llama.cpp/examples/beam-search/beam-search.cpp

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#ifndef _GNU_SOURCE
#define _GNU_SOURCE
#endif
#include "common.h"
#include "llama.h"
#include "build-info.h"
#include <cassert>
#include <cinttypes>
#include <cmath>
#include <cstdio>
#include <cstring>
#include <ctime>
#include <fstream>
#include <iostream>
#include <string>
#include <vector>
#if defined (__unix__) || (defined (__APPLE__) && defined (__MACH__))
#include <signal.h>
#include <unistd.h>
#elif defined (_WIN32)
#define WIN32_LEAN_AND_MEAN
#ifndef NOMINMAX
# define NOMINMAX
#endif
#include <windows.h>
#include <signal.h>
#endif
// Used for debugging to print out beam tokens.
struct ostream_beam_view {
llama_context * ctx;
llama_beam_view beam_view;
};
std::ostream& operator<<(std::ostream& os, const ostream_beam_view & obv) {
os << "p(" << obv.beam_view.p << ") eob(" << std::boolalpha << obv.beam_view.eob << ") tokens(";
for (size_t i = 0 ; i < obv.beam_view.n_tokens ; ++i) {
os << llama_token_to_piece(obv.ctx, obv.beam_view.tokens[i]);
}
return os << ')';
}
// Put here anything you want back in beam_search_callback().
struct beam_search_callback_data {
llama_context * ctx;
std::vector<llama_token> response;
};
// In this case, end-of-beam (eob) is equivalent to end-of-sentence (eos) but this need not always be the same.
// For example, eob can be flagged due to maximum token length, stop words, etc.
bool is_at_eob(const beam_search_callback_data & callback_data, const llama_token * tokens, const size_t n_tokens) {
return n_tokens && tokens[n_tokens-1] == llama_token_eos(callback_data.ctx);
}
// Function matching type llama_beam_search_callback_fn_t.
// Custom callback example is called each time the beams lengths increase:
// * Show progress by printing ',' following by number of convergent beam tokens if any.
// * When all beams converge to a common prefix, they are made available in beams_state.beams[0].
// This is also called when the stop condition is met.
// Collect tokens into std::vector<llama_token> response which is pointed to by callback_data.
void beam_search_callback(void * callback_data_ptr, llama_beams_state beams_state) {
auto& callback_data = *static_cast<beam_search_callback_data*>(callback_data_ptr);
// Mark beams as EOS as needed.
for (size_t i = 0 ; i < beams_state.n_beams ; ++i) {
llama_beam_view& beam_view = beams_state.beam_views[i];
if (!beam_view.eob && is_at_eob(callback_data, beam_view.tokens, beam_view.n_tokens)) {
beam_view.eob = true;
}
}
printf(","); // Show progress
if (const size_t n = beams_state.common_prefix_length) {
callback_data.response.resize(callback_data.response.size() + n);
assert(0u < beams_state.n_beams);
const llama_token * tokens = beams_state.beam_views[0].tokens;
std::copy(tokens, tokens + n, callback_data.response.end() - n);
printf("%zu", n);
}
fflush(stdout);
#if 1 // DEBUG: print current beams for this iteration
std::cout << "\n\nCurrent beams (last_call=" << beams_state.last_call << "):\n";
for (size_t i = 0 ; i < beams_state.n_beams ; ++i) {
std::cout << "beams["<<i<<"]: " << ostream_beam_view{callback_data.ctx,beams_state.beam_views[i]} << std::endl;
}
#endif
}
int main(int argc, char ** argv)
{
gpt_params params;
//params.n_gpu_layers = 200;
//---------------------------------
// Print help :
//---------------------------------
if ( argc < 2 || argv[1][0] == '-' )
{
printf( "Usage: %s MODEL_PATH [BEAM_WIDTH=2] [PROMPT]\n" , argv[0] );
return 1 ;
}
//---------------------------------
// Load parameters :
//---------------------------------
params.model = argv[1];
params.n_beams = 2 < argc ? std::stoi(argv[2]) : 2;
if ( argc > 3 )
{
params.prompt = argv[3];
}
if ( params.prompt.empty() )
{
params.prompt = "### Request:\nHow many countries are there?\n\n### Response:\n";
}
//---------------------------------
// Init LLM :
//---------------------------------
llama_backend_init(params.numa);
llama_model * model;
llama_context * ctx;
std::tie(model, ctx) = llama_init_from_gpt_params( params );
if ( model == NULL )
{
fprintf( stderr , "%s: error: unable to load model\n" , __func__ );
return 1;
}
//---------------------------------
// Tokenize the prompt :
//---------------------------------
std::vector<llama_token> tokens_list = llama_tokenize(ctx, params.prompt, true);
const size_t max_context_size = llama_n_ctx( ctx );
const size_t max_tokens_list_size = max_context_size - 4 ;
if (tokens_list.size() > max_tokens_list_size)
{
fprintf( stderr , "%s: error: prompt too long (%zu tokens, max %zu)\n" ,
__func__ , tokens_list.size() , max_tokens_list_size );
return 1;
}
fprintf( stderr, "\n\n" );
// Print the tokens from the prompt :
for( auto id : tokens_list )
{
std::cout << llama_token_to_piece(ctx, id);
}
std::cout << std::flush;
int n_past = llama_get_kv_cache_token_count(ctx);
if (llama_eval(ctx, tokens_list.data(), tokens_list.size(), n_past, params.n_threads))
{
fprintf(stderr, "%s : failed to eval prompt.\n" , __func__ );
return 1;
}
n_past += tokens_list.size();
beam_search_callback_data callback_data{ctx, {}};
size_t const beam_width = static_cast<size_t>(params.n_beams);
int const n_predict = 256;
llama_beam_search(ctx, beam_search_callback, &callback_data, beam_width, n_past, n_predict, params.n_threads);
std::cout << "\n\n";
for (llama_token const token_id : callback_data.response) {
std::cout << llama_token_to_piece(ctx,token_id);
}
std::cout << std::endl;
llama_free( ctx );
llama_free_model( model );
llama_backend_free();
return 0;
}