gStore/VSTree/EntryBuffer.cpp

/*
 * EntryBuffer.cpp
 *
 *  Created on: 2014-7-3
 *      Author: hanshuo
 */

#include"EntryBuffer.h"

using namespace std;

int EntryBuffer::DEFAULT_CAPACITY = 2*1000*1000;


EntryBuffer::EntryBuffer(int _capacity)
{
    this->capacity = _capacity;
    this->num = 0;
    this->elems = new SigEntry[this->capacity];
}

EntryBuffer::~EntryBuffer()
{
    delete [] this->elems;
}

int EntryBuffer::getCapacity()const
{
    return this->capacity;
}

int EntryBuffer::getNum()const
{
    return this->num;
}

bool EntryBuffer::isEmpty()const
{
    return (this->num == 0);
}

bool EntryBuffer::isFull()const
{
    return (this->num == this->capacity);
}

SigEntry* EntryBuffer::getElem(int _i)
{
    return &this->elems[_i];
}

bool EntryBuffer::insert(const SigEntry& _entry)
{
    if (this->isFull())
    {
        cerr << "error, entry buffer is full, can not insert now in EntryBuffer::insert." << endl;
        return false;
    }

    this->elems[this->num ++] = _entry;

    return true;
}

/* clear the entry buffer and fill it from the entry file until the buffer is full or the file ends. */
int EntryBuffer::fillElemsFromFile(FILE* _p_file)
{
    this->clear();
    SigEntry entry;


    // bug here! if we read an entry, we must put it into buffer. Otherwise this entry will be missed.
//    fread((char *)&entry, sizeof(SigEntry), 1, _p_file);
//    while (!this->isFull() &&  !feof(_p_file))
//    {
//        this->insert(entry);
//        fread((char *)&entry, sizeof(SigEntry), 1, _p_file);
//    }

    while (!this->isFull())
    {
        bool is_reach_EOF = feof(_p_file);
        bool is_entry_read = (fread((char *)&entry, sizeof(SigEntry), 1, _p_file) == 1);
        if (is_reach_EOF || !is_entry_read)
        {
            break;
        }
        this->insert(entry);
    }

    return this->num;
}

void EntryBuffer::clear()
{
    this->num = 0;
}