kernel/vm/SectionReader.cpp

/*
   Copyright (c) 2003, 2021, Oracle and/or its affiliates.

   This program is free software; you can redistribute it and/or modify
   it under the terms of the GNU General Public License, version 2.0,
   as published by the Free Software Foundation.

   This program is also distributed with certain software (including
   but not limited to OpenSSL) that is licensed under separate terms,
   as designated in a particular file or component or in included license
   documentation.  The authors of MySQL hereby grant you an additional
   permission to link the program and your derivative works with the
   separately licensed software that they have included with MySQL.

   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, version 2.0, 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., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301  USA
*/


#include <SectionReader.hpp>
#include "LongSignal.hpp"

#if 0
  Uint32 m_len;
  class SectionSegmentPool & m_pool;
  class SectionSegment * m_head;
  class SectionSegment * m_currentPos;
#endif

SectionReader::SectionReader
(struct SegmentedSectionPtr & ptr, class SectionSegmentPool & pool)
  : m_pool(pool)
{
  if(ptr.p == 0){
    m_pos = 0;
    m_len = 0;
    m_headI= RNIL;
    m_head = 0;
    m_currI= RNIL;
    m_currentSegment = 0;
  } else {
    m_pos = 0;
    m_len = ptr.p->m_sz;
    m_headI= ptr.i;
    m_head = ptr.p;
    m_currI= ptr.i;
    m_currentSegment = ptr.p;
  }
}

SectionReader::SectionReader
(Uint32 firstSectionIVal, class SectionSegmentPool& pool)
  : m_pool(pool)
{
  SectionSegment* firstSeg= m_pool.getPtr(firstSectionIVal);

  m_pos = 0;
  m_len = firstSeg->m_sz;
  m_headI= m_currI= firstSectionIVal;
  m_head = m_currentSegment = firstSeg;
}

void
SectionReader::reset(){
  m_pos = 0;
  m_currI= m_headI;
  m_currentSegment = m_head;
}

bool
SectionReader::step(Uint32 len){
  if(m_pos + len >= m_len) {
    m_pos++;
    return false;
  }
  while(len > SectionSegment::DataLength){
    m_currI= m_currentSegment->m_nextSegment;
    m_currentSegment = m_pool.getPtr(m_currI);

    len -= SectionSegment::DataLength;
    m_pos += SectionSegment::DataLength;
  }

  Uint32 ind = m_pos % SectionSegment::DataLength;
  while(len > 0){
    len--;
    m_pos++;

    ind++;
    if(ind == SectionSegment::DataLength){
      ind = 0;
      m_currI= m_currentSegment->m_nextSegment;
      m_currentSegment = m_pool.getPtr(m_currI);
    }
  }
  return true;
}

bool
SectionReader::getWord(Uint32 * dst){
  if (peekWord(dst)) {
    step(1);
    return true;
  }
  return false;
}

bool
SectionReader::peekWord(Uint32 * dst) const {
  if(m_pos < m_len){
    Uint32 ind = m_pos % SectionSegment::DataLength;
    * dst = m_currentSegment->theData[ind];
    return true;
  }
  return false;
}

bool
SectionReader::updateWord(Uint32 value) const
{
  if(m_pos < m_len){
    Uint32 ind = m_pos % SectionSegment::DataLength;
    m_currentSegment->theData[ind] = value;
    return true;
  }
  return false;
}

bool
SectionReader::peekWords(Uint32 * dst, Uint32 len) const {
  if(m_pos + len > m_len)
    return false;

  Uint32 ind = (m_pos % SectionSegment::DataLength);
  Uint32 left = SectionSegment::DataLength - ind;
  SectionSegment * p = m_currentSegment;

  while(len > left){
    memcpy(dst, &p->theData[ind], 4 * left);
    dst += left;
    len -= left;
    ind = 0;
    left = SectionSegment::DataLength;
    p = m_pool.getPtr(p->m_nextSegment);
  }

  memcpy(dst, &p->theData[ind], 4 * len);
  return true;
}

bool
SectionReader::getWords(Uint32 * dst, Uint32 len){
  if(m_pos + len > m_len)
    return false;

  /* Use getWordsPtr to correctly traverse segments */

  while (len > 0)
  {
    const Uint32* readPtr;
    Uint32 readLen;

    if (!getWordsPtr(len,
                     readPtr,
                     readLen))
      return false;

    memcpy(dst, readPtr, readLen << 2);
    len-= readLen;
    dst+= readLen;
  }

  return true;
}

bool
SectionReader::getWordsPtr(Uint32 maxLen,
                           const Uint32*& readPtr,
                           Uint32& actualLen)
{
  if(m_pos >= m_len)
    return false;

  /* We return a pointer to the current position,
   * with length the minimum of
   *  - significant words remaining in the whole section
   *  - space remaining in the current segment
   *  - maxLen from caller
   */
  const Uint32 sectionRemain= m_len - m_pos;
  const Uint32 startInd = (m_pos % SectionSegment::DataLength);
  const Uint32 segmentSpace = SectionSegment::DataLength - startInd;
  SectionSegment * p = m_currentSegment;

  const Uint32 remain= MIN(sectionRemain, segmentSpace);
  actualLen= MIN(remain, maxLen);
  readPtr= &p->theData[startInd];

  /* If we've read everything in this segment, and
   * there's another one, move onto it ready for
   * next time
   */
  m_pos += actualLen;

  if (((startInd + actualLen) == SectionSegment::DataLength) &&
      (m_pos < m_len))
  {
    m_currI= p->m_nextSegment;
    m_currentSegment= m_pool.getPtr(m_currI);
  }

  return true;
}

bool
SectionReader::getWordsPtr(const Uint32*& readPtr,
                           Uint32& actualLen)
{
  /* Cannot have more than SectionSegment::DataLength
   * contiguous words
   */
  return getWordsPtr(SectionSegment::DataLength,
                     readPtr,
                     actualLen);
}


SectionReader::PosInfo
SectionReader::getPos()
{
  PosInfo pi;
  pi.currPos= m_pos;
  pi.currIVal= m_currI;

  return pi;
}

bool
SectionReader::setPos(PosInfo posInfo)
{
  if (posInfo.currPos > m_len)
    return false;

  if (posInfo.currIVal == RNIL)
  {
    if (posInfo.currPos > 0)
      return false;
    m_currentSegment= 0;
  }
  else
  {
    assert(segmentContainsPos(posInfo));

    m_currentSegment= m_pool.getPtr(posInfo.currIVal);
  }

  m_pos= posInfo.currPos;
  m_currI= posInfo.currIVal;

  return true;
}

bool
SectionReader::segmentContainsPos(PosInfo posInfo)
{
  /* This is a check that the section referenced
   * by this SectionReader contains the position
   * given at the section given.
   * It should not be run in-production
   */
  Uint32 IVal= m_headI;
  Uint32 pos= posInfo.currPos;

  while (pos >= SectionSegment::DataLength)
  {
    /* Get next segment */
    SectionSegment* seg= m_pool.getPtr(IVal);

    IVal= seg->m_nextSegment;
    pos-= SectionSegment::DataLength;
  }

  return (IVal == posInfo.currIVal);
}


#ifdef UNIT_TEST

#define VERIFY(x) if ((x) == 0) { printf("VERIFY failed at Line %u : %s\n",__LINE__, #x);  return -1; }

/* Redefine ArrayPool dependencies to enable standalone Unit-test compile */
void ErrorReporter::handleAssert(const char* message, const char* file, int line, int ec)
{
  printf("Error :\"%s\" at file : %s line %u ec %u\n",
         message, file, line, ec);
  abort();
}

void* ndbd_malloc(size_t size)
{
  return malloc(size);
}

void ndbd_free(void* p, size_t size)
{
  free(p);
}

SectionSegmentPool g_sectionSegmentPool;

/* Create a section of word length given from the
 * Segment Pool supplied
 */
Uint32 createSection(SectionSegmentPool* pool,
                     Uint32 length)
{
  Uint32 pos= 0;

  VERIFY(length > 0);

  Ptr<SectionSegment> first, current;

  VERIFY(pool->seize(first));

  first.p->m_sz= length;
  current= first;

  while (length > SectionSegment::DataLength)
  {
    for (Uint32 i=0; i<SectionSegment::DataLength; i++)
      current.p->theData[i]= pos+i;

    pos+= SectionSegment::DataLength;
    length-= SectionSegment::DataLength;

    SectionSegment* prev= current.p;
    VERIFY(pool->seize(current));
    prev->m_nextSegment= current.i;
  }

  if (length > 0)
  {
    for (Uint32 i=0; i< length; i++)
      current.p->theData[i]= pos+i;
  };

  first.p->m_lastSegment= current.i;

  return first.i;
};

bool freeSection(SectionSegmentPool* pool,
                 Uint32 firstIVal)
{
  Ptr<SectionSegment> p;

  p.i= firstIVal;
  pool->getPtr(p);

  const Uint32 segs= (p.p->m_sz + SectionSegment::DataLength -1) /
    SectionSegment::DataLength;

  pool->releaseList(segs, p.i, p.p->m_lastSegment);

  return true;
}

int checkBuffer(const Uint32* buffer,
                Uint32 start,
                Uint32 len)
{
  for (Uint32 i=0; i<len; i++)
  {
    if (buffer[i] != start + i)
      printf("i=%u buffer[i]=%u, start=%u\n",
             i, buffer[i], start);
    VERIFY(buffer[i] == start + i);
  }
  return 0;
};

#include <random.h>

int testSR(Uint32 iVal, SectionSegmentPool* ssp, Uint32 len)
{
  SectionReader srStepPeek(iVal, *ssp);
  SectionReader srGetWord(iVal, *ssp);
  SectionReader srPosSource(iVal, *ssp);
  SectionReader srPosDest(iVal, *ssp);
  SectionReader srPtrWord(iVal, *ssp);

  VERIFY(srStepPeek.getSize() == len);

  /* Reset the section readers at a random position */
  const Uint32 noResetPos= 9999999;
  Uint32 resetAt= len> 10 ? myRandom48(len) : noResetPos;

  /* Read from the section readers, 1 word at a time */
  for (Uint32 i=0; i < len; i++)
  {
    Uint32 peekWord;
    Uint32 getWord;
    const Uint32* ptrWord;
    Uint32 ptrReadSize;

    /* Check that peek, getWord and getWordsPtr return
     * the same, correct value
     */
    VERIFY(srStepPeek.peekWord(&peekWord));
    if (i < (len -1))
        VERIFY(srStepPeek.step(1));
    VERIFY(srGetWord.getWord(&getWord));
    VERIFY(srPtrWord.getWordsPtr(1, ptrWord, ptrReadSize));
    VERIFY(ptrReadSize == 1);
    //printf("PeekWord=%u, i=%u\n",
    //       peekWord, i);
    VERIFY(peekWord == i);
    VERIFY(peekWord == getWord);
    VERIFY(peekWord == *ptrWord);

    /* Check that one sectionReader with it's position
     * set from the first returns the same, correct word
     */
    SectionReader::PosInfo p= srPosSource.getPos();
    srPosDest.setPos(p);

    Uint32 srcWord, destWord;

    VERIFY(srPosSource.getWord(&srcWord));
    VERIFY(srPosDest.getWord(&destWord));

    VERIFY(srcWord == peekWord);
    VERIFY(srcWord == destWord);

    /* Reset the readers */
    if (i == resetAt)
    {
      //printf("Resetting\n");
      resetAt= noResetPos;
      i= (Uint32) -1;
      srStepPeek.reset();
      srGetWord.reset();
      srPosSource.reset();
      srPosDest.reset();
      srPtrWord.reset();
    }
    else
    {
      if ((myRandom48(400) == 1) &&
          (i < len -1))
      {
        /* Step all readers forward by some amount */
        Uint32 stepSize= myRandom48((len - i) -1 );
        //printf("Stepping %u words\n", stepSize);
        VERIFY(srStepPeek.step(stepSize));
        VERIFY(srGetWord.step(stepSize));
        VERIFY(srPosSource.step(stepSize));
        VERIFY(srPosDest.step(stepSize));
        VERIFY(srPtrWord.step(stepSize));
        i+= stepSize;
      }
    }
  }

  /* Check that there's nothing left in any reader */
  VERIFY(!srStepPeek.step(1));
  VERIFY(!srGetWord.step(1));
  VERIFY(!srPosSource.step(1));
  VERIFY(!srPosDest.step(1));
  VERIFY(!srPtrWord.step(1));

  srStepPeek.reset();
  srGetWord.reset();
  srPosSource.reset();
  srPosDest.reset();
  srPtrWord.reset();

  /* Now read larger chunks of words */
  Uint32 pos= 0;
  Uint32* buffer= (Uint32*) malloc(len * 4);

  VERIFY(buffer != NULL);

  while (pos < len)
  {
    const Uint32 remain= len-pos;
    const Uint32 readSize= remain == 1 ? 1 : myRandom48(remain);
    //printf("Pos=%u Len=%u readSize=%u \n", pos, len, readSize);
    /* Check that peek + step get the correct words */
    VERIFY(srStepPeek.peekWords(buffer, readSize));
    if (len > pos + readSize)
    {
      VERIFY(srStepPeek.step(readSize));
    }
    else
      VERIFY(srStepPeek.step((len - pos) - 1));

    VERIFY(checkBuffer(buffer, pos, readSize) == 0);

    /* Check that getWords gets the correct words */
    VERIFY(srGetWord.getWords(buffer, readSize));
    VERIFY(checkBuffer(buffer, pos, readSize) == 0);

    /* Check that using getPos + setPos gets the correct words */
    VERIFY(srPosDest.setPos(srPosSource.getPos()));
    VERIFY(srPosSource.getWords(buffer, readSize));
    VERIFY(checkBuffer(buffer, pos, readSize) == 0);

    VERIFY(srPosDest.getWords(buffer, readSize));
    VERIFY(checkBuffer(buffer, pos, readSize) == 0);

    /* Check that getWordsPtr gets the correct words */
    Uint32 ptrWordsRead= 0;

    //printf("Reading from ptr\n");
    while (ptrWordsRead < readSize)
    {
      const Uint32* ptr= NULL;
      Uint32 readLen;
      VERIFY(srPtrWord.getWordsPtr((readSize - ptrWordsRead),
                                   ptr,
                                   readLen));
      VERIFY(readLen <= readSize);
      //printf("Read %u words, from pos %u, offset %u\n",
      //       readLen, pos, ptrWordsRead);
      VERIFY(checkBuffer(ptr, pos+ ptrWordsRead, readLen) == 0);
      ptrWordsRead+= readLen;
    }

    pos += readSize;
  }

  /* Check that there's no more words in any reader */
  VERIFY(!srStepPeek.step(1));
  VERIFY(!srGetWord.step(1));
  VERIFY(!srPosSource.step(1));
  VERIFY(!srPosDest.step(1));
  VERIFY(!srPtrWord.step(1));

  /* Verify that ptr-fetch variants do not fetch beyond
   * the length, even if we ask for more
   */
  srPtrWord.reset();
  Uint32 readWords= 0;
  while (readWords < len)
  {
    const Uint32* readPtr;
    Uint32 wordsRead= 0;
    VERIFY(srPtrWord.getWordsPtr(20, readPtr, wordsRead));
    readWords+= wordsRead;
    VERIFY(readWords <= len);
  }

  free(buffer);
  return 0;
}


int main(int arg, char** argv)
{
  /* Test SectionReader
   * -------------------
   * To run this code :
   *   cd storage/ndb/src/kernel/vm
   *   make testSectionReader
   *   ./testSectionReader
   *
   * Will print "OK" in success case and return 0
   */

  g_sectionSegmentPool.setSize(1024);

  printf("g_sectionSegmentPool size is %u\n",
         g_sectionSegmentPool.getSize());

  const Uint32 Iterations= 2000;
  const Uint32 Sections= 5;
  Uint32 sizes[ Sections ];
  Uint32 iVals[ Sections ];

  for (Uint32 t=0; t < Iterations; t++)
  {
    for (Uint32 i=0; i<Sections; i++)
    {
      Uint32 available= g_sectionSegmentPool.getNoOfFree();
      sizes[i] = available ?
        myRandom48(SectionSegment::DataLength *
                   available)
        : 0;

      //if (0 == (sizes[i] % 60))
      //  printf("Iteration %u, section %u, allocating %u words\n",
      //         t, i, sizes[i]);
      if (t % 100 == 0)
        if (i==0)
          printf("\nIteration %u", t);

      if (sizes[i] > 0)
      {
        iVals[i]= createSection(&g_sectionSegmentPool, sizes[i]);

        VERIFY(testSR(iVals[i], &g_sectionSegmentPool, sizes[i]) == 0);
      }
      else
        iVals[i]= RNIL;
    }


    for (Uint32 i=0; i < Sections; i++)
    {
      if (sizes[i] > 0)
        freeSection(&g_sectionSegmentPool, iVals[i]);
    }
  }

  printf("\nOK\n");
  return 0;
}

#endif

#define JAM_FILE_ID 327