comparison lshlib.cpp @ 292:d9a88cfd4ab6

Completed merge of lshlib back to current version of the trunk.

+#include "lshlib.h"
+
+//#define __LSH_DUMP_CORE_TABLES__
+//#define USE_U_FUNCTIONS
+//#define LSH_BLOCK_FULL_ROWS
+
+void err(char*s){cout << s << endl;exit(2);}
+
+Uns32T get_page_logn(){
+  int pagesz = (int)sysconf(_SC_PAGESIZE);
+  return (Uns32T)log2((double)pagesz);  
+}
+
+unsigned align_up(unsigned x, unsigned w){ return ((x) + ((1<<w)-1) & ~((1<<w)-1)); }
+
+void H::error(const char* a, const char* b, const char *sysFunc) {
+  cerr << a << ": " << b << endl;
+  if (sysFunc) {
+    perror(sysFunc);
+  }
+  exit(1);
+}
+
+H::H(Uns32T kk, Uns32T mm, Uns32T dd, Uns32T NN, Uns32T CC):
+#ifdef USE_U_FUNCTIONS
+  use_u_functions(true),
+#else
+  use_u_functions(false),
+#endif
+  bucketCount(0),
+  pointCount(0),
+  N(NN),
+  C(CC),
+  k(kk),
+  m(mm),
+  L(mm*(mm-1)/2),
+  d(dd)
+{
+  Uns32T j;
+  cout << "file size: ~" << (((unsigned long long)L*N*C*sizeof(SerialElementT))/1000000UL) << "MB" << endl;
+  if(((unsigned long long)L*N*C*sizeof(SerialElementT))>4000000000UL)
+    error("Maximum size of LSH file exceded: 12*L*N*C > 4000MB");
+  else if(((unsigned long long)N*C*sizeof(SerialElementT))>1000000000UL)
+    cout << "warning: hash tables exceed 1000MB." << endl;
+
+  if(m<2){
+    m=2;
+    L=1; // check value of L
+    cout << "warning: setting m=2, L=1" << endl;
+  }
+  if(use_u_functions && k%2){
+    k++; // make sure k is even
+    cout << "warning: setting k even" << endl;
+  }
+  __initialize_data_structures();
+  for(j=0; j<L; j++)
+    for(kk=0; kk<k; kk++) {
+      r1[j][kk]=__randr(); // random 1..2^29
+      r2[j][kk]=__randr(); // random 1..2^29
+    }
+}
+
+// Post constructor initialization
+void H::__initialize_data_structures(){  
+  H::P = UH_PRIME_DEFAULT;
+  
+  /* FIXME: don't use time(); instead use /dev/random or similar */
+  /* FIXME: write out the seed somewhere, so that we can get
+     repeatability */
+#ifdef MT19937
+  init_genrand(time(NULL));
+#else
+  srand(time(NULL)); // seed random number generator
+#endif
+  Uns32T i,j;
+  H::h = new bucket**[ H::L ];  
+  H::r1 = new Uns32T*[ H::L ];
+  H::r2 = new Uns32T*[ H::L ];
+  assert( H::h && H::r1 && H::r2 ); // failure
+  for( j = 0 ; j < H::L ; j++ ){
+    H::r1[ j ] = new Uns32T[ H::k ];
+    H::r2[ j ] = new Uns32T[ H::k ];
+    assert( H::r1[j] && H::r2[j] ); // failure
+  }
+
+  for( j = 0 ; j < H::L ; j++ ){
+    H::h[j] = new bucket*[ H::N ];
+    assert( H::h[j] );
+    for( i = 0 ; i < H::N ; i++)
+      H::h[j][i] = 0;
+  }
+}
+
+// Destruct hash tables
+H::~H(){
+  Uns32T i,j;
+  for( j=0 ; j < H::L ; j++ ){
+      delete[] H::r1[ j ];
+      delete[] H::r2[ j ];
+      for(i = 0; i< H::N ; i++)
+	delete H::h[ j ][ i ];
+      delete[] H::h[ j ];
+  }
+  delete[] H::r1;
+  delete[] H::r2;
+  delete[] H::h;
+}
+
+
+// make hash value \in Z
+void H::__generate_hash_keys(Uns32T*g,Uns32T* r1, Uns32T* r2){
+  H::t1 = __computeProductModDefaultPrime( g, r1, H::k ) % H::N;
+  H::t2 = __computeProductModDefaultPrime( g, r2, H::k );
+
+}
+
+#define CR_ASSERT(b){if(!(b)){fprintf(stderr, "ASSERT failed on line %d, file %s.\n", __LINE__, __FILE__); exit(1);}}
+
+// Computes (a.b) mod UH_PRIME_DEFAULT
+inline Uns32T H::__computeProductModDefaultPrime(Uns32T *a, Uns32T *b, IntT size){
+  LongUns64T h = 0;
+
+  for(IntT i = 0; i < size; i++){
+    h = h + (LongUns64T)a[i] * (LongUns64T)b[i];
+    h = (h & TWO_TO_32_MINUS_1) + 5 * (h >> 32);
+    if (h >= UH_PRIME_DEFAULT) {
+      h = h - UH_PRIME_DEFAULT;
+    }
+    CR_ASSERT(h < UH_PRIME_DEFAULT);
+  }
+  return h;
+}
+
+Uns32T H::bucket_insert_point(bucket **pp){
+  Uns32T collisionCount = 0;
+  if(!*pp){
+    *pp = new bucket();
+#ifdef LSH_BLOCK_FULL_ROWS
+    (*pp)->t2 = 0; // Use t2 as a collision counter for the row
+    (*pp)->next = new bucket();
+#endif
+  }
+#ifdef LSH_BLOCK_FULL_ROWS
+  collisionCount = (*pp)->t2;
+  if(collisionCount < H::C){ // Block if row is full
+    (*pp)->t2++; // Increment collision counter
+    pointCount++;
+    collisionCount++;
+    __bucket_insert_point((*pp)->next); // First bucket holds collision count
+  }
+#else
+    pointCount++;
+    __bucket_insert_point(*pp); // No collision count storage
+#endif
+  return collisionCount;
+}
+
+void H::__bucket_insert_point(bucket* p){
+  if(p->t2 == IFLAG){ // initialization flag, is it in the domain of t2?
+    p->t2 = H::t2;
+    bucketCount++; // Record start of new point-locale collision chain
+    p->snext = new sbucket();
+    __sbucket_insert_point(p->snext);
+    return;
+  }
+
+  if(p->t2 == H::t2){
+    __sbucket_insert_point(p->snext);
+    return;
+  }
+
+  if(p->next){
+    __bucket_insert_point(p->next);
+  }
+
+  else{
+    p->next = new bucket();
+    __bucket_insert_point(p->next);
+  }
+
+}
+
+void H::__sbucket_insert_point(sbucket* p){
+  if(p->pointID==IFLAG){
+    p->pointID = H::p;
+    return;
+  }
+
+  // Search for pointID
+  if(p->snext){
+    __sbucket_insert_point(p->snext);
+  }
+  else{
+  // Make new point collision bucket at end of list
+  p->snext = new sbucket();
+  __sbucket_insert_point(p->snext);
+  }
+}
+
+inline bucket** H::__get_bucket(int j){
+  return  *(h+j);
+}
+
+// hash functions G
+G::G(float ww, Uns32T kk,Uns32T mm, Uns32T dd, Uns32T NN, Uns32T CC, float r):
+  H(kk,mm,dd,NN,CC),
+  w(ww),
+  radius(r),
+  maxp(0),
+  calling_instance(0),
+  add_point_callback(0),
+  lshHeader(0)
+{
+  Uns32T j;
+#ifdef USE_U_FUNCTIONS
+  G::A = new float**[ H::m ]; // m x k x d random projectors
+  G::b = new float*[ H::m ];  // m x k random biases
+#else
+  G::A = new float**[ H::L ]; // m x k x d random projectors
+  G::b = new float*[ H::L ];  // m x k random biases
+#endif
+  G::g = new Uns32T*[ H::L ];   //  L x k random projections 
+  assert( G::g && G::A && G::b ); // failure
+#ifdef USE_U_FUNCTIONS
+  // Use m \times u_i functions \in R^{(k/2) \times (d)}
+  // Combine to make L=m(m-1)/2 hash functions \in R^{k \times d}
+  for( j = 0; j < H::m ; j++ ){ // m functions u_i(v)
+    G::A[j] = new float*[ H::k/2 ];  // k/2 x d  2-stable distribution coefficients     
+    G::b[j] = new float[ H::k/2 ];   // bias
+    assert( G::A[j] && G::b[j] ); // failure
+    for( kk = 0; kk < H::k/2 ; kk++ ){
+      G::A[j][kk] = new float[ H::d ];
+      assert( G::A[j][kk] ); // failure
+      for(Uns32T i = 0 ; i < H::d ; i++ )
+	G::A[j][kk][i] = randn(); // Normal
+      G::b[j][kk] = ranf()*G::w;        // Uniform
+    }
+  }
+#else
+  // Use m \times u_i functions \in R^{k \times (d)}
+  // Combine to make L=m(m-1)/2 hash functions \in R^{k \times d}
+  for( j = 0; j < H::L ; j++ ){ // m functions u_i(v)
+    G::A[j] = new float*[ H::k ];  // k x d  2-stable distribution coefficients     
+    G::b[j] = new float[ H::k ];   // bias
+    assert( G::A[j] && G::b[j] ); // failure
+    for( kk = 0; kk < H::k ; kk++ ){
+      G::A[j][kk] = new float[ H::d ];
+      assert( G::A[j][kk] ); // failure
+      for(Uns32T i = 0 ; i < H::d ; i++ )
+	G::A[j][kk][i] = randn(); // Normal
+      G::b[j][kk] = ranf()*G::w;        // Uniform
+    }
+  }
+#endif
+  
+  for( j = 0 ; j < H::L ; j++ ){ // L functions g_j(u_a, u_b) a,b \in nchoosek(m,2)
+    G::g[j] = new Uns32T[ H::k ];   // k x 32-bit hash values, gj(v)=[x0 x1 ... xk-1] xk \in Z
+    assert( G::g[j] );
+  }
+  
+  initialize_partial_functions(); // m partially evaluated hash functions
+}
+
+// Serialize from file LSH constructor
+// Read parameters from database file
+// Load the hash functions, close the database
+// Optionally load the LSH tables into head-allocated lists in core 
+G::G(char* filename, bool lshInCoreFlag):
+  calling_instance(0),
+  add_point_callback(0)
+{
+  int dbfid = unserialize_lsh_header(filename);
+  unserialize_lsh_functions(dbfid);
+  initialize_partial_functions();
+
+  // Format1 only needs unserializing if specifically requested
+  if(!(lshHeader->flags&O2_SERIAL_FILEFORMAT2) && lshInCoreFlag){
+    unserialize_lsh_hashtables_format1(dbfid);
+  }
+
+  // Format2 always needs unserializing
+  if(lshHeader->flags&O2_SERIAL_FILEFORMAT2 && lshInCoreFlag){
+    unserialize_lsh_hashtables_format2(dbfid);
+  }
+
+  close(dbfid);
+}
+
+void G::initialize_partial_functions(){
+
+#ifdef USE_U_FUNCTIONS
+  uu = vector<vector<Uns32T> >(H::m);
+  for( Uns32T aa=0 ; aa < H::m ; aa++ )
+    uu[aa] = vector<Uns32T>( H::k/2 );
+#else
+  uu = vector<vector<Uns32T> >(H::L);
+  for( Uns32T aa=0 ; aa < H::L ; aa++ )
+    uu[aa] = vector<Uns32T>( H::k );
+#endif
+}
+
+
+// Generate z ~ N(0,1)
+float G::randn(){
+// Box-Muller
+  float x1, x2;
+  do{
+    x1 = ranf();
+  } while (x1 == 0); // cannot take log of 0
+  x2 = ranf();
+  float z;
+  z = sqrtf(-2.0 * logf(x1)) * cosf(2.0 * M_PI * x2);
+  return z;
+}
+
+float G::ranf(){
+#ifdef MT19937
+  return (float) genrand_real2();
+#else
+  return (float)( (double)rand() / ((double)(RAND_MAX)+(double)(1)) );
+#endif
+}
+
+// range is 1..2^29
+/* FIXME: that looks like an ... odd range.  Still. */
+Uns32T H::__randr(){
+#ifdef MT19937
+  return (Uns32T)((genrand_int32() >> 3) + 1);
+#else
+  return (Uns32T) ((rand() >> 2) + 1); 
+#endif
+}
+
+G::~G(){
+  Uns32T j,kk;
+#ifdef USE_U_FUNCTIONS
+  for( j = 0 ; j < H::m ; j++ ){
+    for( kk = 0 ; kk < H::k/2 ; kk++ )
+      delete[] A[j][kk];
+    delete[] A[j];
+  }
+  delete[] A;    
+  for( j = 0 ; j < H::m ; j++ )
+    delete[] b[j];
+  delete[] b;
+#else
+  for( j = 0 ; j < H::L ; j++ ){
+    for( kk = 0 ; kk < H::k ; kk++ )
+      delete[] A[j][kk];
+    delete[] A[j];
+  }
+  delete[] A;    
+  for( j = 0 ; j < H::L ; j++ )
+    delete[] b[j];
+  delete[] b;
+#endif
+
+  for( j = 0 ; j < H::L ; j++ )
+    delete[] g[j];
+  delete[] g;
+  delete lshHeader;
+}
+
+// Compute all hash functions for vector v
+// #ifdef USE_U_FUNCTIONS use Combination of m \times h_i \in R^{(k/2) \times d}
+// to make L \times g_j functions \in Z^k
+void G::compute_hash_functions(vector<float>& v){ // v \in R^d
+  float iw = 1. / G::w; // hash bucket width
+  Uns32T aa, kk;
+  if( v.size() != H::d ) 
+    error("v.size != H::d","","compute_hash_functions"); // check input vector dimensionality
+  double tmp = 0;
+  float *pA, *pb;
+  Uns32T *pg;
+  int dd;
+  vector<float>::iterator vi;
+  vector<Uns32T>::iterator ui;
+
+#ifdef USE_U_FUNCTIONS
+  Uns32T bb;
+  // Store m dot products to expand
+  for( aa=0; aa < H::m ; aa++ ){
+    ui = uu[aa].begin();
+    for( kk = 0 ; kk < H::k/2 ; kk++ ){
+      pb = *( G::b + aa ) + kk;
+      pA = * ( * ( G::A + aa ) + kk );
+      dd = H::d;
+      tmp = 0.;
+      vi = v.begin();
+      while( dd-- )
+	tmp += *pA++ * *vi++;  // project
+      tmp += *pb;              // translate
+      tmp *= iw;               // scale      
+      *ui++ = (Uns32T) floor(tmp);   // floor
+    }
+  }
+  // Binomial combinations of functions u_{a,b} \in Z^{(k/2) \times d}
+  Uns32T j;
+  for( aa=0, j=0 ; aa < H::m-1 ; aa++ )
+    for( bb = aa + 1 ; bb < H::m ; bb++, j++ ){
+      pg= *( G::g + j ); // L \times functions g_j(v) \in Z^k      
+      // u_1 \in Z^{(k/2) \times d}
+      ui = uu[aa].begin();
+      kk=H::k/2;
+      while( kk-- )
+	*pg++ = *ui++;      // hash function g_j(v)=[x1 x2 ... x(k/2)]; xk \in Z
+      // u_2 \in Z^{(k/2) \times d}
+      ui = uu[bb].begin();
+      kk=H::k/2;
+      while( kk--)
+	*pg++ = *ui++;      // hash function g_j(v)=[x(k/2+1) x(k/2+2) ... xk]; xk \in Z
+    }
+#else
+  for( aa=0; aa < H::L ; aa++ ){
+    ui = uu[aa].begin();
+    for( kk = 0 ; kk < H::k ; kk++ ){
+      pb = *( G::b + aa ) + kk;
+      pA = * ( * ( G::A + aa ) + kk );
+      dd = H::d;
+      tmp = 0.;
+      vi = v.begin();
+      while( dd-- )
+	tmp += *pA++ * *vi++;  // project
+      tmp += *pb;              // translate
+      tmp *= iw;               // scale      
+      *ui++ = (Uns32T) (floor(tmp));   // floor
+    }
+  }
+  // Compute hash functions
+  for( aa=0 ; aa < H::L ; aa++ ){
+    pg= *( G::g + aa ); // L \times functions g_j(v) \in Z^k      
+    // u_1 \in Z^{k \times d}
+    ui = uu[aa].begin();
+    kk=H::k;    
+    while( kk-- )
+      *pg++ = *ui++;      // hash function g_j(v)=[x1 x2 ... xk]; xk \in Z
+  }
+#endif
+
+}
+
+
+// single point insertion; inserted values are hash value and pointID
+Uns32T G::insert_point(vector<float>& v, Uns32T pp){
+  Uns32T collisionCount = 0;
+  H::p = pp;
+  if(pp>G::maxp)
+    G::maxp=pp; // Store highest pointID in database
+  compute_hash_functions( v );
+  for(Uns32T j = 0 ; j < H::L ; j++ ){ // insertion
+    __generate_hash_keys( *( G::g + j ), *( H::r1 + j ), *( H::r2 + j ) ); 
+    collisionCount += bucket_insert_point( *(h + j) + t1 );
+  }
+  return collisionCount;
+}
+
+
+// batch insert for a point set
+// inserted values are vector hash value and pointID starting at basePointID
+void G::insert_point_set(vector<vector<float> >& vv, Uns32T basePointID){
+  for(Uns32T point=0; point<vv.size(); point++)
+    insert_point(vv[point], basePointID+point);
+}
+
+// point retrieval routine
+void G::retrieve_point(vector<float>& v, Uns32T qpos, ReporterCallbackPtr add_point, void* caller){
+  calling_instance = caller;
+  add_point_callback = add_point;
+  compute_hash_functions( v );
+  for(Uns32T j = 0 ; j < H::L ; j++ ){
+    __generate_hash_keys( *( G::g + j ), *( H::r1 + j ), *( H::r2 + j ) ); 
+    if( bucket* bPtr = *(__get_bucket(j) + get_t1()) )
+#ifdef LSH_BLOCK_FULL_ROWS
+      bucket_chain_point( bPtr->next, qpos);
+#else
+    bucket_chain_point( bPtr , qpos);
+#endif
+  }
+}
+
+void G::retrieve_point_set(vector<vector<float> >& vv, ReporterCallbackPtr add_point, void* caller){
+  for(Uns32T qpos = 0 ; qpos < vv.size() ; qpos++ )
+    retrieve_point(vv[qpos], qpos, add_point, caller);
+}
+
+// export lsh tables to table structure on disk
+// 
+// LSH TABLE STRUCTURE
+// ---header 64 bytes ---
+// [magic #tables #rows #cols elementSize databaseSize version flags dim #funs 0 0 0 0 0 0]
+//
+// ---random projections L x k x d float ---
+// A[0][0][0] A[0][0][1] ... A[0][0][d-1]
+// A[0][1][0] A[0][1][1] ... A[1][1][d-1]
+// ...
+// A[0][K-1][0] A[0][1][1] ... A[0][k-1][d-1]
+// ...
+// ...
+// A[L-1][0][0] A[M-1][0][1] ... A[L-1][0][d-1]
+// A[L-1][1][0] A[M-1][1][1] ... A[L-1][1][d-1]
+// ...
+// A[L-1][k-1][0] A[M-1][1][1] ... A[L-1][k-1][d-1]
+//
+// ---bias L x k float ---
+// b[0][0] b[0][1] ... b[0][k-1]
+// b[1][0] b[1][1] ... b[1][k-1]
+// ...
+// b[L-1][0] b[L-1][1] ... b[L-1][k-1]
+//
+// ---random r1 L x k float ---
+// r1[0][0] r1[0][1] ... r1[0][k-1]
+// r1[1][0] r1[1][1] ... r1[1][k-1]
+// ...
+// r1[L-1][0] r1[L-1][1] ... r1[L-1][k-1]
+//
+// ---random r2 L x k float ---
+// r2[0][0] r2[0][1] ... r2[0][k-1]
+// r2[1][0] r2[1][1] ... r2[1][k-1]
+// ...
+// r2[L-1][0] r2[L-1][1] ... r2[L-1][k-1]
+//
+// ---hash table 0: N x C x 8 ---
+// [t2 pointID][t2 pointID]...[t2 pointID]
+// [t2 pointID][t2 pointID]...[t2 pointID]
+// ...
+// [t2 pointID][t2 pointID]...[t2 pointID]
+//
+// ---hash table 1: N x C x 8 ---
+// [t2 pointID][t2 pointID]...[t2 pointID]
+// [t2 pointID][t2 pointID]...[t2 pointID]
+// ...
+// [t2 pointID][t2 pointID]...[t2 pointID]
+// 
+// ...
+// 
+// ---hash table L-1: N x C x 8 ---
+// [t2 pointID][t2 pointID]...[t2 pointID]
+// [t2 pointID][t2 pointID]...[t2 pointID]
+// ...
+// [t2 pointID][t2 pointID]...[t2 pointID]
+//
+
+// Serial header constructors
+SerialHeader::SerialHeader(){;}
+SerialHeader::SerialHeader(float W, Uns32T L, Uns32T N, Uns32T C, Uns32T k, Uns32T d, float r, Uns32T p, Uns32T FMT):
+  lshMagic(O2_SERIAL_MAGIC),
+  binWidth(W),
+  numTables(L),
+  numRows(N),
+  numCols(C),
+  elementSize(O2_SERIAL_ELEMENT_SIZE),
+  version(O2_SERIAL_VERSION),
+  size(L * align_up(N * C * O2_SERIAL_ELEMENT_SIZE, get_page_logn())   // hash tables
+       + align_up(O2_SERIAL_HEADER_SIZE + // header + hash functions
+		  L*k*( sizeof(float)*d+2*sizeof(Uns32T)+sizeof(float)),get_page_logn())),
+  flags(FMT),
+  dataDim(d),
+  numFuns(k),
+  radius(r),
+  maxp(p){;} // header
+
+float* G::get_serial_hashfunction_base(char* db){
+  if(db&&lshHeader)
+    return (float*)(db+O2_SERIAL_HEADER_SIZE); 
+  else return NULL;
+}
+
+SerialElementT* G::get_serial_hashtable_base(char* db){
+  if(db&&lshHeader)
+    return (SerialElementT*)(db+get_serial_hashtable_offset());
+  else 
+    return NULL;
+}
+  
+Uns32T G::get_serial_hashtable_offset(){
+  if(lshHeader)
+    return align_up(O2_SERIAL_HEADER_SIZE + 
+		    L*lshHeader->numFuns*( sizeof(float)*lshHeader->dataDim+2*sizeof(Uns32T)+sizeof(float)),get_page_logn());
+  else
+    return 0;
+}
+
+void G::serialize(char* filename, Uns32T serialFormat){
+  int dbfid;
+  char* db;
+  int dbIsNew=0;
+
+  // Check requested serialFormat
+  if(!(serialFormat==O2_SERIAL_FILEFORMAT1 || serialFormat==O2_SERIAL_FILEFORMAT2))
+    error("Unrecognized serial file format request: ", "serialize()");
+
+  // Test to see if file exists
+  if((dbfid = open (filename, O_RDONLY)) < 0)
+    // If it doesn't, then create the file (CREATE)
+    if(errno == ENOENT){
+      // Create the file
+      std::cout << "Creating new serialized LSH database:" << filename << "...";
+      std::cout.flush();
+      serial_create(filename, serialFormat);
+      dbIsNew=1;
+    }
+    else
+      // The file can't be opened
+      error("Can't open the file", filename, "open");
+
+  // Load the on-disk header into core
+  dbfid = serial_open(filename, 1); // open for write
+  db = serial_mmap(dbfid, O2_SERIAL_HEADER_SIZE, 1);// get database pointer
+  serial_get_header(db);           // read header
+  serial_munmap(db, O2_SERIAL_HEADER_SIZE); // drop mmap
+
+  // Check compatibility of core and disk data structures
+  if( !serial_can_merge(serialFormat) )
+    error("Incompatible core and serial LSH, data structure dimensions mismatch.");
+  
+  // For new LSH databases write the hashfunctions
+  if(dbIsNew)
+    serialize_lsh_hashfunctions(dbfid);
+  // Write the hashtables in the requested format
+  if(serialFormat == O2_SERIAL_FILEFORMAT1)
+    serialize_lsh_hashtables_format1(dbfid, !dbIsNew);
+  else
+    serialize_lsh_hashtables_format2(dbfid, !dbIsNew);
+
+  if(!dbIsNew){
+    db = serial_mmap(dbfid, O2_SERIAL_HEADER_SIZE, 1);// get database pointer
+    //serial_get_header(db);           // read header
+    cout << "maxp = " << G::maxp << endl;
+    lshHeader->maxp=G::maxp;
+    // Default to FILEFORMAT1
+    if(!(lshHeader->flags&O2_SERIAL_FILEFORMAT2))
+      lshHeader->flags|=O2_SERIAL_FILEFORMAT2;
+    memcpy((char*)db, (char*)lshHeader, sizeof(SerialHeaderT));
+    serial_munmap(db, O2_SERIAL_HEADER_SIZE); // drop mmap
+  }
+
+  serial_close(dbfid);
+}
+
+// Test to see if core structure and requested format is
+// compatible with currently opened database
+int G::serial_can_merge(Uns32T format){
+  SerialHeaderT* that = lshHeader;
+  if( (format==O2_SERIAL_FILEFORMAT2 && !that->flags&O2_SERIAL_FILEFORMAT2) 
+      || (format!=O2_SERIAL_FILEFORMAT2 && that->flags&O2_SERIAL_FILEFORMAT2)
+      || !( this->w == that->binWidth &&
+	 this->L == that->numTables &&
+	 this->N == that->numRows &&
+	 this->k == that->numFuns &&
+	 this->d == that->dataDim &&
+	 sizeof(SerialElementT) == that->elementSize &&
+	 this->radius == that->radius)){
+    serial_print_header(format);
+    return 0;
+  }
+  else
+    return 1;
+}
+
+// Used as an error message for serial_can_merge()
+void G::serial_print_header(Uns32T format){
+  std::cout << "Fc:" << format << " Fs:" << lshHeader->flags << endl;
+  std::cout << "Wc:" << w << " Ls:" << lshHeader->binWidth << endl;
+  std::cout << "Lc:" << L << " Ls:" << lshHeader->numTables << endl;
+  std::cout << "Nc:" << N << " Ns:" << lshHeader->numRows << endl;
+  std::cout << "kc:" << k << " ks:" << lshHeader->numFuns << endl;
+  std::cout << "dc:" << d << " ds:" << lshHeader->dataDim << endl;
+  std::cout << "sc:" << sizeof(SerialElementT) << " ss:" << lshHeader->elementSize << endl;
+  std::cout << "rc:" << this->radius << " rs:" << lshHeader->radius << endl;
+}
+
+int G::serialize_lsh_hashfunctions(int fid){
+  float* pf;
+  Uns32T *pu;
+  Uns32T x,y,z;
+  
+  db = serial_mmap(fid, get_serial_hashtable_offset(), 1);// get database pointer  
+  pf = get_serial_hashfunction_base(db);
+
+  // HASH FUNCTIONS
+  // Write the random projectors A[][][]
+#ifdef USE_U_FUNCTIONS
+  for( x = 0 ; x < H::m ; x++ )
+    for( y = 0 ; y < H::k/2 ; y++ )
+#else
+      for( x = 0 ; x < H::L ; x++ )
+	for( y = 0 ; y < H::k ; y++ )
+#endif
+	  for( z = 0 ; z < d ; z++ )
+	    *pf++ = A[x][y][z];
+  
+  // Write the random biases b[][]
+#ifdef USE_U_FUNCTIONS
+  for( x = 0 ; x < H::m ; x++ )
+    for( y = 0 ; y < H::k/2 ; y++ )
+#else
+      for( x = 0 ; x < H::L ; x++ )
+	for( y = 0 ; y < H::k ; y++ )
+#endif
+	  *pf++=b[x][y];
+  
+  pu = (Uns32T*)pf;
+  
+  // Write the Z projectors r1[][]
+  for( x = 0 ; x < H::L ; x++)
+    for( y = 0 ; y < H::k ; y++)
+      *pu++ = r1[x][y];
+  
+  // Write the Z projectors r2[][]
+  for( x = 0 ; x < H::L ; x++)
+    for( y = 0; y < H::k ; y++)
+      *pu++ = r2[x][y];  
+  
+  serial_munmap(db, get_serial_hashtable_offset());
+  return 1;
+}
+
+int G::serialize_lsh_hashtables_format1(int fid, int merge){
+  SerialElementT *pe, *pt;
+  Uns32T x,y;
+
+  if( merge && !serial_can_merge(O2_SERIAL_FILEFORMAT1) )
+    error("Cannot merge core and serial LSH, data structure dimensions mismatch.");
+
+  Uns32T hashTableSize=sizeof(SerialElementT)*lshHeader->numRows*lshHeader->numCols;  
+  Uns32T colCount, meanColCount, colCountN, maxColCount, minColCount;
+  // Write the hash tables
+  for( x = 0 ; x < H::L ; x++ ){
+    std::cout << (merge ? "merging":"writing") << " hash table " << x << " FORMAT1...";
+    std::cout.flush();
+    // memory map a single hash table for sequential access
+    // Align each hash table to page boundary
+    char* dbtable = serial_mmap(fid, hashTableSize, 1, 
+				align_up(get_serial_hashtable_offset()+x*hashTableSize, get_page_logn()));
+    if(madvise(dbtable, hashTableSize, MADV_SEQUENTIAL)<0)
+      error("could not advise hashtable memory","","madvise");
+    
+    maxColCount=0;
+    minColCount=O2_SERIAL_MAX_COLS;
+    meanColCount=0;
+    colCountN=0;
+    pt=(SerialElementT*)dbtable;
+    for( y = 0 ;  y < H::N ; y++ ){
+      // Move disk pointer to beginning of row
+      pe=pt+y*lshHeader->numCols;
+      
+      colCount=0;
+      if(bucket* bPtr = h[x][y])
+	if(merge)
+#ifdef LSH_BLOCK_FULL_ROWS
+	  serial_merge_hashtable_row_format1(pe, bPtr->next, colCount); // skip collision counter bucket
+	else
+	  serial_write_hashtable_row_format1(pe, bPtr->next, colCount); // skip collision counter bucket
+#else
+      serial_merge_hashtable_row_format1(pe, bPtr, colCount);
+      else
+	serial_write_hashtable_row_format1(pe, bPtr, colCount);
+#endif
+      if(colCount){
+	if(colCount<minColCount)
+	  minColCount=colCount;
+	if(colCount>maxColCount)
+	  maxColCount=colCount;
+	meanColCount+=colCount;
+	colCountN++;
+      }
+    }
+    if(colCountN)
+      std::cout << "#rows with collisions =" << colCountN << ", mean = " << meanColCount/(float)colCountN 
+		<< ", min = " << minColCount << ", max = " << maxColCount 
+		<< endl;
+    serial_munmap(dbtable, hashTableSize);
+  }
+  
+  // We're done writing
+  return 1;
+}
+
+void G::serial_merge_hashtable_row_format1(SerialElementT* pr, bucket* b, Uns32T& colCount){
+  while(b && b->t2!=IFLAG){
+    SerialElementT*pe=pr; // reset disk pointer to beginning of row
+    serial_merge_element_format1(pe, b->snext, b->t2, colCount);  
+    b=b->next;
+  }
+}
+
+void G::serial_merge_element_format1(SerialElementT* pe, sbucket* sb, Uns32T t2, Uns32T& colCount){
+  while(sb){        
+    if(colCount==lshHeader->numCols){
+      std::cout << "!point-chain full " << endl;
+      return;
+    }
+    Uns32T c=0;
+    // Merge collision chains 
+    while(c<lshHeader->numCols){
+      if( (pe+c)->hashValue==IFLAG){
+	(pe+c)->hashValue=t2;
+	(pe+c)->pointID=sb->pointID;
+	colCount=c+1;
+	if(c+1<lshHeader->numCols)
+	  (pe+c+1)->hashValue=IFLAG;
+	break;
+      }
+      c++;
+    }
+    sb=sb->snext;    
+  }
+  return;
+}
+
+void G::serial_write_hashtable_row_format1(SerialElementT*& pe, bucket* b, Uns32T& colCount){
+  pe->hashValue=IFLAG;
+  while(b && b->t2!=IFLAG){
+    serial_write_element_format1(pe, b->snext, b->t2, colCount);
+    b=b->next;
+  }
+}
+
+void G::serial_write_element_format1(SerialElementT*& pe, sbucket* sb, Uns32T t2, Uns32T& colCount){
+  while(sb){        
+    if(colCount==lshHeader->numCols){
+      std::cout << "!point-chain full "	<< endl;
+      return;
+    }
+    pe->hashValue=t2;
+    pe->pointID=sb->pointID;
+    pe++;
+    colCount++;
+    sb=sb->snext;  
+  }
+  pe->hashValue=IFLAG;
+  return;
+}
+
+int G::serialize_lsh_hashtables_format2(int fid, int merge){
+  Uns32T x,y;
+
+  if( merge && !serial_can_merge(O2_SERIAL_FILEFORMAT2) )
+    error("Cannot merge core and serial LSH, data structure dimensions mismatch.");
+
+  // We must pereform FORMAT1 merges in core
+  if(merge)
+    unserialize_lsh_hashtables_format2(fid);
+
+  Uns32T colCount, meanColCount, colCountN, maxColCount, minColCount, t1;
+  lseek(fid, get_serial_hashtable_offset(), SEEK_SET);
+
+  // Write the hash tables
+  for( x = 0 ; x < H::L ; x++ ){
+    std::cout << (merge ? "merging":"writing") << " hash table " << x << " FORMAT2...";
+    std::cout.flush();
+    maxColCount=0;
+    minColCount=O2_SERIAL_MAX_COLS;
+    meanColCount=0;
+    colCountN=0;
+    for( y = 0 ;  y < H::N ; y++ ){
+      colCount=0;
+      if(bucket* bPtr = h[x][y]){
+	t1 = y | O2_SERIAL_FLAGS_T1_BIT;
+	if( write(fid, &t1, sizeof(Uns32T)) != sizeof(Uns32T) ){
+	  close(fid);
+	  error("write error in serial_write_hashtable_format2() [t1]");
+	}
+#ifdef LSH_BLOCK_FULL_ROWS
+	serial_write_hashtable_row_format2(fid, bPtr->next, colCount); // skip collision counter bucket
+#else
+      serial_write_hashtable_row_format2(fid, bPtr, colCount);
+#endif
+      }
+      if(colCount){
+	if(colCount<minColCount)
+	  minColCount=colCount;
+	if(colCount>maxColCount)
+	  maxColCount=colCount;
+	meanColCount+=colCount;
+	colCountN++;
+      }
+    }
+    // Write END of table marker
+    t1 = O2_SERIAL_FLAGS_END_BIT;
+    if( write(fid, &t1, sizeof(Uns32T)) != sizeof(Uns32T) ){
+      close(fid);
+      error("write error in serial_write_hashtable_format2() [end]");
+    }
+
+    if(colCountN)
+      std::cout << "#rows with collisions =" << colCountN << ", mean = " << meanColCount/(float)colCountN 
+		<< ", min = " << minColCount << ", max = " << maxColCount 
+		<< endl;
+  }
+  
+  // We're done writing
+  return 1;
+}
+
+void G::serial_write_hashtable_row_format2(int fid, bucket* b, Uns32T& colCount){
+  while(b && b->t2!=IFLAG){
+    t2 = O2_SERIAL_FLAGS_T2_BIT;
+    if( write(fid, &t2, sizeof(Uns32T)) != sizeof(Uns32T) ){
+      close(fid);
+      error("write error in serial_write_hashtable_row_format2()");
+    }
+    t2 = b->t2;
+    if( write(fid, &t2, sizeof(Uns32T)) != sizeof(Uns32T) ){
+      close(fid);
+      error("write error in serial_write_hashtable_row_format2()");
+    }
+    serial_write_element_format2(fid, b->snext, colCount);
+    b=b->next;
+  }
+}
+
+void G::serial_write_element_format2(int fid, sbucket* sb, Uns32T& colCount){
+  while(sb){
+    if(write(fid, &sb->pointID, sizeof(Uns32T))!=sizeof(Uns32T)){
+      close(fid);
+      error("Write error in serial_write_element_format2()");
+    }
+    colCount++;
+    sb=sb->snext;  
+  }
+}
+
+
+int G::serial_create(char* filename, Uns32T FMT){
+  return serial_create(filename, w, L, N, C, k, d, FMT);
+}
+
+
+int G::serial_create(char* filename, float binWidth, Uns32T numTables, Uns32T numRows, Uns32T numCols, 
+		     Uns32T numFuns, Uns32T dim, Uns32T FMT){
+
+  if(numTables > O2_SERIAL_MAX_TABLES || numRows > O2_SERIAL_MAX_ROWS 
+     || numCols > O2_SERIAL_MAX_COLS || numFuns > O2_SERIAL_MAX_FUNS
+     || dim>O2_SERIAL_MAX_DIM){
+    error("LSH parameters out of bounds for serialization");
+  }
+
+  int dbfid;
+  if ((dbfid = open (filename, O_RDWR|O_CREAT|O_EXCL, S_IRUSR|S_IWUSR|S_IRGRP|S_IWGRP|S_IROTH|S_IWOTH)) < 0)    
+    error("Can't create serial file", filename, "open");
+  get_lock(dbfid, 1);
+  
+  // Make header first to get size of serialized database
+  lshHeader = new SerialHeaderT(binWidth, numTables, numRows, numCols, numFuns, dim, radius, maxp, FMT);  
+  
+  // go to the location corresponding to the last byte
+  if (lseek (dbfid, lshHeader->get_size() - 1, SEEK_SET) == -1)
+    error("lseek error in db file", "", "lseek");
+  
+  // write a dummy byte at the last location
+  if (write (dbfid, "", 1) != 1)
+    error("write error", "", "write");
+  
+  db = serial_mmap(dbfid, O2_SERIAL_HEADER_SIZE, 1);
+
+  memcpy (db, lshHeader, O2_SERIAL_HEADER_SIZE);
+
+  serial_munmap(db, O2_SERIAL_HEADER_SIZE);
+
+  close(dbfid);
+
+  std::cout << "done initializing tables." << endl;
+
+  return 1;  
+}
+
+char* G::serial_mmap(int dbfid, Uns32T memSize, Uns32T forWrite, off_t offset){
+  if(forWrite){
+    if ((db = (char*) mmap(0, memSize, PROT_READ | PROT_WRITE,
+			   MAP_SHARED, dbfid, offset)) == (caddr_t) -1)
+      error("mmap error in request for writable serialized database", "", "mmap");  
+  }
+  else if ((db = (char*) mmap(0, memSize, PROT_READ, MAP_SHARED, dbfid, offset)) == (caddr_t) -1)
+    error("mmap error in read-only serialized database", "", "mmap");  
+      
+  return db;
+}
+
+SerialHeaderT* G::serial_get_header(char* db){
+  lshHeader = new SerialHeaderT();
+  memcpy((char*)lshHeader, db, sizeof(SerialHeaderT));  
+
+  if(lshHeader->lshMagic!=O2_SERIAL_MAGIC)
+    error("Not an LSH database file");
+
+  return lshHeader;
+}
+
+void G::serial_munmap(char* db, Uns32T N){
+  munmap(db, N);
+}
+
+int G::serial_open(char* filename, int writeFlag){
+  int dbfid;
+  if(writeFlag){
+    if ((dbfid = open (filename, O_RDWR)) < 0)    
+      error("Can't open serial file for read/write", filename, "open");
+    get_lock(dbfid, writeFlag);
+  }
+  else{
+    if ((dbfid = open (filename, O_RDONLY)) < 0)
+      error("Can't open serial file for read", filename, "open");
+    get_lock(dbfid, 0);
+  }
+
+  return dbfid;  
+}
+
+void G::serial_close(int dbfid){
+
+  release_lock(dbfid);
+  close(dbfid);
+}
+
+int G::unserialize_lsh_header(char* filename){
+
+  int dbfid;
+  char* db;
+  // Test to see if file exists
+  if((dbfid = open (filename, O_RDONLY)) < 0)
+    error("Can't open the file", filename, "open");
+  close(dbfid);
+  dbfid = serial_open(filename, 0); // open for read
+  db = serial_mmap(dbfid, O2_SERIAL_HEADER_SIZE, 0);// get database pointer
+  serial_get_header(db);           // read header
+  serial_munmap(db, O2_SERIAL_HEADER_SIZE); // drop mmap
+
+  // Unserialize header parameters
+  H::L = lshHeader->numTables;
+  H::m = (Uns32T)( (1.0 + sqrt(1 + 8.0*(int)H::L)) / 2.0);
+  H::N = lshHeader->numRows;
+  H::C = lshHeader->numCols;
+  H::k = lshHeader->numFuns;
+  H::d = lshHeader->dataDim;
+  G::w = lshHeader->binWidth;
+  G::radius = lshHeader->radius;
+  G::maxp = lshHeader->maxp;
+
+  return dbfid;
+}
+
+// unserialize the LSH parameters
+// we leave the LSH tree on disk as a flat file
+// it is this flat file that we search by memory mapping
+void G::unserialize_lsh_functions(int dbfid){
+  Uns32T j, kk;
+  float* pf;
+  Uns32T* pu;
+
+  // Load the hash functions into core
+  char* db = serial_mmap(dbfid, get_serial_hashtable_offset(), 0);// get database pointer again  
+  
+#ifdef USE_U_FUNCTIONS
+  G::A = new float**[ H::m ]; // m x k x d random projectors
+  G::b = new float*[ H::m ];  // m x k random biases
+#else
+  G::A = new float**[ H::L ]; // m x k x d random projectors
+  G::b = new float*[ H::L ];  // m x k random biases
+#endif
+  G::g = new Uns32T*[ H::L ];   //  L x k random projections 
+  assert(g&&A&&b); // failure
+  
+  pf = get_serial_hashfunction_base(db);
+  
+#ifdef USE_U_FUNCTIONS
+  for( j = 0 ; j < H::m ; j++ ){ // L functions gj(v)
+    G::A[j] = new float*[ H::k/2 ];  // k x d  2-stable distribution coefficients     
+    G::b[j] = new float[ H::k/2 ];   // bias
+    assert( G::A[j] && G::b[j] ); // failure    
+    for( kk = 0 ; kk < H::k/2 ; kk++ ){ // Normally distributed hash functions
+#else
+      for( j = 0 ; j < H::L ; j++ ){ // L functions gj(v)
+	G::A[j] = new float*[ H::k ];  // k x d  2-stable distribution coefficients     
+	G::b[j] = new float[ H::k ];   // bias
+	assert( G::A[j] && G::b[j] ); // failure    
+	for( kk = 0 ; kk < H::k ; kk++ ){ // Normally distributed hash functions
+#endif
+	  G::A[j][kk] = new float[ H::d ];
+	  assert( G::A[j][kk] ); // failure
+	  for(Uns32T i = 0 ; i < H::d ; i++ )
+	    G::A[j][kk][i] = *pf++; // Normally distributed random vectors
+	}
+      }
+#ifdef USE_U_FUNCTIONS
+      for( j = 0 ; j < H::m ; j++ ) // biases b
+	for( kk = 0 ; kk < H::k/2 ; kk++ )
+#else
+	  for( j = 0 ; j < H::L ; j++ ) // biases b
+	    for( kk = 0 ; kk < H::k ; kk++ )
+#endif
+	      G::b[j][kk] = *pf++;
+      
+      for( j = 0 ; j < H::L ; j++){ // 32-bit hash values, gj(v)=[x0 x1 ... xk-1] xk \in Z
+	G::g[j] = new Uns32T[ H::k ];   
+	assert( G::g[j] );
+      }
+      
+      
+      H::__initialize_data_structures();
+      
+      pu = (Uns32T*)pf;
+      for( j = 0 ; j < H::L ; j++ ) // Z projectors r1
+	for( kk = 0 ; kk < H::k ; kk++ )
+	  H::r1[j][kk] = *pu++;
+      
+      for( j = 0 ; j < H::L ; j++ ) // Z projectors r2
+	for( kk = 0 ; kk < H::k ; kk++ )
+	  H::r2[j][kk] = *pu++;
+
+  serial_munmap(db, get_serial_hashtable_offset());
+}
+
+void G::unserialize_lsh_hashtables_format1(int fid){
+  SerialElementT *pe, *pt;
+  Uns32T x,y;
+  Uns32T hashTableSize=sizeof(SerialElementT)*lshHeader->numRows*lshHeader->numCols;
+  // Read the hash tables into core
+  for( x = 0 ; x < H::L ; x++ ){
+    // memory map a single hash table
+    // Align each hash table to page boundary
+    char* dbtable = serial_mmap(fid, hashTableSize, 0, 
+				align_up(get_serial_hashtable_offset()+x*hashTableSize, get_page_logn()));
+    if(madvise(dbtable, hashTableSize, MADV_SEQUENTIAL)<0)
+      error("could not advise hashtable memory","","madvise");    
+    pt=(SerialElementT*)dbtable;
+    for( y = 0 ; y < H::N ; y++ ){
+      // Move disk pointer to beginning of row
+      pe=pt+y*lshHeader->numCols;
+      unserialize_hashtable_row_format1(pe, h[x]+y);
+#ifdef __LSH_DUMP_CORE_TABLES__
+      printf("S[%d,%d]", x, y);
+      serial_bucket_dump(pe);
+      printf("C[%d,%d]", x, y);
+      dump_hashtable_row(h[x][y]);
+#endif      
+    }
+    serial_munmap(dbtable, hashTableSize);
+  }  
+}
+
+void G::unserialize_hashtable_row_format1(SerialElementT* pe, bucket** b){
+  Uns32T colCount = 0;  
+  while(colCount!=lshHeader->numCols && pe->hashValue !=IFLAG){
+    H::p = pe->pointID; // current point ID      
+    t2 = pe->hashValue;
+    bucket_insert_point(b);
+    pe++;
+    colCount++;
+  }
+}
+ 
+void G::unserialize_lsh_hashtables_format2(int fid){
+  Uns32T x=0,y=0;
+
+  // Seek to hashtable base offset
+  if(lseek(fid, get_serial_hashtable_offset(), SEEK_SET)!=get_serial_hashtable_offset()){
+    close(fid);
+    error("Seek error in unserialize_lsh_hashtables_format2");
+  }
+
+  // Read the hash tables into core (structure is given in header) 
+  while( x < H::L){
+    if(read(fid, &(H::t1), sizeof(Uns32T))!=sizeof(Uns32T)){
+      close(fid);
+      error("Read error","unserialize_lsh_hashtables_format2()");
+    }
+    if(H::t1&O2_SERIAL_FLAGS_END_BIT)
+      x++; // End of table
+    else
+      while(y < H::N){
+	// Read a row and move file pointer to beginning of next row or table
+	if(!(H::t1&O2_SERIAL_FLAGS_T1_BIT)){
+	  close(fid);
+	  error("State matchine error t1","unserialize_lsh_hashtables_format2()");
+	}
+	y = H::t1 ^ O2_SERIAL_FLAGS_T1_BIT;
+	if(y>=H::N){
+	  close(fid);
+	  error("Unserialized hashtable row pointer out of range","unserialize_lsh_hashtables_format2()");
+	}
+	Uns32T token = unserialize_hashtable_row_format2(fid, h[x]+y);
+	
+#ifdef __LSH_DUMP_CORE_TABLES__
+	printf("C[%d,%d]", x, y);
+	dump_hashtable_row(h[x][y]);
+#endif
+	// Check that token is valid
+	if( !(token&O2_SERIAL_FLAGS_T1_BIT || token&O2_SERIAL_FLAGS_END_BIT) ){
+	  close(fid);
+	  error("State machine error end of row/table", "unserialize_lsh_hashtables_format2()");
+	}
+	// Check for end of table flag
+	if(token&O2_SERIAL_FLAGS_END_BIT){
+	  x++;
+	  break;
+	}
+	// Check for new row flag
+	if(token&O2_SERIAL_FLAGS_T1_BIT)
+	  H::t1 = token;
+      }
+  }
+} 
+ 
+Uns32T G::unserialize_hashtable_row_format2(int fid, bucket** b){
+  bool pointFound = false;
+  if(read(fid, &(H::t2), sizeof(Uns32T)) != sizeof(Uns32T)){
+    close(fid);
+    error("Read error T2 token","unserialize_hashtable_row_format2");
+  }
+  if( !(H::t2==O2_SERIAL_FLAGS_END_BIT || H::t2==O2_SERIAL_FLAGS_T2_BIT)){
+    close(fid);
+    error("State machine error: expected E or T2");
+  }
+  while(!(H::t2==O2_SERIAL_FLAGS_END_BIT || H::t2&O2_SERIAL_FLAGS_T1_BIT)){
+    pointFound=false;
+    // Check for T2 token
+    if(H::t2!=O2_SERIAL_FLAGS_T2_BIT)
+      error("State machine error T2 token", "unserialize_hashtable_row_format2()");
+    // Read t2 value
+    if(read(fid, &(H::t2), sizeof(Uns32T)) != sizeof(Uns32T)){
+      close(fid);
+      error("Read error t2","unserialize_hashtable_row_format2");
+    }
+    if(read(fid, &(H::p), sizeof(Uns32T)) != sizeof(Uns32T)){
+      close(fid);
+      error("Read error H::p","unserialize_hashtable_row_format2");
+    }
+    while(!(H::p==O2_SERIAL_FLAGS_END_BIT || H::p&O2_SERIAL_FLAGS_T1_BIT || H::p==O2_SERIAL_FLAGS_T2_BIT )){
+      pointFound=true;
+      bucket_insert_point(b);
+      if(read(fid, &(H::p), sizeof(Uns32T)) != sizeof(Uns32T)){
+	close(fid);
+	error("Read error H::p","unserialize_hashtable_row_format2");
+      }
+    }
+    H::t2 = H::p; // Copy last found token to t2
+    if(!pointFound)
+      error("State machine error: point", "unserialize_hashtable_row_format2()");    
+  }  
+  return H::t2; // holds current token
+}
+
+void G::dump_hashtable_row(bucket* p){
+  while(p && p->t2!=IFLAG){
+    sbucket* sbp = p->snext;
+    while(sbp){
+      printf("(%0X,%u)", p->t2, sbp->pointID);
+      fflush(stdout);
+      sbp=sbp->snext;
+    }      
+    p=p->next;
+  }
+  printf("\n");
+}
+
+
+// G::serial_retrieve_point( ... )
+// retrieves (pointID) from a serialized LSH database
+//
+// inputs:
+// filename - file name of serialized LSH database
+//       vv - query point set
+//
+// outputs:
+// inserts retrieved points into add_point() callback method
+void G::serial_retrieve_point_set(char* filename, vector<vector<float> >& vv, ReporterCallbackPtr add_point, void* caller)
+{
+  int dbfid = serial_open(filename, 0); // open for read
+  char* dbheader = serial_mmap(dbfid, O2_SERIAL_HEADER_SIZE, 0);// get database pointer
+  serial_get_header(dbheader);           // read header
+  serial_munmap(dbheader, O2_SERIAL_HEADER_SIZE); // drop header mmap
+
+  if((lshHeader->flags & O2_SERIAL_FILEFORMAT2)){
+    close(dbfid);
+    error("serial_retrieve_point_set is for SERIAL_FILEFORMAT1 only");
+  }
+
+  // size of each hash table
+  Uns32T hashTableSize=sizeof(SerialElementT)*lshHeader->numRows*lshHeader->numCols;
+  calling_instance = caller; // class instance variable used in ...bucket_chain_point()
+  add_point_callback = add_point;
+
+  for(Uns32T j=0; j<L; j++){
+    // memory map a single hash table for random access
+    char* db = serial_mmap(dbfid, hashTableSize, 0, 
+			   align_up(get_serial_hashtable_offset()+j*hashTableSize,get_page_logn()));
+    if(madvise(db, hashTableSize, MADV_RANDOM)<0)
+      error("could not advise local hashtable memory","","madvise");
+    SerialElementT* pe = (SerialElementT*)db ;
+    for(Uns32T qpos=0; qpos<vv.size(); qpos++){
+      compute_hash_functions(vv[qpos]);
+      __generate_hash_keys(*(g+j),*(r1+j),*(r2+j)); 
+      serial_bucket_chain_point(pe+t1*lshHeader->numCols, qpos); // Point to correct row
+    }
+    serial_munmap(db, hashTableSize); // drop hashtable mmap
+  }  
+  serial_close(dbfid);    
+}
+
+void G::serial_retrieve_point(char* filename, vector<float>& v, Uns32T qpos, ReporterCallbackPtr add_point, void* caller){
+  int dbfid = serial_open(filename, 0); // open for read
+  char* dbheader = serial_mmap(dbfid, O2_SERIAL_HEADER_SIZE, 0);// get database pointer
+  serial_get_header(dbheader);           // read header
+  serial_munmap(dbheader, O2_SERIAL_HEADER_SIZE); // drop header mmap
+
+  if((lshHeader->flags & O2_SERIAL_FILEFORMAT2)){
+    close(dbfid);
+    error("serial_retrieve_point is for SERIAL_FILEFORMAT1 only");
+  }
+
+  // size of each hash table
+  Uns32T hashTableSize=sizeof(SerialElementT)*lshHeader->numRows*lshHeader->numCols;
+  calling_instance = caller;
+  add_point_callback = add_point;
+  compute_hash_functions(v);
+  for(Uns32T j=0; j<L; j++){
+    // memory map a single hash table for random access
+    char* db = serial_mmap(dbfid, hashTableSize, 0, 
+			   align_up(get_serial_hashtable_offset()+j*hashTableSize,get_page_logn()));
+    if(madvise(db, hashTableSize, MADV_RANDOM)<0)
+      error("could not advise local hashtable memory","","madvise");
+    SerialElementT* pe = (SerialElementT*)db ;
+    __generate_hash_keys(*(g+j),*(r1+j),*(r2+j)); 
+    serial_bucket_chain_point(pe+t1*lshHeader->numCols, qpos); // Point to correct row
+    serial_munmap(db, hashTableSize); // drop hashtable mmap
+  }  
+  serial_close(dbfid);    
+}
+
+void G::serial_dump_tables(char* filename){
+  int dbfid = serial_open(filename, 0); // open for read
+  char* dbheader = serial_mmap(dbfid, O2_SERIAL_HEADER_SIZE, 0);// get database pointer
+  serial_get_header(dbheader);           // read header
+  serial_munmap(dbheader, O2_SERIAL_HEADER_SIZE); // drop header mmap
+  Uns32T hashTableSize=sizeof(SerialElementT)*lshHeader->numRows*lshHeader->numCols;
+  for(Uns32T j=0; j<L; j++){
+    // memory map a single hash table for random access
+    char* db = serial_mmap(dbfid, hashTableSize, 0, 
+			   align_up(get_serial_hashtable_offset()+j*hashTableSize,get_page_logn()));
+    if(madvise(db, hashTableSize, MADV_SEQUENTIAL)<0)
+      error("could not advise local hashtable memory","","madvise");
+    SerialElementT* pe = (SerialElementT*)db ;
+    printf("*********** TABLE %d ***************\n", j);
+    fflush(stdout);
+    int count=0;
+    do{
+      printf("[%d,%d]", j, count++);
+      fflush(stdout);
+      serial_bucket_dump(pe);
+      pe+=lshHeader->numCols;
+    }while(pe<(SerialElementT*)db+lshHeader->numRows*lshHeader->numCols);
+  }
+
+}
+
+void G::serial_bucket_dump(SerialElementT* pe){
+  SerialElementT* pend = pe+lshHeader->numCols;
+  while( !(pe->hashValue==IFLAG || pe==pend ) ){
+    printf("(%0X,%u)",pe->hashValue,pe->pointID);
+    pe++;
+  }
+  printf("\n");
+  fflush(stdout);
+}
+
+void G::serial_bucket_chain_point(SerialElementT* pe, Uns32T qpos){
+  SerialElementT* pend = pe+lshHeader->numCols;
+  while( !(pe->hashValue==IFLAG || pe==pend ) ){
+    if(pe->hashValue==t2){ // new match
+      add_point_callback(calling_instance, pe->pointID, qpos, radius);
+    }
+    pe++;
+  }
+}
+
+void G::bucket_chain_point(bucket* p, Uns32T qpos){
+  if(!p || p->t2==IFLAG)
+    return;
+  if(p->t2==t2){ // match
+    sbucket_chain_point(p->snext, qpos); // add to reporter
+  }  
+  if(p->next){
+    bucket_chain_point(p->next, qpos); // recurse
+  }
+}
+
+void G::sbucket_chain_point(sbucket* p, Uns32T qpos){  
+  add_point_callback(calling_instance, p->pointID, qpos, radius);
+  if(p->snext){
+    sbucket_chain_point(p->snext, qpos);
+  }
+}
+
+void G::get_lock(int fd, bool exclusive) {
+  struct flock lock;
+  int status;  
+  lock.l_type = exclusive ? F_WRLCK : F_RDLCK;
+  lock.l_whence = SEEK_SET;
+  lock.l_start = 0;
+  lock.l_len = 0; /* "the whole file" */  
+ retry:
+  do {
+    status = fcntl(fd, F_SETLKW, &lock);
+  } while (status != 0 && errno == EINTR);  
+  if (status) {
+    if (errno == EAGAIN) {
+      sleep(1);
+      goto retry;
+    } else {
+      error("fcntl lock error", "", "fcntl");
+    }
+  }
+}
+ 
+void G::release_lock(int fd) {
+   struct flock lock;
+   int status;
+   
+   lock.l_type = F_UNLCK;
+   lock.l_whence = SEEK_SET;
+   lock.l_start = 0;
+   lock.l_len = 0;
+   
+   status = fcntl(fd, F_SETLKW, &lock);
+
+  if (status)
+    error("fcntl unlock error", "", "fcntl");
+}