Bug(not a bug maybe): When using static lib, vsag::init() is not always called.

[Coien-rr]

Describe the bug
A clear and concise description of what the bug is.
When using static lib, if I'm not explicitly calling vsag::init(), vsag may be uninitialized.
I ran into a situation where the distance calculation function was invalid and caused the program to crash

if i explicitly calling vsag::init(), vsag can work well, but init log print twice (It's annoying and meaningless

But when using shared lib, everything goes fine.

To Reproduce
Codes to reproduce the behavior:
Just Use simple_hnsw.cpp in examples/, But comments the explicitly calling vsag::init() statement

// paste codes here

// Copyright 2024-present the vsag project
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//     http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

#include <vsag/vsag.h>

#include <iostream>

int
main(int argc, char** argv) {
    // vsag::init();

    int64_t num_vectors = 10000;
    int64_t dim = 128;

    // prepare ids and vectors
    auto ids = new int64_t[num_vectors];
    auto vectors = new float[dim * num_vectors];

    std::mt19937 rng;
    rng.seed(47);
    std::uniform_real_distribution<> distrib_real;
    for (int64_t i = 0; i < num_vectors; ++i) {
        ids[i] = i;
    }
    for (int64_t i = 0; i < dim * num_vectors; ++i) {
        vectors[i] = distrib_real(rng);
    }

    // create index
    auto hnsw_build_paramesters = R"(
    {
        "dtype": "float32",
        "metric_type": "l2",
        "dim": 128,
        "hnsw": {
            "max_degree": 16,
            "ef_construction": 100
        }
    }
    )";
    auto index = vsag::Factory::CreateIndex("hnsw", hnsw_build_paramesters).value();
    auto base = vsag::Dataset::Make();
    base->NumElements(num_vectors)->Dim(dim)->Ids(ids)->Float32Vectors(vectors)->Owner(false);
    index->Build(base);

    // prepare a query vector
    auto query_vector = new float[dim];  // memory will be released by query the dataset
    for (int64_t i = 0; i < dim; ++i) {
        query_vector[i] = distrib_real(rng);
    }

    // search on the index
    auto hnsw_search_parameters = R"(
    {
        "hnsw": {
            "ef_search": 100
        }
    }
    )";
    int64_t topk = 10;
    auto query = vsag::Dataset::Make();
    query->NumElements(1)->Dim(dim)->Float32Vectors(query_vector)->Owner(true);
    auto result = index->KnnSearch(query, topk, hnsw_search_parameters).value();

    // print the results
    std::cout << "results: " << std::endl;
    for (int64_t i = 0; i < result->GetDim(); ++i) {
        std::cout << result->GetIds()[i] << ": " << result->GetDistances()[i] << std::endl;
    }

    // free memory
    delete[] ids;
    delete[] vectors;

    return 0;
}

build config

add_executable (simple_hnsw simple_hnsw.cpp)
target_link_libraries (simple_hnsw vsag_static)

Environment

• OS(Arch Linux):
• vsag version(9195f6955e808b45314bd37db8cbf15b07736ed4):
• compiler version(GCC 14.2.0):
• interface(cpp):
• build mode(debug)

Expected behavior
A clear and concise description of what you expected to happen.
i hope using static vsag lib without explicitly calling vsag::init().
or remove repeat log

Screenshots
If applicable, add screenshots to help explain your problem.

Additional context
Add any other context about the problem here.

[wxyucs]

@Coien-rr thanks for your report. I think it's a bug.

VSAG required initialization to switch to a suitable SIMD backend to accelerate distance calculation. It's calling from a static variable now for ease of use:
(https://github.com/alipay/vsag/blob/6f3af4f8b892807e6baee2dc4de5c067213f0e0a/src/vsag.cpp#L61)

However, it seems that the initialization is not always working. And initial this library with magic statics may not be a good choice. I consider that to add an init() and tini() function and make it required that the user call it explicitly in main functions.

@jiaweizone @LHT129 What's your suggestion?

[Coien-rr]

@wxyucs Thanks for your explanation!
i fixed reinit VSAG error which introduced in using static lib, and propose a pr #112
Is it necessary to check if VSAG is initialized? since the program crashes without any indication
Like this(the code example is same as which in To Reproduce):

 ./build/examples/cpp/simple_hnsw
zsh: segmentation fault (core dumped)  ./build/examples/cpp/simple_hnsw