llama.cpp/examples/save-load-state/save-load-state.cpp

#include "arg.h"
#include "common.h"
#include "llama.h"

#include <vector>
#include <cstdio>


int main(int argc, char ** argv) {
    common_params params;

    params.prompt = "The quick brown fox";
    params.sampling.seed = 1234;

    const std::string_view state_file = "dump_state.bin";

    if (!common_params_parse(argc, argv, params, LLAMA_EXAMPLE_COMMON)) {
        return 1;
    }

    if (params.n_parallel == 1) {
        // the example uses 2 sequences, so when n_parallel == 1, we need to enable unified kv cache
        printf("%s: n_parallel == 1, enabling unified kv cache\n", __func__);
        params.kv_unified = true;
    }

    common_init();

    if (params.n_predict < 0) {
        params.n_predict = 16;
    }

    auto n_past = 0;

    std::string result0;
    std::string result1;
    std::string result2;

    // init
    auto llama_init = common_init_from_params(params);

    auto * model = llama_init->model();
    auto * ctx   = llama_init->context();

    if (model == nullptr || ctx == nullptr) {
        fprintf(stderr, "%s : failed to init\n", __func__);
        return 1;
    }

    auto sparams = llama_sampler_chain_default_params();

    llama_sampler * smpl = llama_sampler_chain_init(sparams);

    llama_sampler_chain_add(smpl, llama_sampler_init_dist(params.sampling.seed));

    // tokenize prompt
    auto tokens = common_tokenize(ctx, params.prompt, true);

    const bool save_state = true;
    if (!common_prompt_batch_decode(ctx, tokens, n_past, params.n_batch, state_file, save_state)) {
        return 1;
    }

    // first run
    printf("\nfirst run: %s", params.prompt.c_str());

    llama_batch batch = llama_batch_init(1, 0, 1);

    for (auto i = 0; i < params.n_predict; i++) {
        auto next_token     = llama_sampler_sample(smpl, ctx, -1);
        auto next_token_str = common_token_to_piece(ctx, next_token);

        printf("%s", next_token_str.c_str());
        result0 += next_token_str;

        common_batch_clear(batch);
        common_batch_add(batch, next_token, n_past, {0}, true);

        if (llama_decode(ctx, batch)) {
            fprintf(stderr, "\n%s : failed to evaluate\n", __func__);
            llama_batch_free(batch);
            return 1;
        }
        n_past += 1;
    }

    printf("\n\n");

    // make new context
    llama_context * ctx2 = llama_init_from_model(model, common_context_params_to_llama(params));

    llama_sampler * smpl2 = llama_sampler_chain_init(sparams);

    llama_sampler_chain_add(smpl2, llama_sampler_init_dist(params.sampling.seed));

    printf("\nsecond run: %s", params.prompt.c_str());

    // load state from file
    std::vector<llama_token> unused_sts(tokens.size()); // unused session tokens.
    size_t n_token_count_out = 0;

    if (!llama_state_load_file(ctx2, state_file.data(), unused_sts.data(), unused_sts.size(), &n_token_count_out)) {
        fprintf(stderr, "\n%s : failed to load state\n", __func__);
        return 1;
    }

    fprintf(stderr, "%s : loaded state with %zu tokens\n", __func__, n_token_count_out);

    // restore state (last tokens)
    n_past = n_token_count_out;
    if (!common_replay_last_token(ctx2, tokens.back(), n_past)) {
        return 1;
    }
    ++n_past;

    // second run
    for (auto i = 0; i < params.n_predict; i++) {
        auto next_token     = llama_sampler_sample(smpl2, ctx2, -1);
        auto next_token_str = common_token_to_piece(ctx2, next_token);

        printf("%s", next_token_str.c_str());
        result1 += next_token_str;

        common_batch_clear(batch);
        common_batch_add(batch, next_token, n_past, {0}, true);

        if (llama_decode(ctx2, batch)) {
            fprintf(stderr, "\n%s : failed to evaluate\n", __func__);
            llama_batch_free(batch);
            return 1;
        }
        n_past += 1;
    }

    printf("\n\n");

    if (result0 != result1) {
        fprintf(stderr, "\n%s : error : the 2 generations are different\n", __func__);
        return 1;
    }

    // make new context
    auto params_ctx3 = common_context_params_to_llama(params);
    params_ctx3.n_seq_max = 2;
    llama_context * ctx3 = llama_init_from_model(model, params_ctx3);

    llama_sampler * smpl3 = llama_sampler_chain_init(sparams);

    llama_sampler_chain_add(smpl3, llama_sampler_init_dist(params.sampling.seed));

    printf("\nsingle seq run: %s", params.prompt.c_str());

    // load state (rng, logits, embedding and kv_cache) from file
    n_token_count_out = 0;

    if (!llama_state_load_file(ctx3, state_file.data(), unused_sts.data(), unused_sts.size(), &n_token_count_out)) {
        fprintf(stderr, "\n%s : failed to load state\n", __func__);
        return 1;
    }

    fprintf(stderr, "%s : loaded state with %zu tokens\n", __func__, n_token_count_out);

    // restore state (last tokens)
    n_past = n_token_count_out;
    if (!common_replay_last_token(ctx3, tokens.back(), n_past)) {
        return 1;
    }
    ++n_past;

    // save seq 0 and load into seq 1
    {
        // save kv of seq 0
        std::vector<uint8_t> seq_store(llama_state_seq_get_size(ctx3, 0));
        const size_t ncopy = llama_state_seq_get_data(ctx3, seq_store.data(), seq_store.size(), 0);
        if (ncopy != seq_store.size()) {
            fprintf(stderr, "\n%s : seq copy data length %zd does not match expected length %zd\n", __func__, ncopy, seq_store.size());
            return 1;
        }
        fprintf(stderr, "%s : seq 0 copied, %zd bytes\n", __func__, ncopy);

        // erase whole kv
        llama_memory_clear(llama_get_memory(ctx3), true);
        fprintf(stderr, "%s : kv cache cleared\n", __func__);

        // restore kv into seq 1
        const size_t nset = llama_state_seq_set_data(ctx3, seq_store.data(), seq_store.size(), 1);
        if (nset != seq_store.size()) {
            fprintf(stderr, "\n%s : seq set data length %zd does not match expected length %zd\n", __func__, nset, seq_store.size());
            return 1;
        }
        fprintf(stderr, "%s : seq 1 restored, %zd bytes\n", __func__, nset);
    }

    // third run with seq 1 instead of 0
    for (auto i = 0; i < params.n_predict; i++) {
        auto next_token     = llama_sampler_sample(smpl3, ctx3, -1);
        auto next_token_str = common_token_to_piece(ctx3, next_token);

        printf("%s", next_token_str.c_str());
        result2 += next_token_str;

        common_batch_clear(batch);
        common_batch_add(batch, next_token, n_past, {1}, true);

        if (llama_decode(ctx3, batch)) {
            fprintf(stderr, "\n%s : failed to evaluate\n", __func__);
            llama_batch_free(batch);
            return 1;
        }
        n_past += 1;
    }

    printf("\n");

    llama_sampler_free(smpl);
    llama_sampler_free(smpl2);
    llama_sampler_free(smpl3);

    llama_batch_free(batch);

    // this one is managed by common_init_result
    //llama_free(ctx);

    llama_free(ctx2);
    llama_free(ctx3);

    if (result0 != result2) {
        fprintf(stderr, "\n%s : error : the seq restore generation is different\n", __func__);
        return 1;
    }

    fprintf(stderr, "\n%s : success\n", __func__);

    return 0;
}