  map_ptr.p->m_entry[firstfree] = rec_ptr.i;
+  ptr.i = firstfree + (map_ptr.p->m_index << LogBase);
+  ptr.p = rec_ptr.p;
+  return true;
+}
+
+template <class T, Uint32 LogBase>
+inline void
+LinearPool<T, LogBase>::release(Ptr<T>& ptr)
+{
+  Uint32 index = ptr.i;
+  // get level 0 map
+  Ptr<Map> map_ptr;
+  get_map(map_ptr, index);
+  // release record
+  Ptr<T> rec_ptr;
+  Uint32 digit = index & DigitMask;
+  rec_ptr.i = map_ptr.p->m_entry[digit];
+  m_records.release(rec_ptr);
+  // remove entry
+  remove_entry(map_ptr, digit);
+  // null pointer
+  ptr.i = RNIL;
+  ptr.p = 0;
+}
+
+template <class T, Uint32 LogBase>
+inline void
+LinearPool<T, LogBase>::verify()
+{
+  if (m_root == RNIL)
+    return;
+  assert(m_levels != 0);
+  Ptr<Map> map_ptr;
+  map_ptr.i = m_root;
+  m_maps.getPtr(map_ptr);
+  verify(map_ptr, m_levels - 1);
+}
+
+// private methods
+
+template <class T, Uint32 LogBase>
+inline void
+LinearPool<T, LogBase>::get_map(Ptr<Map>& map_ptr, Uint32 index)
+{
+  // root map must exist
+  Ptr<Map> tmp_ptr;
+  tmp_ptr.i = m_root;
+  m_maps.getPtr(tmp_ptr);
+  assert(tmp_ptr.p->m_level + 1 == m_levels);
+  // extract index digits up to current root level
+  Uint32 digits[MaxLevels];
+  Uint32 n = 0;
+  do {
+    digits[n] = index & DigitMask;
+    index >>= LogBase;
+  } while (++n < m_levels);
+  assert(index == 0);
+  // walk down indirect levels
+  while (--n > 0) {
+    tmp_ptr.i = tmp_ptr.p->m_entry[digits[n]];
+    m_maps.getPtr(tmp_ptr);
+  }
+  // level 0 map
+  assert(tmp_ptr.p->m_level == 0);
+  map_ptr = tmp_ptr;
+}
+
+template <class T, Uint32 LogBase>
+inline bool
+LinearPool<T, LogBase>::add_root()
+{
+  // new root
+  Ptr<Map> map_ptr;
+  if (! m_maps.seize(map_ptr))
+    return false;
+  Uint32 n = m_levels++;
+  assert(n < MaxLevels);
+  // set up
+  map_ptr.p->m_level = n;
+  if (n == 0) {
+    map_ptr.p->m_occup = 0;
+    map_ptr.p->m_firstfree = 0;
+  } else {
+    // on level > 0 digit 0 points to old root
+    map_ptr.p->m_occup = 1;
+    map_ptr.p->m_firstfree = 1;
+    Ptr<Map> old_ptr;
+    old_ptr.i = m_root;
+    m_maps.getPtr(old_ptr);
+    assert(old_ptr.p->m_parent == RNIL);
+    old_ptr.p->m_parent = map_ptr.i;
+    map_ptr.p->m_entry[0] = old_ptr.i;
+  }
+  // set up free list with Base as terminator
+  for (Uint32 j = map_ptr.p->m_firstfree; j < Base; j++)
+    map_ptr.p->m_entry[j] = j + 1;
+  map_ptr.p->m_parent = RNIL;
+  map_ptr.p->m_index = 0;
+  add_avail(map_ptr);
+  // set new root
+  m_root = map_ptr.i;
+  return true;
+}
+
+template <class T, Uint32 LogBase>
+inline bool
+LinearPool<T, LogBase>::add_map(Ptr<Map>& map_ptr, Ptr<Map> parent_ptr, Uint32 digit)
+{
+  if (! m_maps.seize(map_ptr))
+    return false;
+  assert(parent_ptr.p->m_level != 0);
+  // set up
+  map_ptr.p->m_level = parent_ptr.p->m_level - 1;
+  map_ptr.p->m_occup = 0;
+  map_ptr.p->m_firstfree = 0;
+  // set up free list with Base as terminator
+  for (Uint32 j = map_ptr.p->m_firstfree; j < Base; j++)
+    map_ptr.p->m_entry[j] = j + 1;
+  map_ptr.p->m_parent = parent_ptr.i;
+  map_ptr.p->m_index = digit + (parent_ptr.p->m_index << LogBase);
+  add_avail(map_ptr);
+  return true;
+}
+
+template <class T, Uint32 LogBase>
+inline void
+LinearPool<T, LogBase>::remove_entry(Ptr<Map> map_ptr, Uint32 digit)
+{
+  assert(map_ptr.p->m_occup != 0 && digit < Base);
+  map_ptr.p->m_occup--;
+  map_ptr.p->m_entry[digit] = map_ptr.p->m_firstfree;
+  map_ptr.p->m_firstfree = digit;
+  if (map_ptr.p->m_occup + 1 == Base)
+    add_avail(map_ptr);
+  else if (map_ptr.p->m_occup == 0)
+    remove_map(map_ptr);
+}
+
+template <class T, Uint32 LogBase>
+inline void
+LinearPool<T, LogBase>::remove_map(Ptr<Map> map_ptr)
+{
+  assert(map_ptr.p->m_occup == 0);
+  remove_avail(map_ptr);
+  Ptr<Map> parent_ptr;
+  parent_ptr.i = map_ptr.p->m_parent;
+  Uint32 digit = map_ptr.p->m_index & DigitMask;
+  PtrI map_ptr_i = map_ptr.i;
+  m_maps.release(map_ptr);
+  if (m_root == map_ptr_i) {
+    assert(parent_ptr.i == RNIL);
+    Uint32 used = m_maps.m_superPool.getRecUseCount(m_maps.m_recInfo);
+    assert(used == 0);
+    m_root = RNIL;
+    m_levels = 0;
+  }
+  if (parent_ptr.i != RNIL) {
+    m_maps.getPtr(parent_ptr);
+    // remove child entry (recursive)
+    remove_entry(parent_ptr, digit);
+  }
+}
+
+template <class T, Uint32 LogBase>
+inline void
+LinearPool<T, LogBase>::add_avail(Ptr<Map> map_ptr)
+{
+  Uint32 n = map_ptr.p->m_level;
+  assert(n < m_levels);
+  map_ptr.p->m_nextavail = m_avail[n];
+  if (map_ptr.p->m_nextavail != RNIL) {
+    Ptr<Map> next_ptr;
+    next_ptr.i = map_ptr.p->m_nextavail;
+    m_maps.getPtr(next_ptr);
+    next_ptr.p->m_prevavail = map_ptr.i;
+  }
+  map_ptr.p->m_prevavail = RNIL;
+  m_avail[n] = map_ptr.i;
+}
+
+template <class T, Uint32 LogBase>
+inline void
+LinearPool<T, LogBase>::remove_avail(Ptr<Map> map_ptr)
+{
+  Uint32 n = map_ptr.p->m_level;
+  assert(n < m_levels);
+  if (map_ptr.p->m_nextavail != RNIL) {
+    Ptr<Map> next_ptr;
+    next_ptr.i = map_ptr.p->m_nextavail;
+    m_maps.getPtr(next_ptr);
+    next_ptr.p->m_prevavail = map_ptr.p->m_prevavail;
+  }
+  if (map_ptr.p->m_prevavail != RNIL) {
+    Ptr<Map> prev_ptr;
+    prev_ptr.i = map_ptr.p->m_prevavail;
+    m_maps.getPtr(prev_ptr);
+    prev_ptr.p->m_nextavail = map_ptr.p->m_nextavail;
+  }
+  if (map_ptr.p->m_prevavail == RNIL) {
+    m_avail[n] = map_ptr.p->m_nextavail;
+  }
+  map_ptr.p->m_nextavail = RNIL;
+  map_ptr.p->m_prevavail = RNIL;
+}
+
+template <class T, Uint32 LogBase>
+inline void
+LinearPool<T, LogBase>::verify(Ptr<Map> map_ptr, Uint32 level)
+{
+  assert(level < MaxLevels);
+  assert(map_ptr.p->m_level == level);
+  Uint32 j = 0;
+  while (j < Base) {
+    bool free = false;
+    Uint32 j2 = map_ptr.p->m_firstfree;
+    while (j2 != Base) {
+      if (j2 == j) {
+        free = true;
+        break;
+      }
+      assert(j2 < Base);
+      j2 = map_ptr.p->m_entry[j2];
+    }
+    if (! free) {
+      if (level != 0) {
+        Ptr<Map> child_ptr;
+        child_ptr.i = map_ptr.p->m_entry[j];
+        m_maps.getPtr(child_ptr);
+        assert(child_ptr.p->m_parent == map_ptr.i);
+        assert(child_ptr.p->m_index == j + (map_ptr.p->m_index << LogBase));
+        verify(child_ptr, level - 1);
+      } else {
+        Ptr<T> rec_ptr;
+        rec_ptr.i = map_ptr.p->m_entry[j];
+        m_records.getPtr(rec_ptr);
+      }
+      Ptr<Map> avail_ptr;
+      avail_ptr.i = m_avail[map_ptr.p->m_level];
+      bool found = false;
+      while (avail_ptr.i != RNIL) {
+        if (avail_ptr.i == map_ptr.i) {
+          found = true;
+          break;
+        }
+        m_maps.getPtr(avail_ptr);
+        avail_ptr.i = avail_ptr.p->m_nextavail;
+      }
+      assert(found == (map_ptr.p->m_occup < Base));
+    }
+    j++;
+  }
+}
+
+#endif

storage/ndb/src/kernel/vm/testSuperPool.cpp

@@ -23,6 +23,7 @@ exit $?
    Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA */
 
 #include "SuperPool.hpp"
+#include "LinearPool.hpp"
 #include <NdbOut.hpp>
 
 template <Uint32 sz>
@@ -198,6 +199,74 @@ sp_test(GroupPool& gp)
   delete [] ptrList;
 }
 
+template <class T>
+static void
+lp_test(GroupPool& gp)
+{
+  SuperPool& sp = gp.m_superPool;
+  LinearPool<T, 5> lp(gp);
+  ndbout << "linear pool test" << endl;
+  Ptr<T> ptr;
+  Uint32 loop;
+  for (loop = 0; loop < 3 * loopcount; loop++) {
+    int count = 0;
+    while (1) {
+      bool ret = lp.seize(ptr);
+      lp.verify();
+      if (! ret)
+        break;
+      assert(ptr.i == count);
+      Ptr<T> ptr2;
+      ptr2.i = ptr.i;
+      ptr2.p = 0;
+      lp.getPtr(ptr2);
+      assert(ptr.p == ptr2.p);
+      count++;
+    }
+    ndbout << "seized " << count << endl;
+    switch (loop % 3) {
+    case 0:
+      {
+        int n = 0;
+        while (n < count) {
+          ptr.i = n;
+          lp.release(ptr);
+          lp.verify();
+          n++;
+        }
+        ndbout << "released in order" << endl;
+      }
+      break;
+    case 1:
+      {
+        int n = count;
+        while (n > 0) {
+          n--;
+          ptr.i = n;
+          lp.release(ptr);
+          lp.verify();
+        }
+        ndbout << "released in reverse" << endl;
+      }
+      break;
+    default:
+      {
+        int coprime = random_coprime(count);
+        int n = 0;
+        while (n < count) {
+          int m = (coprime * n) % count;
+          ptr.i = m;
+          lp.release(ptr);
+          lp.verify();
+          n++;
+        }
+        ndbout << "released at random" << endl;
+      }
+      break;
+    }
+  }
+}
+
 static Uint32 pageSize = 32768;
 static Uint32 pageBits = 17;
 
@@ -218,6 +287,8 @@ template static void sp_test<T2>(GroupPool& sp);
 template static void sp_test<T3>(GroupPool& sp);
 template static void sp_test<T4>(GroupPool& sp);
 template static void sp_test<T5>(GroupPool& sp);
+//
+template static void lp_test<T3>(GroupPool& sp);
 
 int
 main()
@@ -231,13 +302,18 @@ main()
   Uint16 s = (Uint16)getpid();
   srandom(s);
   ndbout << "rand " << s << endl;
-  int count = 0;
-  while (++count <= 1) {
+  int count;
+  count = 0;
+  while (++count <= 0) {
     sp_test<T1>(gp);
     sp_test<T2>(gp);
     sp_test<T3>(gp);
     sp_test<T4>(gp);
     sp_test<T5>(gp);
   }
+  count = 0;
+  while (++count <= 1) {
+    lp_test<T3>(gp);
+  }
   return 0;
 }