OW_IndexImpl.cpp

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#include "OW_config.h"
#include "OW_Index.hpp"
#include "OW_FileSystem.hpp"
#include "OW_Exception.hpp"
#include "OW_Format.hpp"
#include "OW_ExceptionIds.hpp"

extern "C"
{
#ifndef OW_WIN32
#include <unistd.h>
#endif
#include <string.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <errno.h>
#include "db.h"
}

extern "C" {
static int recCompare(const DBT* key1, const DBT* key2);
}

namespace OW_NAMESPACE
{

OW_DECLARE_EXCEPTION(Index);
OW_DEFINE_EXCEPTION_WITH_ID(Index);

class IndexImpl : public Index
{
public:
   IndexImpl();
   virtual ~IndexImpl();
   virtual void open(const char* fileName, EDuplicateKeysFlag allowDuplicates = E_NO_DUPLICATES);
   virtual void close();
   virtual IndexEntry findFirst(const char* key=NULL);
   virtual IndexEntry findNext();
   virtual IndexEntry findPrev();
   virtual IndexEntry find(const char* key);
   virtual bool add(const char* key, Int32 offset);
   virtual bool remove(const char* key, Int32 offset=-1L);
   virtual bool update(const char* key, Int32 newOffset);
   virtual void flush();
   void reopen();
   void openIfClosed();
private:
   DB* m_pDB;
   String m_dbFileName;
};
// STATIC
IndexRef
Index::createIndexObject()
{
   return IndexRef(new IndexImpl);
}
IndexImpl::IndexImpl() :
   m_pDB(NULL), m_dbFileName()
{
}
IndexImpl::~IndexImpl()
{
   try
   {
      close();
   }
   catch (...)
   {
      // don't let exceptions escape
   }
}
void
IndexImpl::open(const char* fileName, EDuplicateKeysFlag allowDuplicates)
{
   close();
   BTREEINFO dbinfo;
   m_dbFileName = fileName;
   m_dbFileName += ".ndx";
   ::memset(&dbinfo, 0, sizeof(dbinfo));
   dbinfo.flags = (allowDuplicates == E_ALLDUPLICATES) ? R_DUP : 0;
   dbinfo.compare = recCompare;
   if (FileSystem::canRead(m_dbFileName)
      && FileSystem::canWrite(m_dbFileName))
   {
#ifdef OW_WIN32
      m_pDB = dbopen(m_dbFileName.c_str(), O_RDWR, _S_IREAD | _S_IWRITE,
         DB_BTREE, &dbinfo);
#else
      m_pDB = dbopen(m_dbFileName.c_str(), O_RDWR, S_IRUSR | S_IWUSR,
         DB_BTREE, &dbinfo);
#endif
      if (m_pDB == NULL)
      {
         OW_THROW(IndexException, Format("Failed to open index file: %1, errno =%2(%3)", m_dbFileName, errno, strerror(errno)).c_str());
      }
   }
   else
   {
#ifdef OW_WIN32
      m_pDB = dbopen(m_dbFileName.c_str(), O_TRUNC | O_RDWR | O_CREAT,
         _S_IREAD | _S_IWRITE,  DB_BTREE, &dbinfo);
#else
      m_pDB = dbopen(m_dbFileName.c_str(), O_TRUNC | O_RDWR | O_CREAT,
         S_IRUSR | S_IWUSR,  DB_BTREE, &dbinfo);
#endif
      if (m_pDB == NULL)
      {
         OW_THROW(IndexException, Format("Failed to create index file: %1, errno =%2(%3)", m_dbFileName, errno, strerror(errno)).c_str());
      }
   }
}
void
IndexImpl::reopen()
{
   BTREEINFO dbinfo;
   close();
   ::memset(&dbinfo, 0, sizeof(dbinfo));
   dbinfo.compare = recCompare;
#ifdef OW_WIN32
   m_pDB = dbopen(m_dbFileName.c_str(), O_RDWR, _S_IREAD | _S_IWRITE,
      DB_BTREE, &dbinfo);
#else
   m_pDB = dbopen(m_dbFileName.c_str(), O_RDWR, S_IRUSR | S_IWUSR,
      DB_BTREE, &dbinfo);
#endif
   if (m_pDB == NULL)
   {
      String msg = "Failed to re-open index file: ";
      msg += m_dbFileName;
      OW_THROW(IndexException, msg.c_str());
   }
}
void
IndexImpl::openIfClosed()
{
   if (!m_pDB)
   {
      BTREEINFO dbinfo;
      ::memset(&dbinfo, 0, sizeof(dbinfo));
      dbinfo.compare = recCompare;
#ifdef OW_WIN32
      m_pDB = dbopen(m_dbFileName.c_str(), O_RDWR, _S_IREAD | _S_IWRITE,
         DB_BTREE, &dbinfo);
#else
      m_pDB = dbopen(m_dbFileName.c_str(), O_RDWR, S_IRUSR | S_IWUSR,
         DB_BTREE, &dbinfo);
#endif
      if (m_pDB == NULL)
      {
         String msg = "Failed to re-open index file: ";
         msg += m_dbFileName;
         OW_THROW(IndexException, msg.c_str());
      }
   }
}
void
IndexImpl::close()
{
   if (m_pDB != NULL)
   {
      m_pDB->close(m_pDB);
      m_pDB = NULL;
   }
}
void
IndexImpl::flush()
{
   if (m_pDB != NULL)
   {
      reopen();
      //m_pDB->sync(m_pDB, 0);
   }
}
namespace
{
class OpenCloser
{
public:
   OpenCloser(IndexImpl* pIndex) : m_pIndex(pIndex) 
   {
      m_pIndex->openIfClosed();
   }
   ~OpenCloser()
   {
      m_pIndex->close();
   }
private:
   IndexImpl* m_pIndex;
};
}
// Find exact
IndexEntry
IndexImpl::find(const char* key)
{
   openIfClosed();
   if (m_pDB == NULL)
   {
      OW_THROW(IndexException, "Index file hasn't been opened");
   }
   DBT theKey, theRec;
   theKey.data = const_cast<void*>(static_cast<const void*>(key));
   theKey.size = ::strlen(key)+1;
   if (m_pDB->seq(m_pDB, &theKey, &theRec, R_CURSOR) == 0)
   {
      if (!::strcmp(reinterpret_cast<const char*>(theKey.data), key))
      {
         Int32 tmp;
         memcpy(&tmp, theRec.data, sizeof(tmp));
         return IndexEntry(reinterpret_cast<const char*>(theKey.data), tmp);
      }
   }
   return IndexEntry();
}
bool
IndexImpl::add(const char* key, Int32 offset)
{
   OpenCloser oc(this);
   if (m_pDB == NULL)
   {
      OW_THROW(IndexException, "Index file hasn't been opened");
   }
   DBT theRec, theKey;
   theRec.data = &offset;
   theRec.size = sizeof(offset);
   theKey.data = const_cast<void*>(static_cast<const void*>(key));
   theKey.size = ::strlen(key)+1;
   return (m_pDB->put(m_pDB, &theKey, &theRec, 0) == 0);
}
bool
IndexImpl::remove(const char* key, Int32 offset)
{
   OpenCloser oc(this);
   if (m_pDB == NULL)
   {
      OW_THROW(IndexException, "Index file hasn't been opened");
   }
   DBT theKey;
   theKey.data = const_cast<void*>(static_cast<const void*>(key));
   theKey.size = ::strlen(key)+1;
   IndexEntry ientry = findFirst(key);
   while (ientry)
   {
      if (!ientry.key.equals(key))
      {
         break;
      }
      if (offset == -1L || ientry.offset == offset)
      {
         return (m_pDB->del(m_pDB, &theKey, R_CURSOR) == 0);
      }
      ientry = findNext();
   }
   return false;
}
bool
IndexImpl::update(const char* key, Int32 newOffset)
{
   OpenCloser oc(this);
   if (m_pDB == NULL)
   {
      OW_THROW(IndexException, "Index file hasn't been opened");
   }
   if (!find(key))
   {
      return false;
   }
   DBT theRec, theKey;
   theRec.data = &newOffset;
   theRec.size = sizeof(newOffset);
   theKey.data = const_cast<void*>(static_cast<const void*>(key));
   theKey.size = ::strlen(key)+1;
   return (m_pDB->put(m_pDB, &theKey, &theRec, R_CURSOR) == 0);
}
IndexEntry
IndexImpl::findFirst(const char* key)
{
   openIfClosed();
   if (m_pDB == NULL)
   {
      OW_THROW(IndexException, "Index file hasn't been opened");
   }
   DBT theRec, theKey;
   memset(&theKey, 0, sizeof(theKey));
   memset(&theRec, 0, sizeof(theRec));
   int op = R_FIRST;
   if (key != NULL)
   {
      op = R_CURSOR;
      theKey.data = const_cast<void*>(static_cast<const void*>(key));
      theKey.size = ::strlen(key)+1;
   }
   int cc = m_pDB->seq(m_pDB, &theKey, &theRec, op);
   if (cc == 0)
   {
      Int32 tmp;
      memcpy(&tmp, theRec.data, sizeof(tmp));
      return IndexEntry(reinterpret_cast<const char*>(theKey.data), tmp);
   }
   return IndexEntry();
}
IndexEntry
IndexImpl::findNext()
{
   openIfClosed();
   if (m_pDB == NULL)
   {
      OW_THROW(IndexException, "Index file hasn't been opened");
   }
   DBT theRec, theKey;
   if (m_pDB->seq(m_pDB, &theKey, &theRec, R_NEXT) == 0)
   {
      Int32 tmp;
      memcpy(&tmp, theRec.data, sizeof(tmp));
      return IndexEntry(reinterpret_cast<const char*>(theKey.data), tmp);
   }
   return IndexEntry();
}
IndexEntry
IndexImpl::findPrev()
{
   openIfClosed();
   if (m_pDB == NULL)
   {
      OW_THROW(IndexException, "Index file hasn't been opened");
   }
   DBT theRec, theKey;
   if (m_pDB->seq(m_pDB, &theKey, &theRec, R_PREV) == 0)
   {
      Int32 tmp;
      memcpy(&tmp, theRec.data, sizeof(tmp));
      return IndexEntry(reinterpret_cast<const char*>(theKey.data), tmp);
   }
   return IndexEntry();
}

} // end namespace OW_NAMESPACE

extern "C" {
static int
recCompare(const DBT* key1, const DBT* key2)
{
   if (key1->data && key2->data)
   {
      return strcmp(reinterpret_cast<const char*>(key1->data), 
         reinterpret_cast<const char*>(key2->data));
   }
   else if (key1->data && !key2->data)
   {
      return 1;
   }
   else if (!key1->data && key2->data)
   {
      return -1;
   }
   else // key1->data == 0 && key2->data == 0
   {
      return 0;
   }
}
} // extern "C"

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