VwNativeCacheReader.cpp

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/*
 * Copyright (c) 2009 Yahoo! Inc.  All rights reserved.  The copyrights
 * embodied in the content of this file are licensed under the BSD
 * (revised) open source license.
 *
 * 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 3 of the License, or
 * (at your option) any later version.
 *
 * Written (W) 2011 Shashwat Lal Das
 * Adaptation of Vowpal Wabbit v5.1.
 * Copyright (C) 2011 Berlin Institute of Technology and Max-Planck-Society.
 */

#include <shogun/classifier/vw/cache/VwNativeCacheReader.h>

using namespace shogun;

CVwNativeCacheReader::CVwNativeCacheReader()
    : CVwCacheReader(), char_size(2)
{
    init();
}

CVwNativeCacheReader::CVwNativeCacheReader(char * fname, CVwEnvironment* env_to_use)
    : CVwCacheReader(fname, env_to_use), char_size(2)
{
    init();
    buf.use_file(fd);
    check_cache_metadata();
}

CVwNativeCacheReader::CVwNativeCacheReader(int32_t f, CVwEnvironment* env_to_use)
    : CVwCacheReader(f, env_to_use), char_size(2)
{
    init();
    buf.use_file(fd);
    check_cache_metadata();
}

CVwNativeCacheReader::~CVwNativeCacheReader()
{
    buf.close_file();
}

void CVwNativeCacheReader::set_file(int32_t f)
{
    if (fd > 0)
        buf.close_file();

    fd = f;
    buf.use_file(fd);
    check_cache_metadata();
}

void CVwNativeCacheReader::init()
{
    neg_1 = 1;
    general = 2;
}

void CVwNativeCacheReader::check_cache_metadata()
{
    const char* vw_version=env->vw_version;
    vw_size_t numbits = env->num_bits;

    vw_size_t v_length;
    buf.read_file((char*)&v_length, sizeof(v_length));
    if(v_length > 29)
        SG_SERROR("Cache version too long, cache file is probably invalid.\n")

    char* t=SG_MALLOC(char, v_length);
    buf.read_file(t,v_length);
    if (strcmp(t,vw_version) != 0)
    {
        SG_FREE(t);
        SG_SERROR("Cache has possibly incompatible version!\n")
    }
    SG_FREE(t);

    vw_size_t cache_numbits = 0;
    if (buf.read_file(&cache_numbits, sizeof(vw_size_t)) < ssize_t(sizeof(vw_size_t)))
        return;

    if (cache_numbits != numbits)
        SG_SERROR("Bug encountered in caching! Bits used for weight in cache: %d.\n", cache_numbits)
}

char* CVwNativeCacheReader::run_len_decode(char *p, vw_size_t& i)
{
    // Read an int32_t 7 bits at a time.
    vw_size_t count = 0;
    while(*p & 128)\
        i = i | ((*(p++) & 127) << 7*count++);
    i = i | (*(p++) << 7*count);
    return p;
}

char* CVwNativeCacheReader::bufread_label(VwLabel* const ld, char* c)
{
    ld->label = *(float32_t*)c;
    c += sizeof(ld->label);
    set_minmax(ld->label);

    ld->weight = *(float32_t*)c;
    c += sizeof(ld->weight);
    ld->initial = *(float32_t*)c;
    c += sizeof(ld->initial);

    return c;
}

vw_size_t CVwNativeCacheReader::read_cached_label(VwLabel* const ld)
{
    char *c;
    vw_size_t total = sizeof(ld->label)+sizeof(ld->weight)+sizeof(ld->initial);
    if (buf.buf_read(c, total) < total)
        return 0;
    c = bufread_label(ld,c);

    return total;
}

vw_size_t CVwNativeCacheReader::read_cached_tag(VwExample* const ae)
{
    char* c;
    vw_size_t tag_size;
    if (buf.buf_read(c, sizeof(tag_size)) < sizeof(tag_size))
        return 0;
    tag_size = *(vw_size_t*)c;
    c += sizeof(tag_size);

    buf.set(c);
    if (buf.buf_read(c, tag_size) < tag_size)
        return 0;

    ae->tag.erase();
    ae->tag.push_many(c, tag_size);
    return tag_size+sizeof(tag_size);
}

bool CVwNativeCacheReader::read_cached_example(VwExample* const ae)
{
    vw_size_t mask =  env->mask;
    vw_size_t total = read_cached_label(ae->ld);
    if (total == 0)
        return false;
    if (read_cached_tag(ae) == 0)
        return false;

    char* c;
    unsigned char num_indices = 0;
    if (buf.buf_read(c, sizeof(num_indices)) < sizeof(num_indices))
        return false;
    num_indices = *(unsigned char*)c;
    c += sizeof(num_indices);

    buf.set(c);

    for (; num_indices > 0; num_indices--)
    {
        vw_size_t temp;
        unsigned char index = 0;
        temp = buf.buf_read(c, sizeof(index) + sizeof(vw_size_t));

        if (temp < sizeof(index) + sizeof(vw_size_t))
            SG_SERROR("Truncated example! %d < %d bytes expected.\n",
                  temp, char_size + sizeof(vw_size_t));

        index = *(unsigned char*) c;
        c += sizeof(index);
        ae->indices.push((vw_size_t) index);

        v_array<VwFeature>* ours = ae->atomics+index;
        float64_t* our_sum_feat_sq = ae->sum_feat_sq+index;
        vw_size_t storage = *(vw_size_t *)c;
        c += sizeof(vw_size_t);

        buf.set(c);
        total += storage;
        if (buf.buf_read(c, storage) < storage)
            SG_SERROR("Truncated example! Wanted %d bytes!\n", storage)

        char *end = c + storage;

        vw_size_t last = 0;

        for (; c!=end; )
        {
            VwFeature f = {1., 0};
            temp = f.weight_index;
            c = run_len_decode(c, temp);
            f.weight_index = temp;

            if (f.weight_index & neg_1)
                f.x = -1.;
            else if (f.weight_index & general)
            {
                f.x = ((one_float*)c)->f;
                c += sizeof(float32_t);
            }

            *our_sum_feat_sq += f.x*f.x;

            vw_size_t diff = f.weight_index >> 2;
            int32_t s_diff = ZigZagDecode(diff);
            if (s_diff < 0)
                ae->sorted = false;

            f.weight_index = last + s_diff;
            last = f.weight_index;
            f.weight_index = f.weight_index & mask;

            ours->push(f);
        }
        buf.set(c);
    }

    return true;
}