Serializing and Deserializing Modules
You can also browse this source code online and clone the wasmtime repository to run the example locally.
This example shows how to serialize a compiled module to disk and later deserialize it to skip compilation on the critical path.
serialize.cc
/*
Small example of how to serialize compiled wasm module to the disk,
and then instantiate it from the compilation artifacts.
You can build the example using CMake:
mkdir build && (cd build && cmake .. && \
cmake --build . --target wasmtime-serialize-cpp)
And then run it:
build/wasmtime-serialize-cpp
*/
#include <fstream>
#include <iostream>
#include <sstream>
#include <vector>
#include <wasmtime.hh>
using namespace wasmtime;
std::string readFile(const char *name) {
std::ifstream watFile;
watFile.open(name);
std::stringstream strStream;
strStream << watFile.rdbuf();
return strStream.str();
}
std::vector<uint8_t> serialize() {
std::cout << "Initializing...\n";
Engine engine;
std::cout << "Compiling module...\n";
auto wat = readFile("examples/hello.wat");
Module module = Module::compile(engine, wat).unwrap();
auto serialized = module.serialize().unwrap();
std::cout << "Serialized.\n";
return serialized;
}
void deserialize(std::vector<uint8_t> buffer) {
std::cout << "Initializing...\n";
Engine engine;
Store store(engine);
std::cout << "Deserialize module...\n";
Module module =
Module::deserialize(engine, Span<uint8_t>(buffer.data(), buffer.size()))
.unwrap();
std::cout << "Creating callback...\n";
Func hello_func = Func::wrap(store, []() {
std::cout << "Calling back...\n";
std::cout << "> Hello World!\n";
});
std::cout << "Instantiating module...\n";
Instance instance = Instance::create(store, module, {hello_func}).unwrap();
std::cout << "Extracting export...\n";
Func run = std::get<Func>(*instance.get(store, "run"));
std::cout << "Calling export...\n";
run.call(store, {}).unwrap();
std::cout << "Done.\n";
}
int main() {
auto buffer = serialize();
deserialize(buffer);
return 0;
}