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*
* MODULE: iostream
*
* COPYRIGHT (C) 2007 Laura Toma
*
*
* Iostream is a library that implements streams, external memory
* sorting on streams, and an external memory priority queue on
* streams. These are the fundamental components used in external
* memory algorithms.
* Credits: The library was developed by Laura Toma. The kernel of
* class STREAM is based on the similar class existent in the GPL TPIE
* project developed at Duke University. The sorting and priority
* queue have been developed by Laura Toma based on communications
* with Rajiv Wickremesinghe. The library was developed as part of
* porting Terraflow to GRASS in 2001. PEARL upgrades in 2003 by
* Rajiv Wickremesinghe as part of the Terracost project.
*
* 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. *
* **************************************************************************/
#ifndef __EMBUFFER_H
#define __EMBUFFER_H
#include <stdio.h>
#include <assert.h>
#include <stdlib.h>
#include <math.h>
#include "ami_config.h" //for SAVE_MEMORY
#include "ami_stream.h"
#include "mm.h"
#include "mm_utils.h"
#include "pqheap.h"
#define MY_LOG_DEBUG_ID(x) //inhibit debug printing
//#define MY_LOG_DEBUG_ID(x) LOG_DEBUG_ID(x)
/**********************************************************
DEBUGGING FLAGS
***********************************************************/
//setting this enables checking that the streams/arrays inserted in
//buffers are sorted in increasing order
//#define EMBUF_CHECK_INSERT
//enable checking that stream name is the same as the one stored in
//the buffer name[]
//#define EMBUF_CHECK_NAME
//enable printing names as they are checked
//#define EMBUF_CHECK_NAME_PRINT
//enable printing when streams in a buffer are shifted left to
//check that names are shifted accordingly
//#define EMBUF_DELETE_STREAM_PRINT
//enable printing the name of the stream which is inserted in buff
//#define EMBUF_PRINT_INSERT
//enable printing the stream names/sizes in cleanup()
//#define EMBUF_CLEANUP_PRINT
//enable printing when get/put_stream is called (for each stream)
//#define EMBUF_PRINT_GETPUT_STREAM
//enable printing when get/put_streams is called
//#define EMBUF_PRINT_GETPUT_STREAMS
/***********************************************************/
/*****************************************************************/
/* encapsulation of the key together with stream_id; used during
stream merging to save space;
*/
template<class KEY>
class merge_key {
public:
KEY k;
unsigned int str_id; //id of the stream where key comes from
public:
merge_key(): str_id(0) {}
merge_key(const KEY &x, const unsigned int sid):
k(x), str_id(sid) {}
~merge_key() {}
void set(const KEY &x, const unsigned int sid) {
k = x;
str_id = sid;
}
KEY key() const {
return k;
}
unsigned int stream_id() const {
return str_id;
}
KEY getPriority() const {
return k;
}
friend ostream& operator<<(ostream& s, const merge_key<KEY> &x) {
return s << "<str_id=" << x.str_id << "> " << x.k << " ";
}
friend int operator < (const merge_key &x,
const merge_key &y) {
return (x.k < y.k);
}
friend int operator <= (const merge_key &x,
const merge_key &y) {
return (x.k <= y.k);
}
friend int operator > (const merge_key &x,
const merge_key &y) {
return (x.k > y.k);
}
friend int operator >= (const merge_key &x,
const merge_key &y) {
return (x.k >= y.k);
}
friend int operator != (const merge_key &x,
const merge_key &y) {
return (x.k != y.k);
}
friend int operator == (const merge_key &x,
const merge_key &y) {
return (x.k == y.k);
}
friend merge_key operator + (const merge_key &x,
const merge_key &y) {
assert(0);
return x;
// Key sum = x.k + y.k;
// merge_key f(sum, x.str_id);
// return f;
}
};
/*****************************************************************
*****************************************************************
*****************************************************************
external_memory buffer
Each level-i buffer can store up to <arity>^i * <basesize> items,
where tipically <arity> is \theta(m) and <basesize> is \theta(M);
therefore log_m{n/m} buffers are needed to store N items, one
buffer for each level 1..log_m{n/m}. All buffers must have same
values or <arity> and <basesize>.
Functionality:
A level-i on-disk buffer stores <arity>^i * <basesize> items of
data, organized in <arity> streams of <arity>^{i-1} items each;
<basesize> is same for all buffers and equal to the size of the
level 0 buffer (in memory buffer).
Invariant: all the <arity> streams of a level-i buffer are in
sorted order; in this way sorting the buffer is done by merging the
<arity> streams in linear time.
Items are inserted in level i-buffer only a whole stream at a time
(<arity>^{i-1}*<basesize> items). When all the <arity> streams of
the buffer are full, the buffer is sorted and emptied into a stream
of a level (i+1)-buffer.
The <arity> streams of a buffer are allocated contigously from left
to r ight. The unused streams are NULL; The buffer keeps the index of
the last used(non-NULL) stream. When a buffer becomes full and is
empty, all its buffers are set to NULL.
*****************************************************************
*****************************************************************
***************************************************************** */
/* T is a type with priority of type K and method getPriority() */
template<class T, class Key>
class em_buffer {
private:
//number of streams in a buffer;
unsigned int arity;
//level of buffer: between 1 and log_arity{n/arity}; (level-0 buffer
//has a slightly different behaviour so it is implemented as a
//different class <im_buffer>)
unsigned short level;
//level-i buffer contains m streams of data, each of size
//arity^{i-1}*basesize;
AMI_STREAM<T>** data;
//the buffers can be depleted to fill the internal pq;
//keep an array which counts, for each stream, how many elements
//have been deleted (implicitely from the begining of stream)
long* deleted;
//nb of items in each substream; this can be found out by calling
//stream_len() on the stream, but it is more costly esp in the case
//when streams are on disk and must be moved in and out just to find
//stream length; streamsize is set only at stream creation, and the
//actual size must substract the number of iteme deleted from the
//bos
unsigned long* streamsize;
//index of the next available(empty) stream (out of the total m
//streams in the buffer);
unsigned int index;
//nb of items in a stream of level_1 buffer
unsigned long basesize;
public:
//create a level-i buffer of given basesize;
em_buffer(const unsigned short i, const unsigned long bs,
const unsigned int ar);
//copy constructor;
em_buffer(const em_buffer &buf);
//free the stream array and the streams pointers
~em_buffer();
//return the level of the buffer;
unsigned short get_level() const { return level;}
//return the ith stream (load stream in memory)
AMI_STREAM<T>* get_stream(unsigned int i);
//return a pointer to the streams of the buffer (loads streams in
//memory)
AMI_STREAM<T>** get_streams();
//put the ith stream back to disk
void put_stream(unsigned int i);
//called in pair with get_streams to put all streams back to disk
void put_streams();
//return a pointer to the array of deletion count for each stream
long* get_bos() const { return deleted;}
//return the index of the last stream in buffer which contains data;
unsigned int laststream() const { return index -1;}
//return the index of the next available stream in the buffer
unsigned int nextstream() const { return index;}
//increment the index of the next available stream in the buffer
void incr_nextstream() { ++index;}
//return nb of (non-empty) streams in buffer
unsigned int get_nbstreams() const { return index;}
//return arity
unsigned int get_arity() const { return arity;}
//return total nb of deleted elements in all active streams of the buffer
long total_deleted() const {
long tot = 0;
for (unsigned int i=0; i< index; i++) {
tot += deleted[i];
}
return tot;
}
//mark as deleted one more element from i'th stream
void incr_deleted(unsigned int i) {
assert(i<index);
deleted[i]++;
}
//return the nominal size of a stream (nb of items):
//arity^{level-1}*basesize;
unsigned long get_stream_maxlen() const {
return (unsigned long)pow((double)arity,(double)level-1)*basesize;
}
//return the actual size of stream i; i must be the index of a valid
//stream
unsigned long get_stream_len(unsigned int i) {
//assert(i>= 0 && i<index);
return streamsize[i] - deleted[i];
}
//return the total current size of the buffer; account for the
//deleted elements;
unsigned long get_buf_len() {
unsigned long tot = 0;
for (unsigned int i=0; i< index; i++) {
tot += get_stream_len(i);
}
return tot;
}
//return the total maximal capacity of the buffer
unsigned long get_buf_maxlen() {
return arity * get_stream_maxlen();
}
//return true if buffer is empty (all streams are empty)
bool is_empty() {
return ((nextstream() == 0) || (get_buf_len() == 0));
}
//return true if buffer is full(all streams are full)
bool is_full() const {
return (nextstream() == arity);
}
//reset
void reset();
//clean buffer: in case some streams have been emptied by deletion
//delete them and shift streams left;
void cleanup();
//create and return a stream which contains all elements of all
//streams of the buffer in sorted ascending order of their
//keys(priorities);
AMI_STREAM<T>* sort();
// insert an array into the buffer; can only insert one
// level-i-full-stream-len nb of items at a time; assume the length
// of the array is precisely the streamlen of level-i buffer n =
// (pow(arity,level-1)*basesize); assume array is sorted; return the
// number of items actually inserted
long insert(T* a, long n);
// insert a stream into the buffer; assume the length of the stream
// is precisely the streamlen of level-i buffer n =
// (pow(arity,level-1)*basesize); the <nextstream> pointer of buffer
// is set to point to the argument stream; (in this way no stream
// copying is done, just one pointer copy). The user should be aware
// the the argument stream is 'lost' - that is a stream cannot be
// inserted repeatedly into many buffers because this would lead to
// several buffers pointing to the same stream.
// stream is assumed sorted; bos = how many elements are deleted
// from the begining of stream;
// return the number of items actually inserted
long insert(AMI_STREAM<T>* str,
long bos=0);
//print range of elements in buffer
void print_range();
//print all elements in buffer
void print();
//prints the sizes of the streams in the buffer
void print_stream_sizes();
//print the elements in the buffer
friend ostream& operator<<(ostream& s, em_buffer &b) {
s << "BUFFER_" << b.level << ": ";
if (b.index ==0) {
s << "[]";
}
s << "\n";
b.get_streams();
for (unsigned int i=0; i < b.index; i++) {
b.print_stream(s, i);
}
b.put_streams();
return s;
}
private:
// merge the input streams; there are <arity> streams in total;
// write output in <outstream>; the input streams are assumed sorted
// in increasing order of their keys;
AMI_err substream_merge(AMI_STREAM<T>** instreams,
unsigned int arity,
AMI_STREAM<T> *outstream);
//print to stream the elements in i'th stream
void print_stream(ostream& s, unsigned int i);
#ifdef SAVE_MEMORY
//array of names of streams;
char** name;
//return the designated name for stream i
char* get_stream_name(unsigned int i) const;
//print all stream names in buffer
void print_stream_names();
//checks that name[i] is the same as stream name; stream i must be in
//memory (by a previous get_stream call, for instance) in order to
//find its length
void check_name(unsigned int i);
#endif
};
/************************************************************/
//create a level-i buffer of given basesize;
template <class T, class Key>
em_buffer<T,Key>::em_buffer(const unsigned short i, const unsigned long bs,
const unsigned int ar) :
arity(ar), level(i), basesize(bs) {
assert((level>=1) && (basesize >=0));
char str[100];
sprintf(str, "em_buffer: allocate %d AMI_STREAM*, total %ld\n",
arity, (long)(arity*sizeof(AMI_STREAM<T>*)));
MEMORY_LOG(str);
//allocate STREAM* array
data = new AMI_STREAM<T>* [arity];
//allocate deleted array
sprintf(str, "em_buffer: allocate deleted array: %ld\n",
(long)(arity*sizeof(long)));
MEMORY_LOG(str);
deleted = new long[arity];
//allocate streamsize array
sprintf(str, "em_buffer: allocate streamsize array: %ld\n",
(long)(arity*sizeof(long)));
MEMORY_LOG(str);
streamsize = new unsigned long[arity];
#ifdef SAVE_MEMORY
//allocate name array
sprintf(str, "em_buffer: allocate name array: %ld\n",
(long)(arity*sizeof(char*)));
MEMORY_LOG(str);
name = new char* [arity];
assert(name);
#endif
//assert data
if ((!data) || (!deleted) || (!streamsize)) {
cerr << "em_buffer: cannot allocate\n";
exit(1);
}
//initialize the <arity> streams to NULL, deleted[], streamsize[]
//and name[]
for (unsigned int i=0; i< arity; i++) {
data[i] = NULL;
deleted[i] = 0;
streamsize[i] = 0;
#ifdef SAVE_MEMORY
name[i] = NULL;
#endif
}
//set index
index = 0;
#ifdef SAVE_MEMORY
//streams_in_memory = false;
#endif
}
/************************************************************/
//copy constructor;
template<class T, class Key>
em_buffer<T,Key>::em_buffer(const em_buffer &buf):
level(buf.level), basesize(buf.basesize),
index(buf.index), arity(buf.arity) {
assert(0);//should not get called
MEMORY_LOG("em_buffer: copy constr start\n");
get_streams();
for (unsigned int i=0; i< index; i++) {
assert(data[i]);
delete data[i]; //delete old stream if existing
data[i] = NULL;
//call copy constructor; i'm not sure that it actually duplicates
//the stream and copies the data; should that in the BTE
//sometimes..
data[i] = new AMI_STREAM<T>(*buf.data[i]);
deleted[i] = buf.deleted[i];
streamsize[i] = buf.streamsize[i];
#ifdef SAVE_MEMORY
assert(name[i]);
delete name[i];
name[i] = NULL;
name[i] = buf.name[i];
#endif
}
put_streams();
MEMORY_LOG("em_buffer: copy constr end\n");
}
/************************************************************/
//free the stream array and the streams pointers
template<class T, class Key>
em_buffer<T,Key>::~em_buffer() {
assert(data);
//delete the m streams in the buffer
get_streams();
for (unsigned int i=0; i<index; i++) {
assert(data[i]);
#ifdef SAVE_MEMORY
check_name(i);
delete name[i];
#endif
delete data[i];
data[i] = NULL;
}
delete [] data;
delete [] deleted;
delete [] streamsize;
#ifdef SAVE_MEMORY
delete [] name;
#endif
}
#ifdef SAVE_MEMORY
/************************************************************/
//checks that name[i] is the same as stream name; stream i must be in
//memory (by a previous get_stream call, for instance) in order to
//find its length
template<class T, class Key>
void em_buffer<T,Key>::check_name(unsigned int i) {
#ifdef EMBUF_CHECK_NAME
assert(i>=0 && i < index);
assert(data[i]);
char* fooname;
data[i]->name(&fooname);//name() allocates the string
#ifdef EMBUF_CHECK_NAME_PRINT
cout << "::check_name: checking stream [" << level << "," << i << "] name:"
<< fooname << endl;
cout.flush();
#endif
if (strcmp(name[i], fooname) != 0) {
cerr << "name[" << i << "]=" << name[i]
<< ", streamname=" << fooname << endl;
}
assert(strcmp(fooname, name[i]) == 0);
delete fooname;
#endif
}
#endif
/************************************************************/
//if SAVE_MEMORY flag is set, load the stream in memory; return the
//ith stream
template<class T, class Key>
AMI_STREAM<T>* em_buffer<T,Key>::get_stream(unsigned int i) {
assert(i>=0 && i < index);
#ifdef SAVE_MEMORY
MY_LOG_DEBUG_ID("em_buffer::get_stream");
MY_LOG_DEBUG_ID(i);
if (data[i] == NULL) {
//stream is on disk, load it in memory
assert(name[i]);
MY_LOG_DEBUG_ID("load stream in memory");
MY_LOG_DEBUG_ID(name[i]);
#ifdef EMBUF_PRINT_GETPUT_STREAM
cout << "get_stream:: name[" << i << "]=" << name[i] << " from disk\n";
cout.flush();
#endif
//assert that file exists
FILE* fp;
if ((fp = fopen(name[i],"rb")) == NULL) {
cerr << "get_stream: checking that stream " << name[i] << "exists\n";
perror(name[i]);
assert(0);
exit(1);
}
fclose(fp);
//create an AMI_STREAM from file
data[i] = new AMI_STREAM<T>(name[i]);
assert(data[i]);
} else {
//if data[i] not NULL, stream must be already in memory
MY_LOG_DEBUG_ID("stream not NULL");
MY_LOG_DEBUG_ID(data[i]->sprint());
}
#endif
//NOW STREAM IS IN MEMORY
//some assertion checks
assert(data[i]);
assert(data[i]->stream_len() == streamsize[i]);
#ifdef SAVE_MEMORY
check_name(i);
#endif
return data[i];
}
/************************************************************/
//if SAVE_MEMORY flag is set, put the i'th stream back on disk
template<class T, class Key>
void em_buffer<T,Key>::put_stream(unsigned int i) {
assert(i>=0 && i < index);
#ifdef SAVE_MEMORY
MY_LOG_DEBUG_ID("em_buffer::put_stream");
MY_LOG_DEBUG_ID(i);
if (data[i] != NULL) {
//stream is in memory, put it on disk
MY_LOG_DEBUG_ID("stream put to disk");
MY_LOG_DEBUG_ID(data[i]->sprint());
check_name(i);
#ifdef EMBUF_PRINT_GETPUT_STREAM
cout << "put_stream:: name[" << i << "]=" << name[i] << " to disk\n";
cout.flush();
#endif
//make stream persistent and delete it
data[i]->persist(PERSIST_PERSISTENT);
delete data[i];
data[i] = NULL;
} else {
//data[i] is NULL, so stream must be already put on disk
MY_LOG_DEBUG_ID("stream is NULL");
}
#endif
}
/************************************************************/
//return a pointer to the streams of the buffer
template<class T, class Key>
AMI_STREAM<T>** em_buffer<T,Key>::get_streams() {
#ifdef SAVE_MEMORY
MY_LOG_DEBUG_ID("em_buffer::get_streams: reading streams from disk");
#ifdef EMBUF_PRINT_GETPUT_STREAMS
cout << "em_buffer::get_streams (buffer " << level <<")";
cout << ": index = " << index << "(arity=" << arity << ")\n";
cout.flush();
#endif
for (unsigned int i=0; i<index; i++) {
get_stream(i);
assert(data[i]);
}
#endif
return data;
}
/************************************************************/
//called in pair with load_streams to store streams on disk
//and release the memory
template<class T, class Key>
void em_buffer<T,Key>::put_streams() {
#ifdef SAVE_MEMORY
MY_LOG_DEBUG_ID("em_buffer::put_streams: writing streams on disk");
#ifdef EMBUF_PRINT_GETPUT_STREAMS
cout << "em_buffer::put_streams (buffer " << level <<")";
cout << ": index = " << index << "(arity=" << arity << ")\n";
cout.flush();
#endif
for (unsigned int i=0; i<index; i++) {
put_stream(i);
assert(data[i] == NULL);
}
#endif
}
#ifdef SAVE_MEMORY
/************************************************************/
//return the name of the ith stream
template<class T, class Key>
char* em_buffer<T,Key>::get_stream_name(unsigned int i) const {
assert(i>=0 && i<index);
assert(name[i]);
return name[i];
}
#endif
#ifdef SAVE_MEMORY
/************************************************************/
template<class T, class Key>
void em_buffer<T,Key>::print_stream_names() {
unsigned int i;
for (i=0; i<index; i++) {
assert(name[i]);
cout << "stream " << i << ": " << name[i] << endl;
}
cout.flush();
}
#endif
/************************************************************/
//clean buffer in case some streams have been emptied by deletion
template<class T, class Key>
void em_buffer<T,Key>::cleanup() {
MY_LOG_DEBUG_ID("em_buffer::cleanup()");
#ifdef EMBUF_CLEANUP_PRINT
#ifdef SAVE_MEMORY
if (index>0) {
cout << "before cleanup:\n";
print_stream_names();
print_stream_sizes();
cout.flush();
}
#endif
#endif
//load all streams in memory
get_streams();
//count streams of size=0
unsigned int i, empty=0;
for (i=0; i<index; i++) {
if (get_stream_len(i) == 0) {
//printing..
#ifdef EMBUF_DELETE_STREAM_PRINT
cout<<"deleting stream [" << level << "," << i <<"]:" ;
#ifdef SAVE_MEMORY
cout << name[i];
#endif
cout << endl;
cout.flush();
#endif
#ifdef SAVE_MEMORY
//stream is empty ==> delete its name
assert(name[i]);
delete name[i];
name[i] = NULL;
#endif
//stream is empty ==> reset data
assert(data[i]);
//data[i]->persist(PERSIST_DELETE); //this is done automatically..
delete data[i];
data[i] = NULL;
deleted[i] = 0;
streamsize[i] = 0;
empty++;
}
}
//streams are in memory; all streams which are NULL must have been
//deleted
//shift streams to the left in case holes were introduced
unsigned int j=0;
if (empty) {
#ifdef EMBUF_DELETE_STREAM_PRINT
cout << "em_buffer::cleanup: shifting streams\n"; cout.flush();
#endif
for (i=0; i<index; i++) {
//if i'th stream is not empty, shift it left if necessary
if (data[i]) {
if (i!=j) {
//set j'th stream to point to i'th stream
//cout << j << " set to " << i << endl; cout.flush();
data[j] = data[i];
deleted[j] = deleted[i];
streamsize[j] = streamsize[i];
//set i'th stream to point to NULL
data[i] = NULL;
deleted[i] = 0;
streamsize[i] = 0;
#ifdef SAVE_MEMORY
//fix the names
/* already done assert(name[j]); */
/* delete name[j]; */
name[j] = name[i];
name[i] = NULL;
check_name(j);
#endif
} else {
//cout << i << " left the same" << endl;
}
j++;
} //if data[i] != NULL
}//for i
//set the index
assert(index == j + empty);
index = j;
#ifdef EMBUF_DELETE_STREAM_PRINT
cout << "em_buffer::cleanup: index set to " << index << endl;
cout.flush();
#endif
} //if empty
//put streams back to disk
put_streams();
#ifdef EMBUF_CLEANUP_PRINT
#ifdef SAVE_MEMORY
if (index >0) {
cout << "after cleanup:\n";
print_stream_names();
print_stream_sizes();
cout.flush();
}
#endif
#endif
}
/************************************************************/
//delete all streams
template<class T, class Key>
void em_buffer<T,Key>::reset() {
get_streams();
//make streams not-persistent and delete them
for (unsigned int i=0; i<index; i++) {
assert(data[i]);
assert(streamsize[i] == data[i]->stream_len());
#ifdef SAVE_MEMORY
check_name(i);
assert(name[i]);
delete name[i];
name[i] = NULL;
#endif
data[i]->persist(PERSIST_DELETE);
delete data[i];
data[i] = NULL;
deleted[i] = 0;
streamsize[i] = 0;
}
index = 0;
}
/************************************************************/
//create and return a stream which contains all elements of
//all streams of the buffer in sorted ascending order of
//their keys (priorities);
template<class T, class Key>
AMI_STREAM<T>*
em_buffer<T,Key>::sort() {
//create stream
MEMORY_LOG("em_buffer::sort: allocate new AMI_STREAM\n");
AMI_STREAM<T>* sorted_stream = new AMI_STREAM<T>(); /* will be deleteed in insert() */
assert(sorted_stream);
//merge the streams into sorted stream
AMI_err aerr;
//Key dummykey;
//must modify this to seek after deleted[i] elements!!!!!!!!!!!!!
// aerr = MIAMI_single_merge_Key(data, arity, sorted_stream,
// 0, dummykey);
//could not use AMI_merge so i had to write my own..
get_streams();
aerr = substream_merge(data, arity, sorted_stream);
assert(aerr == AMI_ERROR_NO_ERROR);
put_streams();
return sorted_stream;
}
/************************************************************/
/* merge the input streams; there are <arity> streams in total; write
output in <outstream>;
the input streams are assumed sorted in increasing order of their
keys;
assumes the instreams are in memory (no need for get_streams()) */
template<class T, class Key>
AMI_err em_buffer<T,Key>::substream_merge(AMI_STREAM<T>** instreams,
unsigned int arity,
AMI_STREAM<T> *outstream) {
unsigned int i, j;
//some assertion checks
assert(instreams);
assert(outstream);
for (i = 0; i < arity ; i++ ) {
assert(instreams[i]);
#ifdef SAVE_MEMORY
check_name(i);
#endif
}
std::vector<T*> in_objects(arity); //pointers to current leading elements of streams
AMI_err ami_err;
char str[200];
sprintf(str, "em_buffer::substream_merge: allocate keys array, total %ldB\n",
(long)((long)arity * sizeof(merge_key<Key>)));
MEMORY_LOG(str);
//keys array is initialized with smallest key from each stream (only
//non-null keys must be included)
merge_key<Key>* keys;
//merge_key<Key>* keys = new (merge_key<Key>)[arity];
typedef merge_key<Key> footype;
keys = new footype[arity];
assert(keys);
//count number of non-empty streams
j = 0;
//rewind and read the first item from every stream initializing
//in_objects and keys
for (i = 0; i < arity ; i++ ) {
assert(instreams[i]);
//rewind stream
if ((ami_err = instreams[i]->seek(deleted[i])) != AMI_ERROR_NO_ERROR) {
return ami_err;
}
//read first item from stream
if ((ami_err = instreams[i]->read_item(&(in_objects[i]))) !=
AMI_ERROR_NO_ERROR) {
if (ami_err == AMI_ERROR_END_OF_STREAM) {
in_objects[i] = NULL;
} else {
return ami_err;
}
} else {
//include this key in the array of keys
Key k = in_objects[i]->getPriority();
keys[j].set(k, i);
j++;
}
}
unsigned int NonEmptyRuns = j;
//build heap from the array of keys
pqheap_t1<merge_key<Key> > mergeheap(keys, NonEmptyRuns);
//repeatedly extract_min from heap, write it to output stream and
//insert next element from same stream
merge_key<Key> minelt;
//rewind output buffer
ami_err = outstream->seek(0);
assert(ami_err == AMI_ERROR_NO_ERROR);
while (!mergeheap.empty()) {
//find min key and id of the stream from whereit comes
mergeheap.min(minelt);
i = minelt.stream_id();
//write min item to output stream
if ((ami_err = outstream->write_item(*in_objects[i]))
!= AMI_ERROR_NO_ERROR) {
return ami_err;
}
//read next item from same input stream
if ((ami_err = instreams[i]->read_item(&(in_objects[i])))
!= AMI_ERROR_NO_ERROR) {
if (ami_err != AMI_ERROR_END_OF_STREAM) {
return ami_err;
}
}
//extract the min from the heap and insert next key from same stream
if (ami_err == AMI_ERROR_END_OF_STREAM) {
mergeheap.delete_min();
} else {
Key k = in_objects[i]->getPriority();
merge_key<Key> nextit(k, i);
mergeheap.delete_min_and_insert(nextit);
}
} //while
//delete [] keys;
//!!! KEYS BELONGS NOW TO MERGEHEAP, AND WILL BE DELETED BY THE
//DESTRUCTOR OF MERGEHEAP (CALLED AUUTOMATICALLY ON FUNCTION EXIT) IF
//I DELETE KEYS EXPLICITELY, THEY WILL BE DELETED AGAIN BY DESTRUCTOR,
//AND EVERYTHING SCREWS UP..
return AMI_ERROR_NO_ERROR;
}
/************************************************************/
// insert an array into the buffer; assume array is sorted; return the
// number of items actually inserted; if SAVE_MEMORY FLAG is on, put
// stream on disk and release its memory
template<class T, class Key>
long em_buffer<T,Key>::insert(T* a, long n) {
assert(a);
if (is_full()) {
cout << "em_buffer::insert: buffer full\n";
return 0;
}
//can only insert one full stream at a time
//relaxed..
//assert(n == get_stream_maxlen());
//create the stream
MEMORY_LOG("em_buffer::insert(from array): allocate AMI_STREAM\n");
AMI_STREAM<T>* str = new AMI_STREAM<T>();
assert(str);
//write the array to stream
AMI_err ae;
for (long i=0; i< n; i++) {
ae = str->write_item(a[i]);
assert(ae == AMI_ERROR_NO_ERROR);
}
assert(n == str->stream_len());
//insert the stream in the buffer
return insert(str);
}
/************************************************************/
/* insert a stream into the buffer; the next free entry in the buffer
is set to point to the stream; if SAVE_MEMORY flag is on, the
stream is put to disk;
the <nextstream> pointer of buffer is set to point to the argument
stream; (in this way no stream copying is done, just one pointer
copy). The user should be aware the the argument stream is 'lost' -
that is a stream cannot be inserted repeatedly into many buffers
because this would lead to several buffers pointing to the same
stream.
stream is assume stream is sorted; bos = how many elements must be
skipped (were deleted) from the begining fo stream;
return the number of items actually inserted */
template<class T, class Key>
long em_buffer<T,Key>::insert(AMI_STREAM<T>* str, long bos) {
assert(str);
if (is_full()) {
cout << "em_buffer::insert: buffer full\n";
return 0;
}
//can only insert one level-i-full-stream at a time;
//relaxed..can specify bos;
//not only that, but the length of the stream can be smaller
//than nominal length, because a stream is normally obtained by
//merging streams which can be shorter;
//assert(str->stream_len() == get_stream_len() - bos);
#ifdef EMBUF_CHECK_INSERT
//check that stream is sorted
cout << "CHECK_INSERT: checking stream is sorted\n";
AMI_err ae;
str->seek(0);
T *crt=NULL, *prev=NULL;
while (str->read_item(&crt)) {
assert(ae == AMI_ERROR_NO_ERROR);
if (prev) assert(*prev <= *crt);
}
#endif
//nextstream must be empty
assert(str);
assert(data[nextstream()] == NULL);
assert(deleted[nextstream()] == 0);
assert(streamsize[nextstream()] == 0);
#ifdef SAVE_MEMORY
assert(name[nextstream()] == NULL);
#endif
//set next entry i the buffer to point to this stream
data[nextstream()] = str;
deleted[nextstream()] = bos;
streamsize[nextstream()] = str->stream_len();
#ifdef SAVE_MEMORY
//set next name entry in buffer to point to this stream's name
char* s;
str->name(&s); //name() allocates the string
name[nextstream()] = s;
//put stream on disk and release its memory
str->persist(PERSIST_PERSISTENT);
delete str; //stream should be persistent; just delete it
data[nextstream()] = NULL;
#ifdef EMBUF_PRINT_INSERT
cout << "insert stream " << s << " at buf [" << level
<< "," << nextstream() << "]" << endl;
#endif
#endif
//increment the index of next available stream in buffer
incr_nextstream();
#ifdef EMBUF_PRINT_INSERT
print_stream_sizes();
print_stream_names();
#endif
#ifdef SAVE_MEMORY
MY_LOG_DEBUG_ID("em_buffer::insert(): inserted stream ");
MY_LOG_DEBUG_ID(name[nextstream()-1]);
#endif
//return nb of items inserted
return get_stream_len(nextstream()-1);
}
/************************************************************/
//print the elements of the i'th stream of the buffer to a stream;
//assumes stream is in memory;
template<class T, class Key>
void em_buffer<T,Key>::print_stream(ostream& s, unsigned int i) {
assert(data[i]);
assert((i>=0) && (i<index));
AMI_err ae;
T* x;
s << "STREAM " << i << ": [";
ae = data[i]->seek(deleted[i]);
assert(ae == AMI_ERROR_NO_ERROR);
for (long j = 0; j < get_stream_len(i); j++) {
ae = data[i]->read_item(&x);
assert(ae == AMI_ERROR_NO_ERROR);
s << *x << ",";
}
s << "]\n";
}
/************************************************************/
//print elements range in buffer (read first and last element in each
//substream and find global min and max)
template<class T, class Key>
void em_buffer<T,Key>::print_range() {
T *min, *max;
AMI_err ae;
get_streams();
for (unsigned int i=0; i< index; i++) {
cout << "[";
//read min element in substream i
ae = data[i]->seek(deleted[i]);
assert(ae == AMI_ERROR_NO_ERROR);
ae = data[i]->read_item(&min);
assert(ae == AMI_ERROR_NO_ERROR);
cout << min->getPriority() << "..";
//read max element in substream i
ae = data[i]->seek(streamsize[i] - 1);
assert(ae == AMI_ERROR_NO_ERROR);
ae = data[i]->read_item(&max);
assert(ae == AMI_ERROR_NO_ERROR);
cout << max->getPriority()
<< " (sz=" << get_stream_len(i) << ")] ";
}
for (unsigned int i=index; i< arity; i++) {
cout << "[] ";
}
put_streams();
}
/************************************************************/
//print all elements in buffer
template<class T, class Key>
void em_buffer<T,Key>::print() {
T *x;
AMI_err ae;
get_streams();
for (unsigned int i=0; i<index; i++) {
cout << " [";
ae = data[i]->seek(deleted[i]);
assert(ae == AMI_ERROR_NO_ERROR);
for (unsigned long j=0; j<get_stream_len(i); j++) {
ae = data[i]->read_item(&x);
assert(ae == AMI_ERROR_NO_ERROR);
cout << x->getPriority() << ",";
}
cout << "]" << endl;
}
for (unsigned int i=index; i< arity; i++) {
cout << "[] ";
}
put_streams();
}
/************************************************************/
//print the sizes of the substreams in the buffer
template<class T, class Key>
void em_buffer<T,Key>::print_stream_sizes() {
cout << "(streams=" << index << ") sizes=[";
for (unsigned int i=0; i< arity; i++) {
cout << get_stream_len(i) << ",";
}
cout << "]" << endl;
cout.flush();
}
#endif
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